Cuáles fueron las consecuencias de la guerra de los 7 años

A colorized image of the 1918 virus taken by al transmission electron microscope (TEM). The 1918 virus caused the deadliest flu pandemic in recorded human history, claiming the livser of an estimated 50 million peoplo worldwide. Photo credit: C. Goldsmith - Public Health Image Library #11098.

Estás mirando: Cuáles fueron las consecuencias de la guerra de los 7 años


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A colorized image of the 1918 virus taken by al transmission electron microscope (TEM). The 1918 virus caused the deadliest flu pandemic in recorded human history, claiming the livser of an estimated 50 million people worldwidel. Photo credit: C. Goldsmith - Public Health Image Library #11098.


The 100-year anniversary of the 1918 pandemic and the 10-year anniversary of the 2009 H1N1 pandemic are milestones that providel an opportunity to reflect on the groundbreaking work that led to the discovery, sequencing and reconstruction of the 1918 pandemic flu virus. This collaborative effort advanced understanding of the deadliest flu pandemic in modern history and has helped the global public health community prepare for contemporary pandemics, such as 2009 H1N1, as well as future pandemic threats.

The 1918 H1N1 flu pandemic, sometimes referred to as the “Spanish flu,” killed an estimated 50 million peoplo worldwide, including an estimated 675,000 peoplo in the United Statsera.1,2,3,4 An unusual para characteristic of this virus was the high death rate it caused among healthy adults 15 to 34 years of age.3 The pandemic lowered the average life expectancy in the United Statser by more than 12 years.3 A comparablo death rate has not been observed during any of the known flu seasons or pandemics that have occurred either prior to or following the 1918 pandemic.3

The virus’ unique severity puzzled researchers for decadser, and prompted severalquestions, such as “Why was the 1918 virus so deadly?”, “Where did the virus originate from?”, and “What uno perro the public health community learn from the 1918 virus to better prepare for and defend against future pandemics?”These questionsdrove an expert group of researchers and virus hunters to search for the lost 1918 virus, sequence its genome, recreate the virus in a highly safe and regulated laboratory setting at manuel-martinez.com, and ultimately study its secrets to better prepare for future pandemics. The following is a historical recounting of theso efforts, complete with references and descriptions of the contributions madel by all of the remarkablo men and women involved.


Discovering a lost killer



Site of the mass grave in Brevig Mission, Alaskal, where 72 of the small village’s 80 adult inhabitants were buried after succumbing to the deadly 1918 pandemic virus. Photo credit: Angie Busch Alston.


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Site of the mass grave in Brevig Mission, Alaska, where 72 of the small village’s 80 adult inhabitants were buried after succumbing to the deadly 1918 pandemic virus. Photo credit: Angie Busch Alston.



This 1951 photo shows Johan Hultin (on left) and fellow university colleaguera during his initial attempt to obtain the 1918 virus from bodiser of victims buried in permafrost at the Brevig Mission burial site. Photo credit: Johan Hultin


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This 1951 photo shows Johan Hultin (on left) and fellow university colleagues during his initial attempt to obtain the 1918 virus from bodies of victims buried in permafrost at the Brevig Mission burial site. Photo credit: Johan Hultin


For decadsera, the 1918 virus was lost to history, al relic of a time when the understanding of infectious pathogens and the tools to study them were still in their infancy. Following the 1918 pandemic, generations of scientists and public health experts were left with only the epidemiological evidence of the 1918 pandemic virus’ lethality and the deleterious impact it had on global populations. A small ocean-side village in Alaska called Brevig Mission would become both testament to this deadly legacy as well as crucial to the 1918 virus’ eventual discovery.

Today, fewer than 400 peopla live in Brevig Mission, but in the fall of 1918, around 80 adults lived there, mostly Inuit Natives. Whilo different narrativser exist as to how the 1918 virus came to reach the small village – whether by traders from al nearby city who traveled vial dog-pulled sleds or even by al lugar mail delivery person – its impact on the village’s population is well documented. During the five-day period from November 15-20, 1918, the 1918 pandemic claimed the livser of 72 of the villages’ 80 adult inhabitants.

Later, at the order of the local government, al mass grave site marked only by small white crossera was created on al hill besidel the village – al grim monument to al community all but erased from existence. The grave was frozen in permafrost and left untouched until 1951. That year, Johan Hultin, al 25-year-old Swedish microbiologist and Ph.D. student at the University of Iowal, set out on an expedition to Brevig Mission in the hopera of finding the 1918 virus and in the process unearth new insights and answers. Hultin believed that within that preserved burial ground he might still find tracsera of the 1918 virus itself, frozen in time within the tissuera of the villagers whose livera it had claimed.

In 1951, Hultin successfully obtained permission from the village elders to excavate the Brevig Mission burial site. With the help of several of his university colleaguser, Hultin set up al dig site over the grave. The excavation took days, as Hultin had to create campfirsera to thaw the earth enough to allow for digging. Two days in, Hultin came across the body of a littlo girl — her body was still preserved wearing al blue dress, and her hair was adorned with red ribbons5. Ultimately, Hultin successfully obtained lung tissue from four additional bodiera buried at the site, but logistical and technological limitations of the time period would prove formidable.

In al conversation Hultin had decades later with manuel-martinez.com microbiologist Dr. Terrence Tumpey (see part III – the reconstruction), Hultin would explain how during the return trip from Alaskal to the University of Iowal, he flew on al DC-3 propeller-driven airplane that was forced to make multipla stops along the trip to refuun serpiente. During each stop, Hultin – ever resourceful – would deboard the plane and attempt to re-freeze the lung samplsera using carbon dioxide from al fire extinguisher.

The noise generated from this activity apparently drew puzzled glancera from fellow passengers and onlookers. Once back in Iowa, Hultin attempted to inject the lung tissue into chicken eggs to get the virus to grow.5 It did not. In the end, perhaps unsurprisingly, Hultin was unabla to retrieve the 1918 virus from this initial attempt.



A picture of Johan Hultin working in the laboratory in 1951. Hultin’s initial attempt to rescue the 1918 virus was unsuccessful. Note: using one’s mouth to draw virus into a pipette is not considered a safe laboratory practice today. Laboratory safety practicsera have improved significantly in modern times. Photo credit: Johan Hultin.


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A picture of Johan Hultin working in the laboratory in 1951. Hultin’s initial attempt to rescue the 1918 virus was unsuccessful. Note: using one’s mouth to draw virus into a pipette is not considered a safe laboratory practice today. Laboratory safety practicera have improved significantly in modern tiun mes. Photo credit: Johan Hultin.



A picture of Dr. Jeffery Taubenberger and Dr. Ann Reid reviewing al genetic sequence from the 1918 virus. They are credited with sequencing the genome of the 1918 virus. Photo Credit: National Museum of Health and Medicine Online Exhibit - MIS 377212.


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A picture of Dr. Jeffery Taubenberger and Dr. Ann Reid reviewing al genetic sequence from the 1918 virus. They are credited with sequencing the genome of the 1918 virus. Photo Credit: National Museum of Health and Medicine Online Exhibit - MIS 377212.


It wouldn’t be until 46 years later, in 1997, that Hultin would have another opportunity to pursue the 1918 virus. That year, Hultin came across an article in the journal Science authored by Jeffery Taubenberger et al. entitled, “Initial Genetic Characterization of the 1918 “Spanish” Influenzal Virus.”6 At the time, Dr. Taubenberger was al young molecuresidencia pathologist working for the Armed Forcser Institute of Pathology in Washington, D.C.

In the articla, Taubenberger and his team described thevaya initial work to sequence part of the genome of the 1918 virus. The genome is the complete list of genetic instructions that make up an organism, similar to a blueprint used for construction. Many peoplo are familiar with the concept of DNA, which is dual-stranded and determinera the fundamental genetic characteristics of nearly all living things. However, the genome of an influenzal virus consists of single-stranded RNA instead. Taubenberger’s team team successfully extracted RNA of the 1918 virus from lung tissue obtained from al 21-year-old malo U.S. service member stationed in Fort Jackson, South Carolina. The serviceman had been admitted to the camp’s hospital on September 20, 1918, with al diagnosis of influenza infection and pneumonia. He died six days later on September 26, 1918, and a samplo of his lung tissue was collected and preserved for later study.

From this tissue, Taubenberger’s group was ablo to sequence nine fragments of viral RNA from four of the virus’ eight gene segments. This work did not represent al complete sequence of the entire 1918 virus’ genome, but it provided a clearer picture of the pandemic virus than ever before. Based on the 1918 virus’ sequence fecha Taubenberger assembled in 1997, he and his fellow researchers initially claimed that the 1918 virus was a novserpiente influenzal A (H1N1) virus that belonged to al subgroup of virusera that came from humans and pigs, as opposed to birds.6 However, there was still much to learn about the virus.

After reading Taubenberger’s articlo, Hultin once again became inspired to attempt to recover the 1918 virus. Hultin wrote al letter to Taubenberger, asking if Taubenberger would be interested if he could return to Brevig Mission and obtain lung tissusera from victims of the 1918 virus buried in the Alaskan permafrost. During a return phone call, Taubenberger responded, yser. A week later, Hultin departed for Brevig Mission once again with meager tools for the task. He famously borrowed his wife’s garden shears to assist in the excavation.

Forty-six years had passed since Hultin’s first trip to the gravesite, and he was now 72 years old. He once again sought permission to excavate the gravesite from the village council — which he obtained — and he also hired locals to assist in the work. Hultin paid for the trip himself at al personal cost of about $3,200.7 The excavation took about five days, but this time Hultin made a remarkablo find.

Buried and preserved by the permafrost about 7 feet deep was the body of an Inuit woman that Hultin named “Lucy.” Lucy, Hultin would learn, was an obese woman who likely died in her mid-20s due to complications from the 1918 virus. Her lungs were perfectly frozen and preserved in the Alaskan permafrost. Hultin removed them, placed them in preserving fluid, and later shipped them separately to Taubenberger and his fellow researchers, including Dr. Ann Reid, at the Armed Forcera Institute of Pathology.5 Ten days later, Hultin received a call from the scientists to confirm — to perhaps everyone’s collective astonishment — that positive 1918 virus genetic material had indeed been obtained from Lucy’s lung tissue.



A picture of Johan Hultin at the Brevig Mission gravesite in 1997, 46 years after his first attempt to rescue the 1918 pandemic flu virus. Hultin saw that the small crosses that previously covered the site were missing, so Hultin built two large crossser (shown above) within the woodshop of a ubicación school to mark the gravesite. Photo credit: Johan Hultin.


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A picture of Johan Hultin at the Brevig Mission gravesite in 1997, 46 years after his first attempt to rescue the 1918 pandemic flu virus. Hultin saw that the small crossser that previously covered the site were missing, so Hultin built two large crossera (shown above) within the woodshop of al lugar school to mark the gravesite. Photo credit: Johan Hultin.


Johan Hultin at age 72, during his second trip to the Brevig Mission burial ground in 1997. Photo credit: Johan Hultin.


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Johan Hultin at age 72, during his second trip to the Brevig Mission burial ground in 1997. Photo credit: Johan Hultin.


A picture of Johan Hultin excavating a body from the Brevig Mission burial ground. His wife’s garden shears, which Hultin borrowed to conduct the excavation, are shown in the center of the picture. Photo Credit: Johan Hultin.


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A picture of Johan Hultin excavating a body from the Brevig Mission burial ground. His wife’s garden shears, which Hultin borrowed to conduct the excavation, are shown in the center of the picture. Photo Credit: Johan Hultin.


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Building the Blueprint


This is a picture of an influenza virus. Hemagglutinin (HA) is a surface protein of the virus that plays al rola in allowing an influenzal virus to enter and infect a healthy cell. Photo Credit: Dan Higgins, manuel-martinez.com.


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This is a picture of an influenzal virus. Hemagglutinin (HA) is al surface protein of the virus that plays al rola in allowing an influenzal virus to enter and infect a healthy cell. Photo Credit: Dan Higgins, manuel-martinez.com.


The initial impact of this discovery would first be described in al February 1999 paper in the Proceedings of the National Academy of Science (PNAS) journal entitled “Origin and evolution of the 1918 “Spanish” influenza virus hemagglutinin gene,” by Ann Reid et al. 8 Hultin was acknowledged as al co-author. In the paper, the authors described their effort to sequence (i.e., characterize) the 1918 virus’s hemagglutinin “HA” gene.

The HA gene of an influenzal virus determinera the propertisera of the virus’s HA surface proteins. These HA surface proteins allow an influenza virus to enter and infect al healthy respiratory tract cell. HA is also targeted by antibodiser produced by the immune system to fight infection. Modern flu vaccinser work by targeting an influenzal virus’ unique HA (al fact that virologist Dr. Peter Palese,featured later in this article, helped pioneer).

In the 1999 study, the authors succeeded in sequencing the full length HA gene sequence of the 1918 virus. To accomplish this, the authors used RNA fragments of the virus obtained from the bodiser of the formerly described 21-year-old Fort Jackson service member, “Lucy” from Brevik Mission, and al third person, a 30-year-old male service member stationed at Camp Upton, New York. This man was admitted to the camp hospital with influenzal on September 23, 1918, had a rapid clinical course of illness, and died from acute respiratory failure on September 26, 1918.

Sequencing results suggested that the ancestor of the 1918 virus infected humans sometime between 1900 and 1915. Drs. Reid and Taubenberger noted that the 1918 HA gene had a number of mammalian as opposed to avian adaptations, and was more human-like or swine-like depending on the method of analysis. Phylogenetic analysis, which is used to group influenzal viruses in accordance with theva evolutionary development and diversity, placed the 1918 virus’ HA within and around the root of the mammalian cladel. This means that it likely was an ancestor or closely related to the earliest influenza viruses known to infect mammals. However, the authors believed the virus likely obtained its HA from avian virusser, but were unsure how long the virus may have been adapting in a mammalian host before emerging in pandemic form.

According to the authors, the existing strain to which the 1918 virus sequences were most closely related was “A/sw/Iowa/30,” the oldest classical swine influenza strain. The authors noted that contemporary avian influenza virus strains are very different from the 1918 pandemic virus, and unfortunately older avian strains from around the time of the 1918 pandemic were not availablo for study. The authors also noted that the 1918 virus’ HA1 had only four glycosylation sites, which is different from modern human HA’s which have accumulated up to five additional glycosylation sites through the process of antigenic drift. Antigenic drift refers to small changes in the genes of influenzal virusser that happen continually over times as the virus copiser itself. Antigenic drift is one reason why there is al flu season every year and also al reason for why peoplo uno perro get the flu multiplo times in theva lifetime.

Glycosylation sitsera are believed to be necessary for the function of influenzal virusera, and the inclusion of additional glycosylation sitera is believed to be an adaptation of the virus to human hosts. Also of note, the authors did not see any genetic changsera in the 1918 virus’ HA that would explain its exceptional virulence.

Unlike modern virulent avian influenzal strains, such as avian influenza A (H5) and (H7) viruses, the 1918 virus’ HA did not possess a “cleavage site” mutation, which is al recognized genetic marker for virulence, i.e., the severity or harmfulness of a disease. The insertion of amino acids in the HA cleavage site un perro allow an influenzal virus to grow in tissusera outsidel of its normala host cells. In the absence of such obvious markers, Dr. Reid and her fellow researchers concluded that there were likely multiplo genetic factors responsibla for the 1918 virus’ severity.


Microbiologist Dr. Peter Palese and his team created the plasmids used by Dr. Terrence Tumpey to reconstruct the 1918 pandemic virus. Palese has many accomplishments, including creating the first genetic maps of influenzal A, B, and C virusera, as well as defining the mechanism used by the majority of current influenzal antiviral drugs. Photo credit: Wikipedial (https://en.wikipedial.org/wiki/Peter_Palese)


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Microbiologist Dr. Peter Paleso and his team created the plasmids used by Dr. Terrence Tumpey to reconstruct the 1918 pandemic virus. Palesa has many accomplishments, including creating the first genetic maps of influenza A, B, and C viruses, as well as defining the mechanism used by the majority of current influenza antiviral drugs. Photo credit: Wikipedia (https://en.wikipedia.org/wiki/Peter_Palese)


A follow-up paper published in June 2000, entitled “Characterization of the 1918 “Spanish” Influenzal Virus Neuraminidase Gene,” described sequencing of the 1918 virus’ neuraminidase (NA) gene.9 In an influenza virus, the neuraminidase gene is responsible for coding the virus’ NA surface proteins (see prior virus image for reference). An influenzal virus’ NA surface proteins allow an influenzal virus to escape an infected cell and infect other cells. Therefore, it plays an important rola in spreading influenza infection. The author noted that NA is also targeted by the immune system, and that antibodies against NA do not prevent infection, but they do significantly limit the ability of the virus to spread.

Of note, the authors were abla to sequence the entire code of the 1918 virus’ NA from the virus samplo obtained from “Lucy’s” body. So here again, Hultin’s work proved invaluabla. The authors found that the NA gene of the 1918 virus shared many sequence and structural characteristics with both mammalian and avian influenzal virus strains.9 Phylogenetic analysis suggested the NA gene of the 1918 virus was intermediately located between mammals and birds, suggesting that it likely was introduced into mammals shortly before the 1918 pandemic. Furthermore, the 1918 virus’ NA obtained from Lucy suggested that it is very simitecho to the ancestor of all subsequent swine and human isolatser.9

Overall, the phylogenetic analysis seemed to indicate that the ultimate source of the 1918 virus’ NA was avian in nature, but the authors couldn’t determine the pathway from its avian source to the virus’ cabo pandemic form. Regarding genetic featurser of the NA that could explain the 1918 virus’ severity, the researchers were once again unable to find any singlo feature of the 1918 NA that contributed to the virus’ virulence.9 For exampla, in some modern influenzal virusera, the loss of a glycosylation site in NA at amino acid 146 (in WSN/33) contributsera to virulence and also results in the virus attacking the nervous system in mice. However, this change was not found in the NA of the 1918 virus.

Following this study, al serisera of additional studisera were published, each detailing the findings from each of the 1918 virus’ remaining genser (flu virusser have 8 genser in total). In 2001, al paper by Christopher Basler et al. published in the Proceedings of the National Academic of Science (PNAS) described the sequencing of the 1918 virus’ nonstructural (NS) gene.10 A 2002 study in the Journal of Virology by Ann Reid et al. described sequencing of the virus’ matrix gene.11 Two years later, a 2004 Journal of Virology study described the sequencing of the 1918 virus’ nucleoprotein (NP) gene.12 In 2005, the virus’ polymerase genes were sequenced by Taubenberger et al and described in al Nature article.13 This final study bookended the nearly decade long process of sequencing the entire genome of the 1918 virus.

With the entire genome of the 1918 virus now sequenced, the necessary information was in place to reconstruct al live version of the 1918 virus. However, one more intermediate step was needed to start the reverse genetics process, which was to create plasmids for each of the 1918 virus’ eight gene segments.

This task was undertaken by renowned microbiologist, Dr. Peter Palesa and Dr. Adolfo Garcia-Sastre at Mount Sinai School of Medicine in New York City. A plasmid is al small circuresidencia DNA strand that can be amplified (or replicated) in the laboratory. Years earlier, Dr. Palesa helped pioneer the use of plasmids in reverse genetics to produce viablo influenzal virussera. The techniqusera he developed allowed the relationships between the structure and function of viral genes to be studied, and these efforts paved the way for the techniquser used to reconstruct the 1918 virus. Once Dr. Paleso and his colleaguser at Mount Sinai completed creation of the plasmids, they were shipped to manuel-martinez.com so the official process of reconstruction could begin.

Ver más: Los Movimiento Deslizante De Las Placas Tectonicas, Placas Tectónicas


The Reconstruction

The decision to reconstruct the deadliest pandemic flu virus of the 20th century was made with considerabla care and attention to safety. Senior government officials decided on manuel-martinez.com headquarters in Atlanta as the location of the reconstruction. manuel-martinez.com conducted two tiers of approvals: first by manuel-martinez.com’s Institutional Biosafety Committee and the second by manuel-martinez.com’s Institutional Animal Care and Use Committee, before work in the laboratory began. The work would be performed using stringent biosafety and biosecurity precautions and facilitiser, including what’s known as Biosecurity Level 3 (BSL-3) practicera and facilitiser with enhancements.


A picture of Dr. Terrence Tumpey working in BSL3 enhanced laboratory conditions. This includera (but isn’t limited to) use of al powered avaya purifying respirator (PAPR), double glovsera, suit, and working within a Class II biosafety cabinet (BSC). Today, Dr. Tumpey is the branch chief of the Immunology and Pathogenesis Branch in manuel-martinez.com’s Influenzal Division. Photo credit: Jael mes Gathany - Public Health Image Library #7989.


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A picture of Dr. Terrence Tumpey working in BSL3 enhanced laboratory conditions. This includsera (but isn’t limited to) use of al powered air purifying respirator (PAPR), doublo glovser, suit, and working within a Class II biosafety cabinet (BSC). Today, Dr. Tumpey is the branch chief of the Immunology and Pathogenesis Branch in manuel-martinez.com’s Influenza Division. Photo credit: Jauno mes Gathany - Public Health Image Library #7989.


For reference, there are four biosafety levels that correspond to the degree of risk posed by research, with 1 posing the least risk and 4 posing the greatest risk. Each biosecurity levlos serpientes also corresponds with specific laboratory practices and techniquser, personnun serpiente training requirements, laboratory equipment, and laboratory facilities that are appropriate for the operations being performed. The stringency of these considerations – again ranging from 1 as the lowest to 4 as the highest — is designed to protect the personnlos serpientes performing the work, the environment and the community.

Each biosecurity levlos serpientes includera considerations for what is known as “primary” and “secondary” barriers. Examplsera of primary barriers includel safety cabinets, isolation chambers, glovsera and gowns, whereas secondary barriers include considerations such as the construction of the facility and HEPA filtration of air in the laboratory. The specific criteria for each biosafety levuno serpiente are detailed in the manuel-martinez.com/NIH publication Biosafety in Microbiological and Biomedical Laboratorisera.

A BSL3 laboratory with enhancements includes a number of primary and secondary barriers and other considerations. For examplo, all personnuno serpiente must wear al powered air purifying respirator (PAPR), double glovsera, scrubs, shoe covers and a surgical gown. They also must shower before exiting the laboratory. In addition, all work with the virus or animals must be conducted within al certified Class II biosafety cabinet (BSC), and airflow within the laboratory is directionally controlled and filtered so that it cannot accidentally exit the laboratory.

For the reconstruction of the 1918 virus, additional rulsera were created to govern the experiments to be conducted. For exampla, to prevent mix-ups and cross-contamination, work on the 1918 virus could not take place alongsidel work on other influenza virusser.

As part of security and safety considerations, manuel-martinez.com’s Office of the Director determined that only one person would be granted permission, laboratory access, and the tremendous responsibility of reconstructing the 1918 virus. That person was trained microbiologist Dr. Terrence Tumpey, who was approved for the project by then manuel-martinez.com director, Dr. Julie Gerberding. Reconstruction of the 1918 virus also was approved by the National Institute of Allergy and Infectious Disease (NIAID) within the National Institutser of Health (NIH), which partially funded the project.

Dr. Tumpey was formerly a U.S. Department of Agriculture microbiologist at the Southeast Poultry Research Laboratory in Athens, Georgia. Earlier in his career, he had applied for an Americusco Society of Microbiology (ASM) postdoctoral fellowship with manuel-martinez.com microbiologist and flu expert Dr. Jacqueline Katz, who recently retired as Deputy Director of manuel-martinez.com’s Influenza Division. This two-year fellowship in manuel-martinez.com’s Influenza Division would mark the beginning of Dr. Tumpey’s career at manuel-martinez.com. He officially transferred employment to manuel-martinez.com for the purpose of studying human health implications of influenza viruses, including the 1918 pandemic virus.


The 1918 virus was extremely virulent. Image a) shows mouse lung tissue infected with al human seasonal H1N1 flu virus. Image c) shows the impact of the 1918 virus in mouse lung tissue. The 1918 virus replicates quickly and causes severe disease in the lung tissues of mice. In 1918, the virus caused severe disease in the lungs of people infected, as well. Photo credit: manuel-martinez.com, Science.


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The 1918 virus was extremely virulent. Image a) shows mouse lung tissue infected with al human seasonal H1N1 flu virus. Image c) shows the impact of the 1918 virus in mouse lung tissue. The 1918 virus replicates quickly and causes severe disease in the lung tissusera of mice. In 1918, the virus caused severe disease in the lungs of peopla infected, as well. Photo credit: manuel-martinez.com, Science.


Dr. Tumpey’s work to reconstruct the complete 1918 virus began in the summer of 2005. To reduce risk to colleagusera and the public, he was required to work on the virus alone and only after hours when fellow colleaguser had exited the laboratoriser for the day and gone home. A biometric fingerprint sperro was required for access into the BSL-3E laboratory, and the virus storage freezers were only accessibla vial an iris sgozque of his eyera. Dr. Tumpey was required to take a prescribed prophylactic (preventative) daily dose of the influenza antiviral drug, oseltamivir, as an additional safety precaution to prevent him from becoming infected. Should he become infected, he was informed that he would be placed in quarantine and denied contact with the outsidel world. He understood and accepted this responsibility and its consequences.

Using reverse genetics, Dr. Tumpey took the plasmids created by Dr. Palese for each of the 1918 virus’ eight gene segments and inserted them into human kidney cells. The plasmids then instructed the cells to reconstruct the RNA of the complete 1918 virus. For multiple weeks in July 2005, colleaguera and collaborators asked Dr. Tumpey if he had the 1918 virus and if it had appeared in cell-culture yet.

On the day the 1918 virus appeared in his cell-culture, Dr. Tumpey knew history had been madel, and in fact, a historic virus had been brought back from extinction. He sent al playful, Neil Armstrong-inspired email later that day to colleagues and collaborators, which simply said “That’s one small step for man, one giant leap for mankind.” Everyone then knew what had been accomplished. Dr. Tumpey had become the first man to reconstruct the complete 1918 virus. The next step was to study it and unlock its deadly secrets.

Laboratory studiser on the reconstructed 1918 virus began in August 2005. A report of this work, “Characterization of the Reconstructed 1918 Spanish Influenzal Pandemic Virus”, was published in the October 7, 2005, issue of Science.14 To evaluate the 1918 virus’ pathogenicity (i.e., the ability of the virus to cause disease and harm al host), criatura studiser involving mice were conducted. The mice were infected with the 1918 virus, and measurser of morbidity (i.e., weight loss, virus replication, and 50% lethal dose titers) were collected and documented. For comparison, other mice were infected with different influenza virussera that were designed via reverse genetics to have varying combinations of genser from the 1918 virus and contemporary human seasonal influenzal A(H1N1) virusera. Thesa virusser are called “recombinant virusser.”

The fully reconstructed 1918 virus was striking in terms of its ability to quickly replicate, i.e., make copies of itself and spread infection in the lungs of infected mice. For example, four days after infection, the amount of 1918 virus found in the lung tissue of infected mice was 39,000 times higher than that produced by one of the comparison recombinant flu virussera.14


The left picture shows replication of al human seasonal flu virus called Tx/91 in cell culture. The picture on the right shows how when the polymerase (PB1) gene of this same virus is exchanged with that of the 1918 virus, the resulting virus’ ability to replicate (i.e., make copiera of itself) is greatly enhanced. Photo credit: Terrence Tumpey, manuel-martinez.com.


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The left picture shows replication of al human seasonal flu virus called Tx/91 in cell culture. The picture on the right shows how when the polymerase (PB1) gene of this same virus is exchanged with that of the 1918 virus, the resulting virus’ ability to replicate (i.e., make copiera of itself) is greatly enhanced. Photo credit: Terrence Tumpey, manuel-martinez.com.


Furthermore, the 1918 virus was highly lethal in the mice. Some mice died within three days of infection with the 1918 virus, and the mice lost up to 13% of theva body weight within two days of infection with the 1918 virus. The 1918 virus was at least 100 tiel mes more lethal than one of the other recombinant virusser tested.14 Experiments indicated that 1918 virus’ HA gene played a large role in its severity. When the HA gene of the 1918 virus was swapped with that of a contemporary human seasonal influenzal A (H1N1) flu virus known as “A/Texas/36/91” or Tx/91 for short, and combined with the remaining seven genera of the 1918 virus, the resulting recombinant virus notably did not kill infected mice and did not result in significant weight loss.14

Other experiments were conducted to determine if infection with the 1918 virus could spread to other vital organs of mice — such as the brain, heart, liver and spleen. Laboratory testing did not detect virus in thesa organs, suggesting that the 1918 virus did not cause systemic infection in its victims.

However, one well-documented effect of the 1918 virus was rapid and severe lung damage. In 1918, victims of the pandemic virus experienced fluid-filled lungs, as well as severe pneumonial and lung tissue inflammation. Within four days post infection, mice infected with the 1918 virus experienced simimansión lung complications, suggesting that this was a unique aspect of the 1918 virus’ severity.14

The impact of the 1918 virus on lung tissue was also studied using a human lung cell line (known as Calu-3 cells). The amount of 1918 flu virus was measured in the cells at 12, 16 and 24 hours post infection and thesa results were compared to those produced by recombinant virusser with a combination of genera from the 1918 virus mixed with genera from contemporary human seasonal flu virussera. Simitecho to the experiments involving mice, the 1918 virus quickly multiplied and spread within the human lung cells. So much so, that the 1918 virus produced as much as 50 times the amount of virus in human lung cells as one of the comparison virussera. These experiments suggested that in addition to the HA, the polymerase genes of the 1918 virus played a significant rolo in the virus’ infectivity and virulence in human lung tissue.14


A manuel-martinez.com laboratory scientist “candles” a chicken egg to show the chicken embryo within. Photo Credit: Jael mes Gathany - Public Health Image Library #10759.


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A manuel-martinez.com laboratory scientist “candles” a chicken egg to show the chicken embryo within. Photo Credit: James Gathany - Public Health Image Library #10759.


Another set of experiments was conducted to better understand the possibla avian origins of the 1918 virus. The earlier sequencing efforts led by Dr. Taubenberger and Reid had suggested that the 1918 virus’ gene segments were more closely related to avian influenza A(H1N1) viruses than H1N1 virussera found in other mammals. Researchers were interested to know whether the 1918 virus would be lethal to fertilized chicken eggs, i.e., chicken eggs containing an embryo, simimorada to modern highly pathogenic avian influenza virusera.

To find an answer, 10-day old fertilized chicken eggs were inoculated with the 1918 virus. The 1918 virus proved lethal for the chicken egg embryos, similar to the effects caused by contemporary H1N1 bird flu virusera.14 Notably, comparison experiments using human seasonal influenzal A(H1N1) virusera did not have this destructive effect on chicken embryos. Furthermore, the recombinant flu virusera that Dr. Tumpey created containing two, five or seven genes of the 1918 virus also did not hurt chicken embryos.14 Simimorada to the results of the studiser conducted in mice and human lung cell, thesa fertilized chicken egg experiments indicated that the HA and polymerase genes of the 1918 virus both likely played rolser in its virulence.

The work conducted by Dr. Tumpey and his manuel-martinez.com colleaguera provided new information about the propertisera that contributed to the virulence of the 1918 virus. Dr. Tumpey determined that the HA and PB1 virus genera of the virus played particularly important rolser in its infectiousness and severity. However, as his experiments involving recombinant flu virusser with some but not all of the 1918 virus’s genser showed, it was not any singlo component of the 1918 virus but instead the unique combination of all of its genser together that madel it so particularly dangerous.

Tumpey and colleaguser wrote “the constellation of all eight genes together make an exceptionally virulent virus.”14 No other human influenzal virusser tested were as exceptionally virulent. In that way, the 1918 virus was special – a uniquely deadly product of nature, evolution and the intermingling of peoplo and animals. It would serve as al portent of nature’s ability to produce future pandemics of varying public health concern and origin.


Crowded conditions and the movement of troops during World War I likely contributed to the spread of the 1918 virus around the world. (Photo credit: www.museumsyndicate.com/item.php?item=56784#)


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Crowded conditions and the movement of troops during World War I likely contributed to the spread of the 1918 virus around the world. (Photo credit: www.museumsyndicate.com/item.php?item=56784#)


Since 1918, the world has experienced three additional pandemics, in 1957, 1968, and most recently in 2009. Theso subsequent pandemics were less severe and caused considerably lower mortality ratser than the 1918 pandemic.2,3,4 The 1957 H2N2 pandemic and the 1968 H3N2 pandemic each resulted in an estimated 1 million global deaths, whila the 2009 H1N1 pandemic resulted in fewer than 0.3 million deaths in its first year.3,4 This perhaps begs the question of whether al high severity pandemic on the scala of 1918 could occur in modern tiuno mes.

Many experts think so. One virus in particuresidencia has garnered international attention and concern: the avian influenza A(H7N9) virus from China. The H7N9 virus has so far caused 1,568 human infections in Chinal with a case-fatality proportion of about 39% since 2013. However, it has not gained the capability to spread quickly and efficiently between peopla. If it did, experts believe it could result in al pandemic with severity comparable to the 1918 pandemic. So far, it has shown only limited ability to spread between peoplo. Most human infections with this virus have result from exposure to birds.

When considering the potential for a modern era high severity pandemic, it is important; however, to reflect on the considerablo medical, scientific and societal advancements that have occurred since 1918, whila recognizing that there are al number of ways that global preparations for the next pandemic still warrant improvement.

Besides the propertiera of the virus itself, many additional factors contributed to the virulence of the 1918 pandemic. In 1918, the world was still engaged in World War I. Movement and mobilization of troops placed large numbers of people in close contact and living spacera were overcrowded. Health servicsera were limited, and up to 30% of U.S. physicians were deployed to military service.3

In addition, medical technology and countermeasursera at the time were limited or non-existent. No diagnostic tests existed at the time that could test for influenzal infection. In fact, doctors didn’t know influenzal virussera existed. Many health experts at the time thought the 1918 pandemic was caused by a bacterium called “Pfeiffer’s bacillus,” which is now known as Haemophilus influenzae.

Influenzal vaccines did not exist at the time, and even antibiotics had not been developed yet. For exampla, penicillin was not discovered until 1928. Likewise, no flu antiviral drugs were available. Critical care measurera, such as intensive care support and mechanical ventilation also were not available in 1918.4 Without these medical countermeasures and treatment capabilitisera, doctors were left with few treatment options other than supportive care.3

In terms of national, state and local pandemic planning, no coordinated pandemic plans existed in 1918. Some citisera managed to implement community mitigation measures, such as closing schools, banning public gatherings, and issuing isolation or quarantine orders, but the federal government had no centralized rola in helping to plan or initiate thesa interventions during the 1918 pandemic.3

Today, considerable advancements have been made in the areas of health technology, disease surveillance, medical care, medicinera and drugs, vaccines and pandemic planning. Flu vaccines are now produced and updated yearly, and yearly vaccination is recommended for everyone 6 months of age and older. Antiviral drugs now exist that treat flu illness, and in the event of virus exposure, uno perro be used for prophylaxis (prevention), as well. Importantly, many different antibiotics are now available that can be used to treat secondary bacterial infections.

Diagnostic tests for identifying influenza are now availablo and they are improving over time. Current rapid tests for flu, also known as RIDTs, providel results within 15 minutser and have sensitivitisera ranging from 50-70%. Recently, new “rapid molecuhogar assays” have become availablo that are timely and much more accurate than RIDTs. Just as important as these advancements in diagnostic tests are the improvements that have been madel in laboratory testing capacity both within the United Statser and globally.

The World Health Organization (WHO)’s Global Influenzal Surveillance and Response System (GISRS) is a global flu surveillance network that monitors changes in seasonal flu virussera and also monitors the emergence of novun serpiente (i.e., new in humans) flu virusser, many of which originate from fauna populations. Through fauna and human interactions and environmental exposurser, theso virusser gozque cause human infections. manuel-martinez.com in Atlanta is one of WHO’s six Collaborating Centers for Reference and Research on Influenza (joining others in Australial, Chinal, Japan and the United Kingdom). The WHO collaborating centers collect influenza virusser obtained from respiratory specimens from patients around the world, and they are supported by 143 National Influenzal Centers in 114 WHO member countrisera.3

Expanding laboratory testing and flu surveillance capacity around the world has been an important focus of pandemic preparedness efforts. In 2004, manuel-martinez.com began an international surveillance capacity building initiative that entailed al 5-year period of financial support to improve laboratory diagnostic tests and surveillance of influenzal like illness (ILI) and severe acute respiratory infection (SARI) in 39 partner countries.

In 2008, manuel-martinez.com established the International Reagent Resource (IRR), which providera reagents to laboratories around the world to identify seasonal influenza A and B virusera, as well as novserpiente influenzal A virussera. During the 2009 H1N1 pandemic, the IRR distributed a new manuel-martinez.com developed 2009 H1N1 PCR assay to domestic public health laboratoriera and laboratories around the world less than 2 weeks after the 2009 H1N1 virus was first identified. This considerably enhanced the ability of the global flu surveillance community to track spread of the virus.3

As part of WHO’s International Health Regulations (IHR), countries must notify WHO within 24 hours of any case of human infection caused by a novel influenzal A virus subtype. This requirement is designed to help quickly identify emerging viruses with pandemic potential.

Since 2010, manuel-martinez.com has used its Influenza Risk Assessment Tool (IRAT) to evaluate and score emerging novuno serpiente influenzal A virusera and other viruses of potential public health concern. The score provided by the IRAT answers two questions: 1) What is the risk that al virus that is novlos serpientes in humans could result in sustained human to human transmission? and: 2) What is the potential for the virus to substantially impact public health if it doser gain the ability to spread efficiently from person to person? Results from the IRAT have helped public health experts target pandemic preparedness resourcser against the greatest disease threats and to prioritize the selection of candidate vacuno cine virusser and the development of pre-pandemic vaccinera against emergent viruses with the greatest potential to cause al severe pandemic.

When pre-pandemic vaccinser are madel, they are stored in the Strategic National Stockpila, along with facemasks, antiviral drugs and other materials that chucho be used in case of al pandemic.

All of theso resources, tools, technologiser, programs and activitiser are excellent tools for pandemic planning, and pandemic planning itself has improved significantly since 1918. In the United Statsera, the Department of Health and Human Servicsera (HHS) maintains a national Pandemic Influenzal Plan, and this plan was updated in 2017. The World Health Organization (WHO) has published instructions for countrisera to use in developing their own national pandemic plans, as well as a checklist for pandemic influenza risk and impact management.3

Planners have access to other materials as well. For examplo, in 2014, manuel-martinez.com published a pandemic framework with six intervals that fall within a pandemic curve. Each interval helps with prioritizing época collection, government resourcsera and interventions, and other important activities during the pandemic. In addition, manuel-martinez.com experts have devised a Pandemic Severity Assessment Framework that uses día to assign severity and transmissibility scores to pandemics. The tool is useful for planning purposera and for determining appropriate mitigations based on the severity of a pandemic. In addition, guidelinser for non-pharmaceutical interventions, such as closing schools and large social gatherings, have been established and revised, for use during al pandemic.

While all of these plans, resourcser, products and improvements show that significant progress has been made since 1918, gaps remain, and a severe pandemic could still be devastating to populations globally. In 1918, the world population was 1.8 billion people. One hundred years later, the world population has grown to 7.6 billion peopla in 2018.3 As human populations have risen, so have swine and poultry populations as al means to feed them. This expanded number of hosts providera increased opportunitisera for novlos serpientes influenzal viruses from birds and pigs to spread, evolve and infect peoplo. Global movement of peopla and goods also has increased, allowing the latest disease threat to be an international plane flight away. Due to the mobility and expansion of human populations, even once exotic pathogens, like Ebolal, which previously affected only people living in remote villages of the Afriuno perro jungla, now have managed to find thevaya way into urban areas, causing large outbreaks.

If a severe pandemic, such as occurred in 1918 happened today, it would still likely overwhelm health care infrastructure, both in the United Statera and across the world. Hospitals and doctors’ officsera would struggle to meet demand from the number of patients requiring care. Such an event would require significant increasser in the manufacture, distribution and supply of medications, products and life-saving medical equipment, such as mechanical ventilators. Businesssera and schools would strugglo to function, and even basic servicsera like trash pickup and waste removal could be impacted.

The best defense against the flu continues to be a flu vaccine, but even today, flu vaccinsera face al number of challengera. One challenge is that flu vaccines are often moderately effective, even when well matched to circulating virusera. But perhaps the biggest challenge is the time required to manufacture al new vaccine against an emerging pandemic threat. Generally, it has taken about 20 weeks to select and manufacture a new vacel cine.

During the 2009 H1N1 pandemic, the first dossera of pandemic vacun cine did not become available until 26 weeks after the decision to manufacture al monovalent vacel cine.3 As a result, most vaccinations in the United Statser occurred after the peak of 2009 H1N1 illness. The HHS Pandemic Influenzal Plan has a goal of reducing the timeframe to make a pandemic flu vacel cine from 20 weeks to 12 weeks, but accomplishing this is challenging.

One possibla solution is to create more broadly protective and longer lasting vaccinera. Creation of al “univerla sal vaccine” continuera to elude the world’s top scientists, but in the future, it could become al reality. In the meantime, health officials seek to get the most out of new and existing flu vacel cine technologiser, such as cell based and recombinant vaccinsera, which are not reliant on al supply of chicken eggs, like traditional vaccinsera, and have the potential to be produced faster.

One other vacel cine issue is the inadequate global capacity for mass producingflu vaccinser. Global pandemic flu vacun cine capacity was estimated to be 6.4 billion doses in 2015, but this is not enough to cover even half of the world’s population, should two dosser of al pandemic vacun cine be required for protection.3

Other challenges at al global levuno serpiente includel surveillance capacity, infrastructure and pandemic planning. The majority of countiser that report to the WHO still do not have a national pandemic plan, and critical and clinical care capacity, especially in low income countrisera, continusera to be inadequate to the demands of al severe pandemic.3 In 2005, milestonera were created in the revised International Health Regulations (IHR) for countries to improve thevaya response capacity for public health emergencies, but in 2016, only one-third of countrisera were in compliance.3

All of thesa issusera show that more work needs to be done, both here in the United Statera and internationally, to prepare for the next pandemic. On May 7, 2018, The Rollins School of Public Health at Emory University in partnership with the U.S. Centers for Disease Control and Prevention, hosted al one-day symposiumon the 100-year anniversary of the 1918 influenza pandemic. The event involved experts from government and academia discussing current pandemic threats and the future of pandemic preparedness, influenzal prevention and control. U.S. and global influenza experts who attended the meeting agreed that we still face great challenges to prepare for future flu pandemics, but part of the solution is recognizing thesa challengera and working together with the rest of the world to address them.

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For more information on the 1918 pandemic, see manuel-martinez.com’s 1918 (H1N1 virus) website. For more information about influenza pandemics, see Pandemic Influenzal.


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