The 2009 pandemic H1N1 hemagglutinin stalk remained antigenically stable after circulating in humans for a decade

An H1N1 influenza virus caused a pandemic in 2009 and descendants of this virus continue to circulate seasonally in humans. Upon infection with the 2009 H1N1 pandemic strain (pH1N1), many humans produced antibodies against epitopes in the hemagglutinin (HA) stalk. HA stalk-focused antibody responses were common among pH1N1-infected individuals because HA stalk epitopes were conserved between the pH1N1 strain and previously circulating H1N1 strains. Here, we completed a series of experiments to determine if the pH1N1 HA stalk has acquired substitutions since 2009 that prevent the binding of human antibodies. We identified several amino acid substitutions that have accrued in the pH1N1 HA stalk from 2009-2019. We completed enzyme-linked immunosorbent assays, absorption-based binding assays, and surface plasmon resonance experiments to determine if these substitutions affect antibody binding. Using sera collected from 230 humans (aged 21-80 years), we found that pH1N1 HA stalk substitutions that have emerged since 2009 do not affect antibody binding. Our data suggest that the HA stalk domain of pH1N1 viruses remained antigenically stable after circulating in humans for a decade.

“World in motion” – emulsion adjuvants rising to meet the pandemic challenges

Emulsion adjuvants such as MF59 and AS03 have been used for more than two decades as key components of licensed vaccines, with over 100 million doses administered to diverse populations in more than 30 countries. Substantial clinical experience of effectiveness and a well-established safety profile, along with the ease of manufacturing have established emulsion adjuvants as one of the leading platforms for the development of pandemic vaccines. Emulsion adjuvants allow for antigen dose sparing, more rapid immune responses, and enhanced quality and quantity of adaptive immune responses. The mechanisms of enhancement of immune responses are well defined and typically characterized by the creation of an “immunocompetent environment” at the site of injection, followed by the induction of strong and long-lasting germinal center responses in the draining lymph nodes. As a result, emulsion adjuvants induce distinct immunological responses, with a mixed Th1/Th2 T cell response, long-lived plasma cells, an expanded repertoire of memory B cells, and high titers of cross-neutralizing polyfunctional antibodies against viral variants. Because of these various properties, emulsion adjuvants were included in pandemic influenza vaccines deployed during the 2009 H1N1 influenza pandemic, are still included in seasonal influenza vaccines, and are currently at the forefront of the development of vaccines against emerging SARS-CoV-2 pandemic variants. Here, we comprehensively review emulsion adjuvants, discuss their mechanism of action, and highlight their profile as a benchmark for the development of additional vaccine adjuvants and as a valuable tool to allow further investigations of the general principles of human immunity.

Amantadine Variant - Aryl Conjugates that Inhibit Multiple Amantadine Resistant M2 Mutant Influenza A Viruses

One challenge facing anti-influenza drug development is the heterogeneity of the circulating influenza A viruses, which comprise several strains with variable susceptibility to antiviral drugs. Viruses bearing the S31N mutant of the M2, such as the pandemic 2009 H1N1 and seasonal H3N2, as well as other mutants (L26F, V27A, A30T, G34E) are resistant to amantadine class of drugs. Here, we synthesized and tested many of the second generation amantadine - aryl conjugates, against the WT M2 and all the M2 amantadine resistant strains, i.e. L26F, V27A, S31N, A30T, G34E generated from WSN/33 (S31N) virus. We identified many compounds that are dual in vitro M2 WT and L26F virus inhibitors. Furthermore, few of them (21, 32, 33), having a rimantadine or diamantadine or 4-(1-adamantyl)aniline instead of amantadine in the conjugate, were in vitro inhibitors against M2 WT, L26F and S31N while one of them inhibited also the A30T virus. The electrophysiology (EP) experiments showed that these compounds blocked significantly M2 WT, L26F or even M2 V27A channels but not the M2 S31N. The observation that adamantane variants and derivatives inhibit multiple M2 mutant virus replication in cell culture, without blocking M2 channel-mediated proton current in EP is not uncommon, underlying a mechanism of antiviral activity that has not been identified.

A Man With Flulike Symptoms and Hemorrhagic Brain Lesions

A 52-year-old man is admitted to a neurosciences intensive care unit during winter for management of seizures requiring mechanical ventilation. Two days earlier he reported cough and myalgia. He was found seated on the couch with altered mental state and was minimally responsive. Upon arrival to the emergency department he was febrile at 38.8 °C and tachycardic. Complete blood cell count showed leukocytosis (11.1×109 cells/L, neutrophilic predominance). Computed tomography of the head showed an area of hypodensity in the left temporal lobe. During computed tomography, the patient had generalized convulsions requiring lorazepam, fosphenytoin, and levetiracetam, followed by initiation of a continuous midazolam infusion before seizures were controlled. He was started on broad-spectrum antimicrobials, including acyclovir, and a lumbar puncture was performed. Cerebrospinal fluid protein concentration was 196 mg/dL, and he had 10 white blood cells/µL with lymphocyte predominance. There was no hypoglycorrhachia. After 24 hours, the patient was weaned from the midazolam infusion and maintained on levetiracetam monotherapy. He was extubated but remained encephalopathic. Magnetic resonance imaging performed the day after admission demonstrated numerous T2 hyperintense lesions throughout both cerebral hemispheres including both mesial temporal lobes and right thalamus. Nasopharyngeal polymerase chain reaction was positive for influenza virus A, which was later typed further and identified as pandemic 2009 H1N1 virus. A diagnosis of influenza-associated encephalopathy/encephalitis was made. The patient was treated with oseltamivir, as well as high-dose intravenous methylprednisolone. His encephalopathy gradually improved. Repeated imaging at 3-month follow-up showed resolution of the previously seen abnormalities. His neurologic examination was normal. Postinfectious or parainfectious autoimmunity syndromes refer to neurologic signs and symptoms that develop during or after an infection but are not thought to be caused by direct infection of the nervous system.

Bodiniosides S–Y, Seven New Triterpenoid Saponins from Elsholtzia bodinieri and Their Anti-Influenza Activities

Investigation of the n-BuOH extract of the aerial parts of Elsholtzia bodinieri led to the isolation of seven new triterpenoid saponins, Bodiniosides S–Y (1–7, resp.). Their strictures were elucidated on the basis of spectroscopic techniques, including HSQC, HSBC, and HSQC–TOCSY experiments, together with acid hydrolysis and GC analysis. The anti-influenza activities of compounds 1–7 were evaluated against A/WSN/33/2009 (H1N1) virus in MDCK cells. The results showed that compounds 2 and 5 exhibited moderate anti-influenza activities against A/WSN/33/2009 (H1N1), with inhibition rates of 35.33% and 24.08%, respectively.

Triple reassortment increases compatibility among viral ribonucleoprotein genes of contemporary avian and human influenza A viruses

Compatibility among the influenza A virus (IAV) ribonucleoprotein (RNP) genes affects viral replication efficiency and can limit the emergence of novel reassortants, including those with potential pandemic risks. In this study, we determined the polymerase activities of 2,451 RNP reassortants among three seasonal and eight enzootic IAVs by using a minigenome assay. Results showed that the 2009 H1N1 RNP are more compatible with the tested enzootic RNP than seasonal H3N2 RNP and that triple reassortment increased such compatibility. The RNP reassortants among 2009 H1N1, canine H3N8, and avian H4N6 IAVs had the highest polymerase activities. Residues in the RNA binding motifs and the contact regions among RNP proteins affected polymerase activities. Our data indicates that compatibility among seasonal and enzootic RNPs are selective, and enzoosis of multiple strains in the animal-human interface can facilitate emergence of an RNP with increased replication efficiency in mammals, including humans.

Coding-Complete Genome Sequence of Swine Influenza Virus Isolate A/Swine/Karaganda/04/2020 (H1N1) from Kazakhstan

Here, we report the coding-complete genome sequence of a clinical sample of influenza virus obtained from a pig at a livestock farm in Karaganda, Central Kazakhstan, during a pig study in 2020. Isolate A/Swine/Karaganda/04/2020 (H1N1) belongs to clade 1A.3.2.2 lineage 1A, which includes the 2009 H1N1 pandemic strains.

Disability-Adjusted Life Years for the COVID-19 Pandemic in the Mexican Population

Mexico is one of the countries most affected by the COVID-19 disease. Although there is vast information on the disease, there still are unknown data on the societal and economic cost of the pandemic. To estimate this impact, the disability-adjusted life years (DALYs) can be a useful tool.Objective: To assess the DALYs due to COVID-19 in Mexico.Methods: We used the data released by the Mexican Ministry of Health to estimate the DALYs by the sum of the years of life lived with disability (YLDs) and the years of life lost (YLLs).Results: A total of 1,152,885 confirmed cases and 324,570 suspected cases of COVID-19 have been registered. Half of the cases were men, with a median age of 43.4 ± 16.9 years. About 8.3% died. A total of 39,202 YLDs were attributable to COVID-19. The total YLLs caused by COVID-19 were 2,126,222. A total of 2,165,424.5 DALYs for COVID-19 were estimated. The total DALYs were the highest in people between 50 and 59 years. The DALYs for each COVID-19 case were the highest in individuals between 60 and 79 years.Conclusion: The DALYs generated by the COVID-19 represent a more significant disease burden than that reported for other causes, such as the 2009 H1N1 influenza pandemic. Although it impacts all age groups in terms of disability, the most affected group are people over 50 years of age, whose risk of death is higher.

Social Determinants of Health and COVID-19 Behaviors and Beliefs Toward Immunizations Among Latinxs

Introduction: Sixty million Latinxs make up 26.4% of all COVID-19 cases in the United States. It is uncertain whether behaviors and beliefs of immunizations among Latinxs is influenced by social determinants of health. The purpose of this study was to examine how social determinants of health predict COVID-19 behaviors and beliefs toward immunization among Latinxs. Methods: In this exploratory study, 11 chapters from the National Association of Hispanic Nurses collaborated to recruit participants. The CDC National 2009 H1N1 Flu Survey was adapted to measure behaviors and beliefs about immunizations of COVID-19. The Health Access Survey was used to measure social determinants of health. Instruments were available in both Spanish and English. Results: Participants (n=228) with higher education and health insurance tended to have less worry about taking the vaccine. Access to resources and practicing COVID-19 protective factors was positively associated. Alternative medicine and use of COVID-19 protective factors were negatively associated. Exposure to drugs and violence was associated with a decrease in likelihood to pursue a vaccine. Conclusions: Latinx need education about COVID-19 and vaccinations. Access to health care services must be available. Results highlight the importance of careful measurement when assessing social determinants of health among Latinx.