Mild respiratory COVID can cause multi-lineage neural cell and myelin dysregulation.

COVID survivors frequently experience lingering neurological symptoms that resemble cancer-therapy-related cognitive impairment, a syndrome for which white matter microglial reactivity and consequent neural dysregulation is central. Here, we explored the neurobiological effects of respiratory SARS-CoV-2 infection and found white-matter-selective microglial reactivity in mice and humans. Following mild respiratory COVID in mice, persistently impaired hippocampal neurogenesis, decreased oligodendrocytes, and myelin loss were evident together with elevated CSF cytokines/chemokines including CCL11. Systemic CCL11 administration specifically caused hippocampal microglial reactivity and impaired neurogenesis. Concordantly, humans with lasting cognitive symptoms post-COVID exhibit elevated CCL11 levels. Compared with SARS-CoV-2, mild respiratory influenza in mice caused similar patterns of white-matter-selective microglial reactivity, oligodendrocyte loss, impaired neurogenesis, and elevated CCL11 at early time points, but after influenza, only elevated CCL11 and hippocampal pathology persisted. These findings illustrate similar neuropathophysiology after cancer therapy and respiratory SARS-CoV-2 infection which may contribute to cognitive impairment following even mild COVID.

Astragalus Polysaccharide improves immunogenicity of influenza vaccine as well as modulate gut microbiota in BALB/c mice.

BACKGROUND: Vaccination is the best way to prevent influenza virus infection, and insufficient antibodies make it difficult to resist influenza virus invasion. Astragalus Polysaccharide (APS) has a boosting effect on immunity, so we evaluate the effect of APS as an immune adjuvant for H1N1 influenza vaccines in this study. METHODS: The mice were immunized twice with influenza A (H1N1) vaccine and APS. Subsequently, the serum antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA). The frequency of peripheral immune T cells was determined by flow cytometry. Following this, the immunized mice were exposed to a lethal dose of the virus, and changes in body weight and survival rates were recorded. Hematoxylin-eosin staining was employed to observe pathological alterations in lung and intestinal tissues. Western blot analysis was conducted to detect the expression of intestinal barrier function proteins (Occludin and Claudin-1). ELISA was utilized to measure the expression level of serum inflammatory cytokine TNF-α. Fresh mouse feces were collected after the initial immunization as well as after viral infection for 16S rRNA analysis aimed at detecting alterations in gut microbiota. RESULTS: Compared to the Hemagglutinin (HA) group, the APS group demonstrated higher levels of immunoglobulin G (IgG), IgG1, and IgG3, as well as neutralizing antibody levels. Additionally, it increased the frequency of CD8+ cells to enhance resistance against lethal infection. On day 14 post-infection, the high-dose APS group exhibited a higher survival rate (71.40 %) compared to the HA group (14.28 %), along with faster weight recovery. Furthermore, APS was found to ameliorate alveolar damage in lung tissue and rectify intestinal structural disorder. It also upregulated the expression levels of tight junction proteins Occludin and Claudin-1 in intestinal tissue while reducing serum TNF-α expression levels. In addition, populations of Colidextribacter, Peptococcaceae, and Ruminococcaceae were the dominant gut microbiota in the APS group after viral infection. CONCLUSION: APS has an immune-enhancing effect and is expected to be a novel adjuvant in the H1N1 influenza vaccine.

Guidelines on epidemics in Mexico. Historical perspective.

A perspective of epidemics and pandemics in Mexico is offered, focusing on three time periods, namely, end of the 18th century, the 20th century, and the 21st century, in order to analyze how they were approached by health and government authorities, as well as the challenges they have represented. Historical documentary sources were consulted and, in current cases, participation in them was analyzed. Epidemiological and social historical methodologies were combined. The presence of epidemics in Mexico is a constant on its evolution, which highlights the need for the epidemiological surveillance system to be updated, the importance of being prepared to face an epidemic and to develop a contingency plan.

Se ofrece una perspectiva de las epidemias y pandemias en México en tres periodos: fines del siglo XVIII y siglos XX y XXI, con el fin de analizar cómo las autoridades sanitarias y gubernamentales abordaron estos problemas, así como los desafíos que han representado. Se consultaron fuentes históricas documentales y, en los casos actuales, la participación en ellos. Se combinó metodología epidemiológica e histórica social. La presencia de las epidemias en México es una constante, lo cual evidencia la necesidad de actualizar el sistema de vigilancia epidemiológica, de estar preparados para enfrentar una epidemia y de elaborar un plan de contingencia.

Influenza A (H1N1): Now is it a Thing of the Past?

How to cite this article: Gupta S, Tomar DS. Influenza A (H1N1): Now is it a Thing of the Past? Indian J Crit Care Med 2023;27(7):461-462.

Frequency and distribution of H1N1 influenza A viruses with oseltamivir-resistant mutations worldwide before and after the 2009 pandemic.

H1N1 influenza has brought serious threats to people's health and a high socioeconomic burden to society. Oseltamivir, a kind of neuraminidase (NA) inhibitor, is the second-generation specific drug that is broadly used currently. However, H1N1 influenza viruses have exhibited oseltamivir resistance in the past decades, which might be a hidden danger. To understand the frequency and distribution laws of oseltamivir-resistant viruses, we conducted a thorough and deep analysis of the available NA protein sequences of H1N1 influenza viruses worldwide from 1918 to 2020. The differences and similarities before and after 2009 were also considered since the dominant viruses changed in this period. Results showed that 3.76% of H1N1 viruses harbored oseltamivir resistance currently. Among various significative mutations, H274Y had the highest frequency of 3.30%, while the frequencies of the other mutations were far below this whether before or after 2009. The oseltamivir resistance was mainly found in three hosts, humans, swine, and avian. Different mutation sites could exhibit different distributions in each host. Our results showed that the resistance level reached a peak during the 2007-2008 influenza season and then quickly decreased in 2009. The resistance also displayed a global distribution. The densely populated countries usually had a high resistance level. However, frequent significative mutations were also found in some small countries. Our findings indicated the necessity of monitoring oseltamivir resistance around the world. The study could provide a unique perspective toward the cognition of viruses and facilitate the future study of both pandemic and drug development.

Identification and analysis of B cell epitopes of hemagglutinin of H1N1 influenza virus.

The frequent variation of influenza virus hemagglutinin (HA) antigen is the main cause of influenza pandemic. Therefore, the study of B cell epitopes of HA is of great significance in the prevention and control of influenza virus. In this study, the split vaccine of 2009 H1N1 influenza virus was used as immunogen, and the monoclonal antibodies (mAbs) were prepared by conventional hybridoma fusion and screening techniques. The characteristics of mAbs were identified by ELISA method, Western-blot test and hemagglutination inhibition test (HI). Using the obtained mAbs as a tool, the B cell epitopes of HA were predicted by ELISA blocking test, sandwich ELISA method and computer simulation method. Finally, four mAbs against HA antigen of H1N1 influenza virus were obtained. The results of ELISA and computer prediction showed that there were at least two types of epitopes on HA of influenza virus. The results of this study complemented the existing methods for predicting HA epitopes, and also provided a new method for predicting other pathogenic microorganisms.

Narcolepsy among first- and second-generation immigrants in Sweden: A study of the total population.

AIMS: To study incident narcolepsy in first- and second-generation immigrant groups using Swedish-born individuals and native Swedes as referents. METHODS: The study population included all individuals registered and alive in Sweden at baseline. Narcolepsy was defined as having at least one registered diagnosis of narcolepsy in the Swedish National Patient Register. The incidence of narcolepsy in different immigrant groups was assessed by Cox regression, with hazard ratios (HRs) and 95% confidence intervals (CI). The models were stratified by sex and adjusted for age, geographical residence in Sweden, educational level, marital status, co-morbidities, and neighbourhood socioeconomic status. RESULTS: In the first-generation study, 1225 narcolepsy cases were found; 465 males and 760 females, and in the second-generation study, 1710 cases, 702 males and 1008 females. Fully adjusted HRs (95% CI) in the first-generation study was for males 0.83 (0.61-1.13) and females 0.83 (0.64-1.07), and in the second-generation study for males 0.76 (0.60-0.95) and females 0.91 (95% CI 0.76-1.09). Statistically significant excess risks of narcolepsy were found in first-generation males from North America, and second-generation males with parents from North America, and second-generation females with parents from Latin America. CONCLUSIONS: There were only significant differences in incident narcolepsy between native Swedes and second-generation male immigrants. The observed differences can partly be explained by differences in Pandemrix® vaccinations and are probably not attributable to genetic differences between immigrants and natives.

Duvira Antarctic polysaccharide inhibited H1N1 influenza virus-induced apoptosis through ROS mediated ERK and STAT-3 signaling pathway.

BACKGROUND: The H1N1 influenza virus causes acute respiratory tract infection, and its clinical symptoms are very similar to those of ordinary influenza. The disease develops rapidly. If the flu is not treated, complications such as pneumonia, respiratory failure, and multiple organ damage can occur, resulting in a high fatality rate. Influenza virus mutates rapidly. At present, there is no specific drug for H1N1, so it is an urgent need for clinical care to find new drugs to treat H1N1. MATERIALS AND METHODS: The polysaccharide derived from Durvillaea Antarctica green algae has a certain antiviral effect. In this study, the results of CCK-8, apoptosis cycle detection, JC-1 and Western blotting proved that Duvira Antarctic polysaccharide (DAPP) has the ability to inhibit H1N1 infection. RESULTS: CCK-8 test showed that the DAPP with concentration at 32 µg/mL had no toxicity to MDCK cells. In addition, DAPP reduced cell apoptosis by inhibiting the ERK signaling pathway. Meanwhile, DAPP could increase the expression of STAT3 and significantly inhibited proinflammatory cytokines. CONCLUSIONS: In summary, these results suggested that DAPP may be potential with the ability to resist the H1N1 influenza virus.

Eleven Years of Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: From H1N1 to SARS-CoV-2. Experience and Perspectives of a National Referral Center.

OBJECTIVE: Despite growing expertise and wide application of venovenous extracorporeal membrane oxygenation (VV ECMO) treatment for acute respiratory distress syndrome (ARDS) of different origin and during pandemics (H1N1 Influenza A virus and SARS-CoV-2), large reports are few and pertain mostly to multicenter registries, and randomized trials are difficult to perform. The aim of this study was to report outcomes, trends, and innovations of VV ECMO treatment over the last 11 years. DESIGN, SETTING, AND PARTICIPANTS: Observational study on 142 patients treated at the IRCCS San Raffaele Hospital in Milan from June 2009 (year of the H1N1 pandemic) to May 2020 (SARS-CoV-2 pandemic). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The main causes of ARDS were H1N1 pneumonia in 36% of patients, bacterial pneumonia in 17%, and SARS-CoV-2 in 9%. Seventy-two percent of patients were centralized from remote hospitals, of whom 33% had implanted VV ECMO before transport. The most common cannulation strategy was the dual-lumen catheter cannulation system (55%), and anticoagulation was performed with bivalirudin in most patients (79%). Refractory hypoxia was treated with intravenous beta-blockers (64%), nitric oxide (20%), and pronation (8%). Almost one-third of patients (32%) were extubated while on ECMO. Forty-nine percent of patients were discharged from the intensive care unit, and hospital discharge was 46%; survival was lower in patients requiring VV ECMO for more than three weeks compared with shorter support duration (23% v 56%, p = 0.007). Anticoagulation with bivalirudin was associated with higher survival, compared with heparin (55% v 31%, p = 0.03), and lower thrombocytopenia incidence (69% v 35%, p = 0.003). CONCLUSION: VV ECMO is the pivotal rescue treatment for refractory ARDS-timely treatment and optimal care are needed to optimize therapy, as duration of support is associated with outcome. Anticoagulation with bivalirudin may improve outcome.

Distribution and evolution of H1N1 influenza A viruses with adamantanes-resistant mutations worldwide from 1918 to 2019.

H1N1 influenza is a kind of acute respiratory infectious disease that has a high socioeconomic and medical burden each year around the world. In the past decades, H1N1 influenza viruses have exhibited high resistance to adamantanes, which has become a serious issue. To understand the up-to-date distribution and evolution of H1N1 influenza viruses with adamantanes-resistant mutations, we conducted a deep analysis of 15875 M2 protein and 8351 MP nucleotides sequences. Results of the distribution analyses showed that 77.32% of H1N1 influenza viruses harbored-resistance mutations of which 73.52% were S31N, And the mutant variants mainly appeared in North America and Europe and H1N1 influenza viruses with S31N mutation became the circulating strains since 2009 all over the world. In addition, 80.65% of human H1N1 influenza viruses and 74.61% of swine H1N1 influenza viruses exhibited adamantanes resistance, while the frequency was only 1.86% in avian H1N1 influenza viruses. Studies from evolutionary analyses indicated that the avian-origin swine H1N1 influenza viruses replaced the classical human H1N1 influenza viruses and became the circulating strains after 2009; The interspecies transmission among avian, swine, and human strains over the past 20 years contributed to the 2009 swine influenza pandemic. Results of our study clearly clarify the historical drug resistance level of H1N1 influenza viruses around the world and demonstrated the evolution of adamantanes-resistant mutations in H1N1 influenza viruses. Our findings emphasize the necessity for monitoring the adamantanes susceptibility of H1N1 influenza viruses and draw attention to analyses of the evolution of drug-resistant H1N1 influenza variants.

Metabolomic diferences between COVID-19 and H1N1 influenza induced ARDS.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by lung inflammation and pulmonary edema. Coronavirus disease 2019 (COVID-19) is associated with ARDS in the more severe cases. This study aimed to compare the specificity of the metabolic alterations induced by COVID-19 or Influenza A pneumonia (IAP) in ARDS. METHODS: Eighteen patients with ARDS due to COVID-19 and twenty patients with ARDS due to IAP, admitted to the intensive care unit. ARDS was defined as in the American-European Consensus Conference. As compared with patients with COVID-19, patients with IAP were younger and received more often noradrenaline to maintain a mean arterial pressure > 65 mm Hg. Serum samples were analyzed by Nuclear Magnetic Resonance Spectroscopy. Multivariate Statistical Analyses were used to identify metabolic differences between groups. Metabolic pathway analysis was performed to identify the most relevant pathways involved in ARDS development. RESULTS: ARDS due to COVID-19 or to IAP induces a different regulation of amino acids metabolism, lipid metabolism, glycolysis, and anaplerotic metabolism. COVID-19 causes a significant energy supply deficit that induces supplementary energy-generating pathways. In contrast, IAP patients suffer more marked inflammatory and oxidative stress responses. The classificatory model discriminated against the cause of pneumonia with a success rate of 100%. CONCLUSIONS: Our findings support the concept that ARDS is associated with a characteristic metabolomic profile that may discriminate patients with ARDS of different etiologies, being a potential biomarker for the diagnosis, prognosis, and management of this condition.

Reverse Zoonosis of COVID-19: Lessons From the 2009 Influenza Pandemic.

Over the past decade, pandemics caused by pandemic H1N1 (pH1N1) influenza virus in 2009 and severe acute respiratory syndrome virus type 2 (SARS-CoV-2) in 2019 have emerged. Both are high-impact respiratory pathogens originating from animals. Their wide distribution in the human population subsequently results in an increased risk of human-to-animal transmission: reverse zoonosis. Although there have only been rare reports of reverse zoonosis events associated with the ongoing coronavirus disease 2019 (COVID-19) pandemic from SARS-CoV-2 so far, comparison with the pH1N1 influenza pandemic can provide a better understanding of the possible consequences of such events for public and animal health. The results of our review suggest that similar factors contribute to successful crossing of the host species barriers in both pandemics. Specific risk factors include sufficient interaction between infected humans and recipient animals, suitability of the animal host factors for productive virus infection, and suitability of the animal host population for viral persistence. Of particular concern is virus spread to susceptible animal species, in which group housing and contact network structure could potentially result in an alternative virus reservoir, from which reintroduction into humans can take place. Virus exposure in high-density populations could allow sustained transmission in susceptible animal species. Identification of the risk factors and serological surveillance in SARS-CoV-2-susceptible animal species that are group-housed should help reduce the threat from reverse zoonosis of COVID-19.

[Protective effect of Asarum polysaccharide on H1N1 influenza virus infection and expression of inflammatory factors].

In this paper, Asarum polysaccharides(AP) were extracted, and its composition was analyzed to study the activity against H1 N1 influenza virus in vitro and its intervention effect on mice with kidney Yang deficiency syndrome. AP was prepared by the strategy of water extraction and alcohol precipitation, the content was determined, and its monosaccharide composition was analyzed. The cell Real-time monitoring system and Reed-Muench model were adopted to evaluate the antiviral activity of AP in vitro. And the mouse model of kidney Yang deficiency syndrome was established in vivo to compare the efficacy of Mahuang Xixin Fuzi Decoction(MXF) and AP. MXF group and AP group were treated with clinical equivalent doses of 1.8 g·kg~(-1)·d~(-1) and 0.077 g·kg~(-1)·d~(-1) respectively, once a day for 6 consecutive days. Real-time PCR was used to detect the relative expression of M gene of H1 N1 influenza virus and cytokines in lung tissue. The content of AP in Asarum was 25.22%, and the protein content was 0.8%. And the monosaccharide composition was identified as L-rhamnose, D-arabinose, D-xylose, D-glucose, D-galactose and D-mannose. TI values of Tamiflu, MXF and AP were 30.00, 8.06 and 10.33, respectively. Three different doses of AP could significantly reduce the concentration of virus in supernatant. Compared with the model mice, lung indexes of MXF group and AP group decreased significantly(P<0.05), and the relative expression of M gene decreased significantly(P<0.05). The relative expressions of IL-10 and IFN-γ were up-regulated to varying degrees, while the relative gene expressions of IL-1ß, IL-6 and MCP-1 were down-regulated to different degrees. In addition, AP could significantly enhance the expression of TNF-α(P<0.01). AP had a good anti-influenza virus activity in vitro, and could protect mice with kidney Yang deficiency syndrome by reducing the viral load in lung tissue, decreasing inflammation damage in lung tissue, and regulating the expression of inflammatory cytokines. Compared with the prescription of MXF, AP had a better antiviral activity.

A comparative analysis of control measures on-board ship against COVID-19 and similar novel viral respiratory disease outbreak: Quarantine ship or disembark suspects?

BACKGROUND: Management of novel viral respiratory disease outbreak on-board a ship with person-to-person transmission can be a public health challenge because of close proximity of inhabitants due to confined space and air-conditioned environment. It has a potential to be explosive, with high secondary attack rate (SAR) and cause significant morbidity and mortality. This study compares control measures instituted on-board two ships with similar outbreaks and recommends a standardized evidence-based outbreak response against them. METHODS: This is a descriptive study, showing comparative analysis of control measures instituted on-board two ships, a cruise ship in case of COVID-19 and a warship in case of H1N1 influenza, with novel viral respiratory disease outbreak, at different span of time. Data of the date of onset, clinical details, laboratory results, history of travel, history of contact with positive case and control measures initiated were collected, analysed and compared. RESULTS: Of the two ships compared, one was a cruise ship with 712 COVID-19 cases, with an attack rate (AR) of 19.2% and 13 deaths, and other a warship with 14 cases of H1N1 influenza and an AR of 4.83%. The epidemic curve for both the outbreaks was plotted to study time distribution. CONCLUSION: Active surveillance, early self-reporting and immediate disembarkation of the suspects, along with strict compliance of hand hygiene, cough etiquettes and disinfection enhancement, will help in early mitigation of the outbreak. Health education should be undertaken to impart evidence-based knowledge and alleviate fear of the unknown. Vaccination may not be present but if available should only be administered after strict risk-benefit, cost-benefit and effectiveness analysis.

New type of anti-influenza agents based on benzo[d][1,3]dithiol core.

We synthesized a series of amides with a benzo[d][1,3]dithiol core. The chemical library of compounds was tested for their cytotoxicity and inhibiting activity against influenza virus A/California/07/09 (H1N1)pdm09 in MDCK cells. For each compound, values of CC50, IC50 and selectivity index (SI) were determined. Compounds of this structure type were for the first time found to exhibit anti-influenza activity. The structure of an amide substituent in the tested compounds was demonstrated to have a significant effect on their activity against the H1N1 influenza virus and cytotoxicity. Compound 4d has a high selectivity index of about 30. 4d was shown to be most potent at early stages of viral cycle. In direct fusogenic assay it demonstrated dose-dependent activity against fusogenic activity of hemagglutinin of influenza virus. Based on molecular docking and regression analysis data, viral hemagglutinin was suggested as possible target for these new antiviral agents.

Outcomes of severe H1N1 pneumoniae: A retrospective study at intensive care units.

BACKGROUND: The incidence of acute respiratory distress syndrome (ARDS) and the mortality rate of H1N1 influenza pneumonia are unclear. The aim of this study is to investigate the clinical features and outcomes of adult patients admitted to intensive care units (ICUs) with H1N1 pneumonia related ARDS. METHODS: This retrospective study included patients with confirmed H1N1 influenza pneumonia admitted to the ICUs of a medical center between July 2009 and May 2014. We investigated the patients' characteristics, clinical presentations, illness severities, and outcomes. RESULTS: Sixty-six patients were confirmed to have H1N1 influenza pneumonia requiring mechanical ventilation. Fifty-four of those patients (82%) developed ARDS, while their hospital mortality rate was 33% (22/66). There were no significant differences in the ICU and hospital mortality rates of the ARDS and non-ARDS patients. Among the ARDS patients, there were higher rates of solid malignant disease (22.8% vs. 2.8%, p = 0.038) and sepsis (66.7% vs. 33.3%, p = 0.020) and a higher mean tidal volume (8.9 ± 1.8 vs. 7.8 ± 1.9 ml/kg, p = 0.032) in the non-survivors than the survivors. Logistic regression analysis revealed that a high tidal volume (odds ratio = 1.448, 95 % CI = 1.033-2.030; p = 0.032) and sequential organ failure assessment (SOFA) score (odds ratio = 1.233, 95% CI = 1.029-1.478; p = 0.023) were the risk factors of hospital mortality. CONCLUSION: For H1N1 influenza pneumonia patients admitted to ICUs with mechanical ventilation, there is a high probability of developing ARDS with a modest mortality rate. For patients with ARDS due to H1N1 influenza pneumonia, the tidal volume and SOFA score are the predictors of hospital mortality.

Indications for Proning in Acute Respiratory Distress Syndrome: Expanding the Horizon!

BACKGROUND: Previously prone positioning (PP) was described in addition to invasive mechanical ventilation and it has been known to reduced mortality and improve oxygenation in patients of ARDS. Recently novel timing of prone positioning was described with the use of high-frequency nasal cannula (HFNC) and noninvasive ventilation (NIV) in patients of acute respiratory distress syndrome (ARDS) to avoid the intubation. Here we would like to share a case of severe ARDS where prone positioning was used in a step further ahead. CASE DESCRIPTION: A 38-year-old gentleman presented with the complaints of progressive breathlessness, dry cough and fever for 7 days. Patient was diagnosed as a case of H1N1 pneumonia with severe ARDS. Patient was initially managed with invasive mechanical ventilation according to ARDS-Net protocol. Despite persistent hypoxia he was put on prone positioning for consecutive 4 days. Patient was extubated after 10 days of mechanical ventilation and put on HFNC in view of persistent high oxygen requirement. At this point of time, we attempted prone positioning in addition to HFNC. Patient was comfortable on prone position and put himself in the same condition for prolonged periods. His oxygenation showed a remarkable improvement from PaO2 of 63 (before prone positioning) to 136 mm Hg (after prone positioning). Oxygen supplementation was later tapered off and subsequently, he improved and was shifted to ward. CONCLUSION: Prone positioning is a harmless and still extremely effective intervention which can and should be utilized at all steps of ARDS-management. HOW TO CITE THIS ARTICLE: Lalwani LK, Sharma V, Chaudhry D, Singh PK. Indications for Proning in Acute Respiratory Distress Syndrome: Expanding the Horizon! Indian J Crit Care Med 2020;24(7):589-591.

Development of a Pan-H1 Influenza Vaccine.

The efficacy of current seasonal influenza vaccines varies greatly, depending on the match to circulating viruses. Although most vaccines elicit strain-specific responses, some present cross-reactive epitopes that elicit antibodies against diverse viruses and remain unchanged and effective for several years. To determine whether combinations of specific H1 hemagglutinin (HA) antigens stimulate immune responses that protect against diverse H1 influenza viruses, we evaluated the antibody responses elicited by HA-ferritin nanoparticles derived from six evolutionarily divergent H1 sequences and two computationally optimized broadly reactive antigen (COBRA) HA antigens. Humoral responses were assessed against a panel of 16 representative influenza virus strains from the past 80 years. HAs from the strains A/NewCaledonia/20/1999 (NC99), A/California/04/2009 (CA09), A/HongKong/117/1977 (HK77), COBRA X6, or P1 elicited neutralization against diverse strains, and a combination of three wild-type HA or two COBRA HA nanoparticles conferred significant additional breadth beyond that observed with any individual strain. Therefore, combinations of H1 HAs may constitute a pan-H1 influenza vaccine.IMPORTANCE Seasonal influenza vaccines elicit strain-specific immune responses designed to protect against circulating viruses. Because these vaccines often show limited efficacy, the search for a broadly protective seasonal vaccine remains a priority. Among different influenza virus subtypes, H1N1 has long been circulating in humans and has caused pandemic outbreaks. In order to assess the potential of a multivalent HA combination vaccine to improve the breadth of protection against divergent H1N1 viruses, HA-ferritin nanoparticles were made and evaluated in mice against a panel of historical and contemporary influenza virus strains. Trivalent combinations of H1 nanoparticles improved the breadth of immunity against divergent H1 influenza viruses.

Inhibition of H1N1 influenza virus infection by zinc oxide nanoparticles: another emerging application of nanomedicine.

BACKGROUND: Currently available anti-influenza drugs are often associated with limitations such as toxicity and the appearance of drug-resistant strains. Therefore, there is a pressing need for the development of novel, safe and more efficient antiviral agents. In this study, we evaluated the antiviral activity of zinc oxide nanoparticles (ZnO-NPs) and PEGylated zinc oxide nanoparticles against H1N1 influenza virus. METHODS: The nanoparticles were characterized using the inductively coupled plasma mass spectrometry, x-ray diffraction analysis, and electron microscopy. MTT assay was applied to assess the cytotoxicity of the nanoparticles, and anti-influenza activity was determined by TCID50 and quantitative Real-Time PCR assays. To study the inhibitory impact of nanoparticles on the expression of viral antigens, an indirect immunofluorescence assay was also performed. RESULTS: Post-exposure of influenza virus with PEGylated ZnO-NPs and bare ZnO-NPs at the highest non-toxic concentrations could be led to 2.8 and 1.2 log10 TCID50 reduction in virus titer when compared to the virus control, respectively (P < 0.0001). At the highest non-toxic concentrations, the PEGylated and unPEGylated ZnO-NPs led to inhibition rates of 94.6 and 52.2%, respectively, which were calculated based on the viral loads. There was a substantial decrease in fluorescence emission intensity in viral-infected cell treated with PEGylated ZnO-NPs compared to the positive control. CONCLUSIONS: Taken together, our study indicated that PEGylated ZnO-NPs could be a novel, effective, and promising antiviral agent against H1N1 influenza virus infection, and future studies can be designed to explore the exact antiviral mechanism of these nanoparticles.

A novel small molecule displays two different binding modes during inhibiting H1N1 influenza A virus neuraminidases.

Neuraminidase (NA) inhibitors can suppress NA activity to block the release of progeny virions and are effective against influenza viruses. As potential anti-flu drugs with unique functions, NA inhibitors are greatly concerned by the worldwide scientists. It has been reported recently that one of the novel quindoline derivatives named 7a, could inhibit both A/Puerto Rico/8/34 (H1N1) NA (NAPR) and A/California/04/09 (H1N1) NA (NACA). However, potential structure differences in the active site could be easily detected between the NAPR and NACA according to the flexibilities of their 150-loops located catalytic site. And no obvious 150-cavity could be observed in NACA crystal structure. In order to explore whether 7a could trigger the inhibition against these two NAs in the same way, a serial molecular dynamics simulation approach were applied in this study. The results indicated that 7a could be adopted under a relatively extended pose in the active center of NAPR. While in NACA-7a complex, the derivate preferred to be recognized and located on the side of active center. Interestingly, the potential of 7a was also found to be able to change the flexibility of the 150-loop in NACA that is absent of 150-cavity. Furthermore, a 150-cavity-like architecture could be induced in the active site of NACA. The results of this study revealed two kinds of binding modes of this novel small molecule inhibitor against NAs that might provide a theoretical basis for proposing novel inhibition mechanism and developing future influenza A virus inhibitors.