H5N1 Virus Strains Research Articles

Antiviral Activity of Angelica Tenuissima Nakai against Influenza A Virus.

The influenza A virus poses a serious threat to human health and is an important global public health issue. The drugs currently used for treatment are becoming increasingly ineffective against influenza A viruses and require the development of new antiviral drugs. Angelica tenuissima Nakai (ATN), a traditional herbal medicine belonging to the Umbelliferae family, exhibits a broad range of pharmacological activities, including inflammation, headache, and cold symptoms. In the present study, based on target protein identification, functional enrichment analysis, and gene set comparisons, we first suggested that ATN has potential therapeutic effects against influenza A virus infection. Next, methylthiazol tetrazolium (MTT) and sulforhodamine B colorimetric (SRB) assay results revealed that ATN exhibited low cytotoxicity in Madin-Darby canine kidney (MDCK) cells. The antiviral properties of ATN were observed against H1N1 and H3N2 virus strains. Microscopy confirmed the increased survival rate of the host cells. Further time-of-addition experiments revealed that the addition of ATN before virus adsorption showed similar results to the whole period of treatment. The pre- and co-treated groups showed lower levels of viral RNA (M1 protein). The results of this study suggest that ATN exhibits antiviral properties against the influenza A virus. These therapeutic properties of ATN can serve as a theoretical basis for further research on the applicability of ATN in the development of antiviral agents.

Licensed H5N1 vaccines generate cross-neutralizing antibodies against highly pathogenic H5N1 clade 2.3.4.4b influenza virus.

The emergence of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b viruses and their transmission to dairy cattle and animals, including humans, poses a major global public health threat. Therefore, the development of effective vaccines and therapeutics against H5N1 clade 2.3.4.4b virus is considered a public health priority. In the United States, three H5N1 vaccines derived from earlier strains of HPAI H5N1 (A/Vietnam, clade 1, and A/Indonesia, clade 2.1) virus, with (MF59 or AS03) or without adjuvants, are licensed and stockpiled for pre-pandemic preparedness, but whether they can elicit neutralizing antibodies against circulating H5N1 clade 2.3.4.4b viruses is unknown. In this study, we evaluated the binding, hemagglutination inhibition and neutralizing antibody response generated after vaccination of adults with the three licensed vaccines. Individuals vaccinated with the two adjuvanted licensed H5N1 vaccines generated cross-reactive binding and cross-neutralizing antibodies against the HPAI clade 2.3.4.4b A/Astrakhan/3212/2020 virus. Seroconversion rates of 60-95% against H5 clade 2.3.4.4b were observed after two doses of AS03-adjuvanted-A/Indonesia or three doses of MF59-adjuvanted-A/Vietnam vaccine. These findings suggest that the stockpiled US-licensed adjuvanted H5N1 vaccines generate cross-neutralizing antibodies against circulating HPAI H5N1 clade 2.3.4.4b in humans and may be useful as bridging vaccines until updated H5N1 vaccines become available.

Very Broadly Effective Hemagglutinin-Directed Influenza Vaccines with Anti-Herpetic Activity.

A universal vaccine that generally prevents influenza virus infection and/or illness remains elusive. We have been exploring a novel approach to vaccination involving replication-competent controlled herpesviruses (RCCVs) that can be deliberately activated to replicate efficiently but only transiently in an administration site in the skin of a subject. The RCCVs are derived from a virulent wild-type herpesvirus strain that has been engineered to contain a heat shock promoter-based gene switch that controls the expression of, typically, two replication-essential viral genes. Additional safety against inadvertent replication is provided by an appropriate secondary mechanism. Our first-generation RCCVs can be activated at the administration site by a mild local heat treatment in the presence of an antiprogestin. Here, we report that epidermal vaccination with such RCCVs expressing a hemagglutinin or neuraminidase of an H1N1 influenza virus strain protected mice against lethal challenges by H1N1 virus strains representing 75 years of evolution. Moreover, immunization with an RCCV expressing a subtype H1 hemagglutinin afforded full protection against a lethal challenge by an H3N2 influenza strain, and an RCCV expressing a subtype H3 hemagglutinin protected against a lethal challenge by an H1N1 strain. Vaccinated animals continued to gain weight normally after the challenge. Protective effects were even observed in a lethal influenza B virus challenge. The RCCV-based vaccines induced robust titers of in-group, cross-group and even cross-type neutralizing antibodies. Passive immunization suggested that observed vaccine effects were at least partially antibody-mediated. In summary, RCCVs expressing a hemagglutinin induce robust and very broad cross-protective immunity against influenza.

Glyco-engineered MDCK cells display preferred receptors of H3N2 influenza absent in eggs used for vaccines

Evolution of human H3N2 influenza viruses driven by immune selection has narrowed the receptor specificity of the hemagglutinin (HA) to a restricted subset of human-type (Neu5Acα2-6 Gal) glycan receptors that have extended poly-LacNAc (Galβ1-4GlcNAc) repeats. This altered specificity has presented challenges for hemagglutination assays, growth in laboratory hosts, and vaccine production in eggs. To assess the impact of extended glycan receptors on virus binding, infection, and growth, we have engineered N-glycan extended (NExt) cell lines by overexpressing β3-Ν-acetylglucosaminyltransferase 2 in MDCK, SIAT, and hCK cell lines. Of these, SIAT-NExt cells exhibit markedly increased binding of H3 HAs and susceptibility to infection by recent H3N2 virus strains, but without impacting final virus titers. Glycome analysis of these cell lines and allantoic and amniotic egg membranes provide insights into the importance of extended glycan receptors for growth of recent H3N2 viruses and relevance to their production for cell- and egg-based vaccines.

Plant crude extracts containing oligomeric hemagglutinins protect chickens against highly Pathogenic Avian Influenza Virus after one dose of immunization

Highly pathogenic avian influenza viruses (HPAIV) have been responsible for causing several severe outbreaks across the world. To protect poultry farms and to prevent the possible spread of new influenza pandemics, vaccines that are both efficacious and low-cost are in high demand. We produced stable, large hemagglutinin H5 oligomers in planta by the specific interaction between S•Tag and S•Protein. H5 oligomers combined via S•Tag::S•Protein interaction in plant crude extracts induced strong humoral immune responses, strong neutralizing antibody responses, and resistance in chickens after challenge with a wild type HPAIV H5 virus strain. In all three parameters, plant crude extracts with H5 oligomers induced better responses than crude extracts containing trimers. The neutralizing antibodies induced by by two-dose and one dose immunization with an adjuvanted crude extract containing H5 oligomer protected vaccinated chickens from two lethal H5N1 virus strains with the efficiency of 92% and 100%, respectively. Following housing vaccinated chickens together with ten non-immunized chickens, only one of these chickens had detectable levels of the H5N1 virus. To facilitate the easy storage of a candidate vaccine, the H5 oligomer crude extracts were mixed with adjuvants and stored for 3.5 and 5.5 months at 4 °C, and chickens were immunized with these crude extracts. All these vaccinated chickens survived after a lethal H5N1 virus challenge. H5 oligomer crude extracts are comparable to commercial vaccines as they also induce strong virus-neutralizing immune responses following the administration of a single dose. The cost-effective production of plant crude extract vaccine candidates and the high stability after long-term storage will enable and encourage the further exploration of this technology for veterinary vaccine development.

In Vitro and In Vivo Antiviral Studies of New Heteroannulated 1,2,3-Triazole Glycosides Targeting the Neuraminidase of Influenza A Viruses.

There is an urgent need to develop and synthesize new anti-influenza drugs with activity against different strains, resistance to mutations, and suitability for various populations. Herein, we tested in vitro and in vivo the antiviral activity of new 1,2,3-triazole glycosides incorporating benzimidazole, benzooxazole, or benzotriazole cores synthesized by using a click approach. The Cu-catalyzation strategy consisted of 1,3-dipolar cycloaddition of the azidoalkyl derivative of the respective heterocyclic and different glycosyl acetylenes with five or six carbon sugar moieties. The antiviral activity of the synthesized glycosides against wild-type and neuraminidase inhibitor resistant strains of the avian influenza H5N1 and human influenza H1N1 viruses was high in vitro and in mice. Structure–activity relationship studies showed that varying the glycosyl moiety in the synthesized glycosides enhanced antiviral activity. The compound (2R,3R,4S,5R)-2-((1-(Benzo[d]thiazol-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methoxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate (Compound 9c) had a 50% inhibitory concentration (IC50) = 2.280 µM and a ligand lipophilic efficiency (LLE) of 6.84. The compound (2R,3R,4S,5R)-2-((1-((1H-Benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methoxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate had IC50 = 2.75 µM and LLE = 7.3 after docking analysis with the H5N1 virus neuraminidase. Compound 9c achieved full protection from H1N1 infection and 80% protection from H5N1 in addition to a high binding energy with neuraminidase and was safe in vitro and in vivo. This compound is suitable for further clinical studies as a new neuraminidase inhibitor.

Transcriptome Differences in Normal Human Bronchial Epithelial Cells in Response to Influenza A pdmH1N1 or H7N9 Virus Infection.

Avian influenza A (H7N9) virus infections frequently lead to acute respiratory distress syndrome and death in humans. The emergence of H7N9 virus infections is a serious public health threat. To identify virus–host interaction differences between the highly virulent H7N9 and pandemic influenza H1N1 (pdmH1N1), RNA sequencing was performed of normal human bronchial epithelial (NHBE) cells infected with either virus. The transcriptomic analysis of host cellular responses to viral infection enables the identification of potential cellular factors related to infection. Significantly different gene expression patterns were found between pdmH1N1- and H7N9-infected NHBE cells. In addition, the H7N9 virus infection induced strong immune responses, while cellular repair mechanisms were inhibited. The differential expression of specific factors observed between avian H7N9 and pdmH1N1 influenza virus strains can account for variations in disease pathogenicity. These findings provide a framework for future studies examining the molecular mechanisms underlying the pathogenicity of avian H7N9 virus.

Next Generation of Computationally Optimized Broadly Reactive HA Vaccines Elicited Cross-Reactive Immune Responses and Provided Protection against H1N1 Virus Infection.

Vaccination is the best way to prevent influenza virus infections, but the diversity of antigenically distinct isolates is a persistent challenge for vaccine development. In order to conquer the antigenic variability and improve influenza virus vaccine efficacy, our research group has developed computationally optimized broadly reactive antigens (COBRAs) in the form of recombinant hemagglutinins (rHAs) to elicit broader immune responses. However, previous COBRA H1N1 vaccines do not elicit immune responses that neutralize H1N1 virus strains in circulation during the recent years. In order to update our COBRA vaccine, two new candidate COBRA HA vaccines, Y2 and Y4, were generated using a new seasonal-based COBRA methodology derived from H1N1 isolates that circulated during 2013–2019. In this study, the effectiveness of COBRA Y2 and Y4 vaccines were evaluated in mice, and the elicited immune responses were compared to those generated by historical H1 COBRA HA and wild-type H1N1 HA vaccines. Mice vaccinated with the next generation COBRA HA vaccines effectively protected against morbidity and mortality after infection with H1N1 influenza viruses. The antibodies elicited by the COBRA HA vaccines were highly cross-reactive with influenza A (H1N1) pdm09-like viruses isolated from 2009 to 2021, especially with the most recent circulating viruses from 2019 to 2021. Furthermore, viral loads in lungs of mice vaccinated with Y2 and Y4 were dramatically reduced to low or undetectable levels, resulting in minimal lung injury compared to wild-type HA vaccines following H1N1 influenza virus infection.

Anti-Covid-19 Drug Analogues: Synthesis of Novel Pyrimidine Thioglycosides as Antiviral Agents Against SARS-COV-2 and Avian Influenza H5N1 Viruses.

A class of pyrimidine thioglycoside analogs (6a–h) were synthesized from a reaction of 2-cyano-3,3-dimercapto-N-arylacrylamide (2a–d) and thiourea to produce the corresponding 4-amino-2-mercapto-N-arylpyrimidine-5-carboxamide derivatives (3a–d), and stirring of compounds (3a–d) with peracylated α-d-gluco- and galacto-pyranosyl bromides (4a,b) in DMF–sodium hydride gave the corresponding pyrimidine thioglycosides (5a–h). Deacetylation of the pyrimidine thioglycosides via a reaction with dry NH3/MeOH gave the corresponding free pyrimidine thioglycosides (6a–h). The compounds have been characterized by 13C NMR, 1H NMR, and IR. Pharmacological evaluation of compounds 3a–d, 5a–h, and 6a–h in vitro against SARS-COV-2 and Avian Influenza H5N1 virus strains revealed that some compounds possess interesting activity.

Comparison of hemagglutination inhibition and hemagglutinin pseudovirus neutralization titres in relation to protection against influenza in a mouse model.

The hemagglutination inhibition (HI) test has long been used as a standard measure of antibody response for inactivated influenza vaccines. However, the HI test has limitations, such as insensitivity when using some H3N2 virus strains and failure to detect neutralizing antibodies that target regions distant from the receptor binding site. We therefore examined a hemagglutinin pseudovirus neutralization (PVN) test as a possible supplement or alternative to the HI test. We evaluated the association of HI or PVN titres with protection against influenza infection in mice based on morbidity (where the illness was defined as 25% body weight loss). We assessed this relationship using dose-response models incorporating HI or PVN titres as a variable. The morbidity was correlated with the pre-exposure titres, and such a correlation was well described by a modified dose-response model. The mathematical modelling suggests that PVN titres consistently show a stronger association with invivo protection as compared to HI titres in mice. Given our findings, the PVN test warrants further investigation as a tool for evaluating antibody responses to influenza vaccines containing hemagglutinin. The resulting models may also be useful for analyzing human clinical data to identify potentially protective antibody titres against influenza illness.

Apoferritin nanoparticle based dual-antigen influenza conjugate vaccine with potential cross-protective efficacy against heterosubtypic influenza virus

Ferritin nanoparticles with self-assembling properties have been widely explored as vaccine carrier by displaying foreign antigens through genetic fusion strategy. In the present work, an apoferritin (AFt) nanoparticle was tested as influenza vaccine carrier by chemically conjugating a matrix protein 2 ectodomain (M2e) antigen peptide or/and the full-length hemagglutinin (HA) antigen on the outer surface of the AFt, with heterobifunctional sSMCC or SM(PEG)24 containing PEG chain as linkers. To each AFt nanoparticle, about 30–32 M2e or 1.8 HA antigen could be coupled. The AFt-(PEG)24-M2e, in which the M2e was coupled through SM(PEG)24 containing PEG chain, conferred higher protective efficacy in immunized mice than AFt-M2e did, but was less effective than AFt-(PEG)24-HA. When both M2e and HA were coupled, the synthesized dual-antigen vaccine candidate AFt-(PEG)24-M2e/HA elicited high level of M2e and HA antigen-specific antibodies and conferred 100% protection against lethal infection of homologous PR8 H1N1 virus strain and 70% protection against a heterologous A/FM/1/47 (FM1, H1N1) strain, which was more effective than the M2e or HA single antigen vaccine candidates. The potential cross-protective effect of the dual-antigen vaccine was further demonstrated by significant specific hemagglutination inhibition (HAI) titers in serum of the immunized mice against three other heterologous viral strains including A/Singapore/GP1908/2015 (IVR-180) H1N1, A/Anhui/1/2005 H5N1, and A/Hong Kong H3N2.

Antiviral activity and mechanism of ESC-1GN from skin secretion of Hylarana guentheri against influenza A virus

Development of new and effective antiinfluenza drugs is critical for prophylaxis and treatment of influenza A virus (IAV) infection. A wide range of amphibian skin secretions have been identified to show antiviral activity. Our previously reported ESC-1GN, a peptide from the skin secretion of Hylarana guentheri, displayed good antimicrobial and antiinflammatory effects. Here, we found that ESC-1GN possessed significant antiviral effects against IAVs. Moreover, ESC-1GN could inhibit the entry of divergent H5N1 and H1N1 virus strains with the IC50 values from 1.29 to 4.59 μM. Mechanism studies demonstrated that ESC-1GN disrupted membrane fusion activity of IAVs by interaction with HA2 subunit. The results of site-directed mutant assay and molecular docking revealed that E105, N50 and the residues around them on HA2 subunit could form hydrogen bonds with amino acid on ESC-1GN, which were critical for ESC-1GN binding to HA2 and inhibiting the entry of IAVs. Altogether, these not only suggest that ESC-1GN maybe represent a new type of excellent template designing drugs against IAVs, but also it may shed light on the immune mechanism and survival strategy of H.guentheri against viral pathogens.

Identifying novel amino acid substitutions of hemagglutinin involved in virulence enhancement in H7N9 virus strains

BackgroundTo identify site-specific features of amino acid substitutions that confer enhanced H7N9 virulence in humans, we independently generated mammalian-adapted variants of A/Anhui/1/2013 (AH-H7N9) and A/Shanghai/2/2013 (SH-H7N9) by serial passaging in Madin-Darby canine kidney (MDCK) cells.MethodsVirus was respectively extracted from cell culture supernatant and cells, and was absolutely quantified by using real-time polymerase chain reaction. Viral RNAs were extracted and subjected to sequencing for identifying mutations. Then, site-specific mutations introduced by viral passaging were selected for further constructing HA7 or NA9 mutant plasmids, which were used to generate recombinant viruses. The interaction between the recombinant HA and receptors, H7N9-pseudotyped viruses and receptors were detected.ResultsBoth subtypes displayed high variability in replicative capability and virulence during serial passaging. Analysis of viral genomes revealed multiple amino acid mutations in the hemagglutinin 7 (HA7) (A135T [AH-H7N9], T71I [SH-H7N9], T157I [SH-H7N9], T71I-V223I [SH-H7N9], T71I-T157I-V223I [SH-H7N9], and T71I-T157I-V223I-T40I [SH-H7N9]), and NA9 (N171S [AH-H7N9] and G335S [AH-H7N9]) proteins in various strains of the corresponding subtypes. Notably, quite a few amino acid substitutions indeed collectively strengthened the interactions between H7N9 strains and sialic acid receptors. Moreover, some of the amino acid substitutions identified were highly and specifically cytopathogenic to MDCK cells.ConclusionsThis study demonstrated that AH-H7N9 and SH-H7N9 subtypes can acquire enhanced receptor affinity for sialic receptors through novel amino acid substitutions. Such changes in affinitive interactions are conferred by site-specific mutations of HA7 proteins that affect the virulence and pathology of the virus strain, and/or limited compatibility between the host and the virus strain.

Synthesis of novel pyrimidine thioglycosides as structural analogs of favipiravir (avigan) and their antibird flu virus activity

Novel class of amino pyrimidine thioglycoside derivatives were designed from sodium 2-cyano-3-(arylamino)prop-1-ene-1,1-bis(thiolate) 1a-d and guanidine hydrochloride 2 to afford the corresponding sodium 2,6-diamino-5-aryl-1,2-dihydropyrimidine-4-thiolate 3a-d, which in coupling with peracylated α-D-gluco- and galactopyranosyl bromides 5a,b in DMF gave the corresponding pyrimidine thioglycosides 6a-h. Acidification of 2,6-diamino-5-aryl-1,2-dihydropyrimidine-4-thiolate salts 3a-d with hydrochloric acid formed the corresponding pyrimidine-4-thioles 4a-d. The latter were stirred with peracetylated halo sugars α-D-gluco- and galacto-pyranosyl bromides in sodium hydride and DMF to yield the pyrimidine thioglycosides 6a-h. Deacetylation of the pyrimidine thioglycosides gave the corresponding free pyrimidine thioglycosides 7a-h. The compounds were characterized by 13C NMR, 1H NMR, and IR. The pyrimidine thioglycosides 6a-h and free pyrimidine thioglycosides 7a-h were tested against H5N1 virus strain and exhibited high to moderate activity.

Protective efficacy of a polyvalent influenza A DNA vaccine against both homologous (H1N1pdm09) and heterologous (H5N1) challenge in the ferret model

This study describes the protective efficacy of a novel influenza plasmid DNA vaccine in the ferret challenge model. The rationally designed polyvalent influenza DNA vaccine encodes haemagglutinin and neuraminidase proteins derived from less glycosylated pandemic H1N1 (2009) and H3N2 (1968) virus strains as well as the nucleoprotein (NP) and matrix proteins (M1 and M2) from a different pandemic H1N1 (1918) strain. Needle-free intradermal immunisation with the influenza DNA vaccine protected ferrets against homologous challenge with an H1N1pdm09 virus strain, demonstrated by restriction of viral replication to the upper respiratory tract and reduced duration of viral shedding post-challenge. Breadth of protection was demonstrated in two heterologous efficacy experiments in which animals immunised with the influenza DNA vaccine were protected against challenge with a highly pathogenic avian influenza H5N1 virus strain with reproducible survival and clinical outcomes.

Dynamics and features of manifestation of highly pathogenic avian influenza in the Republic of Tuva

The dynamics and features of the manifestation of highly pathogenic avian influenza A/H5N1 were studied on the territory of the Republic of Tuva, where it was first recorded in 2006 in wild migratory waterfowl of the duck family, mainly great crested grebe ducks. In the epizootic process of highly pathogenic avian flu on the territory of the Republic, causal-temporal relationships with the seasonal migration of wild waterfowl from the countries of South-East Asia have been noted. Epizootics of highly pathogenic avian flu were observed in 2006, 2009, 2010, 2014, 2015, 2016. In 2016, as a result of mutation of the H5N1 virus strain, an outbreak of highly pathogenic avian flu of the H5N8 strain was registered. Outbreaks of highly pathogenic avian flu H5 and H7 subtypes simultaneously with low pathogenic subtypes of avian flu H3 were noted in 2014, H9 – in 2013 and 2014. In the study of blood serum of birds in the years officially free from avian flu, antibodies to hemagglutinins of the virus of different subtypes were detected in 11.2-50.0% of cases. Despite the absence of bird mortality, this indicates a constant circulation of avian influenza agent in the body of waterfowl. On the territory of the Republic, avian flu has not spread among poultry due to natural-geographical, socio-economic conditions. The development of distant pasture farming does not provide for the maintenance and breeding of poultry in the unfavorable area of the lake UvsNuur; the local population does not have a tradition of hunting for wild fowl, which prevents contact between wild and domestic birds; there are no lakes or pond reservoirs near the only poultry farm in the Republic with a small stock, which prevents wild waterfowl from entering and passing through flying passages.

The Dynamics of the Ferret Immune Response During H7N9 Influenza Virus Infection.

As the recent outbreak of SARS-CoV-2 has highlighted, the threat of a pandemic event from zoonotic viruses, such as the deadly influenza A/H7N9 virus subtype, continues to be a major global health concern. H7N9 virus strains appear to exhibit greater disease severity in mammalian hosts compared to natural avian hosts, though the exact mechanisms underlying this are somewhat unclear. Knowledge of the H7N9 host-pathogen interactions have mainly been constrained to natural sporadic human infections. To elucidate the cellular immune mechanisms associated with disease severity and progression, we used a ferret model to closely resemble disease outcomes in humans following influenza virus infection. Intriguingly, we observed variable disease outcomes when ferrets were inoculated with the A/Anhui/1/2013 (H7N9) strain. We observed relatively reduced antigen-presenting cell activation in lymphoid tissues which may be correlative with increased disease severity. Additionally, depletions in CD8+ T cells were not apparent in sick animals. This study provides further insight into the ways that lymphocytes maturate and traffic in response to H7N9 infection in the ferret model.

Whole-genome sequences of two influenza A (H3N2) virus strains isolated from Qinghai, China

Influenza A (H3N2) virus has a faster evolution rate than other types of influenza viruses. In this study, whole genome sequencing was performed to better understand the molecular evolution of influenza H3N2 and the protective effect of influenza virus vaccine in Qinghai Province, China, in 2017. Complete sequences of eight gene segments of two seasonal influenza H3N2 isolates were sequenced and analyzed using DNASTAR and MEGA 6.06 software. Additionally, the three-dimensional structure of the HA protein was predicted using the SWISS-MODEL server. Phylogenetic and amino acid sequence analysis revealed that two Qinghai H3N2 isolates were typical low-pathogenic influenza viruses, and were relatively closely related to the 2016–2017 vaccine strain, 3C.2a-A/Hong Kong/4801/2014. The presence of several antigenic site substitutions (T131K, G/R142K, K160T and R261Q in the HA protein) were specific for the two Qinghai H3N2 virus strains. In addition, amino acid substitution of K160T at the glycosylation site of HA and H75P in PB1-F2 in Qinghai isolates might affect the antibody binding ability and virulence of the influenza virus. The presence of several antigenic site mutations in the Qinghai H3N2 isolates confirmed the evolution of circulating H3N2 strains.

Toward Developing Therapies against Corona Virus: Synthesis and Anti-Avian Influenza Virus Activity of Novel Cytosine Thioglycoside Analogues.

A series of pyrimidine and pyrimidine thioglycoside derivatives were newly synthesized using sodium 2-cyano-3-(arylamino)prop-1-ene-1,1-bis(thiolates) and urea to give the corresponding sodium 6-amino-5-aryl-2-oxo-1,2-dihydropyrimidine-4-thiolates. Stirring of the latter with peracetylated α-d-gluco- and galacto-pyranosyl bromides in DMF afforded the corresponding pyrimidine thioglycosides. On the other hand, treatment of 6-amino-5-aryl-2-oxo-1,2-dihydropyrimidine-4-thiolate salts with hydrochloric acid produced the corresponding pyrimidine-4-thioles, which on stirring with α-d-gluco- and galacto-pyranosyl bromides in sodium hydride and DMF gave the corresponding pyrimidine thioglycosides. Deacetylation of the protected pyrimidine thioglycosides gave the corresponding free pyrimidine thioglycosides. The synthesized compounds have been characterized by 13C NMR, 1H NMR, and IR spectroscopy. The pyrimidine thioglycosides and free pyrimidine thioglycosides were tested against avian influenza H5N1 virus strain and exhibited highest to moderate activity.

Differential Antibody Recognition of H3N2 Vaccine and Seasonal Influenza Virus Strains Based on Age, Vaccine Status, and Sex in the 2017-2018 Season.

An antigenic mismatch between the vaccine and circulating H3N2 strains was hypothesized to contribute to the severity of the 2017-2018 season in North America. Serum and nasal washes were collected from influenza positive and negative patients during the 2017-2018 season to determine neutralizing antibody (nAb) titers and for influenza virus sequencing, respectively. The circulating and vaccine H3N2 virus strains were different clades, with the vaccine strain being clade 3C.2a and the circulating viruses being 3C.2a2 or 3C.3a. At enrollment, both the H3N2 negative and positive patients had greater nAb titers to the egg-adapted vaccine virus compared to the cell-grown vaccine but the H3N2-negative population had significantly greater titers to the circulating 3C.2a2. Among H3N2-positive patients, vaccination, younger age, and female sex were associated with greater nAb responses to the egg-adapted vaccine H3N2 virus but not to the cell-grown vaccine or circulating viruses. For the 2017-2018 circulating viruses, mutations introduced by egg adaptation decreased vaccine efficacy. No increased protection was afforded by vaccination, younger age, or female sex against 2017-2018 circulating H3N2 viruses.