Severe cases of seasonal influenza in Russia in 2017-2018

The 2017-2018 influenza epidemic season in Russia was characterized by a relatively low morbidity and mortality. We evaluated herd immunity prior to the 2017-2018 influenza season in hemagglutination inhibition assay, and performed characterization of influenza viruses isolated from severe or fatal influenza cases and from influenza cases in people vaccinated in the fall of 2017. During the 2017-2018 epidemic season, 87 influenza A and B viruses were isolated and viruses of the 75 influenza cases, including selected viral isolates and viruses analyzed directly from the original clinical material, were genetically characterized. The analyzed A(H1N1)pdm09 viruses belonged to clade 6B.1, B/Yamagata-like viruses belonged to clade 3, and B/Victoria-like viruses belonged to clade 1A and they were antigenically similar to the corresponding vaccine strains. A(H3N2) viruses belonged to clade 3C.2a and were difficult to characterize antigenically and the analysis indicated antigenic differences from the corresponding egg-grown vaccine strain. The next generation sequencing revealed the presence of D222/G/N polymorphism in the hemagglutinin gene in 32% of the analyzed A(H1N1)pdm09 lethal cases. This study demonstrated the importance of monitoring D222G/N polymorphism, including detection of minor viral variants with the mutations, in the hemagglutinin gene of A(H1N1)pdm09 for epidemiological surveillance. One strain of influenza virus A(H1N1)pdm09 was resistant to oseltamivir and had the H275Y amino acid substitution in the NA protein. All other isolates were susceptible to NA inhibitors. Prior to the 2017-2018 epidemic season, 67.4 million people were vaccinated, which accounted for 46.6% of the country's population. Just before the epidemic season 33-47% and 24-30% of blood sera samples collected within the territory of Russia showed the presence of protective antibody titers against vaccine strains of influenza A and influenza B/Victoria-like, respectively. Mass vaccination of the population had evidently reduced the severity of the flu epidemic during the 2017-2018 influenza epidemic season in Russia.

Frequent Genetic Mismatch between Vaccine Strains and Circulating Seasonal Influenza Viruses, Hong Kong, China, 1996-2012

The World Health Organization selects influenza vaccine compositions biannually to cater to peaks in temperate regions. In tropical and subtropical regions, where influenza seasonality varies and epidemics can occur year-round, the choice of vaccine remains uncertain. Our 17-year molecular epidemiologic survey showed that most influenza A(H3N2) (9/11) and B (6/7) vaccine strains had circulated in East Asia >1 year before inclusion into vaccines. Northern Hemisphere vaccine strains and circulating strains in East Asia were closely matched in 7 (20.6%) of 34 seasons for H3N2 and 5 (14.7%) of 34 seasons for B. Southern Hemisphere vaccines also had a low probability of matching (H3N2, 14.7%; B, 11.1%). Strain drift among seasons was common (H3N2, 41.2%; B, 35.3%), and biannual vaccination strategy (Northern Hemisphere vaccines in November followed by Southern Hemisphere vaccines in May) did not improve matching. East Asia is an important contributor to influenza surveillance but often has mismatch between vaccine and contemporarily circulating strains.

Broadening the H5N3 Vaccine Immunogenicity against H5N1 Virus by Modification of Neutralizing Epitopes

The highly pathogenic avian influenza (HPAI) H5N1 virus remains to be one of the world's largest pandemic threats due to the emergence of new variants. The rapid evolution of new sub-lineages is currently the greatest challenge in vaccine development. In this study, we developed an epitope modified non-pathogenic H5N3 (A/duck/Singapore/97) vaccine for broad protection against influenza H5 subtype. H5N3 hemagglutinin (HA) mutant reassortant viruses with A/Puerto Rico/8/34 (PR8) backbone were generated by mutating amino acids at the 140th loop and 190th α-helix of hemagglutinin. The cross-neutralizing efficacy of reverse genetics-derived H5N3HA (RG-H5N3HA) mutants was confirmed by testing reactivity with reference chicken anti-H5N1 clade 2 virus sera. Furthermore, RG-H5N3HA mutant immunized mice induced cross-neutralizing antibodies and cross-protection against distinct H5N1 viral infection. Our findings suggest that the use of non-pathogenic H5 viruses antigenically related to HPAI-H5N1 allows for the development of broadly protective vaccines and reduces the need for biosafety level 3 (BSL3) containment facilities.

Detection and differentiation of influenza viruses with glycan-functionalized gold nanoparticles

Accurate diagnosis of influenza viruses is difficult and generally requires a complex process because of viral diversity and rapid mutability. In this study, we report a simple and rapid strategy for the detection and differentiation of influenza viruses using glycan-functionalized gold nanoparticles (gGNPs). This method is based on the aggregation of gGNP probes on the viral surface, which is mediated by the specific binding of the virus to the glycans. Using a set of gGNPs bearing different glycan structures, fourteen influenza virus strains, including the major subtypes currently circulating in human and avian populations, were readily differentiated from each other and from a human respiratory syncytial virus in a single-step colorimetric procedure. The results presented here demonstrate the potential of this gGNP-based system in the development of convenient and portable sensors for the clinical diagnosis and surveillance of influenza viruses.

Possible Triggering Effect of Influenza Vaccination on Psoriasis

Psoriasis is a chronic, recurrent, immune-mediated inflammatory disease and it can be provoked or exacerbated by a variety of different environmental factors, particularly infections and drugs. In addition, a possible association between vaccination and the new onset and/or exacerbation of psoriasis has been reported by a number of different authors. The aim of this study is to investigate the effects of influenza vaccination on patients with psoriasis. Here, we report the findings from 43 patients suffering from psoriasis (clinical phenotypes as mixed guttate/plaque lesions, palmoplantar or scalp psoriasis) whose diseases had been triggered after influenza vaccination applied in the 2009-2010 season. The short time intervals between vaccination and psoriasis flares in our patients and the lack of other possible triggers suggest that influenza vaccinations may have provocative effects on psoriasis. However, further large and controlled studies need to be carried out to confirm this relationship.

[Two types of NP-NP associations in influenza virus-infected cells]

Two types of NP-NP associations are shown to form in the influenza virus-infected cells. Early NP synthesis gives rise to NP associations stabilized by relatively weak bonds. These structures are designed as NP multimers. The high protease- and heat-sensitivities allow NP-multimers to be regarded as incompletely folded proteins. Post-translationally, NP-multimers transform to compact NP associations (NP oligomers) that are relatively highly heat-and protease-resistant. The NP-multimers untransformed to the folded compact NP-oligomers accumulate in the cells and partially degraded. Whether both types of NP-NP associations may be of significance is under discussion.

DNA vaccine expressing conserved influenza virus proteins protective against H5N1 challenge infection in mice

Influenza vaccination practice, which is based on neutralizing antibodies, requires being able to predict which viral strains will be circulating. If an unexpected strain, as in the 1997 H5N1 Hong Kong outbreak, or even a pandemic emerges, appropriate vaccines may take too long to prepare. Therefore, strategies based on conserved influenza antigens should be explored. We studied DNA vaccination in mice with plasmids expressing conserved nucleoprotein (NP) and matrix (M) from an H1N1 virus. After vaccination, mice were challenged with A/H5N1 viruses of low, intermediate, and high lethality. A/NP+A/M DNA vaccination reduced replication of A/Hong Kong/486/97 (HK/486), a nonlethal H5N1 strain, and protected against lethal challenge with more virulent A/Hong Kong/156/97 (HK/156). After HK/156 exposure, mice survived rechallenge with A/Hong Kong/483/97 (HK/483), although the DNA vaccination alone protected poorly against this highly virulent strain. In the absence of antigenically matched hemagglutinin-based vaccines, DNA vaccination with conserved influenza genes may provide a useful first line of defense against a rapidly spreading pandemic virus.

Role of influenza A virus hemagglutinin in neurovirulence for mammalians

Influenza viruses with potential neuroinvasiveness for humans emerged in Hong Kong in 1997. Prophylactic and therapeutic strategies are urgently needed for controlling the central nervous system complications caused by influenza. Here we review recent advances toward understanding of the possible mechanisms of the neuropathogenesis of influenza virus infection, especially focusing on the role of viral hemagglutinin glycoprotein.