Since the emergence of human H3N2 influenza A viruses in the pandemic of 1968, these viruses have become established as strains of moderate severity. A decline in virulence has been accompanied by glycan accumulation on the hemagglutinin globular head, and hemagglutinin receptor binding has changed from recognition of a broad spectrum of glycan receptors to a narrower spectrum. The relationship...

The demonstrated link between the emergence of H3N2 variant (H3N2v) influenza A viruses (IAVs) and swine exposure at agricultural fairs has raised concerns about the human health risk posed by IAV-infected swine. Understanding the antigenic profiles of IAVs circulating in pigs at agricultural fairs is critical to developing effective prevention and control strategies. Here, 68 H3N2 IAV isolates...

Since August 2011, a total of 12 human infections with influenza A (H3N2) variant viruses with genes from avian, swine, and human viruses (i.e., A [H3N2]v) that had acquired the M gene from influenza A (H1N1)pdm09 virus have been reported to CDC. Eleven of the cases occurred in children aged <10 years. In six cases, no history of recent exposure to swine was noted, suggesting that human-to-huma...

Influenza vaccine seeds produced in chicken eggs are selected through HA and NA surface glycoproteins antigenicity, as well as through high replicative ability. Here we characterize the genetic content of recently used thirteen H3N2 influenza vaccine seeds. Interestingly, sequence analysis of the vaccine seeds shows reassortment events leading to PR8:H3N2 segment constellations, ranging from th...

For over a decade virtually all A(H3N2) influenza viruses have been resistant to the adamantane class of antivirals. However, during the 2017 influenza season in Australia, 15/461 (3.3%) adamantane-sensitive A(H3N2) viruses encoding serine at residue 31 of the M2 protein were detected, more than the total number identified globally during the last 6 years. A return to wide circulation of adaman...

This work presents the results of studies on extract obtained from root Ferula kuhistanica Korov, in relation to 2 strains influenza virus: A/Vlad/2/09(H1N1) and A/Almaty/8/98(H3N2). It has been shown that F. Korov exhibits selective antiviral activity primarily acts virus strain A/Vlad/2/09(H1N1), not showing an inhibitory effect against another antigenic variant this – A/ Almaty/8/98(H3N2). T...

To the Editor: In 1998, a new lineage of triple reassortant infl uenza A (H3N2) virus (TR-H3N2) with genes from humans (hemmaglutinin [HA], neuraminidase [NA], and poly-merase basic 1 [PB1]), swine (matrix [M], nonstructural [NS], and nucleo-protein [NP]), and birds (polymerase acidic [PA] and PB2) emerged in the U.S. swine population. Subsequently, similar viruses were isolated from turkeys (1...

Many viruses evolve rapidly. For example, haemagglutinin (HA) of the H3N2 influenza A virus evolves to escape antibody binding. This evolution of the H3N2 virus means that people who have previously been exposed to an influenza strain may be infected by a newly emerged virus. In this paper, we use Shannon entropy and relative entropy to measure the diversity and selection pressure by an antibod...

BACKGROUND H3N2 influenza viruses circulating in humans and European pigs originate from the pandemic A/Hong Kong/68 virus. Because of slower antigenic drift in swine, the antigenic divergence between swine and human viruses has been increasing. It remains unknown to what extent this results in a reduced cross-protection between recent human and swine H3N2 influenza viruses. OBJECTIVES We exa...