Neuraminidase-mediated haemagglutination of recent human influenza A(H3N2) viruses is determined by arginine 150 flanking the neuraminidase catalytic site

Abstract

Over the last decade, an increasing proportion of circulating human influenza A(H3N2) viruses exhibited haemagglutination activity that was sensitive to neuraminidase inhibitors. This change in haemagglutination as compared to older circulating A(H3N2) viruses prompted an investigation of the underlying molecular basis. Recent human influenza A(H3N2) viruses were found to agglutinate turkey erythrocytes in a manner that could be blocked with either oseltamivir or neuraminidase-specific antisera, indicating that agglutination was driven by neuraminidase, with a low or negligible contribution of haemagglutinin. Using representative virus recombinants it was shown that the haemagglutinin of a recent A(H3N2) virus indeed had decreased activity to agglutinate turkey erythrocytes, while its neuraminidase displayed increased haemagglutinating activity. Viruses with chimeric and mutant neuraminidases were used to identify the amino acid substitution histidine to arginine at position 150 flanking the neuraminidase catalytic site as the determinant of this neuraminidase-mediated haemagglutination. An analysis of publicly available neuraminidase gene sequences showed that viruses with histidine at position 150 were rapidly replaced by viruses with arginine at this position between 2005 and 2008, in agreement with the phenotypic data. As a consequence of neuraminidase-mediated haemagglutination of recent A(H3N2) viruses and poor haemagglutination via haemagglutinin, haemagglutination inhibition assays with A(H3N2) antisera are no longer useful to characterize the antigenic properties of the haemagglutinin of these viruses for vaccine strain selection purposes. Continuous monitoring of the evolution of these viruses and potential consequences for vaccine strain selection remains important.

Influenza A Virus Hemagglutinin–Neuraminidase–Receptor Balance: Preserving Virus Motility

“…Mutations in the active site are primarily observed upon development of resistance against NA inhibitors (NAIs) [64][65][66][67]. As an exception, recent human H3N2 viruses that depend on NA rather than HA for hemagglutination were recently shown to carry HA proteins with very weak receptor-binding properties and NA with presumed low activity due to a mutation in the catalytic site [68]. NA-dependent hemagglutination could also be observed upon passaging of H3N2 viruses on MDCK cells [69].…”

NAction! How Can Neuraminidase-Based Immunity Contribute to Better Influenza Virus Vaccines?

“…The last two points are important, since NA-based immunity, if robust enough, might have a significant impact on the transmission of the virus, which might increase the effectiveness of the influenza virus vaccine even in areas with low vaccine coverage. Finally, it has been reported that some of the currently circulating H3N2 viruses use their NA instead of their HA for attachment to cells ( 66 – 68 ). In this case, anti-NA antibodies might also have HI activity.…”

Passage of influenza A/H3N2 viruses in human airway cells removes artefactual variants associated with neuraminidase-mediated binding

“…It was shown recently [ 9 ] that an H150R mutation in the NA of A/H3N2 viruses was responsible for the NA-mediated agglutination of turkey RBCs. This mutation became fixed in the majority of circulating viruses around 2008.…”