The S190R mutation in the hemagglutinin protein of pandemic H1N1 2009 influenza virus increased its pathogenicity in mice

Abstract

Human influenza viruses preferentially bind to sialic acid-α2,6-galactose (SAα2,6Gal) receptors, which are predominant in human upper respiratory epithelia, whereas avian influenza viruses preferentially bind to SAα2,3Gal receptors. However, variants with amino acid substitutions around the receptor-binding sites of the hemagglutinin (HA) protein can be selected after several passages of human influenza viruses from patients' respiratory samples in the allantoic cavities of embryonated chicken eggs. In this study, we detected an egg-adapted HA S190R mutation in the pandemic H1N1 virus 2009 (pdmH1N1), and evaluated the effects of this mutation on receptor binding affinity and pathogenicity in mice. Our results revealed that residue 190 is located within the pocket structure of the receptor binding site. The single mutation to arginine at position 190 slightly increased the binding affinity of the virus to the avian receptor and decreased its binding to the long human α2,6-linked sialic acid receptor. Our study demonstrated that the S190R mutation resulted in earlier death and higher weight loss in mice compared with the wild-type virus. Higher viral titers at 1 dpi (days post infection) and diffuse damage at 4 dpi were observed in the lung tissues of mice infected with the mutant virus.

In Vitro Properties and Virulence of Contemporary Recombinant Influenza B Viruses Harboring Mutations of Cross-Resistance to Neuraminidase Inhibitors

“…As the original B/Phuket/3073/2013 vaccine strain was passaged in embryonated eggs, we identified in its HA protein the N196D egg-adapted substitution that could potentially increase viral pathogenicity in mice through adaptation to a α2,3 sialic acid receptor. A similar role was previously attributed for the S190R A(H1N1) egg-adapted HA mutation [33,34].…”

The Effect of Mice Adaptation Process on the Pathogenicity of Influenza A/South Africa/3626/2013 (H1N1)pdm09 Model Strain

“…The mechanism of egg adaptation was illustrated early [21,22]. It was shown that the S190R variant of the A/Hunan/26/2016 (H1N1)pdm09 virus had increased pathogenicity in mice [21]. However, in our study, the presence of this component in the population of the virus did not increase its pathogenicity (Figure 5).…”

“…In addition, the R variant is usually a result of egg adaptation. The mechanism of egg adaptation was illustrated early [21,22]. It was shown that the S190R variant of the A/Hunan/26/2016 (H1N1)pdm09 virus had increased pathogenicity in mice [21].…”

Variation in the HA antigenicity of A(H1N1)pdm09-related swine influenza viruses

“…Using CA04 strain-based HA mutants generated by reverse genetics, we identified the S190R substitution in the antigenic site Sb of HA as one of the critical determinants for the differential HA antigenicity of A(H1N1)pdm09-related swIAVs (). It should be noted that the S190R substitution in HA was previously reported as an egg-adapted mutation of human A(H1N1)pdm09 viruses [63], although A/swine/Aichi/KU-OE7/2017 (H1N2), which is the only isolate possessing the S190R substitution in HA among all the A(H1N1)pdm09-related human and swine viruses available in the GISAID database (), was isolated in canine-origin AX4 cells. Importantly, we confirmed by nucleotide sequencing that the HA gene segment detected in the original specimen for A/swine/Aichi/KU-OE7/2017 (H1N2) indeed encoded arginine at amino acid position 190 (data not shown).…”