Evolution of the receptor binding properties of the influenza A(H3N2) hemagglutinin

Abstract

The hemagglutinin (HA) of influenza A(H3N2) virus responsible for the 1968 influenza pandemic derived from an avian virus. On introduction into humans, its receptor binding properties had changed from a preference for avian receptors (α2,3-linked sialic acid) to a preference for human receptors (α2,6-linked sialic acid). By 2001, the avidity of human H3 viruses for avian receptors had declined, and since then the affinity for human receptors has also decreased significantly. These changes in receptor binding, which correlate with increased difficulties in virus propagation in vitro and in antigenic analysis, have been assessed by virus hemagglutination of erythrocytes from different species and quantified by measuring virus binding to receptor analogs using surface biolayer interferometry. Crystal structures of HA–receptor analog complexes formed with HAs from viruses isolated in 2004 and 2005 reveal significant differences in the conformation of the 220-loop of HA1, relative to the 1968 structure, resulting in altered interactions between the HA and the receptor analog that explain the changes in receptor affinity. Site-specific mutagenesis shows the HA1 Asp-225→Asn substitution to be the key determinant of the decreased receptor binding in viruses circulating since 2005. Our results indicate that the evolution of human influenza A(H3N2) viruses since 1968 has produced a virus with a low propensity to bind human receptor analogs, and this loss of avidity correlates with the marked reduction in A(H3N2) virus disease impact in the last 10 y.

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

“…Changes in the haemagglutination activity of A(H3N2) virus isolates from 2000 to 2016 Driven by our own observations and previous reports [18][19][20], the haemagglutination activity of 83 influenza A (H3N2) viruses isolated in MDCK cells from 2000 until 2016 was investigated (Table S1, available in the online Supplementary Material), from which a representative subset is shown in Table 1 …”

“…Since the early 2000s, several groups have observed changes in the haemagglutination behaviour of influenza A(H3N2) viruses, i.e. reduced haemagglutination of commonly used erythrocytes (turkey, chicken and guinea pig erythrocytes) and poor inhibition of haemagglutination by reference post-infection ferret antisera [11,[18][19][20][21][22]. In addition to the changes in the haemagglutination behaviour of HA, the NA activity of influenza A(H3N2) viruses isolated between 2005 and 2009 was also affected [18].…”

Recent evolution of equine influenza and the origin of canine influenza

“…Virus binding to receptor analogs was measured on an Octet RED instrument (ForteBio) as previously described (38). Biotinylated 3′SLN (Neu5Acα2-3Galβ1-4GlcNAcβ) and 6′SLN (Neu5Acα2-6Galβ1-4GlcNAc) were purchased from Lectinity Holdings.…”

“…HAs for wild-type A/Equine/Newmarket/2/ 93, A/Equine/Richmond/1/07, and A/Canine/Colorado/17864/06 along with A/Equine/Richmond/1/07 mutant (S30T) and A/Canine/Colorado/17864/06 mutant (S30T) were subcloned, as previously described, into a modified pAcGP67A vector that carries a TEV protease site, a trimerization foldon domain, and a 6× His tag (38). Large-scale protein expression was performed with 2-3 L of SF9 cells.…”

Development of the cell-ELISA test for the subtype identification of circulating influenza A(H1) and A(H3) viruses

“…This method allows for the determination of the specificity of the antigen -antibody interaction. However, the continuous accumulation of the evolutional mutations in the hemagglutinin (HA) molecule of influenza A(H1N1) and especially A(H3N2) strains during the last decade have brought changes to the HA receptorbinding site that in turn led to the reduction of HA affinity to the receptors of different types of erythrocytes [3][4][5][6]. This effect complicates the identification of the subtype of some modern virus strains by HAI test.…”