Neuraminidase Receptor Binding Variants of Human Influenza A(H3N2) Viruses Resulting from Substitution of Aspartic Acid 151 in the Catalytic Site: a Role in Virus Attachment?

Abstract

This was shown not to be due to an antigenic change in hemagglutinin (HA) but was shown to be the result of a mutation in aspartic acid 151 of neuraminidase (NA) to glycine, asparagine, or alanine, which caused an oseltamivir-sensitive agglutination of RBCs. The D151G substitution was shown to cause a change in the specificity of NA such that it acquired the capacity to bind receptors, which were refractory to enzymatic cleavage, without altering its ability to remove receptors for HA. Thus, the inhibition of NA-dependent agglutination by the inclusion of oseltamivir carboxylate in the assay was effective in restoring the anti-HA specificity of the hemagglutination inhibition (HI) assay for monitoring antigenic changes in HA. Since the NA-dependent binding activity did not affect virus neutralization, and virus populations in clinical specimens possessed, at most, low levels of the "151 mutant," the biological significance of this feature of NA in, for example, immune evasion is unclear. It is apparent, however, that an important role of aspartic acid 151 in the activity of NA may be to restrict the specificity of the NA interaction and its receptor-destroying activity to complement that of HA receptor binding.

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 …”

“…Amino acid substitution 150HR in NA, which was identified to allow the NA-mediated agglutination of erythrocytes that can be blocked by oseltamivir and NA-specific antibodies, is adjacent to amino acid 151, a position at which another substitution (151DG) has been previously described to have a similar effect in influenza A(H3N2) viruses [18]. Amino acid positions 150 and 151 are located in the 150-loop (residues 147-152) at the edge of the catalytic site [24,25].…”

“…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].…”

“…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]. The amino acid substitution aspartic acid to glycine at position 151 (151DG) in NA was shown to cause binding of NA to erythrocytes, which could be reversed by addition of the NAinhibitor oseltamivir in the haemagglutination assay [18].…”

“…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]. The amino acid substitution aspartic acid to glycine at position 151 (151DG) in NA was shown to cause binding of NA to erythrocytes, which could be reversed by addition of the NAinhibitor oseltamivir in the haemagglutination assay [18]. However, the vast majority of recent A(H3N2) viruses with similar changes in haemagglutination behaviour did not have 151DG in NA.…”