The haemagglutinins of influenza A (H1N1) viruses in the ‘O’ or ‘D’ phases exhibit biological and antigenic differences

Abstract

SummaryInfluenza A (H1N1) viruses when initially isolated in mammalian cell cultures (MDCK cells) had different agglutination reactions with chicken and guinea-pig erythrocytes compared to the same viruses after passage. On first isolation the virus HA resembled the ‘O’ phase viruses described originally by Burnet and Bull and agglutinated mammalian but not avian erythrocytes. After passage, the virus HA resembled a classical ‘D’ phase virus and agglutinated both avian and mammalian erythrocytes. Monoclonal and polyclonal antisera detected antigenic differences between the HAs of the viruses in the ‘O’ and ‘D’ phases. The ‘O’ phase virus HA reacted preferentially with antibodies in post infection human antisera. Viruses in the ‘O’ phase replicated poorly in the allantoic cavity of embryonated hens' eggs whilst ‘D’ phase virus replicated in both MDCK cells and in embryonated hens' eggs. At least three distinguishable subpopulations of influenza A (H1N1) viruses may co-exist in clinical throat swab material, including viruses possessing HAs in the ‘O’ and ‘D’ phases and other ‘D’ phase viruses cultivable in embryonated hens' eggs but antigenically distinguishable from the corresponding ‘D’ phase virus in MDCK cells.

Studies on the molecular basis for loss of the ability of recent influenza A (H1N1) virus strains to agglutinate chicken erythrocytes

“…Group I viruses agglutinated goose, human and guineapig erythrocytes and CRBC, while group 2 viruses agglutinated the first three but not CRBC. Azzi et al (1993) also reported the same phenomenon in recently isolated HIN1 viruses. The candidate viral protein for host-specific haemagglutination was considered to be the HA glycoprotein.…”

Detection of influenza antigenic variants directly from clinical samples using polyclonal antibody based proximity ligation assays

“…Minor antigenic variants within a heterogeneous population cannot be assessed by the serological method of HI (Patterson and Oxford, 1986). More importantly, mutations of the receptor binding site in HA (Nobusawa and Nakajima, 1988) (antigenic drift) are causing human seasonal H1N1 (Azzi et al, 1993; Morishita et al, 1993) and H3N2 influenza A viruses (Nobusawa et al, 2000) to lose the ability to bind to RBCs. For example, the mutations at residues 193, 196, 197, and 225 in the human epidemic H1N1 influenza A viruses in 1988 or later caused the loss of their abilities to agglutinate chicken RBCs due to four amino acid changes (Morishita et al, 1996).…”

Influenza vaccines manufacturing in continuous cell lines: problems and solutions

“…The other approach is to perform the reassortment process with PR8 virus in the primary chicken embryo kidney cells instead of eggs. Both ways are associated with the emergence of the adaptation mutations in the HA protein that can change the receptor-binding and antigenic properties, or change the pH of HA fusion [25][26][27].…”