Influenza A virus in Taiwan, 1980–2006: Phylogenetic and antigenic characteristics of the hemagglutinin gene

Abstract

Limited amount of information is available in Taiwan on the genetic or antigenic characteristics of influenza A virus prior to the establishment of a Taiwan surveillance network in 2000. Isolates of H1N1 and H3N2 viruses in Taiwan between 1980 and 2006 were studied, and part of the hemagglutinin gene was analyzed due to its importance in terms of viral infection and antibody neutralization. Results from a phylogenetic analysis indicate continuous evolutionary topology in H3N2 isolates, and two distinct H1N1 lineages. Many genetic relationships between vaccine strains and epidemic isolates appearing in Taiwan before other global locations were also observed and recorded in addition to a gradual increase in the number of N-linked glycosylation sites on partial HA1 proteins since 1980. The results from pairwise comparisons of HA1 nucleotide and deduced amino acid sequences indicate shared identities within groups organized according to their bootstrap and P-values of approximately 95.5-100% and 95.7-100% in H1N1 and 94.5-100% and 93.2-100% in H3N2 viruses, respectively. Comparisons of amino acid substitutions in the five antigenic regions reveal highly non-synonymous changes occurring in the Sb region of H1N1 and in the B region of H3N2. The results of an antigenic analysis using a hemagglutinin inhibition (HI) test indicate the presence of some epidemic strains 1-2 years earlier in Taiwan than in other parts of the world, as well as higher vaccine mismatch rates. This information supports the need for continuous surveillance of emerging influenza viruses in Taiwan, which will be useful for making global vaccine decisions.

Estimating influenza vaccine effectiveness using routine surveillance data among children aged 6–59 months for five consecutive influenza seasons

“…In this study, we did not define the status of partially vaccinated children because many influenza epidemic strains in Taiwan become the vaccine strains 2-3 years later, as shown by hemagglutination sequence comparisons. 9,14 Therefore, children aged 6-59 months were considered immunized if they had received one or more vaccine doses in the current influenza season regardless of previous influenza immunization history.…”

Contribution of antibody production against neuraminidase to the protection afforded by influenza vaccines

“…The HA glycoprotein, which mediates attachment and fusion with the host cell membrane, is the prime target for neutralizing antibodies. Several defined epitopes surrounding the HA receptor binding domain are frequently mutated in the course of antigenic drift variation . HA proteins of type A influenza viruses have been classified into 16 subtypes based on serological cross‐reactivity.…”

Antigenic characterization of novel H1 influenza A viruses in swine

“…There was less amino acid identity in the antigenic sites than in the complete HA1 region, indicating the dominance of non-synonymous substitutions at these sites 46 . Some antigenic variants were identified within clusters ChH1A and A(H1N1)pdm09-like, which had more than 2.4 AU distance compared to the other strains from Figure 4.…”