Multiple Genotypes of Influenza B Virus Circulated between 1979 and 2003

Abstract

The segmented genome of influenza B virus allows exchange of gene segments between cocirculating strains. Through this process of reassortment, diversity is generated by the mixing of genes between viruses that differ in one or more gene segments. Phylogenetic and evolutionary analyses of all 11 genes of 31 influenza B viruses isolated from 1979 to 2003 were used to study the evolution of whole genomes. All 11 genes diverged into two new lineages prior to 1987. All genes except the NS1 gene were undergoing linear evolution, although the rate of evolution and the degree to which nucleotide changes translated into amino acid changes varied between lineages and by gene. Frequent reassortment generated 14 different genotypes distinct from the gene constellation of viruses circulating prior to 1979. Multiple genotypes cocirculated in some locations, and a sequence of reassortment events over time could not be established. The surprising diversity of the viruses, unrestricted mixing of lineages, and lack of evidence for coevolution of gene segments do not support the hypothesis that the reassortment process is driven by selection for functional differences.

Immunogenicity of intramuscular MF59-adjuvanted and intradermal administered influenza enhanced vaccines in subjects aged over 60: A literature review

“…40,42,43 Influenza B viruses fall in 2 major antigenically and genetically distinct lineages, B/Victoria and B/ Yamagata, co-circulating in some years among the population and currently in many countries only one type B strain, representing one of the 2 lineages, can be incorporated into the vaccine. 62,63 Increases in HI antibody titers were found against drifted B strains, both belonging to the same or different lineage as compared to vaccine strain. However, the responses prevalently satisfy, both against the vaccine and the drifted strains, only one of the 3 EMA criteria.…”

Influenza B virus-specific CD8+ T-lymphocytes strongly cross-react with viruses of the opposing influenza B lineage

“…The B/Yamagata/16/1988 lineage was the dominant lineage until the mid-1980s when B/Victoria/2/1987 made a global appearance after its earlier detection in the 1970s in China (Chen et al, 2007). Viruses of both influenza B lineages co-circulated with influenza A/H3N2 and A/H1N1 viruses during various seasonal epidemics (Ambrose & Levin, 2012;CDC, 2009;McCullers et al, 2004). However, the relative contribution of these types and subtypes of influenza virus to the respective epidemics varied over the years.…”

Natural History of Human Respiratory Syncytial Virus Inferred from Phylogenetic Analysis of the Attachment (G) Glycoprotein with a 60-Nucleotide Duplication

“…Accumulated sequence data has provided insights into the pattern of HRSV evolution, which resembles that of influenza B viruses (28,40,56), with the following characteristics. (i) Epidemics are commonly produced by viruses of the two antigenic groups, classified into more than one genotype.…”