Antigenic Site Variation in the Hemagglutinin of Pandemic Influenza A(H1N1)pdm09 Viruses between 2009–2017 in Ukraine

Abstract

The hemagglutinin (HA) is a major influenza virus antigen, which, once recognized by antibodies and substitutions in HA genes, helps virus in escaping the human immune response. It is therefore critical to perform genetic and phylogenetic analysis of HA in circulating influenza viruses. We performed phylogenetic and genetic analysis of isolates from Ukraine, the vaccine strain and reference strains were used to phylogenetically identify trends in mutation locations and substitutions. Ukrainian isolates were collected between 2009–2017 and clustered in the influenza genetic groups 2, 6, 7, and 8. Genetic changes were observed in each of the antigenic sites: Sa – S162T, K163Q, K163I; Sb – S185T, A186T, S190G, S190R; Ca1 – S203T, R205K, E235V, E235D, S236P; Ca2 – P137H, H138R, A141T, D222G, D222N; Cb – A73S, S74R, S74N. In spite of detected mutations in antigenic sites, Ukrainian isolates retained similarity to the vaccine strain A/California/07/09 circulated during 2009–2017. However, WHO recommended a new vaccine strain A/Michigan/45/2015 for the Southern Hemisphere after the emergence of the new genetic groups 6B.1 and 6B.2. Our study demonstrated genetic variability of HA protein of A(H1N1)pdm09 viruses isolated in 2009–2017 in Ukraine. Influenza surveillance is very important for understanding epidemiological situations.

Whole-genome sequencing reveals origin and evolution of influenza A(H1N1)pdm09 viruses in Lincang, China, from 2014 to 2018

“…Consistent with global trends [7,24,32], our analyses from phylogenies using diverse gene segments indicate that all A(H1N1)pdm09 strains in Lincang, China, from 2014 to 2018, originated from the clade 6B, and deeply time-scale analyses reveal that the most recent common ancestor (TMRCA) of all Lincang strains in this study aroused in~2012.4240 year. And recently the subclade 6B.1A has been predominated with a TMRCA in~2016.5683 year for the local areas of southwest china.…”

“…It is well-known that the influenza virus genome consists of eight gene segments and their high variability originates from sequence changes located in eight gene segments (HA, NA, M, NP, NS, PA, PB1 and PB2) [7]. The HA gene encodes the viral surface glycoprotein HA, which is responsible for binding to sialic acids (SAs), serving as the viral receptors on host cells and for fusion of the viral and host cell membranes on endocytosis.…”

In silico analysis and molecular characterization of Influenza A (H1N1) pdm09 virus circulating and causing major outbreaks in central India, 2009-2019

“…One of them is the mutations accumulated in the HA protein of Influenza A/H1N1pdm09 virus ( 21 ). HA protein is present as H0 which cleaved into HA1 and HA2 by the host cell ( 30 ). Influenza A/H1N1pdm09 HA1 subunit contains five antigenic sites Sb, Ca1, Ca2 and Cb ( 30 ).…”

“…HA protein is present as H0 which cleaved into HA1 and HA2 by the host cell ( 30 ). Influenza A/H1N1pdm09 HA1 subunit contains five antigenic sites Sb, Ca1, Ca2 and Cb ( 30 ). In addition to N-glycosylation, mutations in these sites change the antigenicity of influenza A/H1N1pdm09 HA1 and generate different variants that escape the neutralizing antibodies ( 21 ).…”

Progress in the Development of Universal Influenza Vaccines

“…), requiring the development of new targeted vaccines [ 16 ]. Thus, numerous challenges exist with regard to controlling the influenza virus using traditional influenza flu vaccines [ 17 , 18 , 19 , 20 , 21 ], highlighting the urgent need for development of universal influenza vaccines to promote influenza prevention and control.…”