tetano
Editor, Senior Moderator
J Virol. 2014 Feb 12. [Epub ahead of print]
Substitutions near the hemagglutinin receptor-binding site determine the antigenic evolution of influenza A H3N2 viruses in U.S. swine.
Lewis NS, Anderson TK, Kitikoon P, Skepner E, Burke DF, Vincent AL.
Author information
Abstract
Swine influenza A virus is an endemic and economically important pathogen in pigs with the potential to infect other host species. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major component in swine influenza A vaccines. However, as a result of antigenic drift, vaccine strains must be regularly updated to reflect currently circulating strains. Characterizing the cross-reactivity between strains in pigs and seasonal influenza strains in humans is also important in assessing the relative risk of interspecies transmission of viruses from one host population to the other. Hemagglutination inhibition (HI) assay data for swine and human H3N2 viruses were used with antigenic cartography to quantify the antigenic differences among H3N2 viruses isolated from pigs in the USA from 1998-2013 and the relative cross-reactivity between these viruses and current human seasonal influenza A strains. Two primary antigenic clusters were found circulating in the pig population, but with enough diversity within and between the clusters to suggest updates in vaccine strains are needed. We identified single amino acid substitutions likely responsible for antigenic differences between the two primary antigenic clusters and between each antigenic cluster and outliers. The antigenic distance between current seasonal influenza H3 strains in humans and those endemic in swine suggests that population immunity may not prevent the introduction of human viruses into pigs and possibly vice-versa, reinforcing the need to monitor and prepare for potential incursions.
IMPORTANCE:
Influenza A virus (IAV) is an important pathogen in pigs and humans. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major target of vaccines. However, vaccine strains must be updated to reflect current strains. Characterizing the differences between seasonal IAV in humans and swine IAV is important in assessing the relative risk of interspecies transmission of viruses. We found two primary antigenic clusters of H3N2 in the U.S. pig population with enough diversity to suggest updates in swine vaccine strains. We identified changes in the HA protein that are likely responsible for these differences that may be useful in predicting when vaccines need to be updated. The difference between human H3N2 and those in swine is enough that population immunity is unlikely to prevent new introductions of human IAV into pigs or vice-versa, reinforcing the need to monitor and prepare for potential introductions.
PMID:
24522915
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24522915
Substitutions near the hemagglutinin receptor-binding site determine the antigenic evolution of influenza A H3N2 viruses in U.S. swine.
Lewis NS, Anderson TK, Kitikoon P, Skepner E, Burke DF, Vincent AL.
Author information
Abstract
Swine influenza A virus is an endemic and economically important pathogen in pigs with the potential to infect other host species. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major component in swine influenza A vaccines. However, as a result of antigenic drift, vaccine strains must be regularly updated to reflect currently circulating strains. Characterizing the cross-reactivity between strains in pigs and seasonal influenza strains in humans is also important in assessing the relative risk of interspecies transmission of viruses from one host population to the other. Hemagglutination inhibition (HI) assay data for swine and human H3N2 viruses were used with antigenic cartography to quantify the antigenic differences among H3N2 viruses isolated from pigs in the USA from 1998-2013 and the relative cross-reactivity between these viruses and current human seasonal influenza A strains. Two primary antigenic clusters were found circulating in the pig population, but with enough diversity within and between the clusters to suggest updates in vaccine strains are needed. We identified single amino acid substitutions likely responsible for antigenic differences between the two primary antigenic clusters and between each antigenic cluster and outliers. The antigenic distance between current seasonal influenza H3 strains in humans and those endemic in swine suggests that population immunity may not prevent the introduction of human viruses into pigs and possibly vice-versa, reinforcing the need to monitor and prepare for potential incursions.
IMPORTANCE:
Influenza A virus (IAV) is an important pathogen in pigs and humans. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major target of vaccines. However, vaccine strains must be updated to reflect current strains. Characterizing the differences between seasonal IAV in humans and swine IAV is important in assessing the relative risk of interspecies transmission of viruses. We found two primary antigenic clusters of H3N2 in the U.S. pig population with enough diversity to suggest updates in swine vaccine strains. We identified changes in the HA protein that are likely responsible for these differences that may be useful in predicting when vaccines need to be updated. The difference between human H3N2 and those in swine is enough that population immunity is unlikely to prevent new introductions of human IAV into pigs or vice-versa, reinforcing the need to monitor and prepare for potential introductions.
PMID:
24522915
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24522915