SWINE VIRAL DISEASES PATHOGENESIS AND IMMUNOLOGY
Location: Virus and Prion Research Unit
Title: Antigenic map of hemagglutinin (H) 1 proteins of 2010-2011 swine influenza viruses (SIV) in the U.S. swine population
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 7, 2011
Publication Date: N/A
Before 2003, the H1 genes of North American SIV isolates were characterized into 3 phylogenetic clusters, H1-alpha, -beta and -gamma (1). The introduction of human-like H1 viruses into the swine population around 2003-05 generated the fourth and fifth H1 clusters, H1-delta1 and -delta2 (2). An increased number of H1-delta viruses have been detected in recent swine influenza outbreaks in the U.S. swine population (approximately 35- 40% of H1 SIV isolated in 2010, M. R. Gramer unpublished data). This indicates that the H1-delta viruses have become one of the dominant H1 clusters in the swine population. Preliminary genetic data also indicate that these recent viruses are highly variable within their subclusters (M. R. Gramer unpublished data). An antigenic cartography technique was used to study a panel of reference anti-sera to the five H1 clusters and their homoglous or historic and 2008 heterologous H1 viruses, including the pandemic H1N1 2009 (pH1) virus (3). The test applies statistical analysis to antigen binding assay data to create visual antigenic maps. Results revealed that the H1-alpha, -beta, -gamma and pH1 viruses tended to be mapped within 1-2 units of antigenic distance (1 unit equals 2-fold difference of HI titer) indicating antigenic relatedness between the viruses. However, over 3 unit differences (>8-fold differences) were found between these viruses and the H1-delta1 and -delta2 clusters, indicating limited antigenic relatedness. Our current ongoing study will expand the H1 SIV antigenic map by incorporating isolates of the presently circulating 2010-2011 H1 viruses. H1 SIV isolates representing the H1-beta, -gamma, pH1, -delta1 and -delta2 clusters will be genetically and antigenically characterized by whole genome sequencing and antigenic cartography. Reference swine anti-sera to previous H1 SIV isolates(3) and newly generated swine anti-sera to the selected 2010-2011 H1-delta1 and -delta2 clusters as well as anti-sera to human H1 vaccine strains will be used in cross-HI tests to generate an updated antigenic map. Results from this study will provide an indication of the genetic and antigenic evolution of SIV in the U.S. and provide important information for future SIV vaccine strain selection and diagnostic test updates.
1. Vincent A.L., Ma W., Lager K.M., Janke B.H., and Richt J.A., Adv Virus Res 72, 127-154, 2008.
2. Vincent A.L., Ma W., Lager K.M., Gramer M.R., Richt J.A., and Janke B.H., Virus Genes, 2009.
3. Lorusso A., Vincent A.L., Harland M.L., Alt D., Bayles D.O., Swenson S.L., Gramer M.R., Russell C.A., Smith D.J., Lager K.M., and Lewis N.S., J Gen Virol 92, 919-930.