%0 Journal Article
%T Comparison of Human-Like H1 ( -Cluster) Influenza A Viruses in the Swine Host
%A Janice R. Ciacci Zanella
%A Amy L. Vincent
%A Eraldo L. Zanella
%A Alessio Lorusso
%A Crystal L. Loving
%A Susan L. Brockmeier
%A Phillip C. Gauger
%A Bruce H. Janke
%A Marie R. Gramer
%J Influenza Research and Treatment
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/329029
%X Influenza A viruses cause acute respiratory disease in swine. Viruses with H1 hemagglutinin genes from the human seasonal lineage ( -cluster) have been isolated from North American swine since 2003. The objective of this work was to study the pathogenesis and transmission of -cluster H1 influenza viruses in swine, comparing three isolates from different phylogenetic subclusters, geographic locations, and years of isolation. Two isolates from the 2 subcluster, A/sw/MN/07002083/07 H1N1 (MN07) and A/sw/IL/00685/05 H1N1 (IL05), and A/sw/TX/01976/08 H1N2 (TX08) from the 1 sub-cluster were evaluated. All isolates caused disease and were transmitted to contact pigs. Respiratory disease was apparent in pigs infected with MN07 and IL05 viruses; however, clinical signs and lung lesions were reduced in severity as compared to TX08. On day 5 following infection MN07-infected pigs had lower virus titers than the TX08 pigs, suggesting that although this H1N1 was successfully transmitted, it may not replicate as efficiently in the upper or lower respiratory tract. MN07 and IL05 H1N1 induced higher serum antibody titers than TX08. Greater serological cross-reactivity was observed for viruses from the same HA phylogenetic sub-cluster; however, antigenic differences between the sub-clusters may have implications for disease control strategies for pigs. 1. Introduction Influenza A viruses are important infectious agents for humans, avian species, and many mammalian species, including swine. In swine, influenza virus causes an acute infection characterized by high morbidity and very low mortality rates [1]. Influenza viruses of the family Orthomyxoviridae have negative-sense single-stranded eight-segmented genome encoding for up to twelve structural and accessory proteins [2]. The triple reassortant internal gene constellation (TRIG) is the common backbone of the swine influenza viruses currently circulating in North America (for a review, see Vincent et al., 2008 [3]). Within the TRIG viruses, a dominant circulating genotype carries the HA and NA encoding genes of the human seasonal viruses of the H1 lineage (hu-like), identified from pigs in American and Canadian herds [4]. The HA genes of these viruses form the ¦Ä-cluster in phylogenetic analyses of HA genes from North American influenza A viruses of swine. Contemporary ¦Ä-cluster HA genes can be further divided into two sub-clusters, ¦Ä1 and ¦Ä2 [5]. Phylogenetically, the HA sequences of American and Canadian ¦Ä-cluster influenza A viruses appeared to have been derived from at least two independent human-to-pig transmission
%U http://www.hindawi.com/journals/irt/2012/329029/