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J Gen Virol. 2010 May 19. [Epub ahead of print]
Viral reassortment and transmission after coinfection of pigs with classical H1N1 and triple reassortant H3N2 swine influenza viruses.
Ma W, Lager KM, Lekcharoensuk P, Ulery ES, Janke BH, Solorzano A, Webby RJ, Garcia-Sastre A, Richt JA.
Kansas State University;
Abstract
Triple reassortant swine influenza viruses circulating in North American pigs contain the internal genes derived from swine (NP, M, NS), human (PB1) and avian (PA and PB2) influenza viruses forming a constellation of genes that is well conserved and called the triple reassortant internal gene (TRIG) cassette. In contrast, the external genes (HA and NA) are less conserved reflecting multiple reassortant events that have produced viruses with different combinations of HA and NA genes. We hypothesize that the maintenance of the TRIG cassette confers a selective advantage to the virus. To test this hypothesis, pigs were co-infected with the triple reassortant H3N2 A/Swine/Texas/4199-2/98 (Tx/98) and the classical H1N1 A/Swine/Iowa/15/1930 viruses and co-housed with a group of sentinel animals. This direct contact group was subsequently moved into contact with a second group of naive animals. Four different subtypes (H1N1, H1N2, H3N1 and H3N2) of influenza virus were identified in bronchoalveolar lavage fluid collected from lungs of experimentally-infected pigs with most of the viruses containing the TRIG from the Tx/98 virus. Interestingly, only the intact Tx/98 H3N2 virus was transmitted from the infected pigs to the direct contact animals, and from them to the second contact group of pigs. These results demonstrate that multiple reassortments can occur within a host; however, only specific gene constellations are readily transmissible. It is concluded that certain HA and NA gene pairs, in conjunction with the TRIG cassette, may have a competitive advantage over other combinations for transmission and maintenance in swine.
PMID: 20484565 [PubMed - as supplied by publisher]
Viral reassortment and transmission after coinfection of pigs with classical H1N1 and triple reassortant H3N2 swine influenza viruses.
Ma W, Lager KM, Lekcharoensuk P, Ulery ES, Janke BH, Solorzano A, Webby RJ, Garcia-Sastre A, Richt JA.
Kansas State University;
Abstract
Triple reassortant swine influenza viruses circulating in North American pigs contain the internal genes derived from swine (NP, M, NS), human (PB1) and avian (PA and PB2) influenza viruses forming a constellation of genes that is well conserved and called the triple reassortant internal gene (TRIG) cassette. In contrast, the external genes (HA and NA) are less conserved reflecting multiple reassortant events that have produced viruses with different combinations of HA and NA genes. We hypothesize that the maintenance of the TRIG cassette confers a selective advantage to the virus. To test this hypothesis, pigs were co-infected with the triple reassortant H3N2 A/Swine/Texas/4199-2/98 (Tx/98) and the classical H1N1 A/Swine/Iowa/15/1930 viruses and co-housed with a group of sentinel animals. This direct contact group was subsequently moved into contact with a second group of naive animals. Four different subtypes (H1N1, H1N2, H3N1 and H3N2) of influenza virus were identified in bronchoalveolar lavage fluid collected from lungs of experimentally-infected pigs with most of the viruses containing the TRIG from the Tx/98 virus. Interestingly, only the intact Tx/98 H3N2 virus was transmitted from the infected pigs to the direct contact animals, and from them to the second contact group of pigs. These results demonstrate that multiple reassortments can occur within a host; however, only specific gene constellations are readily transmissible. It is concluded that certain HA and NA gene pairs, in conjunction with the TRIG cassette, may have a competitive advantage over other combinations for transmission and maintenance in swine.
PMID: 20484565 [PubMed - as supplied by publisher]
