Swine influenza classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Classification
SIV strains isolated to date have been classified either as Influenzavirus C or one of the various subtypes of the genus Influenzavirus A.[1]
Influenza A
Swine influenza is known to be caused by influenza A subtypes H1N1,[2] H1N2,[2] H3N1,[3] H3N2,[2] and H2N3.[4]
In swine, three influenza A virus subtypes (H1N1, H3N2, and H1N2) are circulating throughout the world. In the United States, the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.[5]
Interaction With H5N1
Avian influenza virus H3N2 is endemic in pigs in China and has been detected in pigs in Vietnam, increasing fears of the emergence of new variant strains.[6] Health experts say pigs can carry human influenza viruses, which can combine (i.e. exchange homologous genome sub-units by genetic reassortment) with H5N1, passing genes and mutating into a form which can pass easily among humans.[7] H3N2 evolved from H2N2 by antigenic shift.[8] In August 2004, researchers in China found H5N1 in pigs.[9]
References
- ↑
Heinen PP (15 September 2003). "Swine influenza: a zoonosis". Veterinary Sciences Tomorrow. ISSN 1569-0830.
Influenza B and C viruses are almost exclusively isolated from man, although influenza C virus has also been isolated from pigs and influenza B has recently been isolated from seals.
- ↑ 2.0 2.1 2.2 "Swine Influenza". Swine Diseases (Chest). Iowa State University College of Veterinary Medicine.
- ↑ Shin JY, Song MS, Lee EH, Lee YM, Kim SY, Kim HK, Choi JK, Kim CJ, Webby RJ, Choi YK (2006). "Isolation and characterization of novel H3N1 swine influenza viruses from pigs with respiratory diseases in Korea". Journal of Clinical Microbiology. 44 (11): 3923–7. doi:10.1128/JCM.00904-06. PMID 16928961.
- ↑ Ma W, Vincent AL, Gramer MR, Brockwell CB, Lager KM, Janke BH, Gauger PC, Patnayak DP, Webby RJ, Richt JA (26 December 2007). "Identification of H2N3 influenza A viruses from swine in the United States". Proc Nat Acad Sci U S A. 104 (52): 20949–54. doi:10.1073/pnas.0710286104. PMC 2409247. PMID 18093945.
- ↑
Yassine HM, Al-Natour MQ, Lee CW, Saif YM (2007). "Interspecies and intraspecies transmission of triple reassortant H3N2 influenza A viruses". Virol J. 28 (4): 129. doi:10.1186/1743-422X-4-129. PMC 2228287. PMID 18045494. Unknown parameter
|month=ignored (help) - ↑
Yu, H. (2008). "Genetic evolution of swine influenza A (H3N2) viruses in China from 1970 to 2006". Journal of Clinical Microbiology. 46 (3): 1067. doi:10.1128/JCM.01257-07. PMID 18199784. Unknown parameter
|month=ignored (help) - ↑ "Bird flu and pandemic influenza: what are the risks?". UK Department of Health.
- ↑ Lindstrom Stephen E, Cox Nancy J, Klimov Alexander (15 October 2004). "Genetic analysis of human H2N2 and early H3N2 influenza viruses, 1957–1972: evidence for genetic divergence and multiple reassortment events". Virology. 328 (1): 101–19. doi:10.1016/j.virol.2004.06.009. PMID 15380362.
- ↑ World Health Organization (28 October 2005). "H5N1 avian influenza: timeline" (PDF).