Olsen Christopher W
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706, USA.
Virus Res. 2002 May 10;85(2):199-210. doi: 10.1016/s0168-1702(02)00027-8.
Since 1997, novel viruses of three different subtypes and five different genotypes have emerged as agents of influenza among pigs in North America. The appearance of these viruses is remarkable because there were no substantial changes in the overall epidemiology of swine influenza in the United States and Canada for over 60 years prior to this time. Viruses of the classical H1N1 lineage were virtually the exclusive cause of swine influenza from the time of their initial isolation in 1930 through 1998. Antigenic drift variants of these H1N1 viruses were isolated in 1991-1998, but a much more dramatic antigenic shift occurred with the emergence of H3N2 viruses in 1997-1998. In particular, H3N2 viruses with genes derived from human, swine and avian viruses have become a major cause of swine influenza in North America. In addition, H1N2 viruses that resulted from reassortment between the triple reassortant H3N2 viruses and classical H1N1 swine viruses have been isolated subsequently from pigs in at least six states. Finally, avian H4N6 viruses crossed the species barrier to infect pigs in Canada in 1999. Fortunately, these H4N6 viruses have not been isolated beyond their initial farm of origin. If these viruses spread more widely, they will represent another antigenic shift for our swine population, and could pose a threat to the world's human population. Research on these novel viruses may offer important clues to the genetic basis for interspecies transmission of influenza viruses.
自1997年以来，三种不同亚型和五种不同基因型的新型病毒已成为北美猪流感的病原体。这些病毒的出现值得关注，因为在此之前的60多年里，美国和加拿大猪流感的总体流行病学没有发生实质性变化。从1930年首次分离到1998年，经典H1N1谱系的病毒几乎是猪流感的唯一病因。1991年至1998年分离出了这些H1N1病毒的抗原漂移变体，但随着1997年至1998年H3N2病毒的出现，发生了更为显著的抗原转变。特别是，具有源自人类、猪和禽病毒基因的H3N2病毒已成为北美猪流感的主要病因。此外，随后在至少六个州的猪中分离出了由三重重配H3N2病毒和经典H1N1猪病毒重配产生的H1N2病毒。最后，1999年禽H4N6病毒跨越物种屏障感染了加拿大的猪。幸运的是，这些H4N6病毒尚未在其最初来源农场之外被分离出来。如果这些病毒传播得更广泛，它们将代表我们猪群的另一次抗原转变，并可能对全球人类构成威胁。对这些新型病毒的研究可能为流感病毒跨物种传播的遗传基础提供重要线索。
