Suarez David L, Senne Dennis A, Banks Jill, Brown Ian H, Essen Steve C, Lee Chang-Won, Manvell Ruth J, Mathieu-Benson Christian, Moreno Valentina, Pedersen Janice C, Panigrahy Brundaban, Rojas Hernán, Spackman Erica, Alexander Dennis J
Southeast Poultry Research Laboratory, Athens, Georgia, USA.
Emerg Infect Dis. 2004 Apr;10(4):693-9. doi: 10.3201/eid1004.030396.
Influenza A viruses occur worldwide in wild birds and are occasionally associated with outbreaks in commercial chickens and turkeys. However, avian influenza viruses have not been isolated from wild birds or poultry in South America. A recent outbreak in chickens of H7N3 low pathogenic avian influenza (LPAI) occurred in Chile. One month later, after a sudden increase in deaths, H7N3 highly pathogenic avian influenza (HPAI) virus was isolated. Sequence analysis of all eight genes of the LPAI virus and the HPAI viruses showed minor differences between the viruses except at the hemagglutinin (HA) cleavage site. The LPAI virus had a cleavage site similar to other low pathogenic H7 viruses, but the HPAI isolates had a 30-nucleotide insert. The insertion likely occurred by recombination between the HA and nucleoprotein genes of the LPAI virus, resulting in a virulence shift. Sequence comparison of all eight gene segments showed the Chilean viruses were also distinct from all other avian influenza viruses and represent a distinct South American clade.
甲型流感病毒在世界各地的野生鸟类中存在，偶尔也会在商业养殖的鸡和火鸡中引发疫情。然而，在南美洲的野生鸟类或家禽中尚未分离出禽流感病毒。最近，智利发生了H7N3低致病性禽流感（LPAI）疫情，涉及鸡群。一个月后，在死亡数量突然增加后，分离出了H7N3高致病性禽流感（HPAI）病毒。对LPAI病毒和HPAI病毒的所有八个基因进行序列分析后发现，除血凝素（HA）裂解位点外，这些病毒之间的差异较小。LPAI病毒的裂解位点与其他低致病性H7病毒相似，但HPAI分离株有一个30个核苷酸的插入片段。该插入片段可能是由LPAI病毒的HA基因和核蛋白基因之间的重组产生的，从而导致了毒力转变。对所有八个基因片段的序列比较表明，智利的这些病毒也与所有其他禽流感病毒不同，代表了一个独特的南美分支。
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