Kawaoka Y, Webster R G
Virology. 1985 Oct 15;146(1):130-7. doi: 10.1016/0042-6822(85)90059-5.
The epidemiological features of the H5N2 outbreak of influenza in poultry were studied by sequencing the HA genes of several viruses isolated during the epidemic. Comparison of the nucleotide sequences of the HA genes indicated there was a single introduction of virulent virus. The variation rate (silent mutations) in the HA gene of the virulent Ck/Penn virus was 9.0 or 14.4% per 10 years depending on the viruses compared and was similar to that in H3 HA gene of human influenza A virus. The virulent and avirulent viruses isolated after October 1983 were derived from a common ancestoral virus and the virulent virus did not supersede the avirulent virus, instead, the virulent and avirulent viruses coexisted and evolved separately during the course of the epidemic. The evolutionary changes in the HA of H5N2 viruses that occurred during the epidemic permitted us to establish that a virus (A/Chick/Washington/84) that was isolated 8 months after the last H5N2 virus had been isolated from poultry in Pennsylvania belonged to the family of potentially dangerous H5N2 viruses and was a direct descendent of the virus that spread to Maryland and Virginia. All of the virulent Ck/Penn viruses retained the amino acid changes at residues 13 and 69 in the HA.
通过对疫情期间分离出的几种病毒的血凝素（HA）基因进行测序，研究了家禽中H5N2流感疫情的流行病学特征。HA基因核苷酸序列的比较表明，强毒病毒是单次传入的。根据所比较的病毒不同，强毒Ck/Penn病毒HA基因的变异率（沉默突变）为每10年9.0%或14.4%，这与甲型人流感病毒H3 HA基因的变异率相似。1983年10月后分离出的强毒和无毒病毒均源自一种共同的祖先病毒，强毒病毒并未取代无毒病毒，相反，在疫情过程中，强毒和无毒病毒共存并分别进化。疫情期间H5N2病毒HA的进化变化使我们能够确定，在宾夕法尼亚州最后一株H5N2病毒从家禽中分离出来8个月后分离出的一株病毒（A/Chick/Washington/84）属于潜在危险的H5N2病毒家族，并且是传播到马里兰州和弗吉尼亚州的病毒的直接后代。所有强毒Ck/Penn病毒在HA的第13和69位氨基酸处均保留了氨基酸变化。
