HA 226/228双位点突变对H5N1禽流感病毒受体结合特异性和致病性的影响

The impact of mutations in hemagglutinin residue 226 and 228 on receptor binding specificity and pathogenicity of H5N1 avian influenza virus

禽流感病毒(AIV)主要识别SAα2,3Gal受体,而人源流感病毒主要识别SAα2,6Gal受体。本研究利用糖链受体结合特性检测方法检测表明,H5N1 AIV A/duck/Guangxi/35/2001(DK/35)可以同时识别SAα2,3Gal和SAα2,6Gal受体,然而HA 226位谷氨酸(Q)到亮氨酸(L)和228位甘氨酸(G)到丝氨酸(S)的双突变,可以导致DK/35更倾向于识别SAα2,6Gal受体。对BALB/c小鼠致病性试验显示,突变病毒株(rDK/35(Q226L/G228S))对小鼠的致病力比野毒株弱,其MLD50为4.7 log10EID50,而DK/35为1.8 log log10EID50。本研究表明H5N1 AIV通过突变可以获得优先与SAα2,6Gal受体特异性结合的能力,为H5N1 AIV的监测预防和对公共卫生风险评估提供一定的参考依据。

The avian influenza virus preferentially recognize α-2, 3-1inked sialic acid （SAs）, while human influenza virus recognize α-2, 6-1inked sialic acid（SAs）. In this study, we tested the receptor specificity of A/duck/Guangxi/35/2001 （H5N1） （DK/35） and its mutant virus rDK/35 （Q226L/C228S） by solid-phase binding assay, and found that DK/35 bound to both α-2, 3 and α-2, 6-1inked SAs, whereas two amino acid changes of Q226L and G228S in HA induced the lack of binding affinity to avian-like receptor （α-2, 3-1inked SAs）, only recognizing the human-like receptor （α-2, 6-1inked SAs）. The change in receptor binding preference also impacted on the pathogenicity of the virus in mice. DK/35 showed highly pathagenicity in mice, with a 50% mouse lethal dose （MLD50） of 1.8 log lOgl0 EIDs0, by contrast the rDK/35（Q226L/GZ28S） was mild pathagenicity, with a MLDs0 of 4.7 log10 EID50.