【摘要】 A/mallard/Huadong/S/2005(S,IVPI=2.65)和A/mallard/Huadong/Y/2003(Y,IVPI=0),是对麻鸭具有不同致病力的病毒。两病毒的HA裂解位点区有2个氨基酸差异,S病毒在HA裂解位点区322是Leu(L322),329位缺失(-329),而Y病毒322位是Gln(Q322),329位是Lys(K329)。根据这两个位点的差异,利用反向遗传系统,以S和Y病毒各自为骨架,拯救HA基因突变病毒,检测获救的突变病毒对麻鸭的毒力。可以得知,以S病毒为骨架,将S病毒HA基因322位Leu替换为Gln和(或)在329位添加Lys,以及用Y病毒的HA(Q322L,K329-)替换S病毒HA,获救的重组病毒对麻鸭亦完全无致病力;但以Y病毒为骨架,将Y病毒HA基因322位Gln替换为Leu和(或)在329位缺失Lys后,Y重组病毒对麻鸭的毒力上升。结果提示,S和Y病毒HA基因裂解位点区322和329氨基酸残基突变或缺失均影响病毒对麻鸭的致病力,且HA基因与其它基因的匹配性显著影响病毒对麻鸭的致病力。更多还原

【Abstract】 Two H5N1 avian influenza viruses(AIV),A/mallard/Huadong/S/2005(S,IVPI=2.65,in mallard)and A/mallard/Huadong/Y/2003(Y,IVPI=0,in mallard),were capable of distinct in pathogenicity to non-immunized mallards(Anas platyrhynchos).There were two amino acid residues difference in the HA cleavage site between two viruses,322(S,Leu;Y,Gln)and 329(S,deletion;Y,Lys).Based on the variation,a series of recombinant viruses carrying HA gene either from S or Y virus with mutation at 322 and/or 329 were constructed via reverse genetics system to explore the influence of the two amino acid residues on viral pathogenicity in mallards.Recombinant viruses with S virus backbone were completely attenuated in terms of their virulence to ducks when position 322(L322Q)and/or position 329(-329K)of HA gene had been mutated.The critical role that L322 and-329 of HA protein from S virus play in the high virulence to ducks were influenced by the entire background of that protein because the recombinant virus with HA gene from Y and other seven genes from S were completely attenuated even if Q322L and K329-mutations of HA gene had been achieved.Recombinant viruses with Y virus backbone significantly increased their virulence to ducks when position 322(Q322L)and/or position 329(K329-)of HA gene had been mutated.All recombinant viruses carrying HA gene from Y with Q322L and/or K329-mutations and other seven genes from S were completely attenuated in terms of virulence to ducks whereas all recombinant viruses carrying HA gene from Y with same mutations and other seven genes from Y gained significant virulence.It seems that the compatibility among eight genes might be an important factor for HA to exert its functions.Results indicated that the mutation at amino acid position 322 and deletion at 329 in HA cleavage site significantly influence the pathogenicity of S and Y viruses in mallard,the compatibility among eight genes also contribute to the pathogenicity of both viruses in mallard.更多还原