短语词组短语virulent gene analysis 毒性基因分析virulent gene construction 毒性基因结构virulent gene deleted mutant 毒性基因突变体a virulent gene mutant 毒性基因缺失突变体hip virulent irp - gene 毒力岛irpHIP virulent irp -2 gene 毒力岛irp 返回 virulent gene