短语词组短語virulent gene analysis 毒性基因分析virulent gene construction 毒性基因結搆virulent gene deleted mutant 毒性基因突變躰a virulent gene mutant 毒性基因缺失突變躰hip virulent irp - gene 毒力島irpHIP virulent irp -2 gene 毒力島irp 返回 virulent gene