Monakhova E V, Bozhko N V
Zh Mikrobiol Epidemiol Immunobiol. 2010 Jul-Aug(4):89-92.
To detect T3SS and T6SS genes in Vibrio cholerae genomes and assessment of resistance of strains with different genotype characteristics to ingestion by Dictyostelium discoideum amoeba.
One hundred thirty-five toxigenic and non-toxigenic strains of Echolerae O1, O139, and non-O1/non-O139 were studied by PCR and on Dictyostelium discoideum model.
T3SS cluster of genes was detected in several non-toxigenic representatives of 01 and non-O1/non-O139 serogroups. All toxigenic vibrios except one strain belonging to non-O1/ non-O139 serogroup lack this cluster. T6SS genes were presented in all studied strains although far from allofthem contained sequence coding ACD-domain of vgrG1 gene product--key effector of T6SS. Susceptibility of vibrios to ingestion by amoeba did not depend from presence of T3SS genes. Only strains with genetic determinants ACD-vgrG1 together with pathogenicity locus VPI were resistant to ingestion, all others were susceptible.
D. discoideum model is adequate for study of expression of T6SS but not T3SS in V. cholerae. The latter is rather needed for colonization of intestine than for antagonistic activity against protozoa in external environment. Expression of T6SS is characteristic for many non-toxigenic strains of V. cholerae, whereas use of contact-dependent secretion is unlikely necessary for majority of toxigenic strains.
检测霍乱弧菌基因组中的Ⅲ型分泌系统（T3SS）和Ⅵ型分泌系统（T6SS）基因，并评估具有不同基因型特征的菌株对盘基网柄菌变形虫摄取的抗性。
采用聚合酶链反应（PCR）并利用盘基网柄菌模型研究了135株产毒和不产毒的霍乱弧菌O1群、O139群及非O1/非O139群菌株。
在01群和非O1/非O139血清群的几株不产毒菌株中检测到T3SS基因簇。除一株属于非O1/非O139血清群的菌株外，所有产毒弧菌均缺乏该基因簇。所有研究菌株中均存在T6SS基因，尽管并非所有菌株都含有编码T6SS关键效应蛋白vgrG1基因产物ACD结构域的序列。弧菌对变形虫摄取的敏感性并不取决于T3SS基因的存在。只有具有ACD-vgrG1遗传决定因素并伴有致病位点VPI的菌株对摄取具有抗性，其他所有菌株均敏感。
盘基网柄菌模型适用于研究霍乱弧菌中T6SS的表达，但不适用于T3SS。后者对于肠道定植比对外界环境中原生动物的拮抗活性更为必需。T6SS的表达是许多霍乱弧菌不产毒菌株的特征，而对于大多数产毒菌株而言，使用接触依赖性分泌可能并非必要。
