comEffect of HtrA gene deletion on virulence of Streptococcus pneumoniae

    HUANG Yuanª²Shuai, XU Songª²Xiao, ZHU Dan, YANG Qiang, LIU Mingª²Fang, CHEN Shuª²Hui, ZHANG Xueª²Mei, YIN Yiª²Bing

    Key Laboratory of Medical Diagnostics, Ministry of Education, Chongqing Medical University, Chongqing 400016, China

    ¡¾Abstract¡¿ AIM: To investigate the effect of HtrA gene deletion on the virulence of Streptococcus pneumoniae. METHODS: HtrAª²deficient strain was constructed by insertion, replication and inactivation, and identified by PCR. Relative quantitative RTª²PCR was used to measure the expression levels of virulent factors and study the virulence change by mice virulence experiments. RESULTS: The expression of virulent factors in HtrAª²deficient strain was lower than that of the wideª²type (P<0.05). Transformation capability of HtrAª²deficient strain obviously decreased. Mice virulence experiments showed the median lethal time of the wideª²type was 22 h, while that of HtrA mutant was 8 d (P<0.01). The elimination of HtrA mutant in mice blood was faster than that of the wideª²type. CONCLUSION: The deficiency of HtrA gene decreases the expression of virulent genes and the transformation capability, which finally reduced the bacterial virulence. ......