[ComE-deficient mutant affects in vivo-induced genes expression in Streptococcus pneumoniae]

To screen in vivo genes of Streptococcus pneumoniae controlled by comE gene.

The comE-deficient strain was constructed by using insertion inactivation and identified by PCR and sequencing. The BALB/c mouse was used as test animal and injected with D39 wild type and D39 comE-deficient strain via intraperitoneal injection. The mice blood was obtained about 24 hours after the injection through posterior orbital venous plexus approach. Then the bacteria induced in vivo were collected from the blood and their RNA were extracted to measure the mRNA expression levels of each in vivo-induced gene by RT-PCR.

The differences of the expressions of 8 in vivo-induced genes in D39 and D39 comE-deficient strain were statistically significant (P < 0.05) and in which spd_0300, spd_0414, spd_ 0622, spd_1663, spd_1719, spd_0235, spd_0873 were up-regulated by transformation and meanwhile spd_1672 was down-regulated.

In vivo-induced genes spd_0300, spd_0414, spd_0622, spd_1663, spd_1719, spd 0235, spd_0873, spd_1672 regulated by transformation were screened out and they may participate in the processes such as growth regulation, temperature reception, carbohydrate metabolism, and lipoids metabolism. The bacterial transformation may enhance the virulence via regulating some in vivo-induced genes expression.