Brucella melitensis invA gene (BME_RS01060) transcription is promoted under acidic stress conditions

The invA gene of Brucella melitensis codes for a NUDIX (nucleoside diphosphate linked to moiety X) hydrolase related to invasiveness. The objective of this work was to evaluate invA transcription under acidic conditions. The invA gene transcription was up regulated at pH 3 and pH 5 observed with semiquantitative real-time PCR in B. melitensis 133 strain. Results indicated that invA gene transcription at pH 3 showed a basal and decreased transcription compared to that of pH 5 incubation. Transcription levels of the dnaK gene were similar to those obtained with invA gene. The survival rates of wild type and invA mutant strains at pH 5 were above 90% in all post-incubation times. In contrast, at pH 3 there was a time-dependent reduction on both strains at 15 min (P < 0.05). These results suggest that invA gene transcription is promoted under acidic conditions in Brucella melitensis.