Immune response induced by recombinant Mycobacterium bovis BCG expressing ROP2 gene of Toxoplasma gondii

Toxoplasma gondii is an obligate intracellular parasite, capable of infecting a variety of mammals and birds. Development of vaccine against T. gondii would be of great medical and veterinary value. In this study, the DNA sequence encoding ROP2 from T. gondii was cloned into the muticopy mycobacterial expression vector, pMV262, under the control of the Bacillus Calmette-Guerin (BCG) hsp60 promoter, and electroporated into BCG. Following selection of kanamycin, the recombinant BCG/pMV262-ROP2 was constructed and the expression of ROP2 was confirmed by Western blotting. The BALB/c mice inoculated with the BCG/pMV262-ROP2 developed specific immune responses against ROP2 protein, and there was an obvious delay in the mortality curve than the control (P<0.05). These results indicated that M. bovis BCG is an adequate vector to express and present antigens of T. gondii, and it may be used to further study the induction of protective immunity in other animals.