Construction of recombinant MVA carrying Pf ama1 gene and evaluation of immune response in vaccinated mice
Objective To construct recombinant MVA carrying Plasmodium falciparum ( Pf ) ama1 gene and evaluate its immune characteristic in mice. Methods MVA recombination vector pⅢdHR.ssp/E which contains Pf ama1 gene segment was built and used to transfect MVA infected BHK21 cells, recombinant viruses carrying host range gene k1l were selected by serially infecting RK13 cells. rMVA/E(K1L) was used to reinfect BHK21 under nonselective growth conditions, k1l was removed by intra-genomic homologous recombination and the final rMVA/E was harvested. rMVA/E genome sequence and AMA1 expression were identified by PCR, IFA and Western blot. Groups of BALB/c mice were immunized with different dosages of purified rMVA/E, level of anti-AMA1 IgG antibodies and their sub-isotypes were then determined by ELISA, and in vitro proliferation of splenocytes was examined. Results Stable recombinant MVA carrying Pf ama1 gene segment had been selected. After three intraperitoneal administration of different doses (10 7-10 8 TCID_ 50 ) rMVA/E, similar levels of IgG were induced in BALB/c mice of which IgG2a was dominant. After re-stimulating with AMA1 antigen all the immune splenocytes produced significant reminiscent reaction. Conclusion Recombinant MVA stably carrying Pf ama1 gene had been successfully constructed and rMVA/E could elicit AMA1 specific immune response in mice.