Expressão de antígenos de Schistosoma mansoni em BCG recombinante.

Abstract

KANNO, A. I. Expression of Schistosoma mansoni antigens in recombinant BCG. 2013.135 p. Ph. D. thesis (Biotechnology) – Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, 2013. BCG is an attenuated bacillus derived from Mycobacterium bovis currently used as prophylactic vaccine to tuberculosis. Its adjuvant properties led BCG to be also investigated as a vector in the expression of foreign antigens as a multivalent vaccine. Genes from viruses, bacteria and parasites antigens are cloned to mycobacterial vectors and with them, recombinant BCG strains (rBCG) are created. In this work, mycobacterial expression vectors were constructed to express Schistosoma mansoni genes: smtsp-2, sm29, smval-4, smval-5 and smstolp-2 in two species, BCG and M. smegmatis and we observe the expression of SmStoLP-2. Mice immunized with these rBCG constructs expressing SmStoLP-2 show a different immune response despite no protection against cercarial challenge could be observed. Another strategy was using codon optimized genes (smtsp-2opt, sm29opt e smval5opt) which allowed the expression of SmTSP-2 e SmVAL-5 only in M. smegmatis. Thereafter, pursuing the expression of S. mansoni antigens in BCG, in a complementary line of work, a library of plasmids containing a mycobacteriophage promoter sequence altered by random mutagenesis was created using the green fluorescent protein as reporter (eGFP). M. smegmatis was used as a primary tool to analyze the strength of these promoters as they showed a wide range in fluorescence between screened transformants. Two of these plasmids – a strong and a weak – defined as such to their ability in producing eGFP were used to express in BCG the proposed S. mansoni antigens and we observe the expression of Sm29 at different levels by each promoter. The rBCG strain expressing high levels of Sm29 induced a specific immune response in immunized mice.