Construction and Evaluation of Recombinant Vaccines againstLeptospirosis
Leptospirosis, caused by bacteria of the genus Leptospira, is classified as a directzoonosis with a wide geographical distribution that is endemic throughout theworld. Epidemics of leptospirosis occur in several countries, mainly those with atropical or subtropical climate, where the prevalence of the illness is elevated. Thisis due mainly to favourable environmental conditions for the proliferation ofrodents, and consequent dissemination of the agent. Among the preventionmeasures, besides antibiotics, vaccines are used in at-risk groups for infection.The implications in terms of public health and the economical losses caused byleptospirosis justify the use of vaccines against leptospira in human or animalpopulations at risk. The development of new strategies for the prevention of theleptospirosis is therefore necessary. The possible strategies for the prevention ofthe leptospirosis include: subunit vaccine, DNA vaccine and the use ofMycobacterium bovis BCG as a carrier to present the antigen. The externalmembrane protein LipL32 was selected for this work because it is only foundamong pathogenic leptospira and is likely to be highly immunogenic. Thus, lipL32was cloned into various expression vectors: pTarget, to create the DNA vaccine;into the vectors pUS973, pUS974 and pUS977, BCG vector; and into pAE toexpress the recombinant protein, the subunit vaccine. Mice were immunized withthe various constructs and the immune response evaluated. Of the vaccinesexamined the best immune response was found with the subunit vaccine.However, with BCG the titre still continued in increase at the end of the experiment.The serum of the vaccinated animals was able to recognize LipL32 in themembrane of the leptospira by indirect immunofluorescence. A monoclonalantibody, anti-LipL32, was also able to inhibit the growth of leptospira in vitro,indicating potential protection by the LipL32 antigen.
Advisor:Odir Antônio Dellagostin
School:Universidade Federal de Pelotas
Source Type:Master's Thesis
Date of Publication:12/20/2004