LemA and Erp Y-like recombinant proteins from Leptospira interrogans protect hamsters from challenge using AddaVax™ as adjuvant

Publication date: 3 May 2018
Source:Vaccine, Volume 36, Issue 19
Author(s): Thaís Larré Oliveira, Rodrigo Andrade Schuch, Guilherme Roig Inda, Bárbara Couto Roloff, Amilton Clair Pinto Seixas Neto, Marta Amaral, Odir Antonio Dellagostin, Daiane Drawanz Hartwig
BackgroundRecombinant subunit vaccines have been extensively evaluated as promising alternatives against leptospirosis. Here, we evaluated two proteins in formulations containing the adjuvant AddaVax™ as vaccine candidates for prevention and control of leptospirosis.MethodsRecombinant proteins rErp Y-like and rLemA were characterized by ELISA to assess their ability to bind extracellular matrix (ECM) components and fibrinogen. Groups of eight hamsters were immunized intramuscularly with rErp Y-like or rLemA mixed with a squalene-based adjuvant (AddaVax), and then vaccine efficacy was determined in terms of protection against a lethal challenge. The humoral immune response was determined by ELISA, and the evidence of sub-lethal infection was evaluated by histopathology and kidney culture.ResultsrLemA protein binds laminin, fibrinogen, and collagen type IV, while rErp Y-like interacts with fibrinogen. Significant protection was achieved for rLemA and rErp Y-like vaccines, which showed 87.5% and 62.5% survivals, respectively. On day 28, the humoral immune response was significantly greater in the vaccine groups as compared to that in the control group, and the response was predominantly based on IgG2/3. The surviving animals showed negative results in culture isolation but presented with tissue lesions in the lungs and kidneys.ConclusionCumulatively, our findings suggest that LemA and Erp Y-like proteins act as adhesins and are able to protect against mortality, but not against tissue lesions. Moreover, AddaVax is a novel adjuvant with potential for improving the immunogenicity of leptospiral vaccines.



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