Hernan H M da Costa, Maribel L Loza, Marcia G Guereschi, Gustavo C Amorim, Andreza C Matias, Marcelo Lancellotti, Ana Carolina P Sousa, Carolina F Osava, Leonardo J Richtzenhain, Marcelo B Labruna, Matias Pablo J Szabó, Carlos R Prudencio, Jair P Cunha-Junior
The identification of areas where pathogenic Rickettsia spp. circulate, using rapid and low-cost serological approaches in sentinel species, may provide essential information for public actions to prevent, diagnose and appropriately treat rickettsiosis. Therefore, in this study we aimed to produce and characterize novel recombinant proteins from Rickettsia rickettsii with potential use in serological detection. The proteins were expressed in Escherichia coli, used in mouse immunization protocols, and also evaluated by indirect IgG ELISA using a cohort of serum samples from wild boars naturally exposed to Rickettsia spp. and from tick-naive farm pigs. The proteins displayed high immunogenicity with the induction of specific murine IgG antibodies, with high avidity after the third dose of immunization. A high IgG seropositivity rate (100%) and antibody avidity (>70%) were observed in wild boar serum samples when evaluated by ELISA. In addition, a significant positive correlation was observed between the swine-specific IgG levels against rPhenAl and rYJBI and the IgG levels against the rOmpA antigen. The novel proteins produced represent promising new immunogenic and antigenic candidates for serological detection of wild animals naturally exposed to Rickettsia spp.