Avaliação da resposta imune induzida por uma quimera de antígenos de Mycopasma hyopneumoniae

Abstract

Enzootic Pneumonia (EP), caused by the bacteria Mycoplasma hyopneumoniae, is one of the most important infectious and respiratory diseases that affects swine production worldwide. The reduction of feed conversion efficiency and the decrease of weight gain, associated to medication costs, causes considerable economic losses in pig production. Commercial bacterins are used worldwide on disease control, however its protection is often incomplete. In this context, it is necessary to search for new alternative prophylaxis. The sequencing of M. hyopneumoniae isolates associated to recombinant DNA technology allowed the identification of several proteins that may be used as potential vaccine targets. Although some recombinant antigens have been tested on different vaccine strategies, they have conferred only limited protection when assessed as single antigens. On the other hand, the use of different antigens in a single vaccine formulation has been shown to be a promising approach to increase their immunogenicity and protective capacity of these vaccines. The aim of this study was to evaluate the immunogenic properties of a chimeric protein consisting of four proteins from M. hyopneumoniae (P97R1, P46, P95 and P42) that are associated with disease pathogenesis. The antigenicity of the chimeric protein was assessed against convalescent pig serum and the immunogenicity was evaluated in mice using two vaccine formulations: a subunit vaccine and an Escherichia coli recombinant bacterin expressing the antigen. The chimeric protein was specifically recognized by sera from convalescent pigs for EP, indicating that it retained the epitopes exposed, similar to the native proteins when individually evaluated. In the experimental study, both vaccine formulations evaluated were immunogenic in mice and induced immune response characterized by the production of IgG1 and IgG2a antibodies against each subunit. Moreover, both recombinant formulations induced antibodies that reacted specifically against native proteins from M. hyopneumoniae. These results warrant further evaluation of this new construct in immune protection assays in pigs.