Desenvolvimento de vacina recombinante de proteína M de Streptococcus equi subsp. equi

Abstract

The business related to equines in Brazil has an important participation in activities as leisure, culture and tourism, being responsible for millions of jobs. The equine distemper caused by Streptococcus equi subsp. equi is a disease of the respiratory tract with economical impact, generating losses with treatment and reduction in the animal performance. To solve this problem, prophylactic measures, such as the vaccination, are important. However, available commercial vaccines do not offer protection to more than 50% of the vaccinated animals. Several studies are being performed aiming the achievement of an efficient vaccine against the Adenitis, where several virulence factors are being evaluated as possible vaccine antigens, specially the M protein (SeM). Thus, the present work aimed the development and evaluation of a recombinant vaccine to the control of the equine distemper composed of the SeM antigen co-administrated with the recombinant Heat-labile enterotoxin B subunit of Escherichia coli (rLTB) and/or aluminium hydroxide (Al(OH)3). A total of 72 female BALB/c mice, divided into eight groups and 18 horses, divided into six groups, were inoculated by intramuscular or intranasal routes. The results obtained in the experiments showed that the rSeM was innocuous and immunogenic in both evaluated species, stimulating the production of specific immunoglobulin anti-rSeM without the addition of immunological adjuvant. Both adjuvant rLTB and Al(OH)3 were not capable to increase the titer of immunoglobulin anti-rSeM in mice, while in horses, the treatment rSeM + rLTB (IM) showed a significant increase in the level of seric immunoglobulin IgG anti-rSeM. Interestingly, the production of anti-rSeM secretory IgA in the upper respiratory tract has a significant increase in horses treated with rSeM + Al(OH)3 (IM). This result is promising to further studies with rSeM as an antigen for vaccines, as well as is the administration of rLTB as an immunological adjuvant.