RESUMEN
Equine theileriosis is a severe equine disease caused by the protozoan Theileria equi, which is prevalent in tropical and subtropical areas. In this study, a recombinant equi merozoite antigen-2 (rEMA-2) of T. equi was used as an immunogen. Two groups of 10 mice each were divided into control and vaccinated groups. Sixty mares seronegative for theileriosis were divided in two groups, one vaccinated and another group as a control animal. Mice and mares of the vaccinated groups were inoculated with 150⯵L of the vaccine containing 50⯵g of rEMA-2 and 2â¯mL of the vaccine containing 200⯵g of rEMA-2, respectively, at days 0 and 21. The immunogenicity of rEMA-2 was evaluated by ELISA and fluorescent antibody test (IFAT) using serum from vaccinated mice, mares and antigenicity in naturally infected horse. At every point throughout the ELISA study, there were significant differences between the vaccinated and control groups (pâ¯<â¯0.05). The vaccine induced 3- and 4-fold IgG increases in mice at the 14th and 28th day, respectively, compared to the control group. The horses' IgG dynamics showed a significant (pâ¯<â¯0.05) increase in the total IgG titer as early as day 7, which increased until day 28â¯at which time a more significant (pâ¯<â¯0.001) IgG titer was observed. In evaluating the isotypes, we observed a trend similar to that of total IgG, where IgG(T) (IgG3-5) were significantly (pâ¯<â¯0.05) more elevated than the other isotypes analyzed, followed by IgGb (IgG4-7) and IgGa (IgG1). Positive fluorescence was detected by IFAT, suggesting that the protein is immunogenic and conserves some epitopes identical to the native T. equi antigens present in the equine blood smear. Thus, our results suggest that rEMA-2 can be a promising vaccinal antigen.
Asunto(s)
Antígenos de Protozoos/inmunología , Pichia/inmunología , Theileria/inmunología , Análisis de Varianza , Animales , Anticuerpos Antiprotozoarios/sangre , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/biosíntesis , Antígenos de Protozoos/genética , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Caballos , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Merozoítos/inmunología , Ratones , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Distribución Aleatoria , Proteínas Recombinantes/inmunologíaRESUMEN
In this study, we tested the in vitro and in vivo larvicidal activity of Bacillus species against gastrointestinal nematodes in cattle, and their viability in the presence of anthelmintics. For in vitro tests, cattle feces naturally infected with trichostrongylides were incubated with spore suspensions of Bacillus circulans (Bcir), B. thuringiensis var. osvaldocruzi (Bto), B. thuringiensis var. israelensis (Bti) or B. thuringiensis var. kurstaki (Btk). Subsequently, residual larvae were counted and identified. All of the Bacillus species showed 60% or more larvicidal effects. Bcir and Bti were selected to be incubated with anthelmintics (moxidectin, nitroxynil and levamisole), and after 24, 72, and 144h, their viability was evaluated. Bti showed highest drug resistance, maintaining a concentration of 1×107CFU/mL. Based on this result, Bti was selected for in vivo tests on calves naturally infected with gastrointestinal nematodes. The calves were dived into four groups: Group 1, Bti suspension of â¼1×109CFU orally administered; Group 2, Bti suspension of â¼1×109CFU orally administered with levamisole (subcutaneously, 150mg); Group 3, only levamisole (subcutaneously, 150mg), and Group 4 untreated. Then 24 and 48h after treatment, larvae numbers were counted. We observed a reduction of 84%, 100%, and 100% after 48h of treatment, respectively, for Groups 1, 2 and 3 treatments in comparison with the untreated. The tested Bacillus species showed larvicidal activity against bovine trichostrongylides, and its association with anthelmintics. It may serve as a promising integrated alternative for control of gastrointestinal nematodes in cattle.