Toxocara canis infection may impair bovine herpesvirus type 5 immunization.

Helminths have developed complex mechanisms to suppress the host immune response. These mechanisms may impair the host vaccine response. This study aimed to evaluate the effect of Toxocara spp. infection on the vaccine immune response to bovine herpesvirus type 5 (BoHV-5). First, 30 heifers received two doses of an experimental BoHV-5 vaccine. At 42nd days after the primo vaccination the vaccine efficacy was evaluated, and the presence of anti-Toxocara antibodies. Second, 20 Balb/c mice were divided into two groups, one infected with T. canis and the other without infection. After infection, both groups received two doses of vaccine. The vaccine immune response was assessed by BoHV-5 serum neutralization and splenic cytokines transcription by qPCR. All heifers positive for Toxocara spp. (40%) showed BoHV-5 SN titer ≤1:32, whereas heifers negative for Toxocara spp. (60%) had BoHV-5 SN titer ≥1: 128. Infected T. canis mice showed BoHV-5 SN titer ≤1:2, whereas mice not infected with T. canis BoHV-5 SN titer ≥1:8. Splenocytes from control mice stimulated with BoHV-5 had a significant (p < .05) mRNA transcription for the cytokines IL-12, IL-17, and IL-23, whereas the same cytokines were down-regulated in T. canis infected mice. These results suggest that Toxocara spp. infection may impair BoHV-5 immunization and should be considered for efficient herd immunization.

Bacillus toyonensis improves immune response in the mice vaccinated with recombinant antigen of bovine herpesvirus type 5.

Probiotics modulate the immune response and can increase the effectiveness of vaccines. Bacillus toyonensis is widely used as a probiotic in animal feed. The aim of this study was to assess the effects of B. toyonensis administration on the immune response to an experimental recombinant vaccine against bovine herpesvirus type 5 (BoHV-5) in mice. Mice were vaccinated with BoHV-5 recombinant glycoprotein D and supplemented with the probiotic B. toyonensis in two regimes: one group received the probiotic only during seven days prior to the initial vaccination while the second group was given the probiotic throughout the experimental period of seven weeks. Animals supplemented with probiotic B. toyonensis in two regimes showed an increase in total immunoglobulin (Ig)G, IgG1 and IgG2a levels in serum, in addition to higher titres of antibodies capable of neutralising the BoHV-5 virus than non-supplemented animals (P<0.05). Splenocytes from the supplemented mice had higher mRNA transcription levels of cytokines interleukin (IL)-4 and IL-12. These results show that the use of this probiotic may significantly contribute to the response elicited by recombinant vaccines, especially those that rely on increasing antibody and cell-mediated immune responses for efficacy. Further, the data support an immunomodulatory effect for probiotic B. toyonensis and imply that enhance effect on the immune response against a BoHV-5 recombinant vaccine in mice.