Humoral Immune Response in Parvoviral Vaccinated Dogs Experimentally Infected with Trypanosoma congolense and Trypanosoma brucei

The humoral immune response in parvoviral vaccinated dogs experimentally infected with single and mixed infection of Trypanosoma congolense and Trypanosoma brucei was studied in mongrel dogs. Twenty mongrel dogs of mixed sexes and approximately 4-6 months of age weighing an average of 6.3 kg were used for the experiment. After the experiment, some of the dogs were given to the department of Veterinary medicine, University of Nigeria, Nsukka while the rest were sold out in dog market. They were acclimatized for three weeks prior to commencement of the study during which time routine treatments and screening were done. The dogs were divided into five groups of four dogs each. Group A was vaccinated and uninfected, group B was unvaccinated and uninfected, group C was vaccinated and infected with T. congolense, group D was vaccinated and infected with T. brucei and group E was vaccinated and infected with T. congolense and T. brucei.

Results obtained from this study provided evidence that dogs vaccinated against canine parvovirus (CPV) produced protective antibody titre whereas those infected with trypanosome parasites failed to mount a strong humoral immune response to CPV vaccination. This was evident by the low Immunoglobulin G (IgG) antibody titre shown in the study. The IgG titre significantly increased after revaccination in all vaccinated groups as evident in the increased S-value. The reduction in the immune response to the vaccination was partially dependent on the species of trypanosomes used in the infection. Furthermore, revaccination with canine parvoviral vaccine enhances immunity against parvovirus in dogs. It was thus concluded that canine trypanosomosis affects the immune response to parvovirus vaccination by decreasing the IgG antibody titre.