Aug 2017 DOI 10.14302/issn.2575-1212.jvhc-17-1662
Díaz Otero FernandoCorresponding author
Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Centro Nacional de Investigación Disciplinaria en Microbiología Animal, Carretera México-Toluca, Km 15.5, D.F., 05110, México
Immunization of cattle with the bacillus Calmette-Guérin (BCG) vaccine, especially neonates, induces protection against Mycobacterium bovis (M. bovis) and has been proposed as a strategy for bovine tuberculosis (bTB) control. Therefore, the aim of this study was to evaluate the immune response induced under field conditions in neonatal calves vaccinated with BCG Phipps, a strain that has rarely been evaluated in the bovine population, using interferon (IFN)-γ and tuberculin tests, flow cytometry and enzyme-linked immunosorbent assay. Two groups (vaccinated and control) of 5 calves were monitored for 12 weeks, and increases in the in vitro IFN-γ production, the percentage of cluster of differentiation (CD)8+ T cells and the activation levels of CD4+ and CD8+ T cells were observed 3 to 4 weeks post-vaccination. Bovine purified protein derivative-specific IFN-γ production was increased about 4.8- and 5.5-fold in vaccinated animals compared to non-vaccinated animals 3 and 4 weeks post-vaccination respectively. CD8+ T cells of the vaccinated group were increased 1.6-, 1.5- and 1.6-fold at weeks 2, 3 and 4 respectively. Levels of activation were 1.7- and 1.9-fold higher for CD4+ T cells and 2.3- and 1.8-fold higher for CD8+ T cells in the vaccinated group at weeks 3 and 4 respectively in response to M. bovis antigens. However, no animals (vaccinated or control) showed positive results for the single intradermal comparative tuberculin test (SICTT). Therefore, our results indicate that vaccination with M. bovis BCG Phipps strain stimulated peripheral blood T cell activity and induced a cell-mediated immune response. In addition, vaccination did not interfere with the SICTT, as previously reported, which indicates that this vaccine could be successfully applied in bTB control campaigns.
Dec 2018 DOI 10.14302/issn.2575-1212.jvhc-18-2487
Fernando Díaz-OteroCorresponding author
Centro Nacional de Investigaciones Disciplinarias en Microbiología Animal, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Carretera México-Toluca, Km. 15.5, C.P. 05110, México D.F.
Parasitic infection by the Fasciola hepatica (F. hepatica) promotes susceptibility towards other infections, such as Mycobacterium bovis. As consequence, could affect diagnostic tests for this disease. Hence, the objective of this study was to assess the impact of F. hepatica coinfection on the most commonly used immunodiagnostic bovine tuberculosis (bTB) tests in field conditions in an enzootic area for both diseases. Thus, from a dairy herd located in Hidalgo State, México, displaying a 59.2% and 28% prevalence of fascioliasis and bTB, respectively. Sixty-one cows were analyzed based on their response towards bTB immunodiagnostic tests, such as Single Intradermal Comparative Tuberculin Test (SICTT), gamma-interferon test (BOVIGAM) and enzyme-linked immunosorbent assay (ELISA), along with the assessment of the F. hepatica parasite load and serodiagnosis by ELISA. Three study groups were formed according to test results. Group 1: coinfected (n=22). Group 2: non-parasitized cows, and positive for bTB tests (n=13) and Group 3: parasitized cows without tuberculosis (n=26). In addition, a group of cows kept in fascioliasis - and tuberculosis-free zones were included (Group 4, n=10). A non-parametric Kruskal-Wallis test and a Dunn test were applied to analyze the results. In Group 1, significant differences were observed regarding IFN-γ production, but not for antibody levels to M. bovis or reactivity towards bovine PPD in relation Group 2. While, Groups 1 and 3 did not display difference in antibody levels against F. hepatica. Differences were observed regarding tuberculosis and Fasciola diagnostic tests when both coinfected and infected groups were compared to controls. It is concluded that F. hepatica coinfection in tuberculous animals studied, depressed the production of IFN-γ towards bovine PPD under in vitro conditions, but its reactivity to the SICTT not show to be altered.