Efficacy of a Vaccine Formula against Tuberculosis in Cattle

Abstract

“Test-and-slaughter” has been successful in industrialized countries to control and eradicate tuberculosis from cattle; however, this strategy is too expensive for developing nations, where the prevalence is especially high. Vaccination with the Calmette-Guérin (BCG) strain has been shown to protect against the development of lesions in vaccinated animals: mouse, cattle and wildlife species. In this study, the immune response and the pathology of vaccinated (BCG-prime and BCG prime-CFP-boosted) and unvaccinated (controls) calves were evaluated under experimental settings. A 106 CFU dose of the BCG strain was inoculated subcutaneously on the neck to two groups of ten animas each. Thirty days after vaccination, one of the vaccinated groups was boosted with an M. bovis culture filtrate protein (CFP). Three months after vaccination, the three groups of animals were challenged with 5×105 CFU via intranasal by aerosol with a field strain of M. bovis. The immune response was monitored throughout the study. Protection was assessed based on immune response (IFN-g release) prechallenge, presence of visible lesions in lymph nodes and lungs at slaughter, and presence of bacilli in lymph nodes and lung samples in histological analysis. Vaccinated cattle, either with the BCG alone or with BCG and boosted with CFP showed higher IFN-g response, fewer lesions, and fewer bacilli per lesion than unvaccinated controls after challenge. Animals with low levels of IFN-g postvaccine-prechallenge showed more lesions than animals with high levels. Results from this study support the argument that vaccination could be incorporated into control programs to reduce the incidence of TB in cattle in countries with high prevalence.

Animal Models of Tuberculosis Vaccine Research: An Important Component in the Fight against Tuberculosis

“…Cattle are the natural host of M. bovis, and these infections are a major cause of economic losses and problems with animal welfare, along with a zoonotic risk, especially in developing countries [99]. BCG-vaccinated cattle always show a higher IFN-γ response, fewer lesions, and fewer bacilli per lesion [100,101]. Compared with nonvaccinated cattle, the microscopically visible bacterial load, CD68 + macrophages, CD3 + T lymphocytes, WC1 + γδ T cells, and CD4 + IFN-γ + T cells were significantly reduced in lymph node granulomas [102,103], and the expression of indoleamine 2,3-dioxygenase (considered to play an immunoregulatory role in the immune response to M. tuberculosis) was decreased in the granulomas of BCG-vaccinated cattle [27].…”

A Retrospective Study on Bovine Tuberculosis in Cattle on Fiji: Study Findings and Stakeholder Responses

“…Bovine tuberculosis (bTB) is a chronic bacterial disease of cattle caused mainly by Mycobacterium bovis , although other zoonotic members of the M. tuberculosis complex may be the cause, such as M. caprae , the common cause of bTB in central Europe ( 1 ). bTB results in serious economic losses for the livestock industry worldwide due to animal disposal, carcass confiscation, premature culling, low production and poor reproductive performance ( 2 ). Further infection in people results in disease that is predominantly extra-pulmonary but cannot be clinically distinguished from M. tuberculosis infection.…”

Resistencia natural contra la tuberculosis en ganado. Revisión

“…Observaciones de campo indican que, a pesar de la alta prevalencia en algunos hatos lecheros, que llega a ser de 25 a 35 %, ésta nunca alcanza el 100 % (6) . Parte de la respuesta a este fenómeno es la alta tasa de desechos sustituidos por nuevos reemplazos, libres de la enfermedad (7) . Se ha observado que algunos animales nunca presentan la enfermedad, a pesar de estar expuestos al patógeno por períodos prolongados (meses e incluso años), lo que sugiere que estos animales pueden ser naturalmente resistentes a la tuberculosis, y quizá a otras enfermedades frecuentes en el hato.…”

“…Se ha observado que algunos animales nunca presentan la enfermedad, a pesar de estar expuestos al patógeno por períodos prolongados (meses e incluso años), lo que sugiere que estos animales pueden ser naturalmente resistentes a la tuberculosis, y quizá a otras enfermedades frecuentes en el hato. Experimentalmente se ha reportado que algunos animales inoculados con altas concentraciones de M. bovis no desarrollan lesiones, reforzando la hipótesis de que en estos animales existe una resistencia innata a la tuberculosis (7) . Investigaciones recientes han intentado identificar marcadores genéticos de resistencia a enfermedades, de modo que se puedan incorporar a la mejora genética de animales con fines comerciales.…”