Vaccination Strategies in a Potential Use of the Vaccine against Bovine Tuberculosis in Infected Herds.

Bovine tuberculosis (bTB) is a disease of cattle that represents a risk to public health and causes severe economic losses to the livestock industry. Recently, one of the strategies recommended for reducing the prevalence of the disease in animals is the use of the BCG vaccine, alone or in combination with proteins. It has been shown that the vaccine elicits a strong immune response, downsizes the number of animals with visible lesions, and reduces the rate of infection as well as the bacillary count. This paper, based on scientific evidence, makes suggestions about some practical vaccination alternatives that can be used in infected herds to reduce bTB prevalence, considering BCG strains, vaccine doses, routes of application, and age of the animals. Our conclusion is that vaccination is a promising alternative to be included in current control programs in underdeveloped countries to reduce the disease burden.

Trypanosoma cruzi and Leishmania spp. in rodents in a peri-urban area of Central Mexico.

Rodents are one of the most relevant groups of mammals involved in the process of zoonotic disease transmission. Their ability to adapt to anthropized environments allows them to come into contact with humans with often negative consequences for the latter. The present study designed to detect the presence of Trypanosoma cruzi and Leishmania spp. in rodents living in the peri-urban area of Queretaro in central Mexico. This research was carried out during two seasons of collection of wild and domestic rodents, in three localities within the peri-urban area of the state of Queretaro. These collections were carried out during the dry season of February-May 2017 and in the rainy season of August-November 2017. Samples were obtained from the tail tip, from which DNA was purified using the DNeasy Blood & Tissue Kit. End-point PCR was used for the identification of Trypanosoma cruzi and Leishmania spp. A total of 82 rodents were caught, represented in three families, six genera and seven species, of which 29 (35.3%) were positive for Trypanosoma cruzi; 13 (15.8%) for Leishmania spp.; and 12 individuals presented co-infection with both parasites (14.6%). This study confirmed the presence of Trypanosoma cruzi and Leishmania spp. in synanthropic rodents in the peri-urban area of Queretaro, where Chagas and Leishmaniosis diseases are not considered endemic. It is necessary to continue researching for the presence of vectors, as well as for the detection of diseases caused by parasites in humans and thus be able to confirm the transmission cycle of Trypanosoma cruzi and Leishmania spp. in this central Mexican city.

Prime Vaccination with Chitosan-Coated Phipps BCG and Boosting with CFP-PLGA against Tuberculosis in a Goat Model.

Attempts to improve the immune response and efficacy of vaccines against tuberculosis in cattle, goats, and other animal species have been the focus of research in this field during the last two decades. Improving the vaccine efficacy is essential prior to running long-lasting and expensive field trials. Studies have shown that vaccine protocols utilizing boosting with proteins improve the vaccine efficacy. The use of polymers such as chitosan and PolyLactic-co-Glycolic Acid (PLGA) improves the immune response against different diseases by improving the interaction of antigens with the cellular immune system and modulating the host immune response. This study shows that the prime BCG vaccination, boosted with a culture filtrate protein (CFP), alone or in combination with chitosan and PolyLactic-co-Glycolic Acid (PLGA), have the potential to reduce tuberculosis (TB) dissemination by reducing the number of animals with lesions, the number of lesions per animal, and the size of the lesions in vaccinated animals, compared with those not vaccinated or those vaccinated with BCG alone. The vaccinated groups showed significantly higher Interferon-γ levels in the blood compared to the control, nonvaccinated group after vaccination, after boosting, and after the challenge with the wild-type Mycobacterium bovis strain.

Efficacy of a vaccine formula against tuberculosis in cattle.

"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 10(6) 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 5×10(5) 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.

Population structure of Mycobacterium bovis isolates from cattle in Mexico.

The molecular fingerprints of 878 isolates of Mycobacterium bovis collected from cattle between 2009 and 2010 in different regions of Mexico were used in this study. One hundred and ninety-four spoligotypes were observed in total with a high degree of heterogeneity. Sixty-four percent of the isolates grouped into just nine spoligotypes, and 27% fell into only two spoligotypes: SB0673 and SB0669; 149 were orphan spoligotypes. The two predominant spoligotypes were found in almost all states in Mexico, especially in central Mexico, where there is a high concentration of dairy cattle; however, some spoligotypes were closely associated with restricted geographical areas. The hypothetical evolutionary relationship among spoligotypes was estimated using the spoligoforest program in the spolTools webpage. Four trees with connected components and nine unconnected nodes were found. The biggest tree had SB0140 strain as a root, suggesting this as the oldest strain in the tree. However, the relationship of this spoligotype with SB0673 and SB0669 was weak. The discriminatory power of spoligotyping for this M. bovis sample of isolates was 0.94, and the recent transmission index (RTI) 0.83, suggesting a high rate of recent transmission of some strains of M. bovis in the population. This parameter indicates that new measures are required to stop the dissemination of tuberculosis in cattle.