RESUMO
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.
RESUMO
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.
