Good Protection but Excessive Pulmonary Inflammation in Balb/C Mice Vaccinated with Mycobacterium Bovis Mce-2A Mutant after Challenge with Homologous Strains

EDGAR ALFONSECA-SILVA; ANGEL CATALDI; FABIANA BIGI; ROGELIO HERNÁNDEZ-PANDO

Mycobacterial Diseases

OMICS Publishing Group

Lugar: Los Angeles; Año: 2012 vol. 2 p. 1 - 2

2161-1068

Tuberculosis (TB) remains a major threat to public and veterinary health. Zoonotic TB (caused by Mycobacteriumbovis) is present in wild animals and cattle in most developing countries, and M. bovis is also able to infect humans on aworldwide basis. Thus, the high incidence of bovine TB is a major economic problem and an additional risk to humanhealth, being the development of new vaccines to prevent both human and bovine TB urgent and a major challenge.The aims of the present study were to characterize the pathogenicity and immunogenicity of M. bovis mce2A mutantin BALB/c mice, and then evaluate its potential as vaccine. Mutant M. bovis mce2A produced limited tissue damage(pneumonia) and lower bacilli burdens than its parental strain when administered in high dose by intratrachealinoculation, and showed limited dissemination when used as subcutaneous vaccine. Challenge experiments usinglow, middle and highly virulent M. tuberculosis or M. bovis strains showed similar protection conferred by mce-2mutant than BCG. Interestingly, vaccinated animals showed low bacilli loads but high inflammatory response whenwere challenged with M. bovis strains, while vaccinated mice challenged with M. tuberculosis exhibited low bacilliburdens and scarce inflammation. Thus, in spite of the high genome homology between M. tuberculosis and M.bovis, it seems that there is higher antigenic recognition and in consequence extensive inflammatory response whenthe strain used as vaccine is homologous to the challenge strain, in this case M. bovis.