Unresponsiveness ofMycobacterium wvaccine in managing acute and chronicLeishmania donovaniinfections in mouse and hamster

Abstract

SUMMARYThe role ofMycobacterium w(Mw) vaccine as an immunomodulator and immunoprophylactant in the treatment of mycobacterial diseases (leprosy and pulmonary tuberculosis) is well established. The fact that it shares common antigens with leishmanial parasites prompted its assessment as an immunostimulant and as an adjunct to known anti-leishmanials that may help in stimulating the suppressed immune status ofLeishmania donovani-infected individuals. The efficacy ofMwvaccine was assessed as an immunomodulator, prophylactically either alone or in combination with anti-leishmanial vaccine, as well as therapeutically as an adjunct to anti-leishmanial treatment inL. donovani-infected hamsters, representing a chronic human Visceral Leishmaniasis (VL) model. Similarly, its efficacy was also evaluated inL. donovani-infected BALB/c mice, representing an acute VL model. The preliminary studies revealed thatMwwas ineffective as an immunostimulant and/or immunoprophylactant in hamsters infected withL. donovani, as estimated by T-cell immunological responses. However, in the BALB/c mice-VL model it appeared as an effective immunostimulant but a futile prophylactic agent. It is therefore inferred that, contrary to its role in managing tuberculosis and leprosy infections,Mwvaccine has not been successful in controlling VL infection, emphasizing the need to find detailed explanations for the failure of this vaccine against the disease.