Live and killed human immunodeficiency virus type-1 increases the intracellular growth of Leishmania donovani in monocyte-derived cells.

We coincubated killed or live human immunodeficiency virus type-1 (HIV-1) with human monocyte-derived cells infected with Leishmania donovani and examined the effect of the virus preparations on the intracellular growth of the parasite. We found that there was significant enhancement (by a mean of 53%, p < 0.001) of intracellular L, donovani growth in the human monocytic leukaemia THP-I cell line coincubated with killed HIV-I. Infection of peripheral blood monocyte-derived macrophages with live HIV-I initiated after L, donovani infection led to an increase in intracellular parasites by an overall mean of 2,8% vs 4.9% (p<0.01) at 2 and 5 d after HIV infection in L, donovani and L, donovani plus HIV-1 infected, respectively, and by an overall mean of 5.0% vs 13.3% (p < 0.001) at 5, 12 and 15 d after HIV-1 infection in L. donovani and L, donovani + HIV-1 infected, respectively. Further, L, donovani infection 2 d after infection with HIV-I led to enhanced parasite growth (34.5%, p < 0.001) compared with cells infected with L, donovani alone (5,5%), and those where HIV-1 mas added after L, donovani (18.1%), In all cases, HIV-1 from live and killed virus preparations led to decreased anti-leishmanial activity of the macrophages as evidenced by decreased control of intracellular multiplication. The findings may suggest a mechanism not requiring live virus to explain hen; HIV-1 coinfection may impair the control of intracellular Leishmania growth in individuals with pre-existing asymptomatic infection leading to the reactivation of the parasite. Moreover, patients with HIV-1 infection might be at increased risk of developing Leishmania infection.