Schistosoma mansoni infection promotes SHIV clade C replication in rhesus macaques.

OBJECTIVE

To evaluate the hypothesis that parasitic infections that induce T-helper type 2 (Th2) immune responses, such as schistosomiasis, upregulate HIV-1 replication.

DESIGN

The effect of concomitant Schistosoma mansoni infection was tested in a primate model of acute and chronic simian-human immunodeficiency virus (SHIV) infection in rhesus macaques using a novel SHIV strain encoding the R5 env gene of a primary HIV clade C isolate from sub-Saharan Africa.

METHODS

S. mansoni-infected rhesus macaques and controls were exposed to SHIV to assess the effects of schistosomiasis on acute viral infection. Effects on chronic viral infection were evaluated by exposing virus-infected animals to parasites. S. mansoni infection was confirmed by the presence of parasite eggs in stool and eosinophilia. Viral RNA loads, cytokine and chemokine mRNA expression were measured by real time reverse transcription-PCR.

RESULTS

S. mansoni coinfection increased the expression of Th2-associated cytokine responses and SHIV replication during both acute and chronic phases of SHIV infection.

CONCLUSIONS

These results support the hypothesis that concomitant schistosomiasis upregulates replication of immunodeficiency viruses in coinfected hosts, raising the possibility that parasite-infected individuals may also be more susceptible to acquisition of HIV-1 infection.