Development of a rectal sexually transmitted infection--HIV coinfection model utilizing Chlamydia trachomatis and SHIVSF162p3.

Background: Rectal sexually transmitted infections (STIs) may increase HIV susceptibility in men who have sex with men (MSM), and Chlamydia trachomatis is prevalent among HIV-positive MSM. To study STIs and HIV infection in MSM, we first evaluated whether cynomolgus macaques can sustain both C. trachomatis and SHIVSF162p3 infections.

Methods: Four SHIVSF162p3 -positive male cynomolgus macaques were used (n = 3 rectally inoculated with 10(6) IFU; n = 1 control). Systemic and rectal SHIV RNA levels and cytokines were measured by real-time PCR and Luminex assays, respectively.

Results: Macaques were successfully Chlamydia infected. Rectal SHIV shedding (P = 0.02 χ(2) ) and levels of G-CSF, IL-1ra, IL-6, IL-8, IFN-γ, and TNF-α (P ≤ 0.01, Mann-Whitney) in rectal secretions increased following infection.

Conclusions: These pilot data successfully demonstrate rectal C. trachomatis-SHIV coinfection in cynomolgus macaques and suggest the feasibility of a rectal C. trachomatis model for SHIV susceptibility and biomedical prevention studies in the context of rectal STIs.