The median time from SHIVSF162P3 infection to STI (or mock) inoculation was 278 days (40 weeks), and the time frame of STI infection follow-up ranged from 32 to 98 days (4.5–14 weeks) (). At the time of STI inoculation, CD4+ T cells levels were within normal levels of SHIV-infected and uninfected animals in our colony; CD4+ T cell levels did not change significantly throughout the course of the study (data not shown).
Study overview: time frame of infection and gynecologic sign presentation
All STI-inoculated macaques (n = 5) were successfully infected with T. vaginalis alone (n = 2), C. trachomatis alone (n = 1), or C. trachomatis and T. vaginalis (n = 2). Two macaques were utilized as STI-negative controls, mock-infected as previously described. Colposcopy was used to visualize the cervicovaginal compartment and characterize the genital mucosa and discharge. In macaques infected with T. vaginalis only, characteristic manifestations of ‘strawberry cervix’ and green, foamy discharge were observed (). Similarly, characteristic gynecologic signs were observed in the macaque infected with C. trachomatis only, such as cervical erythema, blistering and erosion of the cervical mucosa, and mucopurulent discharge (). Signs were most overt in the dual STI-infected macaques. In addition to foamy vaginal discharge, increased severity of erythema and erosion, as well as mucosal edema, was also noted (). Manifestations were most prominent at days 7–10 post-inoculation, although erythema and discharge persisted to varying degrees in all STI-infected animals throughout the study course. Discharge persisted longer and was more consistently observed than mucosal erythema. These observations were compared with mock media-inoculated animals, in which normal genital mucosa and discharge were observed ().
Cervical cell infiltrate collected by cytobrush sampling was examined at different time points throughout the study in the C. trachomatis-only-, dual STI-infected animals, and mock media-inoculated animal. (). An increase in PMNs, relative to baseline, was observed in all STI-infected macaques, rising as high as 42% in one animal (FH3), and peaked at approximately 2–3 weeks post-infection. A similar increase was observed in the percentage of total leukocyte infiltrate (PMNs + mononuclear cells). Increased levels of cell infiltrate were observed only in STI-infected macaques. The number of animals in this pilot study was not powered to achieve statistical significance in these analyses.
Fig. 1 Relative increase in inflammatory cells in cervical cell collections of sexually transmitted infection (STI)-infected macaques. Analyses were conducted in Chlamydia trachomatis-only (96Po58)- and C. trachomatis + Trichomonas vaginalis–infected (more ...)
Cervical colposcopic images from a representative animal (FH3), which was dual STI-infected, are shown in . Compared with baseline, vascularization and edema of the cervix visible by day 7 (post-administration of 1st C. trachomatis inoculums, ) and manifestations worsen by day 10 (post-administration of T. vaginalis and the 2nd C. trachomatis inoculums, ). Pronounced edema and discharge, severe erythema, and points of blistering erosion are visible (). These gynecologic signs are analogous to those documented in women for both C. trachomatis and T. vaginalis infections.
Fig. 2 Cervical colposcopic images of a representative macaque (FH3) (10 × magnification). (A) Cervical mucosa (ectocervix) at baseline, characterized by normal, pink coloration, and presence of scant, clear normal menstrual-related discharge. (B) Cervical (more ...)
Plasma SHIV RNA levels were monitored throughout the study course, but did not fluctuate in response to STI inoculation/infection (). Genital SHIV RNA analysis was also undertaken, but conclusions were limited because of infrequent sample collection (data not shown).
Fig. 3 No impact of sexually transmitted infections on plasma SHIVSF162P3 RNA levels. No differences in plasma SHIV RNA levels (y-axis) was observed in response to Chlamydia trachomatis (96Po58), Trichomonas vaginalis (TD6 and 96Po17), or C. trachomatis + T. (more ...)
Infections were observed a minimum of 32 days (4.6 weeks) to 98 days (14 weeks) before STI treatments were administered. One animal, 96Po17, was euthanized on day 32 of the study, prior to treatment, with a diagnosis of bacterial hepatitis; however, the attending veterinarian determined cause of death was unrelated to T. vaginalis infection. The remaining STIinfected macaques successfully cleared infections with the respective, appropriate treatment(s).
Infections with both C. trachomatis serovars D and E were tested and compared in this study, albeit with small animal numbers. Macaque 96Po58 was infected with serovar E only, whereas macaques 96Po78 and FH3 were both dual-infected with T. vaginalis and C. trachomatis serovars D and E, respectively (). More prolonged erythema and discharge were noted in the serovar D/Trichomonas-infected animal compared with the serovar E/Trichomonas-infected animal. Additionally, up to 500-fold higher levels of mucosal IFN-gamma were observed in the serovar D-infected animal between days 4 and 14 post- STI infection, compared with the serovar E-infected animal (data not shown). From the pinch biopsy sampling, increased vaginal histopathology (leukocyte infiltrate and epithelial sloughing) was also noted in the serovar D-infected animal (data not shown). Cervical histopathologic changes were not detected in any of the STI-infected animals (data not shown).