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

Body Parts Matter: Social, Behavioral, and Biological Considerations for Urethral, Pharyngeal, and Rectal Gonorrhea and Chlamydia Screening Among MSM in Lima, Peru

BACKGROUND

Gonorrhea (Neisseria gonorrhoeae [GC]) and chlamydia (Chlamydia trachomatis [CT]) disproportionately affect men who have sex with men (MSM), and public health implications vary by anatomic site and bacterial agent. Urethral and rectal GC and CT can increase risk of HIV transmission, whereas pharyngeal GC may be a reservoir for antimicrobial resistance. To define screening priorities in Latin America, we compare differences in the prevalence and correlates of urethral, pharyngeal, and rectal GC and CT among MSM in Peru.

METHODS

A cross-sectional sample of 787 MSM from Lima was screened between 2012 and 2014. We described prevalence of urethral, pharyngeal, and rectal GC and CT infection and conducted bivariate analyses of associations with social, behavioral, and biological characteristics. Poisson regression analyses assessed the correlates of each infection at each anatomic site.

RESULTS

The most commonly symptomatic infection (urethral GC; 42.1%) was the least prevalent (2.4%). The most prevalent infections were rectal CT (15.8%) and pharyngeal GC (9.9%). Rectal CT was the least commonly symptomatic (2.4%) infection, and was associated with younger age (adjusted prevalence ratio [95% confidence interval], 0.96 [0.94-0.98]), HIV infection (1.46 [1.06-2.02]), and pasivo (receptive; 3.59 [1.62-7.95]) and moderno (versatile; 2.63 [1.23-5.60]) sexual roles.

CONCLUSIONS

Results highlight limitations of current syndromic screening strategies for sexually transmitted diseases in Peru, wherein urethral CT and rectal GC and CT may be missed due to their frequently asymptomatic presentations. Successful management of GC and CT infections among MSM in low-resource settings requires differentiating between bacterial agent, symptomatic presentation, associated risk factors, and public health implications of untreated infection at different anatomic sites.

A Macaque Model for Rectal Lymphogranuloma Venereum and Non-Lymphogranuloma Venereum Chlamydia trachomatis: Impact on Rectal Simian/Human Immunodeficiency Virus Acquisition

BACKGROUND

Sustained genital tract inflammation caused by sexually transmitted infections (STIs) is known to increase risk of vaginal human immunodeficiency virus (HIV) infections but, to our knowledge, there are no nonhuman primate studies that have evaluated its link to rectal HIV acquisition.

METHODS

Rhesus macaques inoculated with Chlamydia trachomatis (CT) (serovars LGV-L2 and CT-E; n = 7) or saline (n = 7) received up to 20 rectal challenges twice a week of simian/HIV immunodeficiency virus (SHIVSF162p3). SHIV viremia was determined by real-time PCR and Chlamydia infection by APTIMA Combo 2 testing. The rectal cytokine-chemokine levels were evaluated by multiplex bead assays.

RESULTS

Rectal Chlamydia infection was maintained throughout the study. We did not observe significant differences (P = 1.0) in frequency of SHIV acquisition between the STI and control arms. It took fewer SHIV challenges to infect the STI animals although the difference was not significant (P = 0.59). There were no significant differences in peak plasma viremia between STI and control arms (P = 0.63). The association of plasma viremia with rectal shedding was significantly different by arm (P = 0.038).

CONCLUSIONS

In the first such study in a macaque model, we did not observe an increased risk of SHIV acquisition due to rectal Chlamydia coinfection. This macaque model can be further developed and expanded to better investigate the impact of different rectal STIs on HIV acquisition.

Development of a rectal sexually transmitted infection (STI) Model in Rhesus macaques using Chlamydia trachomatis serovars E and L2

BACKGROUND

Rectal STI coinfection models enhance the understanding of rectal HIV transmission risk factors.

MATERIALS AND METHODS

Rhesus macaques (n=9) were exposed to one of three rectal Chlamydia trachomatis (CT) challenges: C. trachomatis L2 (CT-L2 ); C. trachomatis serovar E (CT-E), followed by CT-L2 ; or CT-E, treatment/clearance, then CT-L2 . Infections were monitored by PCR. Weekly blood and rectal secretion/lavage samples were collected for cytokine analyzes and/or epithelial sloughing, occult, and overt blood determinations.

RESULTS

Chlamydial infections were successfully established in each animal, with varying degrees of persistence. Mucosal IL-1beta was upregulated in animals consecutively infected with CT-E then CT-L2 (P=.05). Epithelial sloughing was also significantly increased post-infection in this group (P=.0003).

CONCLUSIONS

This study demonstrates successful rectal infection of rhesus macaques with CT-E and CT-L2 and describes measures of assessing rectal inflammation and pathology. Different infection strategies yield varying inflammatory and pathologic outcomes, providing well-described models for future SIV/SHIV susceptibility studies.

HIV Incidence Among Men Who Have Sex With Men After Diagnosis With Sexually Transmitted Infections

BACKGROUND

Men who have sex with men (MSM) are at high risk for acquiring HIV infection after diagnosis with other sexually transmitted infections (STIs). Identifying the STIs associated with the greatest risk of subsequent HIV infection could help target prevention interventions, particularly preexposure prophylaxis (PrEP).

METHODS

Using matched HIV and STI surveillance data from Washington State from January 1, 2007, to June 30, 2013, we calculated the incidence of new HIV diagnoses after different STI diagnoses among MSM. Men entered observation at the time of their first STI diagnosis during the study period and exited at HIV diagnosis or June 30, 2013. Cox proportional hazards regression was used to conduct a global comparison of rates.

RESULTS

From January 1, 2007, to June 30, 2013, 6577 HIV-negative MSM were diagnosed as having 10,080 bacterial STIs at 8371 unique time points and followed for 17,419 person-years. Two hundred eighty (4.3%) men were subsequently diagnosed as having HIV infection for an overall incidence of 1.6 per 100 person-years (95% confidence interval, 1.4-1.8). The estimated incidence of HIV diagnoses among all MSM in the state was 0.4 per 100 person-years. Men who have sex with men were at the greatest risk for HIV diagnosis after being diagnosed as having rectal gonorrhea (HIV incidence, 4.1 per 100 person-years), followed by early syphilis (2.8), urethral gonorrhea (1.6), rectal chlamydial infection (1.6), pharyngeal gonorrhea (1.1), late syphilis (1.0), and urethral chlamydial infection (0.6; P < 0.0001 overall).

CONCLUSIONS

Men who have sex with men diagnosed as having rectal gonorrhea and early syphilis were at the greatest risk for being diagnosed as having HIV infection after STI diagnosis. These men should be prioritized for more intensive prevention interventions, including PrEP.

Animal and human mucosal tissue models to study HIV biomedical interventions: can we predict success?

Introduction

Preclinical testing plays an integral role in the development of HIV prevention modalities. Several models are used including humanized mice, non-human primates and human mucosal tissue cultures.

Discussion

Pharmaceutical development traditionally uses preclinical models to evaluate product safety. The HIV prevention field has extended this paradigm to include models of efficacy, encompassing humanized mice, non-human primates (typically Asian macaques) and human mucosal tissue (such as cervical and colorectal). As our understanding of the biology of HIV transmission improves and includes the influence of human behaviour/biology and co-pathogens, these models have evolved as well to address more complex questions. These three models have demonstrated the effectiveness of systemic (oral) and topical use of antiretroviral drugs. Importantly, pharmacokinetic/pharmacodynamic relationships are being developed and linked to information gathered from human clinical trials. The models are incorporating co-pathogens (bacterial and viral) and the effects of coitus (mucosal fluids) on drug distribution and efficacy. Humanized mice are being tailored in their immune reconstitution to better represent humans. Importantly, human mucosal tissue cultures are now being used in early clinical trials to provide information on product efficacy to more accurately characterize efficacious products to advance to larger clinical trials. While all of these models have made advancements in product development, each has limitations and the data need to be interpreted by keeping these limitations in mind.

Conclusions

Development and refinement of each of these models has been an iterative process and linkages to data generated among each of them and from human clinical trials are needed to determine their reliability. Preclinical testing has evolved from simply identifying products that demonstrate efficacy prior to clinical trials to defining essential pharmacokinetic/pharmacodynamic relationships under a variety of conditions and has the potential to improve product selection prior to the initiation of large-scale human clinical trials. The goal is to provide researchers with ample information to make conversant decisions that guide optimized and efficient product development.

Rectal application of a highly osmolar personal lubricant in a macaque model induces acute cytotoxicity but does not increase risk of SHIV infection

BACKGROUND

Personal lubricant use is common during anal intercourse. Some water-based products with high osmolality and low pH can damage genital and rectal tissues, and the polymer polyquaternium 15 (PQ15) can enhance HIV replication in vitro. This has raised concerns that lubricants with such properties may increase STD/HIV infection risk, although in vivo evidence is scarce. We use a macaque model to evaluate rectal cytotoxicity and SHIV infection risk after use of a highly osmolar (>8,000 mOsm/kg) water-based lubricant with pH of 4.4, and containing PQ15.

METHODS

Cytotoxicity was documented by measuring inflammatory cytokines and epithelial tissue sloughing during six weeks of repeated, non-traumatic lubricant or control buffer applications to rectum and anus. We measured susceptibility to SHIVSF162P3 infection by comparing virus doses needed for rectal infection in twenty-one macaques treated with lubricant or control buffer 30 minutes prior to virus exposure.

RESULTS

Lubricant increased pro-inflammatory cytokines and tissue sloughing while control buffer (phosphate buffered saline; PBS) did not. However, the estimated AID50 (50% animal infectious dose) was not different in lubricant- and control buffer-treated macaques (p = 0.4467; logistic regression models).

CONCLUSIONS

Although the test lubricant caused acute cytotoxicity in rectal tissues, it did not increase susceptibility to infection in this macaque model. Thus neither the lubricant-induced type/extent of inflammation nor the presence of PQ15 affected infection risk. This study constitutes a first step in the in vivo evaluation of lubricants with regards to HIV transmission.