More than their sum in your parts: the mechanisms that underpin the mutually advantageous relationship between HIV and sexually transmitted infections

Brief Report: Impact of Methamphetamine Use and Rectal STIs on Systemic and Rectal Mucosal Inflammation

BACKGROUND

Methamphetamine (MA) use is associated with sexual risk behavior as well as systemic and mucosal inflammation, suggesting parallel biological and behavioral mechanisms of HIV transmission among men who have sex with men (MSM) who use MA. Data evaluating the combined biological effects of MA use with concomitant rectal gonococcal and/or chlamydial (GC/CT) infection on inflammation are limited.

SETTING

Secondary analysis of stored rectal and plasma specimens from 100 MSM participating in an NIDA-funded longitudinal cohort in Los Angeles, CA.

METHODS

This cross-sectional analysis evaluated systemic and rectal inflammatory markers under 2 conditions: (1) recent MA use (by urine drug screen) and (2) rectal GC/CT infection. We evaluated 50 participants with recent MA use (25 with and 25 without rectal GC/CT) and 50 MSM without MA use (25 with and 25 without rectal GC/CT). Log-transformed plasma and rectal immune markers were regressed on MA exposure and rectal GC/CT, controlling for HIV status and age.

RESULTS

Median age was 32 (range 19-45) years, and 58% of participants were living with HIV. Plasma tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8, IL-1ß, and rectal IL-6 were associated with rectal GC/CT and MA use, independent of HIV status. Higher levels of rectal TNF-α, IL-1ß, and IL-17a were associated with rectal GC/CT.

CONCLUSIONS

Systemic and rectal inflammation was positively associated with rectal GC/CT and MA use. Condomless sex in the setting of GC/CT- and MA-induced immune activation may provide a basis for synergistic biobehavioral mechanisms that promote HIV/STI transmission among MSM who use MA.

An Inventory of South African Medicinal Plants Used in the Management of Sexually Transmitted and Related Opportunistic Infections: An Appraisal and Some Scientific Evidence (1990-2020)

The current work is aimed at generating the first inventory of South African medicinal plants used in the treatment of sexually transmitted and related opportunistic infections associated with HIV-AIDS. This is important in assisting researchers to access a list of plant species to evaluate for potential phytocompounds, as this area of research is greatly lagging in South Africa. A total of 335 medicinal plants from 103 families have been documented in the current work. The most represented families are Fabaceae (11.64%) and Asteraceae (6.27%). Herbs constitute 36.53%, trees 32.34%, shrubs 29.04%, climbers 1.80% and parasites 0.30%. It is worrying that on the plant parts used, the roots constitute 47.18%, while leaves and stem bark yield 16.62 and 15.01%, respectively. Catharanthus roseus exhibited the highest number of citations (19), while Peltophorum africanum had 14 and both Carica papaya and Vachelia karoo had 12. In the mode of administration of the reported medicinal plant species, most of the plants are boiled and taken orally (48.22%), while other plant species are used as mouth washes (3.25%). Although there is reasonable in vitro activity of some of the plant species, validating the relevance of use, there is still a need to explore the mode of action of such plant species; isolated compounds and possible derivatives thereof are of paramount importance and need to be explored as well. Furthermore, toxicological aspects of such plant species need to be explored.

The Intersection of HIV and Syphilis: Update on the Key Considerations in Testing and Management

Purpose of Review

To highlight recent trends in the epidemiology of HIV and syphilis, the impact of the COVID epidemic, our approach to care of co-infected patients, and our views on important next steps in advancing the field.

Recent Findings

HIV and syphilis co-infection has been on the rise in recent years although since the COVID pandemic there is a decrease in new diagnoses—it remains unclear if this represents a true decline or inadequate testing or under-reporting. Standard HIV care should include regular syphilis serology .Treatment and serological follow-up of syphilis in HIV positive and negative patients can be conducted similarly. Challenges remain in the diagnosis and management of neurosyphilis. New models for testing and prevention will be crucial next steps in controlling co-infection.

Summary

The intersection of HIV and syphilis infections continues to pose new and unique challenges in diagnosis, treatment, and prevention.

Prevalence of Neisseria gonorrhoeae and Chlamydia trachomatis in men having sex with men in Port-au-Prince, Haiti: a cross-sectional study

OBJECTIVES

Over the last 15 years, the prevalence of HIV in Haiti has stabilised to around 2.0%. However, key populations remain at higher risk of contracting HIV and other sexually transmitted infections (STIs). The prevalence of HIV is 12.9% among men having sex with men (MSM). There is limited information about the prevalence of other STI in the Haitian population in general and even less among key populations. We assessed the burden of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) and risk factors for infections among MSM in Haiti.

METHODS

A cross-sectional study was conducted. MSM were recruited from seven health facilities in Port-au-Prince. All samples were tested by nucleic acid amplification test, using GeneXpert. A survey was administered to the participants to collect socio-demographic, clinical and risk behaviour data.

RESULTS

A total of 216 MSM were recruited in the study. The prevalence rates of CT and NG were 11.1% and 16.2%, respectively. CT NG co-infections were found in 10/216 (4.6%) of the participants. There were 39 MSM with rectal STI compared with 17 with genital infections. Participants between 18-24 and 30-34 years old were significantly more likely to be infected with NG than those aged 35 years or older (OR: 22.96, 95% CI: 2.79 to 188.5; OR: 15.1, 95% CI: 1.68 to 135.4, respectively). Participants who never attended school or had some primary education were significantly more likely to be infected with NG than those with secondary education or higher (OR: 3.38, 95% CI: 1.26 to 9.07). People tested negative for HIV were significantly more likely to be infected with CT than people living with HIV/AIDS (OR: 3.91, 95% CI: 1.37 to 11.2).

CONCLUSIONS

Periodic risk assessment and testing for STI should be offered in Haiti as part of a comprehensive strategy to improve the sexual health of key populations.

Brief Report: Syphilis Coinfection Is Not Associated With an Increased Risk of Virologic Failure Among HIV-Positive Men Who Have Sex With Men on Antiretroviral Therapy

BACKGROUND

Incidence of syphilis continues to increase among HIV-positive men who have sex with men (MSM) in Ontario. Our objective was to determine the effect of acute syphilis on virologic failure (VF) among virally suppressed HIV-positive MSM taking antiretroviral therapy (ART) and determine if the relationship is confounded by drug use.

SETTING

The OHTN Cohort Study is a voluntary cohort of people receiving HIV care in Ontario. Syphilis and viral load (VL) data were retrieved via linkage with the provincial laboratory.

METHODS

Analyses included 2632 MSM from 2008 to 2015, on ART, with ≥1 questionnaire and 2 consecutive VL of <50 copies per milliliter 6 months apart. VF was defined as (1) VL of ≥1000 copies per milliliter or (2) 2 consecutive VLs of ≥200 copies per milliliter ≥1 month apart. We modeled acute syphilis as a time-varying covariate on VF using Poisson regression. Time-varying drug use was assessed for confounding using an iterative process where potential confounders were removed and then reintroduced into the model. Our model allowed for repeat observations using generalized estimating equations.

RESULTS

VF incidence was 3.5 per 100 person-years [95% confidence interval (CI): 3.4 to 4.2]. The rate ratio for VF for acute syphilis was 1.5 (95% CI: 0.9 to 2.4) in the unadjusted model; 1.6 (95% CI: 1.0 to 2.4) in the model adjusted for age, education, region, and income; and 1.2 (95% CI: 0.7 to 1.9) in the final model with additional adjustment for drug use.

CONCLUSIONS

Acute syphilis was not associated with VF among virologically suppressed MSM on ART. Consequently, ART may still reduce HIV transmission risk to sexual partners.

Physiological Changes from Violence-Induced Stress and Trauma Enhance HIV Susceptibility Among Women

PURPOSE OF REVIEW

This theoretical review identifies physiological mechanisms by which violence against women (VAW) may increase women's susceptibility to HIV through trauma, stress, and immune dysfunction.

RECENT FINDINGS

Research documents systemic and local immune responses are related to stress and trauma from abuse across the life course (i.e., childhood, IPV, adulthood re-victimization). Findings are interpreted within a theoretical framework grounded in the Social Stress Theory and the concept of toxic stress, and highlight the current state of the science connecting: (1) VAW to the physiological stress response and immune dysfunction, and (2) the physiological stress response and inflammation to HIV susceptibility and infection in the female reproductive tract. Despite a dearth of research in human subjects, evidence suggests that VAW plays a significant role in creating a physiological environment conducive to HIV infection. We conclude with a discussion of promising future steps for this line of research.

Gonorrhea in Canada, 2010-2015

Background

Gonorrhea is the second most commonly reported sexually transmitted infection (STI) in Canada after chlamydia, and rates for this STI have been increasing since 1997.

Objective

To summarize trends observed in gonorrhea rates for 2010-2015 in Canada.

Methods

Laboratory-confirmed cases of gonorrhea are reported to the Public Health Agency of Canada (PHAC) by all of the Canadian provinces and territories. The overall national rate was computed, as were rates per sex, age group and province/territory.

Results

In 2015, 19,845 cases of gonorrhea were reported in Canada, corresponding to a rate of 55.4 cases per 100,000 population and a 65.4% increase from 2010 (33.5 cases per 100,000 population). Males had consistently higher rates than did females (70.2 per 100,000 versus 40.6 per 100,000 in 2015) and faster rising rates (85.2% versus 39.5% in 2010-2015). Rates among adults 60 years and older increased faster than rates among younger people, although the highest rates were among those 15-29 years of age. The Northwest Territories, Nunavut and Yukon had the highest gonorrhea rates in 2015.

Conclusion

Males, adolescents and young adults continue to represent the majority of gonorrhea cases. Research is needed to better understand the current trends in gonorrhea infection in order to maintain, evaluate and improve primary and secondary STI prevention activities.

Chlamydia in Canada, 2010-2015

Background

Chlamydia is the most commonly reported notifiable sexually transmitted infection in Canada. Rates have been steadily increasing since 1997.

Objective

To summarize trends in chlamydia rates for the period 2010-2015 in Canada.

Methods

Laboratory-confirmed cases of chlamydia were reported to the Public Health Agency of Canada by all the Canadian provinces and territories. The overall national rate was computed, as were rates per sex, age group and province/territory.

Results

In 2015, a total of 116,499 cases of chlamydia were reported in Canada, corresponding to a rate of 325 cases per 100,000 population. Females accounted for the majority (two-thirds) of chlamydia infections from 2010 to 2015. However, rates among males rose faster during this time period. Youth and young adults aged 15-29 years had the highest rates in 2015. While increased rates were observed over time for most age groups, adults aged 40 years and older had the greatest increase (51%) between 2010 and 2015. Chlamydia rates increased in most provinces during this period, with the highest rates being reported by the Northwest Territories and Nunavut in 2015.

Conclusion

Between 2010 and 2015, chlamydia rates increased by 16.7% and were highest among females and young adults. Although a number of factors may account for this rising trend, the possibility of a true increase in incidence cannot be ruled out. Ongoing monitoring of chlamydia and research into the reasons for the observed changes will help guide sexually transmitted infection (STI) prevention and control activities.

Prevalence of Sexually Transmitted Viral and Bacterial Infections in HIV-Positive and HIV-Negative Men Who Have Sex with Men in Toronto

Background

Hepatitis B (HBV), hepatitis C (HCV) and other sexually transmitted infections (STIs) have been associated with HIV transmission risk and disease progression among gay men and other men who have sex with men (MSM), but the frequency and distribution of STIs in this community in Canada has not been extensively studied.

Methods

We recruited MSM living with and without HIV from a large primary care clinic in Toronto. Participants completed a detailed socio-behavioural questionnaire using ACASI and provided blood for syphilis, HIV, HBV and HCV, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), and human cytomegalovirus (CMV) serology, urine for chlamydia and gonorrhea, and a self-collected anal swab for human papillomavirus (HPV) molecular diagnostics. Prevalences were expressed as a proportion and compared using chi-square.

Results

442 MSM were recruited, 294 living with HIV and 148 without. Active syphilis (11.0% vs. 3.4%), ever HBV (49.4% vs. 19.1%), HCV (10.4% vs. 3.4%), HSV-2 (55.9% vs. 38.2%), CMV (98.3% vs. 80.3%) and high-risk (HR) anal HPV (67.6% vs. 51.7%) infections were significantly more common in men living with HIV. Chlamydia and gonorrhea were infrequent in both groups. Regardless of HIV infection status, age and number of lifetime male sexual partners were associated with HBV infection and lifetime injection drug use with HCV infection.

Conclusions

Syphilis and viral infections, including HBV, HCV, HSV-2, CMV, and HR-HPV, were common in this clinic-based population of MSM in Toronto and more frequent among MSM living with HIV. This argues for the implementation of routine screening, vaccine-based prevention, and education programs in this high-risk population.

Inflammation and HIV Transmission in Sub-Saharan Africa

While the per-contact risk of sexual HIV transmission is relatively low, it is fourfold higher in sub-Saharan Africa, and this may partly explain the major global disparities that exist in HIV prevalence. Genital immune parameters are key determinants of HIV transmission risk, including epithelial integrity and the presence of highly HIV-susceptible intraepithelial or submucosal CD4+ T cell target cells. Biological parameters that may enhance mucosal HIV susceptibility in highly HIV-affected regions of sub-Saharan Africa include increased levels of mucosal inflammation, which can affect both epithelial integrity and target cell availability, as well as the increased mucosal surface area that is afforded by an intact foreskin, contraceptive choices, and intravaginal practices. There are multifactorial causes for increased mucosal inflammation, with the prevalence and nature of common co-infections being particularly relevant.

Enhanced syphilis screening among HIV-positive men (ESSAHM): a study protocol for a clinic-randomized trial with stepped wedge design

BACKGROUND

The current syphilis epidemic among urban men who have sex with men (MSM) has serious implications for those co-infected with human immunodeficiency virus (HIV). Routine and frequent syphilis screening has the potential to ensure early detection and treatment, minimize disease burden, and help control the ongoing spread of syphilis and HIV. We aim to enhance syphilis screening among HIV-positive men by conducting a clinic-based intervention that incorporates opt-out syphilis testing into routine HIV laboratory evaluation for this population. Trial objectives are to determine the degree to which the intervention (1) increases the detection rate of untreated syphilis, (2) increases screening coverage, (3) increases screening frequency, and (4) reaches men at highest risk according to sexual behaviors.

METHODS/DESIGN

The trial is a pragmatic, stepped wedge cluster-randomized controlled trial that introduces the intervention stepwise across four urban HIV clinics in Ontario, Canada. The intervention includes standing orders for syphilis serological testing whenever a male in HIV care undergoes HIV viral load testing, which typically occurs every 3-6 months. The control condition is the maintenance of current, provider-initiated syphilis testing practice. Approximately 3100 HIV-positive men will be followed over 30 months. Test results will be obtained from the centralized provincial laboratory in Ontario and will be supplemented by a standardized clinical worksheet and medical chart review at the clinics. Detailed clinical, psychosocial, and behavioral data is available for a subset of men receiving HIV care who are also participants of the province-wide Ontario HIV Treatment Network Cohort Study. Process evaluation plans include audit and feedback of compliance of the participating centers to identify potential barriers to the introduction of this type of practice into routine care. Health economic components include evaluation of the impact and cost-effectiveness of the intervention.

DISCUSSION

This trial will be the first of its kind in Canada and will provide evidence regarding the feasibility, clinical effectiveness, and cost-effectiveness of a clinic-based intervention to improve syphilis screening among HIV-positive men. Involvement of knowledge users in all stages of trial design, conduct, and analysis will facilitate scale-up should the intervention be effective.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02019043.

High incidence of diagnosis with syphilis co-infection among men who have sex with men in an HIV cohort in Ontario, Canada

BACKGROUND

The re-emergence of syphilis among HIV-positive gay and other men who have sex with men (MSM) requires vigilance. We estimated incidence of and risk factors for first and subsequent syphilis diagnoses among MSM in HIV care in Ontario, Canada.

METHODS

We analyzed data from 2,280 MSM under follow-up from 2006 to 2010 in the Ontario HIV Treatment Network Cohort Study (OCS), a multi-site clinical cohort. We obtained syphilis serology results via record linkage with the provincial public health laboratory. Rates were calculated using Poisson regression.

RESULTS

First syphilis diagnoses occurred at a rate of 2.0 per 100 person-years (95 % CI 1.7, 2.4; 121 cases) whereas the re-diagnosis rate was 7.5 per 100 person-years (95 % CI 6.3, 8.8; 136 cases). We observed higher rates over time and among men who were aged <30 years, receiving care in the two largest urban centers, or had a previous syphilis diagnosis. Syphilis diagnosis was less common among Indigenous men, men with higher CD4 cell counts, and, for first diagnoses only, among men with less than high school education.

CONCLUSIONS

Compared to reported cases in the general male population, incidence of a new syphilis diagnosis was over 300 times greater among HIV-positive MSM but year-to-year changes reflected provincial trends. Re-diagnosis was common, suggesting treatment failure or re-infection. Novel syphilis control efforts are needed among HIV-positive MSM.

In vivo evaluation of a mucoadhesive polymeric caplet for intravaginal anti-HIV-1 delivery and development of a molecular mechanistic model for thermochemical characterization

CONTEXT AND OBJECTIVE

The aim of this study was to develop, characterize and evaluate a mucoadhesive caplet resulting from a polymeric blend (polymeric caplet) for intravaginal anti-HIV-1 delivery.

MATERIALS AND METHODS

Poly(lactic-co-glycolic) acid, ethylcellulose, poly(vinylalcohol), polyacrylic acid and modified polyamide 6, 10 polymers were blended and compressed to a caplet-shaped device, with and without two model drugs 3'-azido-3'-deoxythymidine (AZT) and polystyrene sulfonate (PSS). Thermal analysis, infrared spectroscopy and microscopic analysis were carried out on the caplets employing temperature-modulated DSC (TMDSC), Fourier transform infra-red (FTIR) spectrometer and scanning electron microscope, respectively. In vitro and in vivo drug release analyses as well as the histopathological toxicity studies were carried out on the drug-loaded caplets. Furthermore, molecular mechanics (MM) simulations were carried out on the drug-loaded caplets to corroborate the experimental findings.

RESULTS AND DISCUSSION

There was a big deviation between the Tg of the polymeric caplet from the Tg's of the constituent polymers indicating a strong interaction between constituent polymers. FTIR spectroscopy confirmed the presence of specific ionic and non-ionic interactions within the caplet. A controlled near zero-order drug release was obtained for AZT (20 d) and PSS (28 d). In vivo results, i.e. the drug concentration in plasma ranged between 0.012-0.332 mg/mL and 0.009-0.256 mg/mL for AZT and PSS over 1-28 d.

CONCLUSION

The obtained results, which were corroborated by MM simulations, attested that the developed system has the potential for effective delivery of anti-HIV-agents.

Intravaginal ring eluting tenofovir disoproxil fumarate completely protects macaques from multiple vaginal simian-HIV challenges

Topical preexposure prophylaxis interrupts HIV transmission at the site of mucosal exposure. Intermittently dosed vaginal gels containing the HIV-1 reverse transcriptase inhibitor tenofovir protected pigtailed macaques depending on the timing of viral challenge relative to gel application. However, modest or no protection was observed in clinical trials. Intravaginal rings (IVRs) may improve efficacy by providing long-term sustained drug delivery leading to constant mucosal antiretroviral concentrations and enhancing adherence. Although a few IVRs have entered the clinical pipeline, 100% efficacy in a repeated macaque vaginal challenge model has not been achieved. Here we describe a reservoir IVR technology that delivers the tenofovir prodrug tenofovir disoproxil fumarate (TDF) continuously over 28 d. With four monthly ring changes in this repeated challenge model, TDF IVRs generated reproducible and protective drug levels. All TDF IVR-treated macaques (n = 6) remained seronegative and simian-HIV RNA negative after 16 weekly vaginal exposures to 50 tissue culture infectious dose SHIV162p3. In contrast, 11/12 control macaques became infected, with a median of four exposures assuming an eclipse of 7 d from infection to virus RNA detection. Protection was associated with tenofovir levels in vaginal fluid [mean 1.8 × 10(5) ng/mL (range 1.1 × 10(4) to 6.6 × 10(5) ng/mL)] and ex vivo antiviral activity of cervicovaginal lavage samples. These observations support further advancement of TDF IVRs as well as the concept that extended duration drug delivery devices delivering topical antiretrovirals could be effective tools in preventing the sexual transmission of HIV in humans.

Patterns of syphilis testing in a large cohort of HIV patients in Ontario, Canada, 2000-2009

Background

Since 2000, reported syphilis cases increased ten-fold in Canada, particularly among men who have sex with men (MSM) co-infected with HIV. We characterized temporal patterns of of syphilis testing in a large cohort of HIV patients in Ontario, Canada.

Methods

We analyzed data from a multi-site cohort of people in HIV care from 2000 to 2009. Data were obtained from medical charts, interviews and record linkage with the syphilis test database at the Public Health Ontario Laboratories. We estimated the proportion that had syphilis testing at least once per year and the period and annual prevalence of reactive tests.

Results

Among 4232 participants, the annual proportion tested rose from 2.7% (95%CI 1.9, 3.5) in 2000 to 54.6% (95%CI 52.9, 56.3) in 2009. Testing was most common for participants who were men who have sex with men (MSM), aged <30, recently diagnosed with HIV, were antiretroviral treatment naive, had routine HIV lab testing at least twice in that year, or tested for syphilis in the preceding year. The proportion with at least one reactive test in 2000–09 was 21.0% (95%CI 19.4, 22.7) for MSM, 5.3% (95%CI 3.3, 7.4) for non-MSM males, and 2.6% (95%CI 1.2, 4.0) for women. Among MSM, the annual prevalence of reactive syphilis tests with high RPR titre (≥1:16) peaked at 3.8% in 2009.

Conclusions

The burden of syphilis co-infection rose considerably among HIV-positive MSM, such that by 2009, at least 1 in 5 men had laboratory evidence of current or past infection. Interventions may be needed to boost syphilis testing to achieve goals set by guidelines even in settings with universal health care.

Vaginal microbicides to prevent human immunodeficiency virus infection in women: perspectives on the female genital tract, sexual maturity and mucosal inflammation

Topically applied vaginal microbicides to protect against human immunodeficiency (HIV) virus infection offer an important female-controlled prevention strategy. Microbicides have been in development for more than 2 decades, and have included various agents that disrupt cellular and microbial membranes (surfactants), restore the natural acidic protective pH of the vagina (acid buffers), and those that interfere with interactions between HIV envelope proteins and cellular receptors (anionic polymers). Although none of these candidate microbicides have shown significant protection against HIV in clinical trials, a topical gel, including the antiretroviral drug tenofovir (TFV) 1% was the first microbicide to be tested to show some protection against HIV infection. This review explores the effect of female genital tract biology and anatomy, mucosal inflammation, and age on the effectiveness of microbicides to prevent HIV infection.

Sexual risk taking, STI and HIV prevalence among men who have sex with men in six Indonesian cities

Using surveillance data on men who have sex with men (MSM) from six Indonesian cities, this article reports prevalence of sexual risk taking, HIV and other sexually transmitted infections. Factors associated with HIV, other STIs and consistent condom use were assessed. Behavioral data were collected from 1,450 MSM, among whom 749 were tested for HIV and syphilis and 738 for gonorrhea and Chlamydia. Associations were assessed using multivariate logistic regression. Over 80% of MSM knew HIV transmission routes, 65% of MSM had multiple male sexual partners, 27% unprotected anal sex with multiple male partners, and 27% sex with a female in the prior month. Consistent condom use ranged from 30 to 40% with male partners and 20 to 30% with female partners, depending upon partner type. HIV prevalence averaged 5.2%, but was 8.0% in Jakarta. Prevalence of rectal gonorrhea or Chlamydia was 32%. Multivariate analyses revealed recent methamphetamine use and current rectal gonorrheal or chlamydial infection to be associated with HIV infection. The data confirm diverse sexual networks and substantial sexual risk-taking, despite relatively high levels of education and HIV-related knowledge. In addition to promoting partner reduction and more consistent condom and lubricant use, prevention efforts must also address substance abuse.

Biological factors that may contribute to regional and racial disparities in HIV prevalence

Despite tremendous regional and subregional disparities in HIV prevalence around the world, epidemiology consistently demonstrates that black communities have been disproportionately affected by the pandemic. There are many reasons for this, and a narrow focus on socio-behavioural causes may be seen as laying blame on affected communities or individuals. HIV sexual transmission is very inefficient, and a number of biological factors are critical in determining whether an unprotected sexual exposure to HIV results in productive infection. This review will focus on ways in which biology, rather than behaviour, may contribute to regional and racial differences in HIV epidemic spread. Specific areas of focus are viral factors, host genetics, and the impact of co-infections and host immunology. Considering biological causes for these racial disparities may help to destigmatize the issue and lead to new and more effective strategies for prevention.

In vivo evaluation of the release of zidovudine and polystyrene sulfonate from a dual intravaginal bioadhesive polymeric device in the pig model

This study focused on determining the concentration of zidovudine (AZT) and polystyrene sulfonate (PSS) in the plasma and vaginal tissue of the large white pig from an intravaginal bioadhesive polymeric device (IBPD). Biocompatible polymers were compressed with AZT and PSS into caplet-shaped devices for insertion into the posterior fornix of the pig vagina. A total of 25 pigs were used in this study. Plasma was sampled from the jugular vein at various time points after insertion of the IBPD reaching 28 days. At day 28, the pigs were euthanized and vaginal tissue was removed and digested with subtilisin for AZT and PSS extraction. The mean concentration detected in vaginal tissue at day 28 was 1.214 ± 0.062 mg/mL for AZT and 1.400 ± 0.071 mg/mL for PSS. Plasma concentration was significantly lower for AZT (0.332 ± 0.014 mg/mL) and PSS (0.256 ± 0.013 mg/mL). This indicated higher retention of AZT and PSS within the vaginal tissue. Molecular mechanics simulations blueprinted polymer-drug-mucin force-field interactions and energies that explicated the spatial preference of AZT and PSS for the vaginal tissue. Histopathotoxicity studies revealed negative-to-mild foreign body events and results strongly suggest that the IBPD may be suitable for prolonged intravaginal drug delivery in preventing the transmission of sexually transmitted infections and HIV/AIDS.