Long-acting Injectable PrEP Interest and General PrEP Awareness among People who Inject Drugs in the San Diego-Tijuana Border Metroplex.

Long-acting injectable HIV pre-exposure prophylaxis (LAI-PrEP) could help overcome multilevel challenges to HIV prevention for people who inject drugs (PWID), including those in the binational San Diego-Tijuana metroplex. Yet, general PrEP awareness and interest in LAI-PrEP remain underexplored among PWID. From 2020 to 2021, 562 HIV-negative PWID in San Diego and Tijuana completed surveys assessing general PrEP awareness and interest in oral and LAI-PrEP. Modified Poisson regression examined factors associated with general PrEP awareness. Multinomial logistic regression assessed factors associated with interest in both oral and LAI-PrEP, oral PrEP only, LAI-PrEP only, or neither. General PrEP awareness was low (18%) and associated with experiencing unsheltered homelessness (adjusted prevalence ratio [APR] = 1.50, 95% confidence interval [CI]: 0.96-2.33), past 6-month fentanyl injection (APR = 1.53, 95% CI: 1.04-2.25), and transactional sex (APR = 1.71, 95% CI: 1.06-2.76). Interest in oral PrEP only was most common (44%), followed by LAI-PrEP only (25%) and neither (16%). Compared to the odds of being interested in LAI-PrEP only, the odds of being interested in oral PrEP only were lower among those who were stopped by police (AOR = 0.38, 95% CI: 0.22-0.65), reported past 6-month fentanyl injection (AOR = 0.33, 95% CI: 0.20-0.56), polydrug use (AOR = 0.48, 95% CI: 0.27-0.86), injecting multiple times daily (AOR = 0.26, 95% CI: 0.14-0.46), receptive syringe use (AOR = 0.30, 95% CI: 0.19-0.49), and higher perceived HIV risk (AOR = 0.24, 95% CI: 0.15-0.39). Interest in LAI-PrEP was more common among PWID reporting social and structural factors that could interfere with oral PrEP adherence, suggesting LAI-PrEP implementation could increase PrEP coverage among those most vulnerable to HIV.

NOS2 and COX-2 Co-Expression Promotes Cancer Progression: A Potential Target for Developing Agents to Prevent or Treat Highly Aggressive Breast Cancer.

Nitric oxide (NO) and reactive nitrogen species (RNS) exert profound biological impacts dictated by their chemistry. Understanding their spatial distribution is essential for deciphering their roles in diverse biological processes. This review establishes a framework for the chemical biology of NO and RNS, exploring their dynamic reactions within the context of cancer. Concentration-dependent signaling reveals distinctive processes in cancer, with three levels of NO influencing oncogenic properties. In this context, NO plays a crucial role in cancer cell proliferation, metastasis, chemotherapy resistance, and immune suppression. Increased NOS2 expression correlates with poor survival across different tumors, including breast cancer. Additionally, NOS2 can crosstalk with the proinflammatory enzyme cyclooxygenase-2 (COX-2) to promote cancer progression. NOS2 and COX-2 co-expression establishes a positive feed-forward loop, driving immunosuppression and metastasis in estrogen receptor-negative (ER-) breast cancer. Spatial evaluation of NOS2 and COX-2 reveals orthogonal expression, suggesting the unique roles of these niches in the tumor microenvironment (TME). NOS2 and COX2 niche formation requires IFN-γ and cytokine-releasing cells. These niches contribute to poor clinical outcomes, emphasizing their role in cancer progression. Strategies to target these markers include direct inhibition, involving pan-inhibitors and selective inhibitors, as well as indirect approaches targeting their induction or downstream effectors. Compounds from cruciferous vegetables are potential candidates for NOS2 and COX-2 inhibition offering therapeutic applications. Thus, understanding the chemical biology of NO and RNS, their spatial distribution, and their implications in cancer progression provides valuable insights for developing targeted therapies and preventive strategies.

Gene regulatory effects of a large chromosomal inversion in highland maize.

Chromosomal inversions play an important role in local adaptation. Inversions can capture multiple locally adaptive functional variants in a linked block by repressing recombination. However, this recombination suppression makes it difficult to identify the genetic mechanisms underlying an inversion's role in adaptation. In this study, we used large-scale transcriptomic data to dissect the functional importance of a 13 Mb inversion locus (Inv4m) found almost exclusively in highland populations of maize (Zea mays ssp. mays). Inv4m was introgressed into highland maize from the wild relative Zea mays ssp. mexicana, also present in the highlands of Mexico, and is thought to be important for the adaptation of these populations to cultivation in highland environments. However, the specific genetic variants and traits that underlie this adaptation are not known. We created two families segregating for the standard and inverted haplotypes of Inv4m in a common genetic background and measured gene expression effects associated with the inversion across 9 tissues in two experimental conditions. With these data, we quantified both the global transcriptomic effects of the highland Inv4m haplotype, and the local cis-regulatory variation present within the locus. We found diverse physiological effects of Inv4m across the 9 tissues, including a strong effect on the expression of genes involved in photosynthesis and chloroplast physiology. Although we could not confidently identify the causal alleles within Inv4m, this research accelerates progress towards understanding this inversion and will guide future research on these important genomic features.

Cocirculation and replacement of SARS-CoV-2 variants in crowded settings and marginalized populations along the US-Mexico border.

OBJECTIVE: To interrogate the circulating SARS-CoV-2 lin-eages and recombinant variants in persons living in migrant shelters and persons who inject drugs (PWID). MATERIALS AND METHODS: We combined data from two studies with marginalized populations (migrants in shelters and persons who inject drugs) in Tijuana, Mexico. SARS-CoV-2 variants were identified on nasal swabs specimens and compared to publicly available genomes sampled in Mexico and California. RESULTS: All but 2 of the 10 lineages identified were predomi-nantly detected in North and Central America. Discrepan-cies between migrants and PWID can be explained by the temporal emergence and short time span of most of these lineages in the region. CONCLUSION: The results illustrate the temporo-spatial structure for SARS-CoV-2 lineage dispersal and the potential co-circulation of multiple lineages in high-risk populations with close social contacts. These conditions create the potential for recombination to take place in the California-Baja California border.

Correlates of impulsivity among female sex workers in Mexico.

Impulsivity is a trait characteristic that is associated with sexual risk behavior. We examined correlates of impulsivity among 602 female sex workers (FSWs) enrolled in a sexual risk reduction intervention in Mexico (2016-2020). Impulsivity was positively associated with condomless sex with clients. Higher levels of impulsivity were associated with greater use of alcohol and heavy drugs, use of illicit drugs with clients, sexual/physical abuse history, and clinical depression. Global public health policy that supports free substance abuse treatment in combination with psychotherapeutic treatments (e.g. regulation management skills) and behavioral-focused therapy may help to reduce HIV/STI incidence in this vulnerable population.

Unleashing the full power of LHCb to probe stealth new physics.

In this paper, we describe the potential of the LHCb experiment to detect stealth physics. This refers to dynamics beyond the standard model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.

Chikungunya virus antagonizes cGAS-STING mediated type-I interferon responses by degrading cGAS.

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus known to cause epidemics resulting in predominantly symptomatic infections, which in rare cases cause long term debilitating arthritis and arthralgia. Significant progress has been made in understanding the roles of canonical RNA sensing pathways in the host recognition of CHIKV; however, less is known regarding antagonism of CHIKV by cytosolic DNA sensing pathways like that of cyclic GMP-AMP synthase (cGAS) and Stimulator of Interferon Genes (STING). With the use of cGAS or STING null cells we demonstrate that the pathway restricts CHIKV replication in fibroblasts and immune cells. We show that DNA accumulates in the cytoplasm of infected cells and that CHIKV blocks DNA dependent IFN-ß transcription. This antagonism of DNA sensing is via an early autophagy-mediated degradation of cGAS and expression of the CHIKV capsid protein is sufficient to induce cGAS degradation. Furthermore, we identify an interaction of CHIKV nsP1 with STING and map the interaction to 23 residues in the cytosolic loop of the adaptor protein. This interaction stabilizes the viral protein and increases the level of palmitoylated nsP1 in cells. Together, this work supports previous publications highlighting the relevance of the cGAS-STING pathway in the early detection of (+)ssRNA viruses and provides direct evidence that CHIKV interacts with and antagonizes cGAS-STING signaling.

A Randomized Controlled Trial of a Texting Intervention to Maintain Sexual Risk Reduction with Clients Among Female Sex Workers in Tijuana and Ciudad Juarez, Mexico.

Mobile phone technology may help sustain reductions in HIV/STI transmission risk behaviors among female sex workers (FSWs). We examined the efficacy of a text messaging intervention designed to maintain behavioral improvements in safer sex practices among 602 FSWs in Tijuana and Ciudad Juarez, Mexico. We hypothesized that FSWs who received brief risk reduction counseling and theory-based safer sex maintenance text messages over a 24-month period would have fewer incident HIV/STIs and report greater maintenance of safer sex practices compared to FSWs who received counseling and texts on maintaining general health. Theory-based texts did not change the odds of becoming infected with HIV/STIs in either study site. However, they did lead to significant, sustained protected sex in Tijuana. Theory-based text messaging interventions may help sustain reductions in sexual risk behavior among FSWs.Trial Registration Clinical Trials.gov. Identifier: NCT02447484.

Maternal role strain and depressive symptoms among female sex workers in Mexico: the moderating role of sex work venue.

Stressors that arise in parenting are likely to have an adverse impact on the psychological well-being of female sex workers (FSWs), particularly in low- to middle-income countries (LMIC). This study examined the association between maternal role strain and depressive symptoms among 426 FSW mothers with dependent-age children (aged < 18 years) in Tijuana and Cd. Juarez, Mexico (2016-2017). Four dimensions of maternal role strain (e.g., child emotional and behavioral problems) were examined in relation to maternal depressive symptoms. We also investigated whether the relationship between maternal role strain and depressive symptoms was modified by venue of sex work. Compared to indoor/establishment-based FSWs, street-based FSWs reported significantly more child-related financial strain. In multiple regression analysis, having more depressive symptoms was associated with identifying as a street-based FSW, greater use of drugs, lower emotional support, more child-related financial strain and more emotional and behavioral problems in children. A significant interaction was identified such that the association between maternal role strain and depressive symptoms was stronger for indoor/establishment-based compared to street-based FSWs. These findings suggest the need to address parenting strain and type of sex work venue in the development of counseling programs to improve the mental health of FSWs in LMIC.

8-Hydroxy-2-(1H-1,2,3-triazol-1-yl)-1,4-naphtoquinone derivatives inhibited P2X7 Receptor-Induced dye uptake into murine Macrophages.

Extracellular adenosine 5'-triphosphate (ATP) triggers the P2X7 receptor (P2X7R) ionic channel to stimulate the release of the interleukin-IL-1ß cytokine into macrophages. The current study explored the reaction of six structurally diverse triazole derivatives on P2X7-mediated dye uptake into murine peritoneal macrophages. P2X7R activity determined by ATP-evoked fluorescent dye uptake. Triazole derivatives toxicity measured using dextran rhodamine exclusion based colorimetric assay. A740004 and BBG, both P2X7R antagonist, inhibited ATP-induced dye uptake. In contrast, the derivatives 5a, 5b, 5e, and 5f did not diminish P2X7R activity in concentrations until 100 µM. 5c and 5d analogs caused a potent inhibitory activity on P2X7-induced dye uptake. Dextran Rhodamine exclusion measurements after 24 h of continuous treatment with triazole derivatives indicated a moderated toxicity for all molecules. In conclusion, this study showed that a series of new hybrid 1,2,3-triazolic naphthoquinones reduces P2X7R-induced dye uptake into murine macrophages. In silico analysis indicates a good pharmacokinetic profile and molecular docking results of these analogs indicate the potential to bind into an allosteric site located into the P2X7R pore and juxtaposed with the ATP binding pocket. In this manner, the compounds 5c and 5d may be used as a scaffold for new P2X7R inhibitors with reduced toxicity, and good anti-inflammatory activity.

Impact of time perspectives on texting intervention to reduce HIV/STI transmission among female sex workers in Tijuana and Ciudad Juarez, Mexico.

Text messages may sustain post-counseling gains in behavioral improvements and reduce HIV/STI incidence. However, their effectiveness may depend on the messages' time perspective and characteristics of the individual. We evaluated the impact of time perspective on a text messaging intervention designed to maintain improvements in safer sex practices among drug-using and non-drug-using female sex workers (FSWs) in Tijuana (n = 141) and Cd. Juarez (n = 129), Mexico. FSWs received the efficacious Mujer Segura intervention, and were randomized to receive safer sex maintenance text messages with either a short-term or future-oriented time perspective. The outcome was HIV/STI incidence rate over 6-month follow-up. In Tijuana, combined HIV/STI incidence density was lower among FSWs in the FUTURE group (31.67 per 100 py) compared to women in the SHORT-TERM group (62.40 per 100 py). Conversely, in Cd. Juarez, HIV/STI incidence density was lower (although non-significant) among FSWs in the SHORT-TERM group (19.80 per 100 py) compared to those in the FUTURE group (35.05 per 100 py). These findings suggest that future-oriented text messages may sustain post-counseling improvements in sexual risk behavior among FSWs, but findings may vary by FSWs' characteristics (e.g., drug use), and by region and context.

Educating Hispanics About Clinical Trials and Biobanking.

Hispanics are under-represented in clinical research. To ensure that the Hispanic population benefits from advances in public health and medicine, including personalized medicine, there is a need to increase their participation in clinical trials and biobanking. There is a great need for improving awareness and addressing concerns individuals may have about participation. The purpose of this study was to adapt, implement, and evaluate educational materials about clinical trials and biobanking for Hispanic individuals. We adapted existing materials based on focus group data. We then trained four promotoras de salud to deliver education to Hispanic adults in community settings in Houston, TX. The promotoras educated 101 Hispanic adults, 51 on biobanking and 50 on clinical trials. Study staff administered brief pre- and post-test questionnaires that measured benefits, barriers, norms, self-efficacy, and intention to participate in either clinical trials or biobanking. Our sample was predominately female (83%) and Spanish-speaking (69%) and made less than $25,000 a year (87%). This intervention increased perceived benefits of participating in biobanking and clinical trials, self-efficacy for donating biospecimens, and intention to participate in biobanking if invited. Perceived barriers to participating declined. This study demonstrated that brief education can result in improved perceptions and attitudes related to participation in biobanking and clinical trials, and could increase participation. Researchers and practitioners could use these educational materials to educate Hispanic community members on clinical research potentially increasing participation rates in the future.

Measuring Current Drug Use in Female Sex Workers and Their Noncommercial Male Partners in Mexico: Concordance Between Data Collected From Surveys Versus Semi-Structured Interviews.

BACKGROUND: Self-reports are commonly used to assess prevalence and frequency of drug use, but it is unclear whether qualitative methods like semi-structured interviews are as useful at obtaining such information as quantitative surveys. OBJECTIVES: This study compared drug use occurrence and frequency using data collected from quantitative surveys and qualitative interviews. We also examined whether combining data from both sources could result in significant increases in percentages of current users and whether the concordance between the two sets of data was associated with the type of drug use, age, gender and socioeconomic status. METHODS: Self- reports of recent marijuana, heroin, crack, cocaine, crystal/methamphetamine, inhalant, and tranquilizer use were collected using both methods from a cohort of Mexican female sex workers and their non-commercial male partners (n = 82). RESULTS: Participants were significantly less likely to report marijuana, cocaine and tranquilizer use and frequency of use during the qualitative interviews than during the quantitative surveys. Agreement on frequency of drug use was excellent for crystal/methamphetamine, heroin and inhalant use, and weak for cocaine, tranquilizers and marijuana use. Older participants exhibited significantly higher concordance than younger participants in reports of marijuana and methamphetamine use. Higher monthly income was significantly associated with higher concordance in crack use but lower concordance with marijuana use. CONCLUSIONS: Although use of such data can result in an underreporting of drug use, qualitative data can be quantified in certain circumstances to triangulate and confirm the results from quantitative analyses and provide a more comprehensive view of drug use.

Love, Trust, and HIV Risk Among Female Sex Workers and Their Intimate Male Partners.

OBJECTIVES: We examined correlates of love and trust among female sex workers and their noncommercial male partners along the Mexico-US border. METHODS: From 2011 to 2012, 322 partners in Tijuana and Ciudad Juárez, Mexico, completed assessments of love and trust. Cross-sectional dyadic regression analyses identified associations of relationship characteristics and HIV risk behaviors with love and trust. RESULTS: Within 161 couples, love and trust scores were moderately high (median 70/95 and 29/40 points, respectively) and correlated with relationship satisfaction. In regression analyses of HIV risk factors, men and women who used methamphetamine reported lower love scores, whereas women who used heroin reported slightly higher love. In an alternate model, men with concurrent sexual partners had lower love scores. For both partners, relationship conflict was associated with lower trust. CONCLUSIONS: Love and trust are associated with relationship quality, sexual risk, and drug use patterns that shape intimate partners' HIV risk. HIV interventions should consider the emotional quality of sex workers' intimate relationships.

"Amar te Duele" ("love hurts"): sexual relationship power, intimate partner violence, depression symptoms and HIV risk among female sex workers who use drugs and their non-commercial, steady partners in Mexico.

A significant body of research among female sex workers (FSWs) has focused on individual-level HIV risk factors. Comparatively little is known about their non-commercial, steady partners who may heavily influence their behavior and HIV risk. This cross-sectional study of 214 FSWs who use drugs and their male steady partners aged ≥18 in two Mexico-U.S. border cities utilized a path-analytic model for dyadic data based upon the Actor-Partner Interdependence Model to examine relationships between sexual relationship power, intimate partner violence (IPV), depression symptoms, and unprotected sex. FSWs' relationship power, IPV perpetration and victimization were significantly associated with unprotected sex within the relationship. Male partners' depression symptoms were significantly associated with unprotected sex within the relationship. Future HIV prevention interventions for FSWs and their male partners should address issues of sexual relationship power, IPV, and mental health both individually and in the context of their relationship.

Changes in metal contents in shrimp cultured in NW Mexico (2000-2010).

This study shows the concentrations of Cd, Cu, Pb, and Zn in the muscle and hepatopancreas of Pacific white shrimps, Litopenaeus vannamei, cultured during 2010 in 26 commercial farms of the three main producer states of the Mexican NW, Sonora, Sinaloa, and Nayarit and compares the results to those obtained in 2000 using samples collected in16 farms of the same states. No significant changes were detected in Cd concentrations, but the 2010 Zn levels were significantly higher in all states in the hepatopancreas and in Sinaloa in the case of the muscle. Cu showed a tendency to higher hepatopancreas values in 2010, but differences were significant only in Sonora and for the global mean value. In contrast, Pb was one order of magnitude lower in both organs in 2010, possibly because of the almost 15 years since leaded gasoline was discontinued in Mexico.

Anthocyanins and Phenolic Acids of Hybrid and Native Blue Maize (Zea mays L.) Extracts and Their Antiproliferative Activity in Mammary (MCF7), Liver (HepG2), Colon (Caco2 and HT29) and Prostate (PC3) Cancer Cells.

Blue maize is an excellent source of bioactive components such as phenolic acids and anthocyanins but when it is processed for human consumption, these compounds decrease considerably. Therefore, blue maize could be directed to produce nutraceutical extracts. The aim of this study was to evaluate the relation between anthocyanins composition of acidified and non-acidified extracts from native and hybrid blue maize genotypes and their antiproliferative effect in mammary (MCF7), liver (HepG2), colon (Caco2 and HT29) and prostate (PC3) cancer cells. The most abundant phenolic acid was ferulic acid. Nine anthocyanins were quantified in the extracts, being Cy3-Glu the most abundant. Acylated forms were also obtained in high abundance depending of the extraction method. An extract concentration range of 4.31 to 7.23 mg/mL inhibited by 50% the growth of untransformed cells NIH3T3. Antiproliferative effect on PC3, Caco2, HepG2 and MCF7 cancer cells of acidified extracts from hybrid blue maize was larger than the observed using non-acidified extracts. Among the nine compounds that were quantified in the extracts tested, CyMalGlu I showed the strongest correlation with the reduction of cell viability in Caco2 (-0.876), HepG2 (-0.813), MCF7 (-0.765) and PC3 (-0.894). No significant correlation or differences in antiproliferative effect on HT29 was found among the extracts. The method of extraction of maize anthocyanins must be selected to obtain a high yield of CyMalGlu I more than only Cy3-Glu since acylation affects the inhibition of cancer cell growth.

Challenging the roles of CD44 and lipolysis stimulated lipoprotein receptor in conveying Clostridium perfringens iota toxin cytotoxicity in breast cancer.

BACKGROUND: Translational exploration of bacterial toxins has come to the forefront of research given their potential as a chemotherapeutic tool. Studies in select tissues have demonstrated that Clostridium perfringens iota toxin binds to CD44 and lipolysis stimulated lipoprotein receptor (LSR) cell-surface proteins. We recently demonstrated that LSR expression correlates with estrogen receptor positive breast cancers and that LSR signaling directs aggressive, tumor-initiating cell behaviors. Herein, we identify the mechanisms of iota toxin cytotoxicity in a tissue-specific, breast cancer model with the ultimate goal of laying the foundation for using iota toxin as a targeted breast cancer therapy. METHODS: In vitro model systems were used to determine the cytotoxic effect of iota toxin on breast cancer intrinsic subtypes. The use of overexpression and knockdown technologies confirmed the roles of LSR and CD44 in regulating iota toxin endocytosis and induction of cell death. Lastly, cytotoxicity assays were used to demonstrate the effect of iota toxin on a validated set of tamoxifen resistant breast cancer cell lines. RESULTS: Treatment of 14 breast cancer cell lines revealed that LSR+/CD44- lines were highly sensitive, LSR+/CD44+ lines were slightly sensitive, and LSR-/CD44+ lines were resistant to iota cytotoxicity. Reduction in LSR expression resulted in a significant decrease in toxin sensitivity; however, overexpression of CD44 conveyed toxin resistance. CD44 overexpression was correlated with decreased toxin-stimulated lysosome formation and decreased cytosolic levels of iota toxin. These findings indicated that expression of CD44 drives iota toxin resistance through inhibition of endocytosis in breast cancer cells, a role not previously defined for CD44. Moreover, tamoxifen-resistant breast cancer cells exhibited robust expression of LSR and were highly sensitive to iota-induced cytotoxicity. CONCLUSIONS: Collectively, these data are the first to show that iota toxin has the potential to be an effective, targeted therapy for breast cancer.

Client perspectives on design and implementation of a couples-based intervention to reduce sexual and drug risk behaviors among female sex workers and their noncommercial partners in Tijuana and Ciudad Juárez, México.

This mixed-methods study examined the acceptability of a hypothetical couples-based HIV prevention program for female sex workers and their intimate (non-commercial) male partners in Mexico. Among 320 participants, 67 % preferred couples-based over individual programs, particularly among men. Reasons cited for preferring couples-based programs included convenience and health benefits for both partners. Participants reported that they would benefit from general health information and services, HIV counseling and testing, job training (particularly for men) and other services. However, qualitative interviews revealed that barriers relating to the environment (i.e., poor access to services), providers (i.e., lack of a therapeutic alliance), and intimate relationships (i.e., mistrust or instability) would need to be addressed before such a program could be successfully implemented. Despite women's concerns about privacy and men's preferences for gender-specific services, couples-based HIV prevention programs were largely acceptable to female sex workers and their intimate male partners.

Prevalence and correlates of HIV and sexually transmitted infections among female sex workers and their non-commercial male partners in two Mexico-USA border cities.

Female sex workers (FSWs) acquire HIV and other sexually transmitted infections (STIs) through unprotected sex with commercial and non-commercial (intimate) male partners. Little research has focused on FSWs' intimate relationships, within which condom use is rare. We sought to determine the prevalence and correlates of HIV/STIs within FSWs' intimate relationships in Northern Mexico. From 2010 to 2011, we conducted a cross-sectional survey of FSWs and their non-commercial male partners in Tijuana and Ciudad Juárez, Mexico. Eligible FSWs and their verified male partners were aged ≥18 years; FSWs reported lifetime use of heroin, cocaine, crack, or methamphetamine and recently exchanged sex (past month). Participants completed baseline questionnaires and testing for HIV, chlamydia, gonorrhea, and syphilis. We determined the prevalence and correlates of individuals' HIV/STI positivity using bivariate probit regression. Among 212 couples (n = 424), prevalence of HIV was 2.6 % (n = 11). Forty-two (9.9 %) tested positive for any HIV/STIs, which was more prevalent among women than men (12.7 % vs. 7.1 %, p < 0.05). FSWs with regular sex work clients were less likely to test positive for HIV/STIs than those without regular clients. Similarly, male partners of FSWs who had regular clients were 9 % less likely to have HIV/STIs. Higher sexual decision-making power was protective against HIV/STIs for women. Men who recently used methamphetamine or reported perpetrating any conflict within steady relationships were more likely to test positive for HIV/STIs. Within FSWs' intimate relationships in two Mexican-US border cities, nearly one in ten partners tested positive for HIV/STIs. Couple-based prevention interventions should recognize how intimate relationship factors and social contexts influence HIV/STI vulnerability.