Genomic characterization and molecular evolution analysis of subtype B and BF recombinant HIV-1 strains among Argentinean men who have sex with men reveal a complex scenario.

Currently, data on HIV-1 circulating strains among men who have sex with men (MSM) in Argentina is scarce. In South America, the distribution and the prevalence of BF recombinants are dissimilar and exhibit an underappreciated heterogeneity of recombinant structures. Here, we studied for the first time the genetic diversity of HIV-1 BF recombinants and their evolution over time through in-depth phylogenetic analysis and multiple recombination detection methods involving 337 HIV-1 nucleotide sequences (25 near full-length (NFL) and 312 partial pol gene) obtained from Argentinean MSM. The recombination profiles were studied using multiple in silico tools to characterize the genetic mosaicism, and phylogenetic approaches to infer their relationships. The evolutionary history of BF recombinants and subtype B sequences was reconstructed by a Bayesian coalescent-based method. By phylogenetic inference, 81/312 pol sequences clustered within BF clade. Of them, 46 sequences showed a genetic mosaic with CRF12_BF-like patterns, including plausible second-generation recombinants. Other CRFs_BF like (CRF17, 28, 29, 39, 42, 44, 47) and probable URFs_BF were less frequently found. Phylogenetic and recombination analyses on NFL sequences allowed a meticulous definition of new BF mosaics of genomic patterns. The Bayesian analyses pointed out quite consistent onset dates for the CRFs_BF clade based on B and F gene datasets (~1986 and ~1991 respectively). These results indicate that the CRFs_BF variants have been circulating among Argentinean MSM for about 30 years. This study reveals, through growing evidence showing the importance of MSM in the dynamics of the HIV-1 epidemic in Argentina, the coexistence of CRF12_BF-like and high diversity of strains exhibiting several BF mosaic patterns, including non-reported URFs that may reflect active clusters as potential intervention targets to hinder HIV-1 transmission.

Analysis of reverse transcriptase and protease genes of HIV for antiretroviral drug resistance in treatment-exposed Jamaican pediatrics.

This study reports on the drug resistance profiles for HIV-infected pediatrics in Jamaica who have been exposed to antiretroviral therapy (ART). The genetic diversity of HIV-1 found in these patients was also determined using phylogenetic analysis. The protease-reverse transcriptase (Pro-RT) region of the genome was amplified from 40 samples, sequenced, and analyzed for the identification of antiretroviral resistance-associated mutations (RAMs). All isolates belonged to subtype B and 39 possessed multiple RAMs in the reverse transcriptase genes that would compromise the efficacy of drugs being used to treat these patients. Four isolates possessed RAMs in the protease genes. The overall frequency of HIV drug resistance was 95%. The high frequency of drug resistance is supported by epidemiological data that revealed an equally high frequency of treatment failure (98%) among the study participants. The results of this study indicate the urgent need for greater access to drug resistance testing in Jamaica.

Analysis of protease and reverse transcriptase genes of HIV for antiretroviral drug resistance in Jamaican adults.

This study reports on the drug resistance profiles for HIV-infected adults in Jamaica using genotypic methods. The genetic diversity of HIV-1 found in these patients was also determined using phylogenetic analysis. Epidemiological data were documented for each patient, blood was collected by venous puncture, and plasma was separated and stored. Viral RNA was extracted and analyzed for mutations in the viral genome by the amplification of the protease and reverse transcriptase (Pro-RT) regions using a nested PCR method. The rate of drug resistance among treatment-experienced individuals was 35%, while treatment-naive individuals showed a prevalence of 29%. The overall prevalence of drug resistance mutations in Jamaicans was consistent with the increased use of antiretroviral drugs in the region, with many of the mutations detected reducing susceptibility to the drugs commonly used to treat Jamaican patients. These results indicate the need for regular drug resistant surveillance to guide treatment strategies.

Detection of HIV-1 dual infections in highly exposed treated patients.

BACKGROUND: Genetic characterization of HIV-1 in Argentina has shown that BF recombinants predominate among heterosexuals and injecting drug users, while in men who have sex with men the most prevalent form is subtype B. OBJECTIVES: The aim of this work was to investigate the presence of HIV dual infections in HIV-infected individuals with high probability of reinfection STUDY DESIGN: Blood samples were collected from 23 HIV positive patients with the risk of reinfection from Buenos Aires. A fragment of the HIV gene pol was amplified and phylogenetic analyses were performed. Antiretroviral drug resistance patterns of all the sequences were analyzed. RESULTS: Five dual infections were detected with four patients coinfected with subtype B and BF recombinants and one patient was coinfected with two BF recombinants presenting different recombination patterns. Prolonged infection with a stable clinical condition was observed in the five individuals. Resistance mutation patterns were different between the predominant and the minority strains. CONCLUSIONS: Our results show that HIV dual infection can occur with closely related subtypes, and even with different variants of the same recombinant form in certain populations. Clinical observations showed neither aggressive disease progression nor impact on the resistance patterns in the dually-infected patients.

Significantly longer envelope V2 loops are characteristic of heterosexually transmitted subtype B HIV-1 in Trinidad.

BACKGROUND: In Trinidad and the wider Caribbean, subtype B Human Immunodeficiency Virus-type 1 (HIV-1B) overwhelmingly accounts for HIV infection among heterosexuals; this contrasts with the association of HIV-1B with homosexual transmission and injecting drug use globally. The HIV envelope contains genetic determinants of cell tropism and evasion from immune attack. In this study we investigate the genetic properties of the env V1-C4 of HIV-1B soon after transmission to Trinidadian heterosexuals. This will reveal distinctive genetic features of the strains that cause the HIV-1B epidemic in Trinidad and generate insights to better understand their properties. METHODOLOGY/PRINCIPAL FINDINGS: Quasispecies sampling was performed on the env V1-C4 of HIV-1B strains soon after transmission to heterosexual Trinidadians in a cohort of seroconverters. Phylogenetic relationships were determined for these quasispecies and the length and number of asparagine (N) linked glycosylation sites (NLGS) in their variable loops compared to that for HIV-1B globally. Signature amino acids within the constant domains of the env V1-C4 were identified for heterosexually transmitted HIV-1B from Trinidad relative to HIV-1B globally. HIV-1B obtained from Trinidadian heterosexuals soon after seroconversion had significantly longer V2 loops with one more glycosylation site, shorter V3 loops and no significant difference in V1 or V4 when compared to HIV-1B obtained soon after seroconversion from infected individuals in the rest of the world. HIV-1B soon after seroconversion and during chronic infection of Trinidadians was not significantly different, suggesting that distinctly long V2 loops are characteristic of HIV-1B in Trinidad. A threonine deletion at position 319 (T319-) along with the substitutions R315K and S440R were found to be distinctly associated with HIV-1B from Trinidad compared to HIV-1B globally. CONCLUSIONS: This finding of distinctive genetic features that are characteristic of HIV-1B strains from Trinidad is consistent with the Trinidad epidemic being established by a founder strain or closely related founder strains of HIV-1B.

Genotypic characterization of HIV type 1 in Jamaica.

This study seeks to analyze nearly full-length viral genomes for distinct genetic characteristics that are unique to local or regional strains and to identify regions that have high variability or are highly conserved. Nearly full length sequences of seven HIV-1 samples were obtained to ascertain the circulating subtype diversity in the HIV-1 epidemic in Jamaica as well as conduct detailed sequence analysis. The phylogenetic analysis of the seven sequences showed all the sequences clustering with HIV-1 pure B subtype references. The predicted amino acid sequenced in the V3 loop for the Jamaican samples showed that six samples contained the characteristic conserved tetrapeptide motif GPGR. One occurrence in isolate 09JM.PF09WX displayed a GQGP tetrameric motif similar to that found in a Korean B strain. All seven isolates (100%) were R5 viruses for preferential cofactor usage. These samples were collected from individuals who had tested positive for 1-5 years and were drug naive. The results suggested that the viruses were isolated from patients in the nonprogressive stage of disease. These are early stages in the assessment and the patient should be monitored to predict the progression of the disease and when HAART should begin.

HIV-1 epidemic in the Caribbean is dominated by subtype B.

BACKGROUND: The molecular epidemiology of HIV-1 in the Caribbean has been described using partial genome sequencing; subtype B is the most common subtype in multiple countries. To expand our knowledge of this, nearly full genome amplification, sequencing and analysis was conducted. METHODOLOGY/PRINCIPAL FINDINGS: Virion RNA from sera collected in Haiti, Dominican Republic, Jamaica and Trinidad and Tobago were reverse transcribed, PCR amplified, sequenced and phylogenetically analyzed. Nearly full genomes were completed for 15 strains; partial pol was done for 67 strains. All but one of the 67 strains analyzed in pol were subtype B; the exception was a unique recombinant of subtypes B and C collected in the Dominican Republic. Of the nearly full genomes of 14 strains that were subtype B in pol, all were subtype B from one end of the genome to the other and not inter-subtype recombinants. Surprisingly, the Caribbean subtype B strains clustered significantly with each other and separate from subtype B from other parts of the pandemic. CONCLUSIONS: The more complete analysis of HIV-1 from 4 Caribbean countries confirms previous research using partial genome analysis that the predominant subtype in circulation was subtype B. The Caribbean strains are phylogenetically distinct from other subtype B strains although the biological meaning of this finding is unclear.

HIV-1 epidemic in the Caribbean is dominated by subtype B.

BACKGROUND: The molecular epidemiology of HIV-1 in the Caribbean has been described using partial genome sequencing; subtype B is the most common subtype in multiple countries. To expand our knowledge of this, nearly full genome amplification, sequencing and analysis was conducted. METHODOLOGY/PRINCIPAL FINDINGS: Virion RNA from sera collected in Haiti, Dominican Republic, Jamaica and Trinidad and Tobago were reverse transcribed, PCR amplified, sequenced and phylogenetically analyzed. Nearly full genomes were completed for 15 strains; partial pol was done for 67 strains. All but one of the 67 strains analyzed in pol were subtype B; the exception was a unique recombinant of subtypes B and C collected in the Dominican Republic. Of the nearly full genomes of 14 strains that were subtype B in pol, all were subtype B from one end of the genome to the other and not inter-subtype recombinants. Surprisingly, the Caribbean subtype B strains clustered significantly with each other and separate from subtype B from other parts of the pandemic. CONCLUSIONS: The more complete analysis of HIV-1 from 4 Caribbean countries confirms previous research using partial genome analysis that the predominant subtype in circulation was subtype B. The Caribbean strains are phylogenetically distinct from other subtype B strains although the biological meaning of this finding is unclear.

Epidemiological and molecular characteristics of HIV-1 infection among female commercial sex workers, men who have sex with men and people living with AIDS in Paraguay.

An HIV seroprevalence and molecular study was conducted among 935 subjects: 723 female commercial sex workers, 92 men who have sex with men and 120 HIV-positive volunteers. The reported injection drug use rates were 0.7% in female commercial sex workers and 3% in men who have sex with men. Sexually transmitted infections were reported in 265 (37%) of the female commercial sex workers and 38 (41%) of the men who have sex with men. A total of 20 (2.8%) female commercial sex workers and 12 (13%) men who have sex with men became HIV infected during the study period. A history of sexually transmitted infection increased the risk of subsequent HIV infection twofold (adjusted odds ratio of 2.5) among the female commercial sex workers, while cocaine use had an adjusted odds ratios of 6.61 among men who have sex with men. From 130 samples, and based on heteroduplex mobility assaying for the env gene, with sequencing of part of pol and/or full genomes, subtype B was the predominant subtype identified (66%); followed by subtype F (22%) and subtype C (4%). Recombinant CRF12-BF strains were identified in 6% and CRF17_BF was identified in 2%.

Epidemiological and molecular characteristics of HIV-1 infection among female commercial sex workers, men who have sex with men and people living with AIDS in Paraguay / Características epidemiológicas e moleculares da infecção por HIV-1 entre as mulheres que trabalham no comércio do sexo, entre homens que mantém relações sexuais com homens e nas pessoas convivendo com AIDS no Paraguai

An HIV seroprevalence and molecular study was conducted among 935 subjects: 723 female commercial sex workers, 92 men who have sex with men and 120 HIV-positive volunteers. The reported injection drug use rates were 0.7 percent in female commercial sex workers and 3 percent in men who have sex with men. Sexually transmitted infections were reported in 265 (37 percent) of the female commercial sex workers and 38 (41 percent) of the men who have sex with men. A total of 20 (2.8 percent) female commercial sex workers and 12 (13 percent) men who have sex with men became HIV infected during the study period. A history of sexually transmitted infection increased the risk of subsequent HIV infection twofold (adjusted odds ratio of 2.5) among the female commercial sex workers, while cocaine use had an adjusted odds ratios of 6.61 among men who have sex with men. From 130 samples, and based on heteroduplex mobility assaying for the env gene, with sequencing of part of pol and/or full genomes, subtype B was the predominant subtype identified (66 percent); followed by subtype F (22 percent) and subtype C (4 percent). Recombinant CRF12-BF strains were identified in 6 percent and CRF17_BF was identified in 2 percent.

Um estudo de soroprevalência e de avaliação molecular do HIV foi realizado com 935 indivíduos: 723 mulheres que trabalhavam no comércio do sexo, 92 homens que mantinham relações sexuais com outros homens e com 120 voluntários HIV-positivos. O relato de uso de drogas injetáveis foi de 0,7 por cento nas mulheres que trabalhavam no comércio do sexo e de 3 por cento nos homens que mantinham relações sexuais com outros homens. Infecções sexualmente transmitidas foram relatadas por 265 (37 por cento) das mulheres que trabalhavam no comércio do sexo e em 38 (41 por cento) dos homens que mantinham relações sexuais com homens. Um total de 20 (2,8 por cento) mulheres que trabalhavam no comércio do sexo e 12 (13 por cento) homens que mantinham relações sexuais com homens se infectou com HIV durante o período do estudo. História prévia de infecção sexualmente transmitida aumentou em duas vezes o risco de infecção subseqüente por HIV (odds ratio ajustado de 2,5) entre as mulheres que trabalhavam no comércio do sexo, enquanto cocaína apresentou odds ratio ajustado de 6,61 entre os homens que mantinham relações sexuais com outros homens. De 130 amostras, com base no ensaio da mobilidade heteroduplex para o gene env, com sequenciamento de parte do pol e/ou genomas completos, o subtipo B foi o subtipo mais identificado (66 por cento); seguido pelo subtipo F (22 por cento) e subtipo C (4 por cento). Cepas recombinantes CRF12-BF foram identificadas em 6 por cento e CRF17_BF foi identificada em 2 por cento.

Human immunodeficiency virus and tuberculosis in Argentina: prevalence, genotypes and risk factors.

The objective of this study was to determine the prevalence and genetic variability of human immunodeficiency virus type 1 (HIV-1) and other sexually transmitted infections (STIs) among 205 patients with clinical diagnosis of tuberculosis (TB) in Buenos Aires in 2001. Infections with hepatitis B virus (HBV), HIV-1, hepatitis C virus (HCV), Treponema pallidum and human T-cell lymphotropic virus types I/II were diagnosed in 37/187 (19.8 %), 35/205 (17.1 %), 22/187 (11.8 %), 13/187 (7.0 %) and 4/181 (2.2 %) patients, respectively. Almost one in three participants (33.1 %) presented at least one infection in addition to TB. Multiresistance to TB drugs (isoniazid plus rifampicin) was detected in the isolates recovered from three patients. Injecting drug use was detected as the main risk factor for HIV, HBV and HCV infections. Of ten patients who died, eight were infected with HIV. HIV genetic characterization showed the presence of two different subtypes. Env subtype F was found in 13/24 samples (54.2 %) and subtype B in 11/24 samples (45.8 %) by heteroduplex mobility assay. Sequencing of the protease/RT region was performed in ten samples: three were characterized as subtype B and seven as B/F recombinants by bootscanning analysis. Phylogenetic analysis of four full-length sequences showed that three were the circulating recombinant form CRF12_BF. The results of this study suggest an urgent need to detect HIV infection in high-risk groups to prevent future HIV transmission as well as morbidity and mortality associated with TB by providing highly active antiretroviral therapy (HAART) and/or TB treatment. Collaboration between TB and HIV programmes seems to be the best approach to decrease the incidence of these diseases, especially in high-prevalence HIV settings.

Immigration status and HIV-risk related behaviors among female sex workers in South America.

This study compares immigrant (i.e., foreigner) with non-immigrant (i.e., local/native) HIV-related risk behaviors among female sex workers (FSW) in South America. A total of 1,845 FSW were enrolled in Argentina, Bolivia, Ecuador, and Uruguay. According to their nationality, 10.1% of participants were immigrant FSW. Immigrant FSW were more likely to be younger in Argentina; to work in a disco/bar in Bolivia; to be single and use illegal drugs in Ecuador; and to work in a brothel, consume alcohol, and have sex with foreign clients in Uruguay. HIV-related sexual and drug use behaviors were more common among immigrant FSW in Bolivia, Ecuador, and Uruguay. Country-specific HIV/STI prevention and control programs should be developed for immigrant FSW populations in South America.

High genetic variability of HIV-1 in female sex workers from Argentina.

BACKGROUND: A cross-sectional study on 625 Female Sex Workers (FSWs) was conducted between 2000 and 2002 in 6 cities in Argentina. This study describes the genetic diversity and the resistance profile of the HIV-infected subjects. RESULTS: Seventeen samples from HIV positive FSWs were genotyped by env HMA, showing the presence of 9 subtype F, 6 subtype B and 2 subtype C. Sequence analysis of the protease/RT region on 16 of these showed that 10 were BF recombinants, three were subtype B, two were subtype C, and one sample presented a dual infection with subtype B and a BF recombinant. Full-length genomes of five of the protease/RT BF recombinants were also sequenced, showing that three of them were CRF12_BF. One FSW had a dual HIV-1 infection with subtype B and a BF recombinant. The B sections of the BF recombinant clustered closely with the pure B sequence isolated from the same patient. Major resistance mutations to antiretroviral drugs were found in 3 of 16 (18.8%) strains. CONCLUSION: The genetic diversity of HIV strains among FSWs in Argentina was extensive; about three-quarters of the samples were infected with diverse BF recombinants, near twenty percent had primary ART resistance and one sample presented a dual infection. Heterosexual transmission of genetically diverse, drug resistant strains among FSWs and their clients represents an important and underestimated threat, in Argentina.

Buenos Aires cohort of men who have sex with men: prevalence, incidence, risk factors, and molecular genotyping of HIV type 1.

The prevalence, incidence, risk factors, and molecular genotyping of HIV-1 infection among men who have sex with men (MSM) were assessed through a prospective cohort study. The study was conducted in Buenos Aires from February 2003 to December 2004. Sociodemographic, sexual risk behavior data, and blood samples for HIV testing were collected at baseline and at 6 and 12 months. Cox regression analysis was applied to determine risk factors associated with HIV seroconversion. HIV-positive samples were analyzed by partial (pro/RT) and full-length genome sequencing. Of 811 HIV-negative participants evaluated at baseline, 327 volunteers that fulfilled the inclusion criteria were enrolled. Retention rates at 6 and 12 months were 97.2% and 91.5%, respectively. Twelve MSM seroconverted for HIV infection [incidence rate = 3.9 (95% CI = 2.0-6.7) per 100 person-years]. HIV seroconversion was associated with a greater number of different sexual contacts in the preceding 6 months (> or =10, hazard ratio = 3.3, 95% CI: 1.1-10.4). By partial pro/RT genotyping analysis, 83% HIV-positive samples were subtype B and 17% samples were BF recombinants, most of these being unique recombinant forms. This study describes for the first time the recruitment and follow-up of a cohort of MSM in Argentina. Retention rates and HIV incidence rate were high. These data should be considered as a promising potential population for HIV vaccine trials.

Association of herpes simplex virus type 2 infection and syphilis with human immunodeficiency virus infection among men who have sex with men in Peru.

BACKGROUND: We evaluated associations between human immunodeficiency virus (HIV) infection, herpes simplex virus type 2 (HSV-2) infection, and syphilis among men who have sex with men (MSM) in Peru. METHODS: A surveillance survey of 3280 MSM was conducted; sexual behavior was assessed with a structured computer-assisted self-interview, and serum antibody testing was performed for HIV, HSV-2, and Treponema pallidum. RESULTS: HIV, HSV-2, and syphilis seroprevalences of 13.9%, 46.3%, and 13.4% were detected, respectively. HSV-2 seroprevalence was twice as high in HIV-infected subjects (80.5%) than it was in HIV-uninfected subjects (40.8%) (P < .01), and HSV-2 seropositivity (adjusted odds ratio [AOR], 5.66) was found to be strongly associated with HIV infection. In addition, homosexual self-definition (AOR, 3.12), exchange of sex for money (AOR, 1.61), unprotected sex (no condom) (AOR, 2.81), history of sex work (AOR, 1.89), oral receptive sex (AOR, 1.43), and cocaine use before/during sex (AOR, 2.53) within the preceding 6 months, as well as such sexually transmitted infections (STIs) and STI syndromes as proctitis (AOR, 2.80), genital ulcer disease (GUD) (AOR, 2.06), prior syphilis (AOR, 2.64), genital warts (AOR, 1.70), and self-reported STIs within the preceding 6 months (AOR, 1.61), were also found to be significant predictors of HIV infection. CONCLUSIONS: We found a strong association between HSV-2 seropositivity and HIV infection. Intervention measures against GUD due to HSV-2 infection and syphilis, such as routine testing, early detection, HSV-2 suppressive treatment, and condom distribution, need to be enhanced as part of STI prevention strategies at a national level to effectively reduce HIV infection among MSM in Peru.

First report of an HIV-1 triple recombinant of subtypes B, C and F in Buenos Aires, Argentina.

We describe the genetic diversity of currently transmitted strains of HIV-1 in men who have sex with men (MSM) in Buenos Aires, Argentina between 2000 and 2004. Nearly full-length sequence analysis of 10 samples showed that 6 were subtype B, 3 were BF recombinant and 1 was a triple recombinant of subtypes B, C and F. The 3 BF recombinants were 3 different unique recombinant forms. Full genome analysis of one strain that was subtype F when sequenced in pol was found to be a triple recombinant. Gag and pol were predominantly subtype F, while gp120 was subtype B; there were regions of subtype C interspersed throughout. The young man infected with this strain reported multiple sexual partners and sero-converted between May and November of 2004. This study reported for the first time the full genome analysis of a triple recombinant between subtypes B, C and F, that combines in one virus the three most common subtypes in South America.

First case of HIV Type 1 subtype F among men who have sex with men in Colombia.

To study the molecular epidemiology of human immunodeficiency virus (HIV) strains among men who have sex with men (MSM), the main high-risk group for HIV infection in Colombia, 113 HIV-positive MSM subjects recruited in Bogotá during the year 2002 were genotyped. By heteroduplex mobility assay (env HMA) all samples were classified as subtype B. Partial sequencing of the protease and the reverse transcriptase (Pro/RT) regions performed on a random subset of 10 samples revealed that nine were classified as subtype B, and one sample was subtype F. The specimen that is subtype F in pol and subtype B in env is likely to be is either a recombinant or a dual infection. In this study, we identify the HIV F subtype for the first time in Colombia.

Molecular epidemiology of human immunodeficiency virus-infected individuals in Medellin, Colombia.

To study the molecular epidemiology of human immunodeficiency virus type 1 (HIV-1) strains in Medellín, Colombia, 115 HIV-1-positive individuals who were recruited from an HIV outpatient hospital (Universitario San Vicente de Paul) during the period from July 2001 to January 2002 were genotyped. All samples were analyzed by envelope heteroduplex mobility assay and found to be subtype B. Twenty-four samples were randomly selected for sequencing of the protease and the reverse transcriptase regions; all isolates were found to be subtype B. Phylogenetic analysis of seven nearly full-length genomes showed that all samples were subtype B. This study shows that the HIV epidemic in Colombia continues to be dominated by the subtype B virus. The predominance of subtype B genotypes of HIV-1 strains in Medellín resembles what is seen in the nearby countries of Peru, Ecuador, and Venezuela.

Epidemiology of human immunodeficiency virus, viral hepatitis (B and C), treponema pallidum, and human T-cell lymphotropic I/II virus among men who have sex with men in Buenos Aires, Argentina.

BACKGROUND: Human immunodeficiency virus (HIV) and sexually transmitted infections (STI) are prevalent among men who have sex with men (MSM). GOAL: To estimate the prevalence of HIV and STIs in this group. STUDY: A total of 694 MSM were tested for HIV, hepatitis B (HBV), hepatitis C (HCV), human T-cell lymphotropic (HTLV-I/II) viruses and Treponema pallidum infection. RESULTS: HIV, HBV, and T pallidum were detected in 13.8%, 37.7%, and 16.9% of subjects, respectively. Prevalences of 1.9% and 0.3% were detected for HCV and HTLV-I/II. A prior history of STI was the most predictor for HIV, HBV, and T pallidum. Use of illegal drugs, blood transfusion history, and multiple sexual partners were associated with HCV. The 2 most common co-infections were HBV/T pallidum and HIV/HBV. CONCLUSIONS: Infection with HIV, HBV, and T pallidum was elevated among MSM. Routine testing, education, vaccine-based prevention, and control programs need to be implemented in this high-risk population.

Prevalences, genotypes, and risk factors for HIV transmission in South America.

HIV cross-sectional studies were conducted among high-risk populations in 9 countries of South America. Enzyme-linked immunosorbent assay screening and Western blot confirmatory testing were performed, and env heteroduplex mobility assay genotyping and DNA sequencing were performed on a subset of HIV-positive subjects. HIV prevalences were highest among men who have sex with men (MSM; 2.0%-27.8%) and were found to be associated with multiple partners, noninjection drug use (non-IDU), and sexually transmitted infections (STIs). By comparison, much lower prevalences were noted among female commercial sex workers (FCSWs; 0%-6.3%) and were associated mainly with a prior IDU and STI history. Env subtype B predominated among MSM throughout the region (more than 90% of strains), whereas env subtype F predominated among FCSWs in Argentina and male commercial sex workers in Uruguay (more than 50% of strains). A renewed effort in controlling STIs, especially among MSM groups, could significantly lessen the impact of the HIV epidemic in South America.