Improved strategies for HIV diagnosis among men who have sex with men (MSM) in Buenos Aires, Argentina, a population with a high prevalence and incidence of HIV infection.

BACKGROUND: In Argentina, HIV diagnosis in adults is made using one or two enzyme immunoassay tests and a confirmatory test. These strategies may fail to identify infected individuals during early primary infection, which represents an important public health problem among groups with a high HIV incidence, such as men who have sex with men (MSM) (6.3% persons/year). The general objective of this study was to contribute to reducing HIV transmission among MSM through the identification of antibody-negative, nucleic acid-positive individuals. FINDINGS: A total of 1549 MSM were recruited for an HIV seroprevalence study. A total of 161 (10.4%) MSM were HIV-positive and 14 (0.9%) were indeterminate. Among the 1374 negative individuals, 16 (1.2%) exhibited reactive results in the screening assay. Indeterminate Western blot (WB) samples and negative WB samples (with discordant results in the screening) were analysed to detect HIV nucleic acid by viral load testing. Up to 23.1% of HIV-indeterminate WB samples and 7.1% of HIV-negative WB samples with discordant results in the screening assays had detectable nucleic acid. Overall, 14.8% of the samples with discordant or indeterminate results were identified as HIV-positive using direct diagnosis. With the identification of four new cases using the nucleic acid detection test, the HIV prevalence in MSM increased by 0.3% (from 10.4 to 10.7%). CONCLUSIONS: The results of this study suggest the importance of including nucleic acid detection in the HIV algorithm for MSM with HIV-indeterminate WB results and those with HIV-negative WB results and discordant results in screening assays, in order to decrease HIV transmission among this population with a high HIV prevalence and incidence.

Two simultaneous hepatitis B virus epidemics among injecting drug users and men who have sex with men in Buenos Aires, Argentina: characterization of the first D/A recombinant from the American continent.

Previous studies have revealed that hepatitis B virus (HBV)/D and HBV/F predominate among blood donors from Buenos Aires, Argentina. In the present study, blood samples from two high-risk groups were analysed: 160 corresponding to street- and hospital-recruited injecting drug users [81.2% showing the 'anti-hepatitis B core antigen (anti-HBc) only' serological pattern] and 20 to hepatitis B surface antigen (HBsAg)(+)/anti-HBc(+) men who have sex with men. HBV genotypes were assigned by polymerase chain reaction amplification followed by restriction fragment length polymorphism and confirmed by nucleotide sequencing of two different coding regions. HBV DNA was detected in 27 injecting drug users (16.9%, occult infection prevalence: 7.7%), and 14 men who have sex with men (70%). HBV/A prevailed among injecting drug users (81.8%) while HBV/F was predominant among men who have sex with men (57.1%). The high predominance of HBV/A among injecting drug users is in sharp contrast to its low prevalence among blood donors (P = 0.0006) and men who have sex with men (P = 0.0137). Interestingly, all HBV/A S gene sequences obtained from street-recruited injecting drug users encoded the rare serotype ayw1 and failed to cluster within any of the known A subgenotypes. Moreover, one of the HBV strains from a hospital-recruited injecting drug user was fully sequenced and found to be the first completely characterized D/A recombinant genome from the American continent. Data suggest that two simultaneous and independent HBV epidemics took place in Buenos Aires: one spreading among injecting drug users and another one sexually transmitted among the homosexual and heterosexual population.

Resistance profiles to antiretroviral drugs in HIV-1 drug-naive patients in Argentina.

The drug resistance profile of treatment-naive HIV-infected individuals living in Buenos Aires, Argentina, was studied. Samples taken from 94 drug-naive individuals with established HIV infection and 13 patients with primary HIV infection were assessed by nucleotide sequencing and LIPA. The prevalence of drug-associated primary mutations in individuals with established infection was very low. In the viral protease region, 1/86 (1.2%) individuals carried the D30N mutation, whereas 1/85 (1.2%) had the M41L mutation in the reverse transcriptase (RT) region. Secondary mutations in both the protease and RT regions were found in almost 90% of the individuals. In individuals with primary infection, primary mutations were detected in 2/13 (15.4%) patients, one of them carrying M461 mutation in the protease while the other patient had a mutation at codon 184 of the RT. In accordance with current drug resistance testing guidelines, the results of this study suggest that susceptibility tests need not be performed at this time prior to initiation of antiretroviral therapy in HIV-1-infected people in Argentina. However, the public health implications of this subject warrant follow-up studies that will examine a larger number of drug-naive patients, not only in Buenos Aires but also in other major Argentinian cities and in rural areas.

Documentation of subtype C HIV Type 1 strains in Argentina, Paraguay, and Uruguay.

HIV subtypes B, F, and BF recombinants have been previously reported in South America. This report describes the presence of HIV-1 subtype C infection in the countries of Argentina, Uruguay, and Paraguay dating back to at least 1999. Surveillance for uncommon non-B/non-F subtype viruses circulating in South America has been conducted in samples obtained from nine countries. Peripheral blood mononuclear cells (PBMC), dried filter paper (FP), and fresh blood (FB) samples were collected from HIV-positive patients from Ecuador, Colombia, Venezuela, Peru, Chile, Bolivia, Argentina, Uruguay, and Paraguay. From a total of 2962 HIV seropositive samples examined during a 9-year period (1995-2003), only 11 (0.4%) were found to be infected with non-B/non-F HIV variants. Eight of these 11 strains were determined to be subtype C by heteroduplex mobility assay (HMA). Five of these 8 strains were further characterized by sequencing and phylogenetic analysis of the protease (Pro) and reverse transcriptase (RT) region of the genome and two were sequenced full length. One of the strains was found to be a unique BC recombinant. The spread of a third subtype of HIV, subtype C, should raise the question of its potential future role in the HIV epidemic in this region.

[Distribution of subtypes and recombinant of HIV. Situation in Argentina]. / Distribución de subtipos y recombinantes del HIV. Situación en la Argentina.

Soon after HIV (Human Immunodeficiency Virus) was discovered, its characteristics level of diversity and variability was established. So far, within HIV-1 it is known that there exist 3 main groups, 9 subtypes and at least 12 recombinant forms. Not only does this diversity affect taxonomy, but also prophylaxis and therapy for HIV infection. Numerous studies worldwide have demonstrated the influence this variability has on both diagnosis and monitoring assays as well as on the pathogenesis of HIV infection. In Argentina, from the molecular point of view, the epidemic shows a complex pattern. HIV-1 subtypes B and F have been described as well as a recombinant B/F form. Epidemiology and molecular data suggest high percentage levels and a great diversity of these recombinant forms in the heterosexual population.

[HIV-1 virus transmission through maternal milk]. / Transmisión del HIV-1 a través de la leche materna.

Human immunodeficiency virus type 1 (HIV-1) may be vertically transmitted during the pre, peri or postpartum period. Postnatal transmission as well as an increased risk of vertical transmission with breastfeeding has been shown for HIV-1 in several reports. Breastfeeding was here analyzed as a risk of HIV-1 transmission in a group of infants born to HIV-1 infected mothers. Among the 215 children studied in our population a significant difference was detected between those who were breastfed vs those who were bottle fed and finally became infected (p < 0.000000, R.R. = 4.29). We also report the case of a postnatal infection in a baby born to an HIV-1 seropositive father and a seronegative mother. Due to the risk of infection of the mother she had been thoroughly controlled when pregnant and after delivery. Mother and child were negative when retested at delivery, and at 10 months post-partum. At the age of 32 months the child attended the outpatient clinic with generalized lymphadenopathy and right parotitis. HIV-1 infection was then confirmed in both mother and child. At that time it was discovered that the baby had been breastfed up to the age of 24 months. This is the first reported child in Argentina whose infection may undoubtedly be attributed to breastfeeding.

[Molecular characterization of HTLV-II from an intravenous drug addict with AIDS in Argentina]. / Caracterización molecular de HTLV-II de un paciente drogadicto endovenoso con SIDA de la Argentina.

Ten intravenous drug user AIDS patients were studied to determine the presence of HTLV-I/II infection. Sera were screened by particle agglutination test and by an in house indirect immunofluorescence assay using MT2 (HTLV-I) and C19 (HTLV-II) producing cell lines. Out of the ten sera, one was confirmed HTLV-II positive by Western blot. Peripheral blood mononuclear cells were obtained from this patient, separated through a Ficoll-Hypaque gradient and DNA was extracted and amplified by semi-nested PCR. The amplified product obtained was cloned and sequenced. Results demonstrated the presence of HTLV-II proviral DNA and comparison of the obtained sequence with different HTLV-II prototypes led to classify the virus into subtype a. This is the first molecular characterization of HTLV-II in an intravenous drug user in Argentina.

Human immunodeficiency virus bDNA assay for pediatric cases.

Techniques to quantify plasma HIV-1 RNA viral load (VL) are commercially available, and they are adequate for monitoring adults infected by HIV and treated with antiretroviral drugs. Little experience on HIV VL has been reported in pediatric cases. In Argentina, the evaluation of several assays for VL in pediatrics are now being considered. To evaluate the pediatric protocol for bDNA assay in HIV-infected children, 25 samples from HIV-infected children (according to CDC criteria for pediatric AIDS) were analyzed by using Quantiplex HIV RNA 2.0 Assay (Chiron Corporation) following the manufacturer's recommendations in a protocol that uses 50 microliters of patient's plasma (sensitivity: 10,000 copies/ml). When HIV-RNA was not detected, samples were run with the 1 ml standard bDNA protocol (sensitivity: 500 HIV-RNA c/ml). Nine samples belonged to infants under 12 months of age (group A) and 16 were over 12 months (group B). All infants under one year of age had high HIV-RNA copies in plasma. VL ranged from 30,800 to 2,560,000 RNA copies/ml (median = 362,000 c/ml) for group A and < 10,000 to 554,600 c/ml (median = < 10,000) for group B. Only 25% of children in group B had detectable HIV-RNA. By using the standard test of quantification, none of the patients had non detectable HIV-RNA, ranging between 950 and 226,200 c/ml for group B (median = 23,300 RNA c/ml). The suggested pediatric protocol could be useful in children under 12 months of age, but 1 ml standard protocol must be used for older children. Samples with undetectable results from children under one year of age should be repeated using the standard protocol.

[Antigenic variants of the respiratory syncytial virus in Argentina and Uruguay]. / Variantes antigénicas del virus respiratorio sincicial en Argentina y Uruguay.

The characterization of RSV antigenic variants was carried out on 160 nasopharyngeal aspirates from children under 5 years of age, from Argentina and Uruguay, with acute respiratory infection and a previously positive etiological diagnosis for RSV. Results for Argentina were: 20.9% of samples belonged to subtype A, 76.9% to subtype B and the remaining 2.2% to new subtypes as yet uncharacterized. Results for Uruguay were: 5.6% of samples belonged to subtype A, 81% to subtype B and 13.5% to other subtypes. Subtype B was predominant in both countries. The correlation of RSV antigenic variants with the clinical picture and epidemiological profile is currently underway.

Troublesome diagnosis in two children born to HIV-1 infected mothers.

In order to assess early HIV infection vertically transmitted in children it is necessary to use techniques that directly detect HIV. Positive results were found in some rare cases who later seemed to have cleared the infection. We communicate two cases of children with troublesome diagnosis. Two girls born to HIV-1 infected mothers were followed-up since birth up to 40 months old, with viral culture, polymerase chain reaction (PCR), p24 antigen detection and serologic techniques. PCRs were positive in three opportunities at 2, 8 and 30 months of age in the first child and confirmatory tests for specific antibodies remained indeterminate up to the age of 34 months. Positive viral DNAs were detected in two opportunities in the second child at 2 and 4 months of age. Western Blots were negative since 25 months. No virus was recovered nor was p24 antigen detected during the whole period of study in either child. Sequestration of the virus in lymphatic tissue, low replicative ability of the virus and/or immunological tolerance can be postulated in the first case. In patient 2, it could be hypothesized that infection, if any, had cleared up.

Incidence of HIV type 1 infection, antiretroviral drug resistance, and molecular characterization in newly diagnosed individuals in Argentina: A Global Fund Project.

An HIV incidence estimation was performed among men who have sex with men (MSM), drug users (DUs), sex workers (SWs), and pregnant women (PW) from Argentina. Volunteers older than 18 years old without a previous HIV-positive diagnosis were included. HIV-positive samples were analyzed by the Serological Testing Algorithm for Recent HIV Seroconversion (STARHS) to estimate incidence. By partial RT-PCR and sequencing of the HIV pol gene, an HIV subtype and resistance profile were determined. A total of 12,192 volunteers were recruited from October 2006 to September 2008. A higher HIV prevalence was detected among trans SWs (33.9%, 38/112), male SWs (10.8%, 12/111), and MSM 10.4% (161/1549). HIV incidence estimates by STARHS was also higher on trans SWs (11.31 per 100 person-years), male SWs (6.06 per 100 person-years), and MSM (6.36 per 100 person-years). Antiretroviral primary resistant mutations were detected in 8.4% of the study group, with a higher frequency in female DUs (33.3%). Phylogenetic analysis showed that 124 (57.9%) samples were subtype B, 84 (39.3%) intersubtype BF recombinants, 5 (2.3%) subtype C, and 1 (0.5%) subtype F in the pol region. Subtype B was most commonly found in MSM and male SWs whereas the intersubtype BF recombinant was more prevalent in female DUs, female SWs, and PW. Given the high HIV prevalence and incidence found in most of these groups, monitoring the continuing spread of the HIV epidemic is essential for determining public health priorities, assessing the impact of interventions, and estimating current and future health care needs.

Seroprevalence of and risk factors for HIV-1 infection among female commercial sex workers in South America.

OBJECTIVE: Assessment of HIV prevalence and associated risk behaviours among female commercial sex workers (FCSW) across major cities in South America. METHODS: Seroepidemiological, cross sectional studies of 13 600 FCSW were conducted in nine countries of South America during the years 1999-2002. Participants were recruited in brothels, massage parlours, hotels, and streets where anonymous questionnaires and blood samples were collected. HIV infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot confirmatory tests. RESULTS: The overall HIV seroprevalence was 1.2% (range 0.0%-4.5%). The highest HIV seroprevalences were reported in Argentina (4.5%) and Paraguay (2.6%); no HIV infected FCSW were detected in Venezuela and Chile. Consistent predictors of HIV seropositivity were: (1) a previous history of sexually transmitted infections (STI, AORs = 3.8-8.3), and (2) 10 years or more in commercial sex work (AORs = 2.2-24.8). In addition, multiple (> or =3) sexual contacts (AOR = 5.0), sex with foreigners (AOR = 6.9), use of illegal drugs (AOR = 3.2), and marijuana use (AOR = 8.2) were associated with HIV seropositivity in Southern Cone countries. CONCLUSIONS: Consistently low HIV seroprevalences were detected among FCSW in South America, particularly in the Andean region. Predictors of HIV infection across the continent were STI and length of commercial sex work; however, use of illegal drugs, especially marijuana, and sexual contacts with foreigners were also found to be associated risk factors in the Southern Cone region. Interventions for the control of HIV and other STI need to be region and country specific; drug use appears to have an ever increasing role in the spread of HIV among heterosexually active populations.

Argentine hemorrhagic fever: a biologic marker.

Mortality rates and viral replication in blood and brains of Wistar rats between 6 h and 26 days of age inoculated with two strains of Junin virus of different virulence were compared. Viral growth curves in brains showed no differences between strains. However, differences in mortality rates were significant among rats between 1 and 3 days of age. When the intracerebral (i.c.) route was used, high mortality rates were induced by the attenuated XJC13 strain and low mortality rates were induced by the pathogenic XJ strain. On the other hand, when the intraperitoneal or subcutaneous route was used, mortality rates were reversed: low for the attenuated strain and high for the pathogenic one. The use of different doses of each virus and the application of various routes of inoculation in 2-day-old rats showed that 10(3) TCID50 by the i.c. route resulted in the greatest difference in mortality rates.

Mother-to-child transmission of drug-resistant HIV.

Mother-to-child transmission of HIV-I is responsible for the infection of hundreds of thousands of infants every year. The use of prophylactic antiretroviral treatments has brought about a dramatic decrease in the risk of transmission. Nevertheless, vertical transmission can still occur. In some cases, the presence of drug-resistant HIV-I strains in the mother has been responsible for the failure of the prophylactic scheme. Moreover, these strains have also been detected in the newborn. The aim of this review is to provide updated information on mother-to-child transmission of drug-resistant HIV strains and to help guide treatment decisions during pregnancy.