Trends in Transmission of Drug Resistance and Prevalence of Non-B Subtypes in Patients with Acute or Recent HIV-1 Infection in Barcelona in the Last 16 Years (1997-2012).

OBJECTIVES: To evaluate the prevalence of transmitted drug resistance (TDR) and non-B subtypes in patients with acute/recent HIV-1 infection in Barcelona during the period 1997-2012. METHODS: Patients from the "Hospital Clínic Primary HIV-1 Infection Cohort" with a genotyping test performed within 180 days of infection were included. The 2009 WHO List of Mutations for Surveillance of Transmitted HIV-1 Drug Resistance was used for estimating the prevalence of TDR and phylogenetic analysis for subtype determination. RESULTS: 189 patients with acute/recent HIV-1 infection were analyzed in 4 time periods (1997-2000, n=28; 2001-4, n=42; 2005-8, n=55 and 2009-12, n=64). The proportion of patients with acute/recent HIV-1 infection with respect to the total of newly HIV-diagnosed patients in our center increased over the time and was 2.18%, 3.82%, 4.15% and 4.55% for the 4 periods, respectively (p=0.005). The global prevalence of TDR was 9%, or 17.9%, 9.5%, 3.6% and 9.4% by study period (p=0.2). The increase in the last period was driven by protease-inhibitor and nucleoside-reverse-transcriptase-inhibitor resistance mutations while non-nucleoside-reverse-transcriptase inhibitor TDR and TDR of more than one family decreased. The overall prevalence of non-B subtypes was 11.1%, or 0%, 4.8%, 9.1% and 20.3 by study period (p=0.01). B/F recombinants, B/G recombinants and subtype F emerged in the last period. We also noticed an increase in the number of immigrant patients (p=0.052). The proportion of men-who-have-sex-with-men (MSM) among patients with acute/recent HIV-1 infection increased over the time (p=0.04). CONCLUSIONS: The overall prevalence of TDR in patients with acute/recent HIV-1 infection in Barcelona was 9%, and it has stayed relatively stable in recent years. Non-B subtypes and immigrants proportions progressively increased.

Longitudinal HIV-1 gp120-C2V3C3 phylogenetic surveillance and tropism evolution in patients under HAART.

This 8-year longitudinal study was aimed to analyze the HIV-1 gp120-C2V3C3 sequence dynamics, their phylogenetic relationships and tropism evolution in patients under HAART. Such viral analysis comprised two compartments: plasma and PBMC. Fifty gp120-C2V3C3 genomic sequences were characterized from 16 patients: 41 from plasma when viremia was measurable and 9 from PBMCs if plasma viral load was undetectable. The vast majority of HIV isolates (43 out of 50) were ascribed to BF subtype, irrespective of the compartment (plasma or mononuclear-cells) analyzed. A statistically well-supported clustering phenomenon was observed for each patient sampling data. Each cluster comprised viral sequences from both compartments analyzed. In the vast majority of cases, the viral sequences obtained along active production periods were intermingled with those identified from proviral sequences. A substantial stability of co-receptor tropism for the HIV BF subtype was observed over an 8-year followup.

An analysis of 332 fatalities infected with pandemic 2009 influenza A (H1N1) in Argentina.

BACKGROUND: The apparent high number of deaths in Argentina during the 2009 pandemic led to concern that the influenza A H1N1pdm disease was different there. We report the characteristics and risk factors for influenza A H1N1pdm fatalities. METHODS: We identified laboratory-confirmed influenza A H1N1pdm fatalities occurring during June-July 2009. Physicians abstracted data on age, sex, time of onset of illness, medical history, clinical presentation at admission, laboratory, treatment, and outcomes using standardize questionnaires. We explored the characteristics of fatalities according to their age and risk group. RESULTS: Of 332 influenza A H1N1pdm fatalities, 226 (68%) were among persons aged <50 years. Acute respiratory failure was the leading cause of death. Of all cases, 249 (75%) had at least one comorbidity as defined by Advisory Committee on Immunization Practices. Obesity was reported in 32% with data and chronic pulmonary disease in 28%. Among the 40 deaths in children aged <5 years, chronic pulmonary disease (42%) and neonatal pathologies (35%) were the most common co-morbidities. Twenty (6%) fatalities were among pregnant or postpartum women of which only 47% had diagnosed co-morbidities. Only 13% of patients received antiviral treatment within 48 hours of symptom onset. None of children aged <5 years or the pregnant women received antivirals within 48 h of symptom onset. As the pandemic progressed, the time from symptom-onset to medical care and to antiviral treatment decreased significantly among case-patients who subsequently died (p<0.001). CONCLUSION: Persons with co-morbidities, pregnant and who received antivirals late were over-represented among influenza A H1N1pdm deaths in Argentina, though timeliness of antiviral treatment improved during the pandemic.

Characterization of full-length HIV-1 CRF17_BF genomes and comparison to the prototype CRF12_BF strains.

The aim of this work is to characterize the full-length intersubtype recombinant structure of the HIV-1 Circulating Recombinant Form CRF17_BF. A single genome of CRF17_BF was originally described in 2001 as being largely similar to CRF12_BF. Since then, more genomes of CRF17_BF have been sequenced but not adequately described in publications. Here we describe CRF17_BF as a genuine CRF, and analyze its recombination pattern based on bootscan analyses, subtype signature patterns, and phylogenetic reconstruction of subtype-delimited segments. We show that CRF17_BF can be distinguished from CRF12_BF in several regions of the genome, including vpu, pol, env and nef. A complete and accurate characterization and description of recombination breakpoints in CRFs is required for a proper surveillance of HIV-1 genotypes, and important for epidemiological purposes.

Drug resistance mutations in HIV pol sequences from Argentinean patients under antiretroviral treatment: subtype, gender, and age issues.

We studied drug resistance mutations (DRMs) in 2623 pol sequences. Out of 94,828 amino acid substitutions that were detected, 8749 corresponded to nucleoside reverse transcriptase inhibitor (NRTI), 3765 to nonnucleoside reverse transcriptase inhibitor (NNRTI), and 7141 to protease inhibitor (PI) resistance-associated mutations. The most common DRMs were L10I, I54V, L90M, V82A, A71V, L10V, M46I, M184V, M41L, T215Y, D67N, L210W, K70R, N348I, V118I, K103N, Y181C, G190A, K101E, V108I, L100I, V90I, K101Q, and A98G. As expected, DRMs frequencies depended on viral genotype. The amounts of NRTI and PI resistance mutations among B and BF sequences from children were higher than among sequences from adults. The frequencies of PI and NRTI resistance mutations among B and BF sequences from adult men were higher than among sequences from women. Some of these observations can be explained in light of the available epidemiological information, but some cannot, indicating that further studies are needed to understand the antiretroviral resistance epidemics in Argentina.

Analysis of HIV type 1 BF recombinant sequences from South America dates the origin of CRF12_BF to a recombination event in the 1970s.

HIV-1 epidemics in South America are believed to have originated in part from the subtype B epidemic initiated in the Caribbean/North America region. However, circulation of BF recombinants in similar proportions was extensively reported. Information currently shows that many BF recombinants share a recombination structure similar to that found in the CRF12_BF. In the present study, analyzing a set of 405 HIV sequences, we identified the most likely origin of the BF epidemic in an early event of recombination. We found that the subtype B epidemics in South America analyzed in the present study were initiated by a founder event that occurred in the early 1970s, a few years after the introduction of these strains in the Americas. Regarding the F/BF recombinant epidemics, by analyzing a subtype F genomic segment within the viral gene gag present in the majority of the BF recombinants, we found evidence of a geographic divergence very soon after the introduction of subtype F strains in South America. Moreover, through analysis of a subtype B segment present in all the CRF12_BF-like recombination structure, we estimated the circulation of the subtype B strain that gave rise to that recombinant structure around the same time period estimated for the introduction of subtype F strains. The HIV epidemics in South America were initiated in part through a founder event driven by subtype B strains coming from the previously established epidemic in the north of the continent. A second introduction driven by subtype F strains is likely to have encountered the incipient subtype B epidemic that soon after their arrival recombined with them, originating the BF epidemic in the region. These results may explain why in South America the majority of F sequences are found as BF recombinants.

In-depth analysis of the origins of HIV type 1 subtype C in South America.

The South American HIV-1 epidemic is characterized by the co-circulation of subtype B and BF recombinant variants. Together with the B and BF genotypes, HIV-1 subtype C (HIV-1C), F1, and several other recombinants have been reported. The epidemiological significance and immune correlates of these "non-B-non-BF" strains circulating in South America are still uncertain and therefore are increasingly attracting the interest of the scientific community. In this study, the South American HIV-1C epidemic was studied using new technologies for the phylogenetic analysis of large datasets. Our results indicate that there is a major clade encompassing most of the South American HIV-1C strains. These analyses also agreed that some strains do not group inside this major clade, suggesting that there could be HIV-1C sequences of different origins circulating in South America. Others have proposed different hypotheses about the origins of HIV-1C strains from South America. This study shows that an exact single origin cannot be determined, a fact that could be attributed to sampling problems, phylogenetic uncertainty, and the shortage of historical and epidemiological data. Currently, the reported data indicate that HIV-1C strains were introduced in Brazil and afterward spread to other regions of South America. By using character optimization on the obtained phylogenetic trees, we observed that Argentina could also be a point in which the HIV-1C epidemic entered South America.

HLA-driven convergence of HIV-1 viral subtypes B and F toward the adaptation to immune responses in human populations.

BACKGROUND: Cytotoxic T-Lymphocyte (CTL) response drives the evolution of HIV-1 at a host-level by selecting HLA-restricted escape mutations. Dissecting the dynamics of these escape mutations at a population-level would help to understand how HLA-mediated selection drives the evolution of HIV-1. METHODOLOGY/PRINCIPAL FINDINGS: We undertook a study of the dynamics of HIV-1 CTL-escape mutations by analyzing through statistical approaches and phylogenetic methods the viral gene gag sequenced in plasma samples collected between the years 1987 and 2006 from 302 drug-naïve HIV-positive patients. By applying logistic regression models and after performing correction for multiple test, we identified 22 potential CTL-escape mutations (p-value<0.05; q-value<0.2); 10 of these associations were confirmed in samples biologically independent by a Bayesian Markov Chain Monte-Carlo method. Analyzing their prevalence back in time we found that escape mutations that are the consensus residue in samples collected after 2003 have actually significantly increased in time in one of either B or F subtype until becoming the most frequent residue, while dominating the other viral subtype. Their estimated prevalence in the viral subtype they did not dominate was lower than 30% for the majority of samples collected at the end of the 80's. In addition, when screening the entire viral region, we found that the 75% of positions significantly changing in time (p<0.05) were located within known CTL epitopes. CONCLUSIONS: Across HIV Gag protein, the rise of polymorphisms from independent origin during the last twenty years of epidemic in our setting was related to an association with an HLA allele. The fact that these mutations accumulated in one of either B or F subtypes have also dominated the other subtype shows how this selection might be causing a convergence of viral subtypes to variants which are more likely to evade the immune response of the population where they circulate.

Antiretroviral resistance among HIV type 1-infected women first exposed to antiretrovirals during pregnancy: plasma versus PBMCs.

Resistance-associated mutations (RAMs) in plasma samples from HIV-1-infected women who received antiretroviral (ARV) prophylaxis during pregnancy was assessed and correlated with the detection of RAMs in peripheral blood mononuclear cells (PMBCs). The study population was composed of HIV-1-infected women enrolled in a prospective cohort study in Latin America and the Caribbean (NISDI Perinatal Study) as of March 1, 2005, who were diagnosed with HIV-1 infection during the current pregnancy, who received ARVs during pregnancy for prevention of mother-to-child transmission of HIV-1, and who were followed through at least the 6-12 week postpartum visit. Plasma samples collected at enrollment during pregnancy and at 6-12 weeks postpartum were assayed for RAMs. Plasma results were compared to previously described PBMC results from the same study population. Of 819 enrolled subjects, 197 met the eligibility criteria. Nucleic acid amplification was accomplished in 123 plasma samples at enrollment or 6-12 weeks postpartum, and RAMs were detected in 22 (17.9%; 95%CI: 11.7-25.9%). Previous analyses had demonstrated detection of RAMs in PBMCs in 19 (16.1%). There was high concordance between RAMs detected in plasma and PBMC samples, with only eight discordant pairs. The prevalence of RAMs among these pregnant, HIV-1-infected women is high (15%). Rates of detection of RAMs in plasma and PBMC samples were similar.

HIV type 1 genetic diversity surveillance among newly diagnosed individuals from 2003 to 2005 in Buenos Aires, Argentina.

To perform a diversity surveillance study we characterized viral subtypes among newly diagnosed individuals in Buenos Aires city. Plasma samples were collected from 322 drug-naive newly diagnosed HIV-1 individuals attending two voluntary counseling and testing centers. Sequences of pol and vpu genes were obtained from 283 samples and viral subtype was characterized by Neighbor-joining trees and Bootscanning analysis. BF recombinants were found in 56.9% followed by subtype B strains (39.2%). CRF12_BF structure was found in 27% of BF while another 27% had that structure only in one of both genes analyzed. Unusual non-B-non-BF strains were found in 3.9% (11/283). They were further analyzed by database searching and maximum likelihood trees in order to track their origin. Two subtype C sequences were found to be related to South American isolates while another two subtype C sequences and the subtype C segment of a BC recombinant were found to be related to isolates from Senegal. We also identified the CRF16_A2D previously found in Argentina and the CRF06_cpx commonly prevalent in Africa. The B segment of a BD recombinant was also found to be related to the Argentinean Bs suggesting a recombination between an African and a local strain. We also found a BK and two BA recombinants. In conclusion, CRF16_A2D and a new line of subtype C (of Senegalese origin) seem to be successfully established and are now spreading in Buenos Aires. BF recombinants keep recombining with local strains losing the CRF12_BF structure. Altogether they are changing the diversity of HIV in Argentina.

HCV genotype distribution among HIV co-infected individuals in Argentina: relationship with host and viral factors.

Coinfection with hepatitis C virus (HCV) in individuals infected with HIV is associated with a higher incidence of liver injury hepatic decompensation, and decreased survival than that observed in an HIV-monoinfected population. While prevalence studies on HIV/HCV coinfection have been performed in the U.S. and in some European countries, little is known about HCV genotype distribution in Latin America. The main objective was to evaluate the HCV prevalence and genotypes among HIV co-infected patients, and their relationship with HCV viral load, serum ALT level and T lymphocyte CD4+ cell count. These data pursue to increase the knowledge from South America about a pressing problem from HIV-infected patients. Retrospectively collected specimens from 593 HIV-positive individuals in Argentina were tested for anti-HCV These were analyzed for HCV-RNA qualitatively and quantitatively. The HCV genotype was determined by the RFLP method. One hundred and twenty-nine (21.7%) HIV-infected individuals were anti-HCV positive; 65.9% of them exhibited detectable HCV-RNA. Genotype 1 (43, la/c; 9, 1b; and 5, 1a/c+1b) was present in 57, while 1, 14 and 13 were infected with genotype 2, 3 or a mix, respectively. Co-infected individuals were more likely to be male, without significant differences in age and CD4+ cell counts than HIV-monoinfected individuals. HCV infection prevalence in patients co-infected with HIV highlights the impending public health impact of this problem. Considering the increasing rate of HCV genotypes with lower response rates to treatment among HIV co-infected patients, antiretroviral therapy success might be jeopardized by HCV coinfection.

Drug-resistance surveillance among newly HIV-1 diagnosed individuals in Buenos Aires, Argentina.

OBJECTIVE: Our objective was to estimate primary resistance in an urban setting in a developing country with a long history of antiretroviral delivery and high coverage levels. DESIGN: We carried out a resistance surveillance study according to WHO HIV-Resistance Guidelines. METHODS: Blood samples were collected from 323 drug-naive HIV-1 infected individuals diagnosed at two HIV voluntary counselling and testing centers in Buenos Aires. Viral-load, CD4 cell counts and detuned assays were performed on all samples. The pol gene was sequenced and the resistance profile determined. Phylogenetic analysis was performed by neighbor-joining trees and bootscanning analysis. RESULTS: We found that 12 (4.2%) of the 284 samples sequenced harbored primary resistance mutations, of which K103N, M41L and V108I were most prevalent. Phylogenetic analysis revealed evidence for the transmission of the K103N mutation among the drug-naive population. The proportion of recent infections identified by the detuned assay was 10.1%. CONCLUSIONS: Levels of primary resistance in Buenos Aires are still low, despite a long history of ARV delivery and high coverage levels.

HCV genotype distribution among HIV co-infected individuals in Argentina: Relationship with host and viral factors / Distribución de los genotipos de HCV entre individuos co-infectados con HIV en Argentina: su relación con factores del huésped y del virus

Coinfection with hepatitis C virus (HCV) in individuals infected with HIV is associated with a higher incidence of liver injury, hepatic decompensation, anddecreased survival than that observed in an HIVmonoinfected population. While prevalence studies on HIV/HCV coinfection have been performed in theU.S. and in some European countries, little is known about HCV genotype distribution in Latin America.The main objective was to evaluate the HCV prevalence and genotypes among HIV co-infected patients, and their relationship with HCV viral load, serumALT level and T lymphocyte CD4+ cell count. These data pursue to increase the knowledge from South America about a pressing problem from HIV-infectedpatients. Retrospectively collected specimens from 593 HIV-positive individuals in Argentina were tested foranti-HCV. These were analyzed for HCV-RNA qualitatively and quantitatively. The HCV genotype was determined by the RFLP method. One hundred andtwenty-nine (21.7%) HIV-infected individuals were anti-HCV positive; 65.9% of them exhibited detectable HCV- RNA. Genotype 1 (43, 1a/c; 9, 1b;and 5, 1a/c+1b) was present in 57, while 1, 14 and 13 were infected with genotype 2, 3 or a mix, respectively.Co-infected individuals were more likely to be male, without significant differences in age and CD4+ cell counts than HIV-monoinfected individuals.HCV infection prevalence in patients co-infected with HIV highlights the impending public health impact of this problem. Considering the increasingrate of HCV genotypes with lower response rates to treatment among HIV co-infected patients, antiretroviraltherapy success might be jeopardized by HCV coinfection.

La coinfección con el virus de hepatitis C (HCV) en individuos infectados con HIV está asociada con una mayor incidencia de injuria y descompensación hepática,y un menor tiempo de supervivencia respecto de la población mono-infectada por HIV. Mientras que diferentesestudios de prevalencia de la coinfecciónHIV/HCV se han llevado a cabo en Estados Unidos y países de Europa, la información de la distribución degenotipos de HCV en Latinoamérica es escasa. El objetivo de este estudio fue evaluar la prevalencia de HCVy la distribución de sus genotipos entre pacientes coinfectados con HIV, y su relación con la carga viral deHCV, los niveles séricos de ALT y el recuento de linfocitos T CD4+. Estos datos pretenden incrementar el conocimiento desde la región de Sudamérica acerca de este acuciante problema en pacientes infectados con HIV.Retrospectivamente se colectaron especímenes desde 593 pacientes infectados con HIV en Argentina enquienes se investigó la presencia de anticuerpos anti-HCV. Se pesquisó además la presencia de RNA viral deHCV tanto cualitativa como cuantitativamente. El genotipo de HCV se determinó por la técnica de RFLP.Ciento veintinueve (21.7%) individuos infectados con HIV fueron positivos para anti-HCV; 65.9% de ellos exhibieron RNA de HCV detectable. El genotipo 1(43, 1a/c; 9, 1b; y 5, 1a/c+1b) se presentó en 57 individuos, en tanto que 1, 14 y 13 estaban infectados porlos genotipos 2, 3 o mezcla de ellos, respectivamente. Predominó el sexo masculino entre los individuos concoinfección, en tanto que no se advirtieron diferencias significativas respecto de los pacientes infectados sólocon HIV en lo referido a edad y recuento de linfocitos T CD4+. La prevalencia de infección por HCV en pacientescoinfectados con HIV resalta el impacto de esta problemática en la salud pública. Considerando la creciente tasa de genotipos de HCV con menor respuestaal tratamiento entre los pacientes coinfectados con HIV, el efecto...

HCV genotype distribution among HIV co-infected individuals in Argentina: Relationship with host and viral factors / Distribución de los genotipos de HCV entre individuos co-infectados con HIV en Argentina: su relación con factores del huésped y del virus

Coinfection with hepatitis C virus (HCV) in individuals infected with HIV is associated with a higher incidence of liver injury, hepatic decompensation, anddecreased survival than that observed in an HIVmonoinfected population. While prevalence studies on HIV/HCV coinfection have been performed in theU.S. and in some European countries, little is known about HCV genotype distribution in Latin America.The main objective was to evaluate the HCV prevalence and genotypes among HIV co-infected patients, and their relationship with HCV viral load, serumALT level and T lymphocyte CD4+ cell count. These data pursue to increase the knowledge from South America about a pressing problem from HIV-infectedpatients. Retrospectively collected specimens from 593 HIV-positive individuals in Argentina were tested foranti-HCV. These were analyzed for HCV-RNA qualitatively and quantitatively. The HCV genotype was determined by the RFLP method. One hundred andtwenty-nine (21.7%) HIV-infected individuals were anti-HCV positive; 65.9% of them exhibited detectable HCV- RNA. Genotype 1 (43, 1a/c; 9, 1b;and 5, 1a/c+1b) was present in 57, while 1, 14 and 13 were infected with genotype 2, 3 or a mix, respectively.Co-infected individuals were more likely to be male, without significant differences in age and CD4+ cell counts than HIV-monoinfected individuals.HCV infection prevalence in patients co-infected with HIV highlights the impending public health impact of this problem. Considering the increasingrate of HCV genotypes with lower response rates to treatment among HIV co-infected patients, antiretroviraltherapy success might be jeopardized by HCV coinfection.(AU)

La coinfección con el virus de hepatitis C (HCV) en individuos infectados con HIV está asociada con una mayor incidencia de injuria y descompensación hepática,y un menor tiempo de supervivencia respecto de la población mono-infectada por HIV. Mientras que diferentesestudios de prevalencia de la coinfecciónHIV/HCV se han llevado a cabo en Estados Unidos y países de Europa, la información de la distribución degenotipos de HCV en Latinoamérica es escasa. El objetivo de este estudio fue evaluar la prevalencia de HCVy la distribución de sus genotipos entre pacientes coinfectados con HIV, y su relación con la carga viral deHCV, los niveles séricos de ALT y el recuento de linfocitos T CD4+. Estos datos pretenden incrementar el conocimiento desde la región de Sudamérica acerca de este acuciante problema en pacientes infectados con HIV.Retrospectivamente se colectaron especímenes desde 593 pacientes infectados con HIV en Argentina enquienes se investigó la presencia de anticuerpos anti-HCV. Se pesquisó además la presencia de RNA viral deHCV tanto cualitativa como cuantitativamente. El genotipo de HCV se determinó por la técnica de RFLP.Ciento veintinueve (21.7%) individuos infectados con HIV fueron positivos para anti-HCV; 65.9% de ellos exhibieron RNA de HCV detectable. El genotipo 1(43, 1a/c; 9, 1b; y 5, 1a/c+1b) se presentó en 57 individuos, en tanto que 1, 14 y 13 estaban infectados porlos genotipos 2, 3 o mezcla de ellos, respectivamente. Predominó el sexo masculino entre los individuos concoinfección, en tanto que no se advirtieron diferencias significativas respecto de los pacientes infectados sólocon HIV en lo referido a edad y recuento de linfocitos T CD4+. La prevalencia de infección por HCV en pacientescoinfectados con HIV resalta el impacto de esta problemática en la salud pública. Considerando la creciente tasa de genotipos de HCV con menor respuestaal tratamiento entre los pacientes coinfectados con HIV, el efecto...(AU)

Analysis of HIV type 1 diversity in pregnant women from four Latin American and Caribbean countries.

Worldwide, the distribution of HIV-1 subtypes and intersubtype recombinants is not homogeneous. In Latin America and the Caribbean, HIV-1 subtype B predominates. However, in the south of Brazil and in countries of the Southern cone (Argentina, Chile, Paraguay, and Uruguay) there is a different distribution of viral subtypes and intersubtype recombinants. The aim of this work was to analyze HIV-1 diversity in a cohort of pregnant women (with primarily heterosexual acquisition of the infection) who were diagnosed with HIV-1 infection during their current pregnancy and who received ARVs during pregnancy for perinatal transmission prophylaxis. Analysis of 121 partial pol sequences from subjects enrolled in Argentina, Brazil, the Bahamas, and Mexico was performed by phylogenetic and recombinant characterization. Different prevalences of subtype B were observed (100% for specimens from Mexico and the Bahamas, 61% for Brazil, and 30% for Argentina). Subtypes C and F were found, along with BC, BF, FC, and CBF recombinants in specimens from Brazilians. A high prevalence of BF recombinants was found (70%) in specimens from Argentina. The different patterns of HIV- 1 subtypes and intersubtype recombinants in South America (Argentina and Brazil) compared to those in Central and North America should be considered in the design of future HIV-1 vaccine trials.

HIV-1 genetic diversity in Argentina and early diagnosis of perinatal infection.

HIV-1 diagnosis of perinatally exposed children is usually performed by molecular biology-based methods, allowing the direct detection of the virus. Thus, HIV-1 genomic variability within and across strains plays a major role in relation to the sensitivity of these tests, often leading to misdiagnosis. We describe the performance of an in-house multiplex nested PCR (nPCR) for early detection of HIV-1 infection in perinatally exposed children born in Argentina, where the percentage of diverse BF recombinants is as high as 80%. After evaluation of 1316 HIV-1 perinatally exposed children collected over a 7-year period, the specificity and sensitivity of the diagnostic nPCR was of 100% and 99.2% respectively, with only two false negative cases indicating a good performance of the diagnostic nPCR in the Argentine pediatric cohort. In search of unusual HIV-1 subtypes among 22 HIV-1 infected cases presenting partial or complete HIV-1 gene amplification failure, we performed phylogenetic and recombination analysis of a vpu-env fragment in addition to gag and env Heteroduplex Mobility Assay screening. The most unusual findings included two subtypes A and a novel BC recombinant, while the majority of the strains were a variety of different BF recombinants. These results indicate the presence of novel and heterogeneous genotypes in our country and the need of continuous viral surveillance not only for diagnostic test optimization but also for the eventual implementation of a successful vaccine.