Genetic heterogeneity and subtyping of human Hepatitis E virus isolates from Uruguay.

Hepatitis E virus (HEV) infection is an important public health concern in many developing countries causing waterborne outbreaks, as well as sporadic autochthonous hepatitis. It is transmitted primarily by the fecal-oral route. However, zoonotic transmission from animal reservoirs to human has also been suggested. Genotype 3 is the most frequent genotype found in South America and the HEV epidemiology in this region seems to be very complex. However, data about the molecular characterization of HEV isolates of the region is still lacking and further investigation is needed. Our study characterized human HEV strains detected in a 1-year period in Uruguay, by extensive sequence analysis of three regions of the HEV genome. Uruguayan strains were closely related to a set of European strains and in turn, were dissimilar to Brazilian, Argentinean and Bolivian isolates. Additionally, the co-circulation of viral subtypes 3i and 3h was observed. Circulation of subtype 3i had been reported in Argentina and Bolivia whereas sequences of subtype 3h are rare and had never been reported in Latin America. In order to contribute to shedding light over the molecular epidemiology of this emergent infection in the region, we thoroughly analyzed the genetic variability of HEV strains detected in Uruguay, providing the largest dataset of sequences of HEV ever reported in a country in South America.

Detection and molecular characterization of sporadic cases of acute human hepatitis E virus infection in Uruguay.

In developing countries, hepatitis E virus (HEV) infection is a public-health concern because it causes epidemics and waterborne outbreaks. In South America, few HEV strains have been characterized at the molecular level. We report the detection and molecular analysis of the first set of sporadic cases of autochthonous human genotype 3 HEV infection in Uruguay.

Hepatitis C virus among non-injecting cocaine users (NICUs) in South America: can injectors be a bridge?

AIM: To investigate the factors associated with hepatitis C virus (HCV) infection among non-injecting cocaine users (NICUs) and to compare practices associated with HCV and HIV infection. DESIGN: An intercountry cross-sectional study. Setting Buenos Aires and Montevideo metropolitan areas. PARTICIPANTS: A total of 871 NICUs. MEASUREMENTS: NICUs were interviewed and their blood was drawn and used for HCV, HIV, HBV surface antigen (HbsAg), HB-anticore and Venereal Disease Research Laboratory (VRDL) antibody assays. Bivariate and multivariate logistic regression analyses included comparisons of HCV and HIV mono-infected participants with HCV-HIV seronegatives. FINDINGS: Prevalence rates were 8.8 [95% confidence interval (CI): 6.9-10.8) for HCV and 7.9 (95% CI: 6.1-9.7) for HIV. HCV-infected NICUs were twice as likely as HCV-HIV seronegatives to have shared straws for cocaine snorting or sniffing, even when adjusted for other variables. HCV prevalence rates ranged from 3.6% among NICUs who denied sharing straws and having had an injection drug user (IDU) or an HIV-positive sexual partner to 12.6% among participants who reported ever having shared straws or having had either an IDU- or HIV-positive sexual partner (χ(2) (trend) = 6.56, P = 0.01). CONCLUSIONS: Non-injecting cocaine users from South America are vulnerable to multiple infections and HCV infection appears to occur through the sharing of straws. HCV infection is associated with intimate relationships with IDUs or HIV-seropositive partners, supporting the hypothesis that HCV risk may be due primarily to risk-taking behaviour associated with drugs in this population.

Identification of a new HIV Type 1 circulating recombinant form (CRF38_BF1) in Uruguay.

Recombination has been shown to be an important force in HIV-1 evolution. Recombination contributes to an increase in genetic variation and hinders vaccine design efforts. Several molecular epidemiology studies in South America described the circulation of subtypes B, F, and C as well as several B/F1 recombinants. This study performed by nucleotide sequencing in at least two genes of 89 samples from Uruguay has shown a complex HIV-1 epidemic characterized by the cocirculation of subtype B, and subtype C strains, together with an important group of BF1 recombinant viruses, including isolates similar to CRF12_BF. In addition we identified a new circulating recombinant form, designated CRF38_BF(1), which was dominant in the recombinant virus group.

Human influenza A viruses isolated in South America: genetic relations, adamantane resistance and vaccine strain match.

In order to gain insight into the genetic relations among H3N2 Influenza A virus (IAV) circulating in the South American region from 1999 to 2007, to investigate the presence of adamantane-resistant strains in this region, and to establish the genetic relations among that strains and vaccine strains recommended for the Southern hemisphere, 11 haemagglutinin (HA) H3 IAV sequences obtained from Uruguayan patients were aligned with corresponding sequences from 68 H3 IAV strains isolated in South America and 9 H3 IAV vaccine strains. Maximum likelihood phylogenetic tree analysis was performed using the GTR evolutionary model. The results of these studies indicate that multiple clades co-circulate during most influenza seasons in South America. Strikingly, one strain isolated in Uruguay in 2005 and all strains isolated in that country during the 2007 season bear an HA adamantane-resistant polymorphism. No other strain isolated in South America previous to the 2005 season bears that HA characteristic amino acid change. Only vaccine strains recommended for the 2007 season were assigned to the same cluster with all available IAV isolated in South America for that season. Evolution of IAV in this region appears to be shaped by re-introduction of new strains.

Juquitiba-like hantavirus from 2 nonrelated rodent species, Uruguay.

Serologic and genetic analyses indicate that a Juquitiba-like hantavirus circulates in Maldonado, Uruguay. This virus is carried by 2 rodent species, Oligoryzomys nigripes and Oxymycterus nasutus. The same hantavirus in 2 nonrelated species can be explained by a spillover infection or a host-switching event.

Influenza B viruses isolated in Uruguay during the 2002-2005 seasons: genetic relations and vaccine strain match.

Monitoring antigenic and genetic variations of circulating influenza viruses is critical for the selection of annual vaccine strains. In order to gain insight into the molecular evolution of Influenza B viruses (IBV) isolated in Uruguay in 2002 and 2005 outbreaks, antigenic and phylogenetic studies were carried out for the Hemagglutinin (HA) gene. Antigenic relations among Uruguayan and reference strains isolated elsewhere were performed by means of hemagglutination inhibition assays (HAI). Genetic relations of HA genes from Uruguayan as well as 41 IBV strains isolated elsewhere were established by means of the construction of phylogenetic trees. HAI assays showed a distant antigenic relationship among the 2002 Uruguayan isolates and the 2002 vaccine strain B/Sichuan/379/99. Phylogenetic analysis also revealed a distant genetic relationship among Uruguayan and 2002 vaccine strains. All 2005 IBV Uruguayan strains were both antigenically and genetically related to B/Victoria lineage-viruses. The results of these studies revealed that 2002 IBV Uruguayan strains have a distant antigenic and genetic relation with the 2002 IBV vaccine strain used in Uruguay. The high rate of susceptible individuals in the youngest cohort (<25 years) might be related to the fact that the B/Victoria lineage-viruses were not previously circulating in Uruguay.

HIV seroincidence estimates among at-risk populations in Buenos Aires and Montevideo: use of the serologic testing algorithm for recent HIV seroconversion.

Using the serological testing algorithm for recent HIV seroconversion, we estimated annualized incidences (per 100 person-years) of HIV-1 infection in different at-risk groups in Buenos Aires and Montevideo, during a 5-year period between 1998 and 2003. HIV-positive serum samples from 9 serosurveys conducted among men who have sex with men, patients attending clinics for a sexually transmitted infections consult (STIs), female commercial sex workers, injecting drug users (IDUs), noninjecting cocaine users (NICUs), asymptomatic women screened for HIV infection, and patients with tuberculosis were used. HIV incidences were as follows: 6.7 for men who have sex with men, 2.0 for STIs, 1.3 for female commercial sex workers, 0.0 for Argentinean IDUs, 10.3 for Uruguayan IDUs, 3.1 for Argentinean NICUs, 4.4 for Uruguayan NICUs, and 2.4 for patients with tuberculosis. Among asymptomatic women screened for HIV infection, incidence rose from 0.4 in 1998 to 4.6 in 1999 and to a high of 10.2 in the year 2000. Unexpectedly, high HIV incidences were detected among at-risk groups in Buenos Aires and Montevideo. This pattern shows an emerging HIV epidemic among heterosexuals stemming from core HIV-infected at-risk groups. There is an urgent need for development and implementation of specific prevention strategies to address this burgeoning epidemic.

Genetic characterization of respiratory syncytial viruses isolated from consecutive acute respiratory infections in a HIV infected child.

BACKGROUND: Human respiratory syncytial virus (HRSV) was isolated from a 2-year-old child suffering from perinatally transmitted AIDS in the course of three distinct episodes of respiratory infections. The first episode occurred in the winter of 1994, the following two episodes of cough and fever occurred two and 4 months after the initial episode. OBJECTIVE: To analyze the genetic variability of the child's HRSV strains, and with contemporary circulating HRSV isolates. RESULTS: The three child's HRSV isolates belonged to group B. Sequence analysis of the attachment (G) protein gene (which has the highest degree of antigenic and genetic diversity in HRSV), demonstrated no difference in the sequence obtained from the three isolates recovered from the child. Comparison of the child's HRSV strain with contemporary circulating group B HRSV isolates showed a close sequence similarity with one of them. CONCLUSIONS: The immunodeficiency in an HIV-positive child may have resulted in the recurrent isolation of one HRSV strain. Although it cannot be discarded the possibility that the recurrent episodes might be re-infections, it is unlikely in view of the lack of change in the HRSV glycoprotein G. This is the first study that analyzes the genetic variation in HRSV isolates from consecutive respiratory disease episodes in an immunosuppressed patient.

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.

Seroincidence and phylogeny of human immunodeficiency virus infections in a cohort of commercial sex workers in Montevideo, Uruguay.

A cohort study involving 60 human immunodeficiency virus (HIV)-negative male transvestite commercial sex workers (CSWs) was conducted in Montevideo, Uruguay in 1999-2001. Serum samples were tested for HIV by an enzyme-linked immunosorbent assay screening with immunoblot confirmation. Six participants seroconverted for an incidence-density rate of 6.03 (95% confidence interval = 2.21-13.12) per 100 person-years. Inconsistent condom use during client sex (adjusted hazard ratio [AHR] = 6.7), during oral sex (AHR = 5.6), and at the last sexual encounter (AHR = 7.8), and use of marihuana (AHR = 5.4) were marginally associated with HIV seroconversion. Five samples were genotyped in the protease and reverse transcriptase regions; three were subtypes B and two were BF recombinants. Full genome analysis of four samples confirmed all three subtype B samples and one of the two BF recombinants. Male transvestite CSWs sustained a high rate of HIV infection. Larger prospective studies are required to better define subtypes and associated sexual and drug-related risk factors.

Evaluation of a new NASBA assay for the qualitative detection of hepatitis C virus based on the NucliSens Basic Kit reagents.

BACKGROUND: Direct detection of HCV RNA by nucleic acid amplification methods is an essential tool in the diagnosis of HCV infections. In-house developed methods based on reverse transcribed polymerase chain reaction (RT-PCR) are widely used but they are laborious and usually lack the standardization required by clinical laboratories. OBJECTIVES: To evaluate the sensitivity and the clinical performance of an HCV specific nucleic acid sequence based amplification (NASBA) assay based on the commercially available, NucliSens Basic Kit (bioMérieux) reagents. STUDY DESIGN: The analytical sensitivity of the Basic Kit-based HCV assay (BK-HCV) was determined using dilutions of the First World Health Organization International Standard for HCV RNA. The performance of the BK-HCV was evaluated at two study sites in comparison with in-house RT-nested PCR (RT-nPCR) by testing a total of 77 plasma specimens. Additional HCV laboratory tests such as Amplicor HCV v2.0 (Roche Diagnostics) and genotype were also included in the comparative analysis. RESULTS: The sensitivity of the BK-HCV was 100-150 IU/ml HCV RNA (85-100% hit rate). When evaluating the clinical performance, we found 96-100% correlation between BK-HCV and RT-nPCR, and 85-91% correlation between BK-HCV and Amplicor. The level of efficiency of the BK-HCV for detecting prevalent HCV genotypes was equal to in house RT-nPCR and Amplicor. CONCLUSIONS: The BK-HCV offers adequate sensitivity for diagnostic purposes and equivalent clinical performance to in-house RT-nPCR assays. The BK-HCV could become a suitable alternative to the in-house amplification methods, providing standardized reagents and procedures, plus rapid results to clinical laboratories.

Genetic variation in the VP7 gene of human rotavirus isolated in Montevideo-Uruguay from 1996-1999.

The gene encoding the protein VP7 that induces the major neutralizing response has been sequenced from 34 human rotaviruses isolated from children with acute diarrhea in Montevideo (Uruguay) over a 4-year period (1996-1999). These sequences were analyzed and compared to representative corresponding sequences available on databases. In most years, serotype G1 was present as the single serotype, except in 1999 when serotypes G1 and G4 were present simultaneously. Two G1 VP7 lineages were identified. Serotype G2 was present in 1997. The G4 isolates are grouped with Argentine strains and emerged during 1998 in a recently defined sublineage. Neither serotype G3 nor the emerging serotype G9 were isolated during the study. Antigenic domains of isolates and of representative reference strains of each serotype were compared. Sequences of strains isolated during the same year, showed a high degree of homology among strains belonging to the same serotype.

Yellow pigmy rice rat (Oligoryzomys flavescens) and hantavirus pulmonary syndrome in Uruguay.

During 5,230 trapping nights, 672 small mammals were trapped in the areas where most hantavirus pulmonary syndrome (HPS) cases occur in Uruguay. Yellow pygmy rice rats (Oligoryzomys flavescens) were the only rodents that showed evidence of antibodies to hantavirus, with a seroprevalence of 2.6%. The rodents were trapped in all the explored environments, and most of the seropositive rodents were found in habitats frequented by humans. Nucleotide sequences were obtained from four HPS case-patients and four yellow pygmy rice rats of the M genome segment. Sequence comparison and phylogenetic analysis showed that rodent-borne viruses and viruses from three HPS case-patients form a well-supported clade and share a 96.4% identity with the previously characterized Central Plata hantavirus. These results suggest that yellow pygmy rice rat (O. flavescens) may be the host for Central Plata, a hantavirus associated with HPS in the southern area of Uruguay.

Antigenic and genetic variability of human respiratory syncytial viruses (group A) isolated in Uruguay and Argentina: 1993-2001.

The antigenic and genetic diversity of G glycoprotein from 25 human respiratory viruses (group A) isolated during nine consecutive epidemics (1993-2001) in Montevideo, Uruguay, and 7 strains isolated in Buenos Aires, Argentina, in the same period were analyzed. Genetic variability was evaluated by partial sequence of the G protein gene. Phylogenetic analysis indicated that most Uruguayan and Argentinean group A isolates clustered into three genotypes: GA5, GA2, and GA1. Some strains clustered into the GA3 genotype characterized previously. The antigenic analysis was carried out with a panel of anti-G monoclonal antibodies that recognized conserved and strain-specific epitopes. A close correlation between the antigenic and genetic relatedness of the strains analyzed was observed.

Sexual transmission of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus type 1 infections among male transvestite comercial sex workers in Montevideo, Uruguay.

Prostitution may constitute a risk behavior for infection with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). We conducted a seroepidemiologic study among 200 male transvestite commercial sex workers (CSWs) in Montevideo, Uruguay in 1999. Evidence of exposure to HBV, HCV, and HIV was found in 101 (50.5%), 13 (6.5%), and 43 (21.5%) individuals, respectively. Positivity for HIV was correlated with both HBV (odds ratio [OR] = 2.15, 95% confidence interval [CI] = 1.01-4.67) and HCV (OR = 3.47, 95% CI = 0.90-12.79) infection. Predictors of infection were older age (> or = 26 years; P < 0.01) for all 3 viruses and time in CSW (> or = 5 years; P < 0.05) for HBV and HIV. Prior history of use of drugs (OR = 3.54, 95% CI = 1.09-11.52) and sexual contact with foreigners (OR = 9.2, 95% CI = 1.16-73.12) were found to be associated only with HCV infection. Sexual transmission of these viruses constitutes a significant problem among male transvestite CSWs.

Molecular Epidemiology of HIV Type 1 in Ecuador, Peru, Bolivia, Uruguay, and Argentina.

Surveillance for HIV infection among people at increased risk was conducted in five countries in South America. Seroprevalence studies were conducted in more than 36,000 people in Ecuador, Peru, Boliva, Uruguay, and Argentina, along with genetic analysis of the HIV-1 strains. In all countries, the prevalence of HIV-1 among men who have sex with men (MSM) was high (3-30%), whereas the prevalence among female commercial sex workers (FCSMs) was low (0.3-6%). By envelope heteroduplex mobility assay, subtype B predominated in MSM communities and in FCSWs in Ecuador, Bolivia, and Peru. A new genetic screening assay, the multiregion hybridization assay for subtypes B and F (MHA-bf), was developed to improve large-scale genetic screening in South America. MHA-bf can screen four regions of the genome for subtype B or subtype F, and thus can detect most recombinants. The sensitivity of MHA-bf when applied to a panel of pure subtypes and CRF12_BF was 100%, and 88% of unique recombinants were also detected as recombinant. Using MHA-bf, more than 80% of samples from Ecuador, Peru, and Bolivia were classified as pure subtype B, whereas in Uruguay and Argentina this proportion was only 30 to 40%. BF recombinants were the most prevalent form of HIV-1 in Uruguay and Argentina. Subtype B is the most common subtype in countries lacking injecting drug use (IDU) epidemics, whereas BF recombinants are more common in countries where extensive IDU epidemics have been documented, suggesting the ontogeny of recombinant strains in particular risk groups in South America.