Dissemination of the Omicron Variant and Its Sub-Lineages among Residents and Travelers in Its First Year of Emergence in Venezuela

The emergence of the SARS-CoV-2 Variant of Concern (VOC), Omicron, has been characterized by an explosive number of cases in almost every part of the world. The dissemination of different sub-lineages and recombinant genomes also led to several posterior waves in many countries. The circulation of this VOC and its major sub-lineages (BA.1 to BA.5) was monitored in community cases and in international travelers returning to Venezuela by a rapid partial sequencing method. The specific sub-lineage assignment was performed by complete genome sequencing. Epidemic waves of SARS-CoV-2 cases were observed among international travelers during 2022, a situation not seen before December 2021. The succession of the Omicron VOC sub-lineages BA.1 to BA.5 occurred sequentially, except for BA.3, which was almost not detected. However, the sub-lineages generally circulated two months earlier in international travelers than in community cases. The diversity of Omicron sub-lineages found in international travelers was related to the one found in the USA, consistent with the most frequent destination of international travel from Venezuela this year. These differences are compatible with the delay observed sometimes in Latin American countries in the circulation of the different lineages of the Omicron VOC. Once the sub-lineages were introduced in the country, community transmission was responsible for generating a characteristic distribution of them, with a predominance of sub-lineages not necessarily similar to the one observed in travelers or neighboring countries.

First Case of Monkeypox in Venezuela: Partial Complete Genome Sequence Allowed Its Grouping into the West African Clade II

The ongoing epidemic of monkeypox virus (MPXV) infection has already reached more than 50,000 persons worldwide until the end of August 2022. We report the first case detected in Venezuela. The patient reported traveling from Spain and contact with friends tested positive for MPXV after his return. Partial complete genome phylogenetic analysis allowed to group the isolate within the clade II of MPXV, the major one circulating worldwide. No other case of MPXV has been detected until the end of August 2022 in the country, although the presence of undiagnosed cases due to the fear of stigmatization cannot be ruled out.

Changes in clinical characteristics and outcomes of patients hospitalized with COVID-19 during two years of the pandemic: experience in a venezuelan hospital

OBJECTIVES.

To determine changes in the clinical characteristics and in-hospital outcomes of patients hospitalized for COVID-19 in a private hospital in Caracas during two years of the pandemic.

MATERIALS AND METHODS.

Retrospective, observational study of patients hospitalized for COVID-19. We evaluated the correspondence between waves of hospital admissions and circulating variants of SARS-CoV-2 in the general population of the Capital District and Miranda state.

RESULTS.

A total of 1025 patients (569 men and 456 women) were included, with a mean age of 62.9 SD: 16.2 years. Four waves of hospital admissions were identified: first (March-November 2020) 150/1025 (14.6%) cases; second (December 2020 to May 2021) 415/1025 (40.5%) cases; third (June-December 2021) 344/1025 (33.6%) cases; fourth (January-February 2022) 116/1025 (11.3%) cases. The mean age was higher in the fourth wave (first: 64.0±15.7, second: 61.4±15.8, third: 62.1±16.5, and fourth wave: 68.5±16.4), while the proportion of male patients (first: 66.7%, second: 58.8%, third: 50.3%, and fourth wave: 44.8%), patients with severe-critical illness (first: 65.3%, second: 57%, third: 51.7%, and fourth wave: 44.8%), in-hospital stay (first: 9.1±6.0, second: 9.0±7.3, third: 8.8±7.7, and fourth wave: 6.9±5.0 days), ICU admissions (first: 23.3%, second: 15.7%, third: 14.0%, and fourth wave: 11.2%; p=0.027) and mortality (first: 21. 8%, second: 10.7%, third: 9.1%, and fourth wave: 7.1%; p<0.001) progressively decreased over time.

CONCLUSIONS.

The results show lower frequency of severe cases and improvement of in-hospital outcomes in two years of the pandemic. Changes in circulating variants, improvements in disease management and vaccination are likely to have influenced these results.

Detection of the Omicron variant of SARS-CoV-2 in international travelers returning to Venezuela

Background

By the end of 2021, the SARS-CoV-2 Variant of Concern (VOC) Delta was predominant in most of the world. At the end of November, the Omicron variant was first detected in South Africa. This variant was immediately classified as VOC, due to the explosive increase of cases in South Africa, and the great number of mutations exhibited by this new lineage. Since then, Omicron VOC displaced Delta one in almost every country. Venezuela implemented in May 2021 molecular testing of all the passengers arriving at Venezuelan airports.

Methods

In this study, we analyzed the presence of variants of SARS-CoV-2 in those positive samples, by sequencing a small fragment of the Spike genomic region.

Results

The Omicron variant was found in passengers arriving to Venezuela from the beginning of December. Complete genome analysis confirmed the presence of the Omicron VOC. The detection of this VOC coincided with an unprecedented increase in the frequency of passengers with positive nucleic acid testing.

Conclusions

Genomic surveillance of samples for international travelers returning to Venezuela allowed us to rapidly detect the introduction of the Omicron variant in the country.

Detection of the Omicron variant of SARS-CoV-2 by restriction analysis targeting the mutations K417N and N440K of the spike protein

By the end of 2021, the Omicron variant of concern (VOC) emerges in South Africa. This variant caused immediate concern, due to the explosive increase in cases associated with it and the large number of mutations it exhibits. In this study, the restriction sites that allow detecting the mutations K417N and N440K in the Spike gene are described. This analysis allows us to propose a rapid method for the identification of cases infected with the Omicron variant. We show that the proposed methodology can contribute to provide more information on the prevalence and rapid detection of cases of this new VOC.

World Society for Virology first international conference: Tackling global virus epidemics

This communication summarizes the presentations given at the 1st international conference of the World Society for Virology (WSV) held virtually during 16-18 June 2021, under the theme of tackling global viral epidemics. The purpose of this biennial meeting is to foster international collaborations and address important viral epidemics in different hosts. The first day included two sessions exclusively on SARS-CoV-2 and COVID-19. The other two days included one plenary and three parallel sessions each. Last not least, 16 sessions covered 140 on-demand submitted talks. In total, 270 scientists from 49 countries attended the meeting, including 40 invited keynote speakers.

Introduction and rapid dissemination of SARS-CoV-2 Gamma Variant of Concern in Venezuela

In less than two years since SARS-CoV-2 emerged, the new coronavirus responsible for COVID-19, has accumulated a great number of mutations. Many of these mutations are located in the Spike protein and some of them confer to the virus higher transmissibility or partial resistance to antibody mediated neutralization. Viral variants with such confirmed abilities are designated by WHO as Variants of Concern (VOCs). The aim of this study was to monitor the introduction of variants and VOCs in Venezuela. A small fragment of the viral genome was sequenced for the detection of the most relevant mutations found in VOCs. This approach allowed the detection of Gamma VOC. Its presence was confirmed by complete genome sequencing. The Gamma VOC was detected in Venezuela since January 2021, and in March 2021 was predominant in the East and Central side of the country, representing more than 95% of cases sequenced in all the country in April–May 2021. In addition to the Gamma VOC, other isolates carrying the mutation E484K were also detected. The frequency of this mutation has been increasing worldwide, as shown in a survey of sequences carrying E484K mutation in GISAID, and was detected in Venezuela in many probable cases of reinfection. Complete genome sequencing of these cases allowed us to identify E484K mutation in association with Gamma VOC and other lineages. In conclusion, the strategy adopted in this study is suitable for genomic surveillance of variants for countries lacking robust genome sequencing capacities. In the period studied, Gamma VOC seems to have rapidly become the dominant variant throughout the country.

SARS-CoV-2 genetic diversity in Venezuela: Predominance of D614G variants and analysis of one outbreak

SARS-CoV-2 is the new coronavirus responsible for COVID-19 disease. The first two cases of COVID-19 were detected in Venezuela on March 13, 2020. The aim of this study was the genetic characterization of Venezuelan SARS-CoV-2 isolates. A total of 7 full SARS-CoV-2 genome sequences were obtained by Sanger sequencing, from patients of different regions of Venezuela, mainly from the beginning of the epidemic. Ten out of 11 isolates (6 complete genomes and 4 partial spike genomic regions) belonged to lineage B, bearing the D614G mutation in the Spike protein. Isolates from the first outbreak that occurred in the Margarita Island harbored an in-frame deletion in its sequence, without amino acids 83–85 of the NSP1 of the ORF1. The search for deletions in 48,635 sequences showed that the NSP1 gene exhibit the highest frequency of deletions along the whole genome. Structural analysis suggests a change in the N-terminal domain with the presence of this deletion. In contrast, isolates circulating later in this island lacked the deletion, suggesting new introductions to the island after this first outbreak. In conclusion, a high diversity of SARS-CoV-2 isolates were found circulating in Venezuela, with predominance of the D614G mutation. The first small outbreak in Margarita Island seemed to be associated with a strain carrying a small deletion in the NSP1 protein, but these isolates do not seem to be responsible for the larger outbreak which started in July.

Understanding Severe Acute Respiratory Syndrome Coronavirus 2 Replication to Design Efficient Drug Combination Therapies

BACKGROUND

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its disease CO-VID-19 has strongly encouraged the search for antiviral compounds. Most of the evaluated drugs against SARS-CoV-2 derive from drug repurposing of Food and Drug Administration-approved molecules. These drugs have as target three major processes: (1) early stages of virus-cell interaction, (2) viral proteases, and (3) the viral RNA-dependent RNA polymerase.

SUMMARY

This review focused on the basic principles of virology and pharmacology to understand the importance of early stages of virus-cell interaction as therapeutic targets and other main processes vital for SARS-CoV-2 replication. Furthermore, we focused on describing the main targets associated with SARS-CoV-2 antiviral therapy and the rationale of drug combinations for efficiently suppressing viral replication. Key Messages: We hypothesized that blocking of both entry mechanisms could allow a more effective antiviral effect compared to the partial results obtained with chloroquine or its derivatives alone. This approach, already used to achieve an antiviral effect higher than that offered by every single drug administered separately, has been successfully applied in several viral infections such as HIV and HCV. This review will contribute to expanding the perception of the possible therapeutic targets in SARS-CoV-2 infection and highlight the benefits of using combination therapies.

SARS-CoV-2 host tropism: An in silico analysis of the main cellular factors

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The role in host selectivity of ACE2, Tmprss2 and GPR78 in SARS-CoV-2 was explored.

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Differences in the SARS-CoV-2 RBD binding mode with ACE2 of secondary hosts could be associated with host permissiveness.

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Nafamostat could be considered a good inhibitor of mammalian hosts TMPRSS2 proteins.

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In silico studies confirm that the spike protein could interact with GRP78 in studied mammalian hosts.

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TMPRSS2 and GRP78 do not seem to play a role in host selectivity.

Recent reports have shown that small and big felines could be infected by SARS-CoV-2, while other animals, like swines and mice, are apparently not susceptible to this infection. These findings raise the question of the role of cell factors associated with early stages of the viral infection in host selectivity. The cellular receptor for SARS-CoV-2 is the Angiotensin Converting Enzyme (ACE2). Transmembrane protease serine 2 (TMPRSS2) has been shown to prime the viral spike for its interaction with its receptor. GRP78 has also been proposed as a possible co-receptor. In this study, we used several bioinformatics approaches to bring clues in the interaction of ACE2, TMPRSS2, and GRP78 with SARS-CoV-2. We selected several mammalian hosts that could play a key role in viral spread by acting as secondary hosts (cats, dogs, pigs, mice, and ferrets) and evaluated their predicted permissiveness by in silico analysis. Results showed that ionic pairs (salt bridges, N–O pair, and long-range interactions) produced between ACE2 and the viral spike has an essential function in the host interaction. On the other hand, TMPRSS2 and GRP78 are proteins with high homology in all the evaluated hosts. Thus, these proteins do not seem to play a role in host selectivity, suggesting that other factors may play a role in the non-permissivity in some of these hosts. These proteins represent however interesting cell targets that could be explored in order to control the virus replication in humans and in the intermediary hosts.

Variation in Hepatitis C Virus Subtype Distribution during 20 Years in Venezuela

OBJECTIVE

Hepatitis C virus (HCV) infection is a public health problem and a major cause of chronic hepatitis. This virus exhibits a great genetic variability, with 8 genotypes and numerous subtypes. The aim of this study was to evaluate the fluctuations of HCV subtypes during 2 decades in Venezuela.

METHODS

HCV genotypes were determined by direct sequencing of the 5'-noncoding region in 392 isolates circulating in patients attended during the years 2014-2015. HCV subtype assignment was confirmed in a subset of samples (n = 24) by partial sequencing of the NS5B region. The genotype distribution was compared with the one observed in a previous study of patients followed up during the years 1994-1996 and 2005-2006.

RESULTS

Some variation was observed in the HCV genotype distribution over these 20 years. HCV genotype 1b prevalence was reduced significantly from 1994-1995 to 2004-2005, as previously described, and then remained constant. During the last 10 years, a significant decrease of HCV subtype 2b (36/237 in 2005-2006 vs. 24/392 in 2014-2015, p < 0.001) was observed. Patients infected with HCV G2acj were significantly older than the ones infected with G1 (53 vs. 47 years, p = 0.004), and male sex was significantly more prevalent among G3a-infected patients compared to the other ones (71 vs. 47%, p = 0.047).

CONCLUSIONS

Fluctuations in HCV subtype distribution have been observed over 2 decades in Venezuela. Different major mode of transmission and susceptibility to the available HCV treatment during each period might be playing a role in the observed fluctuations in HCV subtype distribution.

Methoxyflavones from Marcetia taxifolia as HIV-1 Reverse Transcriptase Inhibitors

Methoxyflavones are flavonoid widely distributed in plants and has been reported as potent antitumor agents and some of them have shown activity against HIV-1. In this work, two methoxyflavones isolated from Marcetia taxifolia were evaluated in vitro and in silico as HIV-1 inhibitors. Pentamethoxyflavone (5,3’-dihydroxy-3,6,7,8,4’-pentamethoxyflavone) (PMF) and Hexamethoxyflavone (5-Hydroxy-3,6,7,8,3’,4’-hexamethoxyflavone) (HMF) showed activity against HIV-1. The EC50 for HMF was 0.05 μM and 0.04 μM for PMF. The methoxyflavones also inhibited HIV-1 reverse transcriptase (RT), with an IC50 of 4.1 μM for HMF and 0.4 μM for PMF. PMF exhibited an IC50 lower than nevirapine (1.4 μM). These results are in agreement with the in silico prediction for the interaction of these flavonoids with RT. Furthermore, the effect of some methoxyflavones with different patterns of methoxylation was evaluated on RT activity in a virtual screening; found that the inhibitory activity was inversely proportional to the degree of methoxylation.

The role of the glycosyl moiety of myricetin derivatives in anti-HIV-1 activity in vitro

Background

Plant extracts are sources of valuable compounds with biological activity, especially for the anti-proliferative activity against pathogens or tumor cells. Myricetin is a flavonoid found in several plants that has been described as an inhibitor of Human immunodeficiency virus type 1 (HIV-1) through its action against the HIV reverse transcriptase, but myricetin derivatives have not been fully studied. The aim of this study was to evaluate the anti-HIV-1 activity of glycosylated metabolites obtained from Marcetia taxifolia and derived from myricetin: myricetin rhamnoside and myricetin 3-(6-rhamnosylgalactoside).

Methods

Compounds were obtained from organic extracts by maceration of aerial parts of M. taxifolia. All biological assays were performed in the MT4 cell line. Antiviral activity was measured as inhibition of p24 and reverse transcriptase with a fluorescent assay.

Results

Both flavonoids have antiviral activity in vitro, with an EC50 of 120 µM for myricetin 3-rhamnoside (MR) and 45 µM for myricetin 3-(6-rhamnosylgalactoside) (MRG), both significantly lower than the EC50 of myricetin (230 µM). Although both compounds inhibited the reverse transcriptase activity, with an IC50 of 10.6 µM for MR and 13.8 µM for MRG, myricetin was the most potent, with an IC50 of 7.6 µM, and an inhibition greater than 80%. Molecular docking approach showed correlation between the free energy of binding with the assays of enzyme inhibition.

Conclusions

The results suggest that glycosylated moiety might enhance the anti-HIV-1 activity of myricetin, probably by favoring the internalization of the flavonoid into the cell. The inhibition of the HIV-1 reverse transcriptase is likely responsible for the antiviral activity.

Glycosylated Flavonoids from Psidium guineense as Major Inhibitors of HIV-1 Replication in vitro

Flavonoids are present in practically all plants and many biological activities have been described for them. The flavonoid quercetin is a common molecule for which anti-HIV activity has been demonstrated. Avicularin and guajaverin are derivatives of quercetin with a glycoside substituent in their structure. In this work, a mixture of both derivatives was purified from an extract of Psidium guinense. The mixture exhibited activity against HIV-1 in vitro, with an IC50 of approximately 8.5 μg/mL, which compares favorably with the IC50 of 53 μg/mL of quercetin. The mixture also inhibited HIV-1 reverse transcriptase (RT), with an IC50 of 7.2 μM, compared to 0.6 μM for quercetin. These results are in agreement with the in silico prediction for the interaction of these flavonoids with RT and suggest that the glycosylic moiety could favor the transport of the compound into the cell. However, the glycosidic moiety might be cleaved intracellularly, being the resultant quercetin responsible for the antiviral activity.

[Present and future of therapy against hepatitis C]

Around 3% of the human population is infected with hepatitis C virus (HCV) and 70-80% of these individuals develop a chronic infection. There is no vaccine available against HCV and up to 50% of the infected patients do not respond to standard therapy, based on the combination of interferon-alpha (IFN-α) and ribavirin. Recently, direct acting antiviral drugs against HCV have been made available for treatment, leading to a significant improvement in therapeutic success. In 2014, the U.S. Food and Drug Administration approved ledipasvir plus sofosbuvir to treat the chronic infection, the first IFN- and ribavirin-free approved treatment. With such treatment, the eradication of the disease would be feasible, although drug costs are high. Host target therapy represents an emerging alternative, based on the understanding of host factors involved in the HCV infection. This therapy might show at least two theoretical benefits, increasing the number of options for therapy and raising the genetic barrier for selection of resistant variants. New treatment regimens may consist of classical therapy combined with host target-based therapy, hopefully in a synergistic manner.

Genetic diversity of hepatitis B virus and mutations associated to hepatocellular carcinoma in patients from Venezuela, with different stages of liver disease

Globally, about 50% of liver cancer originates as a result of long term infection with hepatitis B virus (HBV), and some genotypes and mutations have been associated with an increased severity of infection. The aim of this study was to evaluate the genetic diversity of HBV in patients from Venezuela, with chronic infection, cirrhosis and hepatocellular carcinoma (HCC) and to compare the occurrence of mutations in all patient groups. Samples from patients with different pathologies of the liver, associated with HBV infection, were collected. The HBV S region was analyzed for genotype determination and, when available, the whole genome sequence was examined for mutations analysis. Genotype F was the most common genotype (87%). While the HBV subgenotype F3 was the most frequent genotype in the whole group of samples (44%), the subgenotype F2 predominated in HCC patients (56%). Mutations were more common in HCC and cirrhosis cases (p=0.01). The A1762T mutation was significantly associated with the advanced stage of liver disease (p=0.008). Additionally, mutations were more common in early stages of liver disease in HBV subgenotype F2-infected patients, and a significant association between this subgenotype and the emergence of T 1753C, A1762T, A1762T/G1764A (p=0.04) and C1773T (p=0.001) mutations in chronic patients was found, when compared to the HBV subgenotype F3. By comparing F2 with all other HBV subgenotypes, a positive association for the three basal core promoter (BCP) mutants (A1762T, A1762T/G1764A p=0.01, G1764A p=0.04) was found. These results suggest that the HBV subgenotype F2 might be associated to more severe forms of liver disease in comparison with the HBV subgenotype F3.

The Evolving HIV-1 Epidemic in Warao Amerindians Is Dominated by an Extremely High Frequency of CXCR4-Utilizing Strains

We previously reported a high prevalence of HIV-1 infection in Warao Amerindians from Venezuela due to the rapid spread of a single B subtype strain. In this study we evaluated the coreceptor use of the HIV-1 strains infecting this Amerindian community. Sequences of the HIV-1 V3 loop from 56 plasma samples were genotyped for coreceptor use. An extremely high frequency of CXCR4 strains was found among HIV-1-infecting Waraos (47/49, 96%), compared to HIV-1 strains infecting the non-Amerindian Venezuelan population (35/79, 44%, p < 0.00001). Evolutionary analysis showed that a significant number of infections occurred between 1 and 12 months before collection and that a great proportion (50-70%) of HIV-1 transmissions occurred within the very early phase of infection (≤12 months). This is consistent with an initial infection dominated by an X4 strain or a very rapid selection of X4 variants after infection. This Amerindian population also exhibits the highest prevalence of tuberculosis in Venezuela, being synergistically bad prognostic factors for the evolution of morbidity and mortality in this vulnerable population.

Genetic diversity of Venezuelan alphaviruses and circulation of a Venezuelan equine encephalitis virus subtype IAB strain during an interepizootic period

Several species of alphaviruses have been previously described in the Americas, some of which are associated with encephalitis and others are associated with arthralgia. Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV) are endemic to Venezuela, with the former being responsible for major outbreaks of severe and often fatal disease in animals and humans. The aim of this study was to analyze the genetic diversity of Venezuelan alphaviruses isolated during two decades (1973-1999) of surveillance in northern Venezuela. Phylogenetic analysis indicated the circulation of a VEEV subtype IAB strain 8 years after the last reported outbreak. Thirteen strains within two subclades of South American lineage III of EEEV were also found in Venezuela. Considerable genetic variability was observed among Venezuelan Una virus strains, which were widely distributed among the clades. The first Venezuelan Mayaro sequence was also characterized.

Genetic diversity of hepatitis B virus and hepatitis C virus in human immunodeficiency virus type 1-co-infected patients from Venezuela

The aim of this study was to evaluate the prevalence and genetic diversity of hepatitis B virus (HBV) and hepatitis C virus (HCV) in human immunodeficiency virus type 1 (HIV-1)-co-infected Venezuelan patients. The prevalence of HBV and HCV markers of infection in HIV-1 patients was 14% for anti-hepatitis B core antigen, 3% for hepatitis B surface antigen and 0.7% for anti-HCV, respectively. HBV prevalence was higher than HCV, as expected for a country where sexual intercourse, not intravenous drug use, is the main mode of HIV-1 transmission. The HCV genotype distribution in HIV-1-co-infected patients was similar to that obtained in HCV-mono-infected patients, but genotype 1a was more frequent in HIV-1-infected patients. The HBV genotype distribution exhibited differences between mono-infected and HIV-1-co-infected individuals. HBV F3 was the most common subgenotype in both groups, followed by F1b in HIV-1 co-infection and F2 in HBV mono-infection. In addition, genotype G (single infection) was found in an HIV-1-co-infected individual. A high prevalence of occult HBV infection was detected in HIV-1-co-infected naïve patients (18%), with F2 being the most common genotype (75%). To the best of our knowledge, these results correspond to the first description of frequency and molecular characterization of HBV and HCV in HIV-1 Venezuelan patients.

Hepatitis E virus infection in Latin America: a review

Data reported during recent years reveal the complex picture of the epidemiology of hepatitis E virus (HEV) infection in Latin America. Whereas in countries like Argentina and Brazil is almost identical to the characteristic of most countries from North America and Europe, HEV in the Caribbean and Mexico involves the water-borne, non-zoonotic viral genotypes responsible for epidemics in Asia and Africa. Nevertheless, Latin America has been considered a highly endemic region for hepatitis E in the scientific literature, a generalization that ignores the above complexity. In addition, reports from isolated Amerindian communities, which display well known, important and very specific epidemiological features for hepatitis B and D virus infections are neither taken into account when considering the epidemiology of hepatitis E in the region. This review updates compilation of the available information for the HEV infection, both among humans and other mammals, in Latin America, discusses the strengths and the weaknesses of our current knowledge, and identifies future areas of research.

Infection with transfusion-transmitted virus (TTV) in humans and other primates in Venezuela

Tranfusion-transmitted virus (TTV), a single-stranded circular DNA virus that chronically infects humans and other animals, displays a high degree of genetic diversity and was originally thought to be associated with hepatitis. The prevalences of TTV infection among different populations of humans and non-human primates from Venezuela have now been evaluated, using serum samples and three different detection tests. All three tests were PCR-based, one involving a hemi-nested PCR and primers based on the N22 open-reading-frame-1 region (N22-PCR), another employing 55 cycles with primers from the more conserved untranslated region (UTR-PCR), and the other using a hemi-nested PCR with primers from the same region (HUTR-PCR). The overall prevalences of human infection appeared much higher with the HUTR-PCR (52%) than with the N22-PCR (13%) or the UTR-PCR (5%). When the products amplified by N22-PCR from 28 human isolates of TTV were sequenced, only two genotypes of the virus were detected. The non-human sera tested came from primates kept in a zoo in north-western Venezuela. TTV DNA was detected, by HUTR-PCR, in both of the chimpanzee sera tested but not in any of the sera from the 11 New-World primates or the other 12 Old-World primates that were investigated. The results, particularly those of the HUTR-PCR, indicate that TTV infection is common in Venezuela, especially in populations, such as many Amerindian groups, who live under poor sanitary conditions. Although TTV infection may be relatively rare among non-human primates from the New World, this will have to be investigated further, using many more samples collected throughout the Americas.

Prevalence of amino acid mutations in hepatitis C virus core and NS5B regions among Venezuelan viral isolates and comparison with worldwide isolates

BACKGROUND

Recent reports show that R70Q and L/C91M amino acid substitutions in the core from different hepatitis C virus (HCV) genotypes have been associated with variable responses to interferon (IFN) and ribavirin (RBV) therapy, as well to an increase of hepatocellular carcinoma (HCC) risk, liver steatosis and insulin resistance (IR). Mutations in NS5B have also been associated to IFN, RBV, nucleoside and non-nucleoside inhibitors drug resistance. The prevalence of these mutations was studied in HCV RNA samples from chronically HCV-infected drug-naïve patients.

METHODS

After amplification of core and NS5B region by nested-PCR, 12 substitutions were analyzed in 266 Venezuelan HCV isolates subtype 1a, 1b, 2a, 2c, 2b, 2j (a subtype frequently found in Venezuela) and 3a (n = 127 and n = 228 for core and NS5B respectively), and compared to isolates from other countries (n = 355 and n = 646 for core and NS5B respectively).

RESULTS

R70Q and L/C91M core substitutions were present exclusively in HCV G1b. Both substitutions were more frequent in American isolates compared to Asian ones (69% versus 26%, p < 0.001 and 75% versus 45%, p < 0.001 respectively). In Venezuelan isolates NS5B D310N substitution was detected mainly in G3a (100%) and G1a (13%), this later with a significantly higher prevalence than in Brazilian isolates (p = 0.03). The NS5B mutations related to IFN/RBV treatment D244N was mainly found in G3a, and Q309R was present in all genotypes, except G2. Resistance to new NS5B inhibitors (C316N) was only detected in 18% of G1b, with a significantly lower prevalence than in Asian isolates, where this polymorphism was surprisingly frequent (p < 0.001).

CONCLUSIONS

Genotypical, geographical and regional differences were found in the prevalence of substitutions in HCV core and NS5B proteins. The substitutions found in the Venezuelan G2j type were similar to that found in G2a and G2c isolates. Our results suggest a high prevalence of the R70Q and L/C91M mutations of core protein for G1b and D310N substitution of NS5B protein for the G3a. C316N polymorphism related with resistance to new NS5B inhibitors was only found in G1b. Some of these mutations could be associated with a worse prognosis of the disease in HCV infected patients.

Evidence of at least two introductions of HIV-1 in the Amerindian Warao population from Venezuela

BACKGROUND

The Venezuelan Amerindians were, until recently, free of human immunodeficiency virus (HIV) infection. However, in 2007, HIV-1 infection was detected for the first time in the Warao Amerindian population living in the Eastern part of Venezuela, in the delta of the Orinoco river. The aim of this study was to analyze the genetic diversity of the HIV-1 circulating in this population.

METHODOLOGY/PRINCIPAL FINDINGS

The pol genomic region was sequenced for 16 HIV-1 isolates and for some of them, sequences from env, vif and nef genomic regions were obtained. All HIV-1 isolates were classified as subtype B, with exception of one that was classified as subtype C. The 15 subtype B isolates exhibited a high degree of genetic similarity and formed a highly supported monophyletic cluster in each genomic region analyzed. Evolutionary analyses of the pol genomic region indicated that the date of the most recent common ancestor of the Waraos subtype B clade dates back to the late 1990s.

CONCLUSIONS/SIGNIFICANCE

At least two independent introductions of HIV-1 have occurred in the Warao Amerindians from Venezuela. The HIV-1 subtype B was successfully established and got disseminated in the community, while no evidence of local dissemination of the HIV-1 subtype C was detected in this study. These results warrant further surveys to evaluate the burden of this disease, which can be particularly devastating in this Amerindian population, with a high prevalence of tuberculosis, hepatitis B, among other infectious diseases, and with limited access to primary health care.

Unusual presentation of hepatitis B serological markers in an Amerindian community of Venezuela with a majority of occult cases

Background

Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DNA in the absence of HBsAg in the serum of patients. The aim of this study was to characterize HBV infection among a Piaroa community, an Amerindian group which exhibits significant evidence of exposure to HBV but relatively low presence of HBsAg, and to explore the presence of OBI in this population.

Results

Of 150 sera, with 17% anti-HBc and 1.3% HBsAg prevalence, 70 were tested for the presence of HBV DNA. From these, 25 (36%) were found positive for HBV DNA by PCR in the core region. Two of these 25 sera were HBsAg positive, indicating an overt infection. Of the remaining 68 sera tested, 23 exhibited OBI. Of these, 13 were HBV DNA out of 25 anti-HBc positive (52%) and 10 HBV DNA positive, out of 43 anti-HBc negative (23%), with a statistical significance of p = 0.03. Viral DNA and HBsAg were present intermittently in follow up sera of 13 individuals. Sequence analysis in the core region of the amplified DNA products showed that all the strains belonged to HBV genotype F3. The OBI isolates displayed 96-100% nucleotide identity between them. One isolate exhibited the co-circulation of a wild type variant with a variant with a premature stop codon at the core protein, and a variant exhibiting a deletion of 28 amino acids.

Conclusions

The frequency of OBI found in this Amerindian group warrants further studies in other communities exhibiting different degrees of HBV exposure.

Inhibition of hepatitis B virus and human immunodeficiency virus (HIV-1) replication by Warscewiczia coccinea (Vahl) Kl. (Rubiaceae) ethanol extract

The primary objective of this study was to search for natural products capable of inhibiting hepatitis B virus (HBV) replication. The research design, methods and procedures included testing hydro-alcoholic extracts (n = 66) of 31 species from the Venezuelan Amazonian rain forest on the cell line HepG2 2.2.15, which constitutively produces HBV. The main outcomes and results were as follows: the species Euterpe precatoria, Jacaranda copaia, Jacaranda obtusifolia, Senna silvestris, Warscewiczia coccinea and Vochysia glaberrima exerted some degree of inhibition on HBV replication. The leaves of W. coccinea showed a significant antiviral activity: 80% inhibition with 100 µg mL⁻¹ of extract. This extract also exerted inhibition on covalently closed circular deoxyribonucleic acid (cccDNA) production and on HIV-1 replication in MT4 cells (more than 90% inhibition with 50 µg mL⁻¹ of extract). Initial fractionation using organic solvents of increasing polarity and water showed that the ethanol fraction was responsible for most of the antiviral inhibitory activities of both the viruses. It was concluded that Warscewiczia coccinea extract showed inhibition of HBV and HIV-1 replication. Bioassay-guided purification of this fraction may allow the isolation of an antiviral compound with inhibitory activity against both viruses.

Genetic history of hepatitis C virus in Venezuela: high diversity and long time of evolution of HCV genotype 2

BACKGROUND

The subtype diversity of the hepatitis C virus (HCV) genotypes is unknown in Venezuela.

METHODOLOGY/PRINCIPAL FINDINGS

Partial sequencing of the NS5B region was performed in 310 isolates circulating in patients from 1995 to 2007. In the samples collected between 2005 and 2007, HCV genotype 1 (G1) was the most common genotype (63%), composed as expected of mainly G1a and G1b. G2 was the second most common genotype (33%), being G2a almost absent and G2j the most frequent subtype. Sequence analysis of the core region confirmed the subtype assignment performed within the NS5b region in 63 isolates. The complete genome sequence of G2j was obtained. G2j has been described in France, Canada and Burkina Fasso, but it was not found in Martinique, where several subtypes of G2 circulate in the general population. Bayesian coalescence analysis indicated a most recent common ancestor (MRCA) of G2j around 1785, before the introduction of G1b (1869) and G1a (1922). While HCV G1a and G1b experienced a growth reduction since 1990, coincident with the time when blood testing was implemented in Venezuela, HCV G2j did not seem to reach growth equilibrium during this period.

CONCLUSIONS/SIGNIFICANCE

Assuming the introduction of G2j from Africa during the slave trade, the high frequency of G2j found in Venezuela could suggest: 1- the introduction of African ethnic groups different from the ones introduced to Martinique or 2- the occurrence of a founder effect. This study represents an in-depth analysis of the subtype diversity of HCV in Venezuela, which is still unexplored in the Americas and deserves further studies.

Absence of primary integrase resistance mutations in HIV type 1-infected patients in Venezuela

The preexistence of mutations to integrase inhibitors in HIV-1-infected Venezuelan patients was evaluated. The integrase region of the HIV-1 genome was amplified by nested-PCR and sequenced in 57 isolates from both naive (n = 24) and treated patients who received protease and/or reverse transcriptase inhibitors (PI and RTI, n = 33), but were never exposed to integrase inhibitors. Only one primary integrase resistance mutation, not conferring drug resistance by itself, was found among these patients, although several minor viral mutations, equally distributed among naive and PI- and RTI-treated patients, were also found. In the limited number of samples, no relation was found among the presence of resistance mutations to PI or RTI and the presence of minor mutations to integrase. The absence of resistance to integrase inhibitors may be related to the recent introduction of these drugs in our country. The availability of in-house assays allows for a more comprehensive surveillance of drug resistance to integrase inhibitors in Venezuela.

A comparative epidemiological study of hepatitis B and hepatitis D virus infections in Yanomami and Piaroa Amerindians of Amazonas State, Venezuela

OBJECTIVES

To report the prevalences of hepatitis B (HBV) and hepatitis D (HDV) infections in remote and more accessible Yanomami and Piaroa Venezuelan Amazonian Amerindian populations; to estimate incidence per susceptible.

METHODS

Clinico-epidemiological evaluation was carried out in 9 Piaroa villages. Blood samples were tested for HBV core antibody (anti-HBc), surface antigen (HBsAg) and HDV antibody (anti-HDV). Results were analysed using logistic regression, and estimates made of HBV forces of infection (FOI). Prevalences and FOI were also estimated for 4 Yanomami villages.

RESULTS

Mean Piaroa anti-HBc and HBsAg prevalences were 27.4% and 5.1%, respectively (up to 53% and 19% in the remote Autana region). Mean Yanomami anti-HBc and HBsAg prevalences were, respectively, 58.0% (range 43-70%) and 14.3% (31% in the village with highest HBsAg). No significant difference was found between sexes, with age and maternal HBsAg the only risk factors for HBV identified in multivariate regression of Piaroa data. Only 4 Piaroa and 2 Yanomami individuals were anti-HDV positive.

CONCLUSION

Piaroa HBV prevalences were generally higher in remote villages than in less remote ones, with prevalences in Yanomami villages even higher. Anti-HBc prevalence was 47% in one Yanomami village with a history of HBV vaccination but no HBsAg cases were identified, suggestive of previously cleared or possibly transient infection or vaccine escape. Despite a past history of HDV epidemic outbreaks and HBsAg levels in some villages appearing sufficient to facilitate HDV transmission, anti-HDV prevalence was low; it remains to be established why no recent outbreaks have been reported.

Comparative analysis of polymorphisms in the HIV type 1 pol gene in the proviral DNA and viral RNA in the peripheral compartment

The aim of this study was to evaluate the presence of mutations and polymorphisms associated with drug resistance among HIV-1-infected patients in proviral DNA and viral RNA extracted from PBMCs and plasma, respectively, in 34 HIV-1-infected patients (11 naive and 23 receiving HAART). Additional drug resistance mutations were found in only one compartment in 14 of 23 treated patients. Mutations conferring resistance to an additional drug were found in plasma in only 7 of 23 patients. A greater number of differences was found in strains in patients infected for at least more than 9 years, compared to naive patients and patients for whom the time since the first diagnosis was lower (p < 0.02). This study confirms the usefulness of simultaneous testing of different compartments for assessing drug resistance in the pol region and suggests that the heterogeneity observed in different compartments might be increased with time of infection and treatment experience.

HIV diversity in Venezuela: predominance of HIV type 1 subtype B and genomic characterization of non-B variants

The aim of this study was the analysis of human immunodeficiency virus (HIV) diversity in Venezuela, and the characterization of variants other than subtype B. A total of 425 HIV isolates, collected between 2003 and 2008, were analyzed. The sequence of at least one genomic region (Pol, Env, Vif, or Nef ) was available for all of them and at least two genomic regions were analyzed in 46% of them. From the 425 HIV isolates analyzed, 421 (99.1%) were classified as HIV-1 subtype B. The four non-subtype B isolates correspond to one subtype C, one recombinant AG, and two HIV-2 isolates. This study shows that HIV-1 subtype B is still highly predominant in Venezuela. Whereas some sporadic cases of other HIV types can be found, they do not seem to have disseminated to the present.

Helicobacter pylori seroprevalence in Amerindians from isolated locations

Helicobacter pylori seems universally distributed in all human populations, with high prevalence in the third world. Because H. pylori is an ancestral indigenous microbe of the human stomach, we hypothesized that its prevalence in isolated Amerindians would be high. A serologic study was performed on 19 Guahibo-Piaroa and 17 Warao in Venezuela, using H. pylori whole cell (WC) and CagA antigens from US strains. For Guahibo-Piaroa Amerindians, CagA seropositivity was 95%, but WC seropositivity was only 74%. For Warao, both CagA and WC seropositive proportions were low (65% and 76%, respectively). Because all CagA-seropositive individuals carry H. pylori, the results suggest that there has been bacterial antigen divergence, probably caused by genetic drift/natural selection, on humans and their microbes in isolated human groups.

Subgenotype diversity of hepatitis B virus American genotype F in Amerindians from Venezuela and the general population of Colombia

The objective of this study was the evaluation of the genetic diversity found in HBV circulating among Venezuelan Amerindians and the general population in Colombia. Phylogenetic analysis of the S region in 194 isolates showed that genotype F is highly predominant in Colombia and Venezuela. This might be related to the genetic background of the population. F3 is the main subgenotype which circulates in both countries. Phylogenetic analysis of 61 complete genome sequences of HBV American genotypes confirms the presence of two genotypes F and H, and 4 F subgenotypes. In Venezuela, subgenotypes F1, F2, and F3 circulate in East and West Amerindians, while only F3 was found among South Amerindians. Japreira community derived from Yucpa Amerindians around 150 years ago. However, several Japreira HBV sequences were forming a clade that can be classified as subgenotype 2b, differing from Yucpa sequences that belong mainly to subgenotype F3. The apparent absence of correlation between the phylogenetic groupings of HBV isolates with the ethnical origin in aboriginal populations might be suggesting a recent origin of HBV American subgenotypes, or a genetic drift effect.

Replacement of hepatitis C virus genotype 1b by genotype 2 over a 10-year period in Venezuela

BACKGROUND

Changes in hepatitis C virus (HCV) genotype distribution with time have been reported in several countries.

GOALS

To explore eventual changes in HCV genotype distribution in Venezuela over a 10 years period.

STUDY

HCV genotype was determined by direct sequencing of the 5' noncoding region, in 236 isolates circulating in patients treated during years 2005 to 2006. Genotype distribution was compared with the one observed in 43 patients followed during years 1994 to 1996.

RESULTS

The prevalence HCV genotype 1 and 2 was 70% and 26%, respectively, in patients followed during years 1994 to 1996. The frequency of genotype 2 was significantly increased to 41% (P=0.04) in patients treated during years 2005 to 2006. A significant reduction in HCV genotype 1b prevalence (48% to 27%, P=0.01) was also observed after this 10 years period, whereas the prevalence of HCV genotype 1a did not change over time (22% vs. 27%, NS). Transfusion was more significantly associated with infection with HCV genotype 1b than with other genotypes (52% vs. 20%, P=0.002).

CONCLUSIONS

HCV subtype 1b seems to have been displaced by HCV genotype 2 in a relatively short period, without increase in the frequency of genotype 3. The low frequency of HCV genotype 3 in Venezuela might be due to the fact that intravenous drug use in Venezuela is less common than in other countries. The implementation of anti-HCV testing in blood banks since 1994 in Venezuela, might have contributed to the reduction in the frequency HCV genotype 1b infection.

Hepatitis B virus genetic diversity in Latin America

Hepatitis B virus (HBV) infection is still a significant health concern in Latin America, where around 11 million persons are infected. Amerindian populations exhibit the highest prevalences of infection in the region. HBV exhibits a degree of variability intermediate between DNA and RNA viruses. This plasticity leads to the generation of several mutants and genotypic variability. Eight HBV genotypes (A-H) have been described, based on a minimum divergence of 8% of the complete genome sequences. HBV genotype F is the most divergent of the HBV genotypes, is autochthonous to South America and is highly predominant in the Northern region of South America. The recently described HBV genotype H is closely related to genotype F and seems to be restricted to Central and North America. Recombination among different HBV strains seems to be frequent, although it has not been described yet between American genotypes. Inside HBV genotype F, four subgenotypes have been described, which exhibit a geographic pattern of distribution. The clinical and biologic importance of the genotypic diversity of HBV is of major concern at the present moment and has been studied in Asia and Europe. In contrast, it is not known whether infection with the American HBV genotypes F and H is associated with a rapid or slow development of disease. The origin of HBV is still an open question. Depending on the model used for the phylogenetic analysis, an Asian or an American origin of HBV has been proposed. By revisiting the genotypic diversity of HBV, an alternative explanation is that human HBV genotypes might have emerged by several zoonotic introductions, both in the Old and the New World.

Levels of complement C3 and C4 components in Amerindians living in an area with high prevalence of tuberculosis

The levels of complement C3 and C4 components were determined in non-indigenous (creoles) and indigenous (Warao) populations, the latter with an extremely high tuberculosis (TB) rate. Serum samples from 209 adults were studied and classified in 4 groups taking into account tuberculin skin tests (TST): (1) the group of Warao patients (58 positive for the TST, WP TST+ and 9 negative for the TST, WP TST-), (2) the group of creole patients (34 positive for the TST, CP TST+ and 9 negative for the TST, CP TST-), (3) the group of healthy Warao controls (38 positive and 14 negative for TST, WC TST+ and WC TST-, respectively), (4) the creole controls (26 positive and 21 negative for the TST, CC TST+ and CC TST-, respectively). With respect to the results concerning the measurement of both complement C3 and C4 components with the exception of the WC TST and the CC groups, the WP TST+ and WP TST- as well as WC TST+ groups showed a significant frequency of individuals with decreased levels of complement C3 component (20.6, 33.3, and 26.3%, respectively) and also C4 component (12.0, 11.1, and 13.3%, respectively) in comparison to both creole patients (CP TST+, 8.82% and CP TST-, 0% and CP TST+, 5.88% and CP TST-, 0%) for C3 and C4, respectively. The study of these parameters carried out in 15 Warao subjects with active infection, before and after anti-TB chemotherapy,statisticallyconfirmedthat the effective chemotherapy did not restore normal levels of the complement C3 and C4 components among Warao patients. Aditional tests for hepatitis B or hepatitis C infection, and the profile of the hepatic proteins were not associated to the deficiency in production of the complement components. In conclusion, the results show that within the Warao population, a high percentage of subjects exhibit decreased levels of both complement C3 and C4 components independent of latent or active infection and the status of TST.

Non-immune thrombocytopenia responsive to antiretroviral therapy and HIV-2 infection

HIV-2 infection was documented for the first time in Venezuela, in a heterosexual couple. Two identical subtype A viral strains exhibiting multiple resistance mutations to antiretroviral drugs were identified. One of the patients suffered from progressive non-immune thrombocytopenia and extranodal NK/T-cell type lymphoma, an association not previously described for HIV-2. His hematological condition promptly improved after onset of an effective antiretroviral therapy.

Characterization of neuraminidase-resistant mutants derived from rotavirus porcine strain OSU

Infection by some rotavirus strains requires the presence of sialic acid on the cell surface, its infectivity being reduced in cells treated with neuraminidase. A neuraminidase treatment-resistant mutant was isolated from the porcine rotavirus strain OSU. In reassortant strains, the neuraminidase-resistant phenotype segregated with the gene coding for VP4. The mutant retained its capacity to bind to sialic acid. The VP4 sequence of the mutant differed from that of the parental OSU strain in an Asp-to-Asn substitution at position 100. Neutralization escape mutants selected from an OSU neuraminidase-sensitive clone by monoclonal antibodies that failed to recognize the neuraminidase-resistant mutant strain carried the same mutation at position 100 and were also neuraminidase resistant. Neuraminidase sensitivity was restored when the mutation at position 100 was compensated for by a second mutation (Gln to Arg) at position 125. Molecular mechanics simulations suggest that the neuraminidase-resistant phenotype associated with mutation of OSU residue 100 from Asp to Asn reflects the conformational changes of the sialic acid cleft that accompany sialic acid binding.

Genotypic variability of hepatitis viruses associated with chronic infection and the development of hepatocellular carcinoma

At least five hepatitis viruses are known to date. Infection by enterically transmitted viruses (HAV and HEV) is generally benign compared with the disease caused by parenterally transmitted viruses (HBV, HCV, and HDV). Chronic infection by HBV is common and may evolve to cirrhosis and hepatocellular carcinoma (HCC). Eight HBV genotypes (A-H) have been described, with the South American genotype F being the most divergent. Seven clades of HDV have been described; among them, the South American genotype III is associated to a high frequency of fulminant hepatitis. HCV infection leads to a high rate of chronicity and HCC. From the six HCV genotypes, infection with genotype 1 might have the worst prognostic. Chronic infection by HCV and HBV is the major risk factor for HCC, which occurs, in the majority of the cases, as a consequence of cirrhosis. However, there is growing evidence that some HBV and HCV proteins might contribute to the generation of HCC. Some HBV and HCV variants and specific mutations within the viral genomes might be more frequently associated with the evolution to HCC. Although more studies are needed, emerging evidence indicates that it might be important to address the genetic variability of these viruses and their contribution to the development of HCC.

Calicivirus infection in human immunodeficiency virus seropositive children and adults

BACKGROUND

The importance of enteric viral infections in HIV-related diarrhea is uncertain. Human caliciviruses have emerged as a leading cause of acute diarrhea worldwide.

OBJECTIVES

To evaluate the importance of calicivirus infections in HIV-related diarrhea. Study design 151 fecal samples collected from children and adults infected with HIV, with and without diarrhea, were examined. In addition, 89 fecal samples from non HIV-infected children and adults were also tested. Samples were analyzed by RT-PCR using primer sets specific to Norovirus genogroup I or genogroup II as well as primers designed to react with both Noroviruses and Sapovirus genus.

RESULTS

Viruses were detected with equal frequencies in stools from HIV infected and non-infected adults (12%). However, specimens from HIV infected children were more likely than those of HIV-negative children to have caliciviruses (51% versus 24%, P<0.05). Viral infections were not significantly associated with diarrhea neither in children nor in adults, regardless of HIV status. Viruses genetically related to the common Lordsdale virus (Norovirus genogroup II) and London/92 virus (Sapovirus) clusters were detected circulating among children.

CONCLUSIONS

These results suggest that caliciviruses may be an important opportunistic pathogen in children infected with HIV.

A novel type of VP4 carried by a porcine rotavirus strain

The gene encoding the VP8* trypsin-cleavage product of the VP4 protein of porcine rotavirus strain A34 was sequenced, and the predicted amino acid (aa) sequence was compared to the homologous region of all known P genotypes. The aa sequence of the VP8* of strain A34 shared low identity, ranging from 39% (bovine strain B223, P8[11]) to 76% (human strain 69M, P4[10]), with the homologous sequences of representative strains of the remaining 21 P genotypes. Phylogenetic relationships showed that the VP8* of strain A34 shares a common evolutionary lineage with those of human 69M (P4[10]) and equine H-2 (P4[12]) strains. Hyperimmune sera raised to strain A34 and to a genetic reassortant strain containing the VP4 gene from strain A34, both with high homologous neutralization titer via VP4, failed to neutralize strains representative of 15 different P genotypes. These results indicate that strain A34 should be considered as prototype of a new P genotype and serotype (P14[23]) and provide further evidence for the vast genetic and antigenic diversity of group A rotaviruses.

[Study of immune response in Warao children from communities with high tuberculosis prevalence]

The present study was carried out in a Warao childhood population with extremely high tuberculosis (TB) rate of 3190/100,000 in 0-15 years old children. One hundred seven serum and saliva samples were tested, 32 from patients with active TB (27 positive and 5 negative for the tuberculin skin test, TST) and 75 apparently healthy contact children (45 positive and 30 negative for the TST). The innate, immunoglobulin and cellular responses were studied. The results showed that both, patients and controls, had a high percentage of children with increased levels of complement C3 and C4 components. A high percentage of children with increased total serum IgA and IgG (13.8% and 79.3% respectively) was observed in children with TB in comparison to control children (0% and 69.2%). A high percentage of control children had increased levels of IgM and sIgA (69.2% and 56.16%, respectively) in comparison to patients (48.3% and 31.25%). Both groups showed children with increased levels of IgE. The results concerning to the cellular immune response to PPD and the BCG vaccination status showed that there was a correlation between an increase in PPD reactivity and age. The PPD reactivity in children less than 7 years old was similar and also independent of the BCG vaccination status. A significant number of children without or with scars (46.8% and 27.6%, respectively) showed induration values of 0 mm to tuberculin skin test. The Candida reactivity showed a high percentage of children (80%) with anergy status. In conclusion, an increase in the levels of complement components C3 and C4 and hypergammaglobulinemia was observed in Warao children, and these results were independent from PPD reactivity and BCG vaccination. The isotype results showed that the decrease in sIgA could be and active disease marker, while the increase in IgM levels could represent a marker of recent disease.

The T(1858) variant predisposing to the precore stop mutation correlates with one of two major genotype F hepatitis B virus clades

The precore mutation G(1896)-->A occurs frequently in anti-HBe-positive carriers of HBsAg with T(1858) in the stem of the encapsidation signal. Hepatitis B virus (HBV) genotype F, considered an Amerindian genotype, subdivides into two clades and the precore mutation occurs in Central American F strains. To investigate the relationship between substitutions at position 1858 and these clades, the precore and small S genes of 48 strains of HBV genotype F were subjected to phylogenetic analyses. Isolates of one clade, formed mainly of Central American strains, all had T(1858) and Thr(45) in the S gene, whereas in the other clade, formed mainly of South American strains and one strain from Polynesia, all had C(1858) and Leu(45). The latter strain was related to strains from Venezuela and Colombia, supporting an Amerindian contribution to the Polynesian population. The position of the Polynesian strain in the phylogenetic tree indicates that the two clades have resulted from an early split, showing a high degree of genetic stability of the stem of the HBsAg encapsidation signal.