Rodolfo Campos

Cytotoxic effect of Argentine medicinal plant extracts on human hepatocellular carcinoma cell line

Methanolic extracts from Achyrocline satureioides (Dc.) Lam, Aristolochia macroura Gomez, Lithraea molleoides (Vell.) Engl., Schinus molle L., unlike those from Celtis spinosa Spreng, Chenopodium ambrosioides L., Petiveria alliacea L., and Plantago major L. showed cytotoxic activity against a human hepatocellular carcinoma cell line, Hep G2. Schinus molle L. was the most active (IC50=50+/-7 microg/ml). These results call for further studies of these extracts.

Molecular epidemiology of hepatitis B virus in Latin America

Hepatitis B virus (HBV) is an etiological agent of acute and chronic liver disease existing throughout the world. The high genetic variability of HBV is reflected by eight genotypes (A to H), each one with a particular geographical prevalence. The global pattern of HBV genotypes is associated with the distribution of human populations among the different continents and may reflect the patterns of human migrations. Genotypes F and H are considered indigenous to Latin America. The most prevalent genetic group of Central and South America, genotype F, is subdivided into two subtypes and five clusters associated with defined geographic areas. Genotype H has been described in Mexico and Central America. This pattern provides a tool to reconstruct the initial immigration of ancestral Amerindians from Asia and their further spread through Central and South America. Other HBV genotypes found in different Latin American countries may reflect migration from other geographical areas into the region. Genotypes A and D are the signature of the European colonization that started in the sixteenth century, including slave trade from Africa. Genotypes B and C indicate the arrival of people from Southeast Asia. The impact of HBV genotypes on the natural course of HBV infection and response to treatment has been studied recently and controversial results have been obtained. The majority of the current information concerns with genotypes B and C. In contrast, very few data are available on the Latin American HBV genotypes F and H. It has been reported that liver failure and death may be more frequent in patients infected with genotype F. More studies are needed to assess the association between H13V genotypes and clinical course of infection, especially in Latin America.

Bovine leukemia virus can be classified into seven genotypes: evidence for the existence of two novel clades

Previous studies have classified the env sequences of bovine leukemia virus (BLV) provirus from different locations worldwide into between two and four genetic groupings. These different studies gave unique names to the identified groups and no study has yet integrated all the available sequences. Thus, we hypothesized that many of the different groups previously identified actually correspond to a limited group of genotypes that are unevenly distributed worldwide. To examine this hypothesis, we sequenced the env gene from 28 BLV field strains and compared these sequences to 46 env sequences that represent all the genetic groupings already identified. By using phylogenetic analyses, we recovered six clades, or genotypes, that we have called genotypes 1, 2, 3, 4, 5 and 6. Genotypes 1-5 have counterparts among the sequence groupings identified previously. One env sequence did not cluster with any of the others and was highly divergent when compared with the six genotypes identified here. Thus, an extra genotype, which we named 7, may exist. Similarity comparisons were highly congruent with phylogenetic analyses. Furthermore, our analyses confirmed the existence of geographical clusters.

Phylogenetic analysis of the hepatitis B virus (HBV) genotype F including Argentine isolates

Summary. Seven human hepatitis B virus (HBV) genotypes have been described. Genotype F, indigenous to the Americas, is the most diverging group. Our in-depth analysis of the genetic distances of this genotype included ten Argentine samples. Phylogenetic analysis on the small (S) gene of the surface antigen showed four different clusters within genotype F, which were associated with a well-defined geographical origin. Even closely connected sequences sharing a common ancestor had shown some characteristics or markers indicating geographical differentiation. Nucleotide sequences and amino acids translated according to the polymerase open reading frame (P-ORF), rather than S-ORF, yielded a more discriminating analysis.

Effect of lysosomotropic agents on the foot-and-mouth disease virus replication

The effect of two lysosomotropic agents, NH4Cl and chloroquine, on the foot-and-mouth disease virus (FMDV) replicative cycle was studied. When the drugs were present throughout the viral replicative cycle, an important inhibition of viral RNA synthesis and virus production was detected. The inhibition of viral RNA synthesis was maximal when the drugs were present from 30 min before virus infection up to 30 min after that. Otherwise, if the agents were added once the viral synthesis has started (150 min p.i.) the effect was not evident. The agents neither exerted direct virucidal effects, nor did they affect viral adsorption. The results indicate that the lysosomotropic agents affect preferentially an early intracellular event during the viral infective cycle.

Hepatitis B virus genetic diversity in Argentina: Dissimilar genotype distribution in two different geographical regions; description of hepatitis B surface antigen variants

BACKGROUND The hepatitis B virus (HBV) molecular epidemiological data of Argentina are still scarce, since most of the previous analyses have been performed in the Metropolitan Region. OBJECTIVES To deepen the current molecular and epidemiological information about the geographical distribution of HBV genotypes and subgenotypes, and to describe the hepatitis B surface antigen (HBsAg) variants circulating in Argentina. STUDY DESIGN Eighty-eight Argentine partial HBsAg sequences from both the Northern and the Metropolitan Regions of the country were analyzed along with 67 Argentine HBV sequences existing in GenBank. RESULTS Phylogenetic and amino acid sequence analysis grouped the 88 samples as genotypes A (14.8%), D (21.6%) and F (63.6%). In the Northern Region, 44 out of the 48 sequences analyzed (91.7%) grouped as genotype F. Differently, in the Metropolitan Region, the 40 samples grouped as genotype F (30.0%), genotype D (42.5%), and genotype A (27.5%). An elevated proportion (14.8%) of the genomes presented mutations in the major hydrophilic region (MHR). CONCLUSIONS The different genotype distribution in both Argentine regions indicates that the epidemiological landscape of HBV infection appears to be the result of the diverse human migratory movements that have given shape to the present population. Our findings show that the prevalence of HBsAg variants is quite significant among the Argentine population.

Modification of foot-and-mouth disease virus after serial passages in the presence of antiviral polyclonal sera

Foot-and-mouth disease virus (FMDV) shows a remarkable antigenic variability. Like other RNA viruses, this virus has a high rate of mutation. It has been proposed that selection exerted by the hosts antibodies could play a major role in the rapid evolution of FMDV. The present work reports the selection of FMDV antibody-resistant populations (Nr), after serial passages of cloned FMDV A24 Cruzeiro strain on secondary monolayers of bovine fetal kidney cells in the presence of subneutralizing antiviral polyclonal sera (APS). After a limited number of passages under selective pressure, the virus population showed the following characteristics: (1) increased resistance to neutralization by APS; (2) altered electrophoretic mobility of structural viral proteins (VP1); (3) remarkable plaque size reduction, (4) a pronounced thermosensitivity (ts); and (5) decreased pathogenicity for mice, in both uncloned and cloned small plaque size populations. This indicates that FMDV populations under antibody pressure in vitro, have acquired, in addition to expected characteristics of natural FMDV variants (resistance to neutralization and altered viral structural proteins), phenotypic markers which correspond to attenuated, less virulent variants.

Evolutionary history of Hepatitis B virus genotype F: an in-depth analysis of Argentine isolates.

A revised analysis on the evolutionary history of hepatitis B virus (HBV) genotype F is herein presented with the incorporation of two new complete genomes from Argentina. The study of the phylogenetic-tree topology, genetic distances, and amino acid mutations confirmed with high reliability the existence of four different genetic clusters of this genotype. Argentine isolates were located in two groups of viruses that showed a great inner homogeneity but, interestingly, divergence between them was in the order of that existing among groups from different locations. Although the origin of these two viral populations is not clear, they do not seem to derive from each other, therefore the existence of at least two founder viral populations in Argentina is a more acceptable explanation.

Early steps in FMDV replication: further analysis on the effects of chloroquine

We have previously demonstrated that chloroquine and NH4Cl, two well-known lysosomotropic drugs inhibit foot-and-mouth disease virus (FMDV) replication. This fact points to the relevance of an acidic environment during FMDV penetration. In the present report, we show that chloroquine prevents the cell-mediated disruption of 140 S virions into 12 S particles. This dissociation, which resembles that caused by low pH in vitro, might be an initial uncoating step. Furthermore, we demonstrated that a decrease in the environmental pH counteracts the effect of chloroquine indicating that viral disruption is a low-pH cell-mediated process. The fact that it still occurs at low temperature (20 degrees) and shortly after viral adsorption suggests not only that prelysosomal vesicles represent the putative site for uncoating but also cause the virion to uncoat.

Hepatitis B virus in Buenos Aires, Argentina: genotypes, virological characteristics and clinical outcomes

Hepatitis B virus (HBV) is classified into eight major genotypes, A-H, which are geographically distributed worldwide. The aim of this work was to describe the clinical characteristics associated with the HBV genotypes circulating in Buenos Aires city. The study included 139 patients infected with HBV, whose clinical courses were classified as acute symptomatic self-limiting hepatitis, inactive carrier state and chronic active hepatitis (HBV e-antigen (HBeAg)-positive and HBeAg-negative). The HBV genotypes were determined in 128 patients by PCR-restriction fragment length polymorphism and phylogenetic analysis. Biochemical, virological, clinical and histological features were analysed. A differential distribution of genotypes between acute symptomatic and chronic infections was found. Among the acute cases, genotype F was predominant (65.2%, 30/46) and genotype D was rare (4.3%, 2/46), whereas among the chronic infections, a homogeneous distribution of genotypes A (26.8%, 22/82), D (31.7%, 26/82) and F (36.6%, 30/82), with an unusual presence of genotypes B (1.2%, 1/82) and C (3.7%, 3/82), was observed. Regarding the liver histology of chronically infected patients, genotype F tended to display higher histological activity indexes. Mutations related to HBV surface antigen immunoreactivity, antiviral resistance and HBeAg-negative status were studied. This work constitutes, to our knowledge, the first description of the clinical characteristics related to HBV genotypes in Argentina, where the distribution of genotypes in patients with acute infection has not been reported previously. Finally, it was established that genotype F is the prevalent genotype among the acute symptomatic infections in Buenos Aires city, and that it shows a tendency to cause an adverse disease outcome among the chronic cases.