Persistent infection of human intestinal Caco-2 cell line by Coxsackieviruses B.

Coxsackieviruses B (CV-B, Picornaviridae family, genus Enterovirus) are characterized by their ability to cause cytopathic effects in tissue culture. These viruses are considered highly cytolytic, but can establish persistence/latency in susceptible cells, indicating that a regulatory mechanism may exist to shut off viral protein synthesis and replication under certain situations. The persistence of coxsackieviral B RNA is of great interest because of its implication in the pathogenesis of several chronic human diseases. However, a few studies have dealt with the persistence of these viruses at the intestinal level. The aim of this study is to test the capacity of the six CV-B serotypes to establish persistent infection in human intestinal Caco-2 cell line. Ten CV-B isolates, including CV-B3 prototype strain (Nancy) and a recombinant isolate (B3-B4), were tested. Six CV-B isolates were found to establish persistent infections in Caco-2 cell line. Persistent replication was proved by the detection of viral RNA from cell cultures, VP1 capsid protein detection by immunofluorescence (IF) staining, and the release of infectious particles up to two months and a half after infection without any obvious cytolysis. In addition, our results suggest that the establishment of a persistent infection is serotype-independent.

[Molecular phylogeny and genetic variability of echovirus 30 based on the analysis of the 3' end of the VP1 gene]. / Phylogénie moléculaire et variabilité génétique des échovirus 30 basées sur l'analyse de la région 3' terminale du gène VP1.

Echovirus 30 represent one of the most frequently isolated enterovirus serotype, incriminated in various pathologies, essentially aseptic meningitis. Several works studied the molecular epidemiology of these viruses. By analysing a region of 260 nucleotides situated in the end of the VP1 gene (region regrouping the majority of the sequences of the Echovirus 30), we proposed to realise a synthesis work which regroup the main epidemiological studies on the Echovirus 30. We established a phylogenetic profile of 87 Echovirus strains geographically distinct and isolated during a half a century (1957-2003). The phylogentic tree permitted to distinguish 2 genogroups which the nucleotide divergence exceeds 20%. The 2 genogroups also present internal subdivisions named genotypes which the nucleotide divergence is more than 15%. Finally, we noted phylogenetic regroupings within a same genotype. The general profile of the phylogenetic tree is characterised by a distribution of the Echovirus 30 strains in the time independently of their geographically isolation, which reveals a genetic evolution of these viruses related to their high genetic plasticity and the rapid circulation from a geographic area to another.

A 1-year study of the epidemiology of hepatitis A virus in Tunisia.

This 1-year (September 2000 to August 2001) prospective study investigated the presence of hepatitis A virus (HAV) in the population of Monastir, Tunisia (86 serum samples), in the influents and effluents of two wastewater treatment plants, and in shellfish harvested in the coastal areas of Monastir, Bizerte and Sfax (January 2001 to May 2001). The virus was detected by RT-PCR using primers targeted at the VP3-VP1 region. An epidemic of HAV infection was observed during the winter months, with a peak in January. The presence of the virus was relatively constant in the influents and effluents of the wastewater treatment plants, and the virus was found in shellfish from the Monastir area during the months of January and February. The genotype IA strain was recovered most frequently from human serum and wastewater samples. The observation that the peak of the epidemic was during the winter months suggests that transmission of HAV is related to climatic factors and, presumably, to shellfish consumption.

[Model of coxsackievirus B3 persistent infection in orally-inoculated BALB/c mouse]. / Modèle d'infection persistante à coxsackievirus B3 chez la souris BALB/c inoculée par voie orale.

Many mouse models of human enterovirus disease have been pro- posed, concerning both acute and persistent infection. However, rather paradoxically since the usual way of contamination is fecal-oral, most of them used a systemic route of infection. The aim of the present work was to follow the development of an experimental enterovirus infection and to study the viral persistence at the organ level. Twenty-eight female 3-week old BALB/c mice were infected with 5 x 10(4) TCID(50) of coxsackievirus B3 (CV-B3), Nancy strain, by oral route using a rigid cannula introduced into the stomach. The kinetics of infection was studied by sacrificing 2 animals at different times post infection (from 1 hour to 90 days). The presence of the virus in various organs (small intestine, heart, pancreas, lung, spleen, kidney, liver) was studied by cell culture and RT-PCR. As soon as one hour post infection, the virus was detected in the small intestine. In the heart, the virus was present at 24 and 48 hours post infection by RT-PCR and culture, respectively. At 5 days post infection, all the organs but the liver were found infected. The virus was detected up to 15 days in kidney, 21 days in pancreas, 30 days in lung and spleen, and 45 days in intestine, by both culture and PCR. The heart was still found infected 90 days post infection by both techniques. These results show the dramatic cardiotropism of CV-B3 inoculated by oral route, with a detection of the virus very soon in the course of infection (24 hours) and a persistence of the virus for more than 3 months. The intestine, the initial target of enterovirus infection, can also be considered as a site of viral persistence.