Dorra Rezig

Molecular characterisation of a coxsackievirus A24 that caused an outbreak of acute haemorrhagic conjunctivitis, Tunisia 2003

This study reports the genetic characteristics of coxsackievirus A24 isolates from Tunisia, including a coxsackievirus A24 variant (CVA24v) that caused an outbreak of acute haemorrhagic conjunctivitis (AHC) between September and November 2003. The virus genome was detected by PCR from conjunctival swabs obtained from patients with AHC. Four virus isolates were obtained from PCR-positive samples and were serotyped by sequence analysis of the VP1 and VP4 genomic region and by seroneutralisation. Phylogenetic analysis of the VP1, VP4 and 3C genomic regions was performed. Other Tunisian CVA24 isolates from paralytic cases and healthy individuals were also amplified, sequenced and included in the phylogenetic analysis. The epidemic strain belonged to the CVA24 serotype. Phylogenetic analysis of the 3C region of the genome revealed a strong relationship between the Tunisian epidemic strain and strains that caused outbreaks in Korea (2002) and Guadeloupe and French Guiana (2003). Phylogenetic analysis of the VP1 and VP4 regions showed a clear distinction between serotype CVA24 isolates from conjunctivitis and non-conjunctivitis cases. This is the first study to report an outbreak of AHC caused by CVA24v in the North African region.

Phylogenetic analysis of complete VP1 sequences of echoviruses 11 and 6: high genetic diversity and circulation of genotypes with a wide geographical and temporal range

Echovirus 6 (E6) and echovirus 11 (E11) are common causes of meningitis and other human diseases; they are among the most frequently isolated enteroviruses worldwide. In the present work we have studied genetic variability over the entire VP1 gene of selected isolates representing a wide geographical and temporal range. Fifty new sequences from North Africa were included, together with previously published sequences from different countries. The sequence diversity between strains of the same type was high: 22 and 30 % for E6 and E11, respectively. Phylogenetic analysis revealed five genogroups within each type, the genetic diversity within a genogroup generally being <20 %. Some genogroups were further subdivided into genotypes, most containing isolates that had circulated over a wide geographical (several countries from different continents) and temporal (up to two decades) range. Several genotypes were also shown to co-circulate in a region during the same period of time. These features differ from other enteroviruses that divide into temporal or geographical clusters. This study reports new sequences from North Africa, updates the molecular epidemiology of E6 and E11, and proposes a new genogroup in each type.

[Retrospective study of viral causes of central nervous system infections in Tunisia (2003-2009)].

OBJECTIVES To determine the role of enteroviruses, Herpesviridae, West Nile virus and Sandfly Toscana virus in central nervous system (CNS) infections in Tunisia. METHODOLOGY 847 cerebrospinal fluid (CSF) samples, 427 serum samples and 23 stool samples were collected from 1071 patients hospitalized for CNS viral infections from January 2003 through December 2009. All CSF samples were first tested by PCR to detect enteroviruses and Herpesviridae. In specific epidemic contexts in patients negative for these viruses, arbovirus infection was tested by ELISA. RESULTS Virological testing was positive in 17.5% of cases. West Nile virus and enteroviruses accounted for 58% of them, enteroviruses 23.5%, Herpesviridae 8.5%, and Toscana virus 10%. West Nile virus infection was observed only in 2003, during an outbreak in coastal regions. Toscana virus circulated regularly throughout the study period. Enteroviruses were responsible for grouped cases of aseptic meningitis in both 2003 and 2005. Arboviruses and enteroviruses were detected mainly in summer and autumn. Herpesviridae were associated with sporadic cases of meningoencephalitis. CONCLUSION This report on viral causes of CNS infections in Tunisia shows that West Nile virus and enteroviruses appear to circulate mainly during epidemics, while the circulation of Toscana virus seems continuous. Negative virus findings may be due, at least in part, to late sampling, inappropriate sample collection and transportation to the virology lab, or failure to test for the right virus. It is essential to promote collaboration between clinicians and biologists to maximize the likelihood of diagnosis.

Phylogenetic Analysis of Echovirus 11 in the 3′ End of the VP1

Objective: Echovirus 11 is one of the most frequently isolated enterovirus serotypes, causing a wide range of clinical diseases. We studied the genetic diversity in the 3′ end of the VP1 gene of strains from different geographical origin in the world. Methods: The sequences in the 3′ end of the VP1 of 11 Tunisian isolates were determined and aligned with the published sequences to establish a phylogenetic profile. Results: The grouping of the sequences was similar to what was previously reported by analyzing the whole VP1 gene with 4 genogroups, designated A–D, and 5 lineages in genogroup D. All Tunisian strains belonged to genogroup D, together with other sequences mainly from the USA and Europe. Contrary to the sequences from the USA isolated during the last 3 decades, which mostly belonged to the D4 lineage, those from Tunisia belonged to different lineages within genogroup D according to their isolation date: isolates from the early 1990s belonged to D3, those of the mid 1990s to D4 and the most recent ones to D5. Conclusion: Our findings further widen the interest of partial sequencing in the VP1 to study the molecular epidemiology of echovirus 11 and indicate that the genetic evolution of circulating strains may differ from one country to another according to the region’s epidemiological specificities.

Cytopathic effect of Human cosavirus (HCoSV) on primary cell cultures of human embryonic lung MRC5

Human cosaviruses (HCoSVs) are newly discovered viruses in Picornaviridae family. Until now, most published studies reported HCoSV detection using molecular techniques and genetic characterization of the virus. Nevertheless, no laboratory has yet reported the replication of these viruses in cultured cell lines. In the present work, the propagation of HCoSV strains isolated from human fecal specimens in MRC5 cell line and their induced cytopathic effects (CPE) was studied. The first sign of virus growth was observed 24-48h after inoculation. The cells rounded up and clumped together rapidly; empty areas became visible and, on the third day of CPE, a remarkable decrease in live cells was observed. This represents the first report on in vitro model of HCoSV replication which opens up opportunities for future investigations of these new viruses.

Variabilité génétique des échovirus de type 3

Ce travail a pour but d’etudier la variabilite genetique et antigenique dans la region VP1 des echovirus de type 3 (E-3), serotype d’enterovirus incrimine dans des cas de meningites, d’atteintes neuromusculaires et de diabete de type 1 chez l’homme. Quarante-six sequences VP1 de souches E-3, dont 9 isolees chez des enfants tunisiens ont ete incluses. Analyses phylogenetiques et taux de divergence nucleotidique ont ete etudies sur la totalite de la VP1 et sur une portion de 290 nucleotides dans la partie 5’ de la VP1. Les sequences en acides amines ont ete deduites a la recherche de determinants antigeniques specifiques de genotypes. Les sequences E-3 se sont reparties en deux genogroupes, I et II ; la variabilite genetique globale au sein du serotype atteint 29,1 %. Le genogroupe I comporte des sequences assez heterogenes, certaines se regroupent en un genotype avec au plus 15,1 % de divergence. Les sequences du genogroupe II ont un maximum de divergence de 13,8 % et correspondraient a un seul genotype. Les deux genogroupes co-circulent et ont une distribution temporospatiale a large etendue. Des substitutions d’acides amines, pouvant etre specifiques de genogroupe, de genotype ou de variants particuliers, ont ete relevees. Ce travail est une premiere tentative de classification des E-3 en genogroupes et genotypes et rapporte de nouvelles sequences d’origine nord-africaine. Il contribue a une meilleure connaissance de l’epidemiologie moleculaire des enterovirus en general et des E-3 en particulier, serotype jusque-la tres peu etudie dans la litterature.