Genetic variability of human adenovirus type 8 causing epidemic and sporadic cases of keratoconjunctivitis.

Human adenovirus type 8 (HAdV-8) is a main aetiological agent of keratoconjunctivitis. It has been reported from both epidemic and sporadic cases. The aim of our study was to investigate the genetic characteristics and chronological pattern of HAdV-8 strains that have been circulating in Tunisia over a 14-year period. Fourteen HAdV-8 isolates from a keratoconjunctivitis outbreak that occurred in 2000 and from sporadic cases between 2001 and 2013 were studied. Nucleotide sequences from the hexon, fiber and penton base genes were determined, including hypervariable regions of the hexon (loops 1 and 2), the fiber (knob) and the penton base (HVR 1 and RGD loops). The sequences were compared to each other and to those of HAdV-8 strains. The Tunisian sequences were unique when compared to the previously published sequences. Also, despite a relatively low degree of genetic variation in the three genomic regions, phylogenetic analysis and alignment of amino acid sequences showed that the sequence from the year 2000 and two other sequences from the year 2013 were similar to each other and differed from the isolates that circulated in the intervening year by two main amino acid changes in the loop 1 hexon gene and the knob-fiber gene. Our results confirm the genetic variability of HAdV-8 and document the chronological changes of circulating genetic variants.

Molecular epidemiology of coxsackievirus type B1.

Coxsackievirus type B1 (CVB1) has emerged globally as the predominant enterovirus serotype and is associated with epidemics of meningitis and chronic diseases. In this report, the phylogeny of CVB1 was studied based on the VP1 sequences of 11 North African isolates and 81 published sequences. All CVB1 isolates segregated into four distinct genogroups and 10 genotypes. Most of the identified genotypes of circulating CVB1 strains appear to have a strict geographical specificity. The North African strains were of a single genotype and probably evolved distinctly. Using a relaxed molecular clock model and three different population models (constant population, exponential growth and Bayesian skyline demographic models) in coalescent analysis using the BEAST program, the substitution rate in CVB1 varied between 6.95 × 10(-3) and 7.37 × 10(-3) substitutions/site/year in the VP1 region. This study permits better identification of circulating CVB1, which has become one of the most predominant enterovirus serotypes in humans.

[Genetic variability of type 3 echoviruses]. / Variabilité génétique des échovirus de type 3.

The aim of the present work was to assess the genetic and antigenic variability in the VP1 region of type 3 echviruses (E-3), an enterovirus serotype associated to meningitis, neuro-muscular diseases and type 1 diabetes in human. Forty-six VP1 sequences of E-3, among which 9 were isolated in tunisian infants, were included. Phylogenetic analyses and nucleotidic divergence rates were studied in the complete VP1 region and in a 290-nucleotides fragment in the 5' part of the P1. Aminoacid sequences were deduced in the aim to identify genotype-specific antigenetic determinants. E-3 sequences divided into two genogroups, I and II; the genetic variability within the E-3 serotype reached 29.1%. Genogroup I included sequences with a relatively high genetic diversity among each other, some of them grouped in one genotype with at most 15.1% divergence rate. The sequences included in Genogroup II have a maximum of 13.8% divergence corresponding probably to only one genotype. The two genogroups have a concomitant circulation and a wide geographical and temporal distribution. Aminoacid substitutions that may be specific to genogroups, genotypes and special variant were noted. This work provides a first tentative of classification of E-3 into genogroups and genotypes and reports new E-3 sequences from North Africa. It contributes to a better understanding of the molecular epidemiology of human enteroviruses, and of Echoviruses type 3 in particular, a serotype that remains insufficiently studied in the international literature.

Update on molecular characterization of coxsackievirus B5 strains.

Among Coxsackie B viruses, Coxsckievirus B5 is one of the most predominant serotypes in human, it is frequently associated with cases of neurological diseases, epidemics of meningitis and is a common cause of cardiomyopathy and diabetes. In the present study 27 isolates of Coxsackievirus B5 from North Africa, obtained from cerebrospinal fluid and stool samples of healthy individuals, patients with acute flaccid paralysis or aseptic meningitis were investigated by partial sequencing in the 5' half of the VP1 region and compared to the up-to-date published Coxsackievirus B5 sequences in the same genomic region. Four distinct genomic groups and ten different clusters were individualized. Most of the isolates from Algeria and Tunisia belonged to two clusters. For both, the sequences from North Africa clustered mainly with sequences from European countries, the majority isolated recently during the 2000s. The analysis of the alignment of amino-acids sequences in the VP1 gene revealed four major substitutions in strains from different clusters, we also noticed changes in the BC-loop region; this region is associated with viral antigenicity. This study permit to better identify circulating Coxsackievirus B5 strains throughout the world and their genetic relationship. The protein analysis showed changes that could imply some antigenic significance. J. Med. Virol. 83:1247-1254, 2011. © 2011 Wiley-Liss, Inc.

Clinical epidemiological and molecular aspects of rubella outbreak with high number of neurological cases, Tunisia 2011-2012.

BACKGROUND: A large and unusually prolonged rubella outbreak occurred in Tunisia from April 2011 to July 2012 and was characterized by a high number of neurological cases. OBJECTIVES: To describe the outbreak and to perform virus genotyping of isolated virus strains. STUDY DESIGN: From January 2011 to December 2012, 5000 sera for serological diagnosis of acute rubella and 31 cerebrospinal fluid from patients with neurological symptoms were tested for the presence of rubella immunoglobulins G and M. Real-time PCR was performed on 49 throat swabs, 21 cerebrospinal fluid and 27 serum samples. Positive samples were assessed for virus genotyping by sequencing and the obtained sequences were compared to those previously isolated in the country. RESULTS: Acute rubella was confirmed in 280 patients including 15 neonates, 217 children and adults with mild rash and 48 patients with severe rubella (mainly encephalitis, n = 39). Most of acquired rubella cases (60.7%) were aged over 12 years with a male predominance observed in the age group 12-25 years (79%). Females belonged essentially to the unvaccinated age groups under 12 and over 25 years. Among the 23 samples tested positive by real-time PCR, six could be genotyped and clustered with either the 1E genotype, previously detected in Tunisia, or the 2B genotype which has never been isolated in Tunisia before. CONCLUSIONS: Gender and age distributions of the patients reflect the impact of the selective rubella vaccination program adopted in Tunisia since 2005. Genotype 1E continues to circulate and genotype 2B was probably recently introduced in Tunisia.