A. Trabelsi

Relationship between electropherotypes and VP7/VP4 genotypes of group A rotaviruses detected between 2000 and 2007 in Tunisian children.

BACKGROUND Rotaviruses are the most frequent agents associated with diarrhoea in children worldwide. Analysis of mobility of the 11 segments of genomic RNA by polyacrylamide gel electrophoresis (PAGE) yields a pattern which is characteristic for a particular rotavirus isolate. The group A rotaviruses can be further characterized by analysis of VP7 and VP4 genes specificities, responsible for rotavirus classification into G and P genotypes, respectively. The aim of the present study was to detect a relationship between electropherotype pattern and molecular characteristics of the rotavirus strains. MATERIAL AND METHODS Were analyzed 278 rotavirus-positive specimens by PAGE and G/P-genotyped by multiplex semi-nested RT-PCR. Pearsons correlation tests were used for statistical analysis. RESULTS Twelve different electropherotypes were visualized, eight with a long profile (186 cases) and four with a short one (87 cases). Concerning VP7 types, G2 viral strains were found to be predominant and were detected in 91 specimens (32.7%). Strains with G1, G3, G4, G8 and G9 specificities were detected in 62 (22.3%), 82 (29.5%), 13 (4.7%), two (0.7%) and seven cases (2.5%), respectively. The results of VP4 genotyping showed a predominance of P[8] genotype which comprised half of the strains identified (139 cases, 50%). VP4 P[4], P[6] and P[11] were found in 83 (29.9%), 31 (11.1%) and 11 (4.0%) specimens, respectively. A high rate of mixed strains was also found (1.8% mixed electropherotypes, 7.6% G-mixed and 5% P-mixed strains). Electropherotype pattern of rotavirus strains was significantly correlated with VP7 genotype (p=0.018) and with VP4 genotype specificities (p<0.001).

271 Distribution of NSP4 Genotypes of Group A Rotavirus Strains Circulating in Tunisian Children from 2006 to 2008

Background and Aims Non-structural protein 4 (NSP4), encoded by group A rotavirus (RVA) genome segment 10, is the first recognized virus-encoded enterotoxin. Recently, a new classification system for RVAs was proposed and a total of 14 NSP4 genotypes (E1 to E14) are currently described. Methods A total of 1391 faecal specimens collected from children under 5 years old were screened by ELISA for the presence of RVA antigen. NSP4-encoding genes of RVA positive strains were analyzed using a semi-nested RT-PCR. Results Genotypes E1 and E2 were identified in 183 (70.1%) and 78 (29.9%) samples, respectively. This report represents the first investigation on the genetic diversity of RVA NSP4 genes in Tunisia. Tunisian RVA strains analysed in the present study belonged to 2 different genotypes: E1 and E2. Such a result is concordant with literature data: indeed, although 14 RV NSP4 genotypes have been identified to date, previous molecular characterization has shown that most of the diversity in the NSP4-encoding gene lies in genotypes E1 and E2. Other studies, however, have detected unusual strains carrying genotypes E3 and E13. Moreover, a predominance of NSP4 genotype E1 was observed over the entire period of study, from 2006 to 2008. Such a result was also quite expected as previous investigations have also shown that NSP4 genotype E1 was largely predominant among children worldwide. Conclusions These results underline the need for further investigations to assess the validity of NSP4 as a suitable target for epidemiologic surveillance of rotavirus infections and vaccine development.