Mouna Ben Hadj Fredj

Centre Hospitalier Universitaire de Sahloul, Justiniapolis, Sūsah, Tunisia

Are you Mouna Ben Hadj Fredj?

Claim your profile

Publications (9)29.95 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: But de l’étude La protéine NSP4 des rotavirus du groupe A (RVA) a été reconnue comme une entérotoxine virale, elle joue un rôle important dans la pathogenèse virale et la morphogenèse. Les domaines impliqués dans les interactions structurelles et fonctionnelles ont été caractérisés principalement à partir de la souche simienne SA11. Il existe actuellement 15 génotypes différents (E1-E15) de la protéine NSP4. Méthodes Le but de cette étude est d’analyser les séquences en acides aminés de 46 souches RVA afin de déterminer les différences entre les génotypes E1 et E2. Un autre aspect de cette étude porte sur les propriétés structurales et physico-chimiques de ces souches. Résultats La comparaison des séquences en aa de la protéine NSP4 a montré que les divergences entre les génotypes E1 et E2 ont été essentiellement observées dans le domaine de liaison à la protéine VP4, le domaine variable interspécifique (ISVD) et le domaine de liaison à la particule à double couche (DLP). Il est intéressant de noter que les mutations inhabituelles des aa 131 et 138, résidus connus pour être importants dans la pathogenèse, ont été trouvées dans une souche rare appartenant au génotype E2. En ce qui concerne l’aspect structural, aucune différence significative n’a été notée. Conclusion La présence de variations ponctuelles au sein des différentes souches peut indiquer que la protéine NSP4 mute principalement par accumulation de mutations ponctuelles.
    Pathologie Biologie 01/2014; · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Group A rotaviruses (RVA) are the leading cause of severe gastroenteritis in infants and young children worldwide. Due to their epidemiological complexity, it is important to compare the genetic characteristics of vaccine strains with the RVA strains circulating before the introduction of the vaccine in the Tunisian immunization program. In the present study, the nucleotide sequences of VP7 and VP8∗ (n=31), the main targets for neutralizing antibodies, were determined. Comparison of antigenic epitopes of 11 G1P[8], 12 G2P[4], 4 G3P[8], 2 G4P[8], 1 G6P[9] and 1 G12P[8] RVA strains circulating in Tunisia from 2006 to 2011 with the RVA strains present in licensed vaccines showed that multiple amino acid differences existed in or near putative neutralizing domains of VP7 and VP8∗. The Tunisian G3 RVA strains were found to possess a potential extra N-linked glycosylation site. The Tunisian G4 RVA were closely related to the G4 vaccine strain in RotaTeq, belonging to the same lineage, but the alignment of their VP7 amino acids revealed an insertion of an asparagine residue at position 76 which is close to a glycosylation site (aa 69-71). Despite several differences detected between Tunisian and vaccine strains, which may affect binding of neutralizing antibodies, both vaccines are known to protect against the vast majority of the circulating genotypes, providing an indication of the high vaccine efficiency that can be expected in a future rotavirus immunization program.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 05/2013; · 3.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In Tunisia in 2008, an unusual G6P[9] rotavirus, RVA/human-wt/TUN/17237/2008/G6P[9], rarely found in humans, was detected in a child. To determine the origin of this strain, we conducted phylogenetic analyses and found a unique genotype constellation resembling rotaviruses belonging to the feline BA222-like genotype constellation. The strain probably resulted from direct cat-to-human transmission.
    Emerging Infectious Diseases 04/2013; 19(4):630-4. · 6.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Non-structural protein 4 (NSP4), encoded by group A rotavirus (RVA) genome segment 10, is a multifunctional protein and the first recognized virus-encoded enterotoxin. Recently, a new classification system for RVAs was proposed and a total of 14 NSP4 genotypes (E1-E14) are currently described. The most common NSP4 genotypes in humans are Wa-like E1 and DS-1-like E2. This report represents the first investigation on the genetic diversity of RVA NSP4 genes in Tunisia from 2006 to 2008. In the present study, the NSP4-encoding genes of human RVA strains with different G/P-genotype combinations were analyzed. NSP4 genes of 261 RVA-positive fecal samples were analyzed using a semi-nested reverse transcriptase-polymerase chain reaction and in addition the NSP4 gene of 46 representative RVA strains were sequenced. Phylogenetic analysis of the Tunisian NSP4 nucleotide sequences revealed the presence of two NSP4 genotypes. Genotype E1 was found to be associated with G1P[8], G3P[6], G3P[8], G4P[6] and G4P[8], whereas genotype E2 was associated with G2P[4], G2P[6] and G6P[9] samples. These results support the hypothesis that P[8] carrying RVA strains usually possess the E1 genotype, whereas P[4] carrying RVA strains usually possess the E2 genotype. P[6] carrying strains were found with both E1 and E2. The unusual G6P[9] strains possessed a E2 genotype with a possible animal origin. These results underline the need for further investigations to assess the validity of NSP4 as a suitable target for epidemiologic surveillance of RVA infections and vaccine development.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 03/2012; 12(5):997-1004. · 3.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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 determine the evolution of group A Rotavirus strains circulating in Tunisia over a 3-year period (2005–2007).
    Fuel and Energy Abstracts 01/2011; 59(4).
  • [Show abstract] [Hide abstract]
    ABSTRACT: An epidemiological survey investigating rotavirus infection in children was undertaken in the coastal region of Tunisia from January 2000 through September 2003. A total of 309 fecal specimens were screened by enzyme-linked immunosorbent assay and latex agglutination assay for the presence of group A rotavirus antigen. The detection rate was 26.2%. Rotavirus outbreaks showed a temperature-dependant pattern (P = .026) but no significant association with rainfall. Rotavirus strains isolated were analyzed by RNA polyacrylamide gel electrophoresis and were characterized antigenically by monoclonal antibodies to the VP6 subgroup. Eight RNA electropherotypes were identified, with 3 long and 5 short different RNA profiles. Among VP6 typeable strains, all isolates with a long electrophoretic pattern carried the subgroup II specificity, whereas those with a short profile belonged to subgroup I. In total, 48 rotavirus-positive samples were analyzed for G and P typing by reverse-transcription polymerase chain reaction. A total of 8 different G and P combinations were found: G1P[8] (35.7%), G1P[6] (21.4%), G2P[4] (4.8%), G3P[4] (4.8%), G4P[6] (4.8%), G8P[8] (4.8%), G3P[8] (2.3%), and G4P[8] (2.3%). Mixed infections were detected in 19.1% of stool samples. The emergence in Tunisia of unconventional types, such as G8VP7 specificity, highlights the need for a continual survey of the uncommon strains in North Africa.
    The Journal of Infectious Diseases 09/2010; 202 Suppl:S252-7. · 5.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Among human rotaviruses, G9 has emerged as the fifth most important genotype circulating globally. Ongoing surveillance of rotavirus in Tunisia during the past 10 years identified the first G9 strains in 2004. These strains exhibited the P[8] VP4 genotype and had a long RNA electrophoretype. The G9 strains were characterized by phylogenetic analysis of the VP7 gene sequence and showed high identity with other human rotavirus G9 strains belonging to the rotavirus VP7 lineage group III.
    The Journal of Infectious Diseases 11/2009; 200 Suppl 1:S239-43. · 5.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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 determine the evolution of group A Rotavirus strains circulating in Tunisia over a 3-year period (2005-2007). A total of 1503 stool samples collected from children less than five years old, consulting or hospitalised in Tunisia for diarrhoea between 2005 and 2007, were screened for the presence of group A Rotaviruses. Rotavirus-positive specimens were further analyzed by PAGE and G/P-genotyped by multiplex semi-nested RT-PCR. Rotaviruses were detected in 323 stool samples over 1503 (21 %). Long electropherotypes predominated in Tunisia during the whole period of study (N=158 vs N=82 short electropherotypes). VP7 genotyping showed the cocirculation of five different genotypes: G1, G2, G3, G4 and G9. VP4 typing detected four different P-genotypes: P[8], P[4], P[6] and P[11]. Rotavirus strains with G3P[8] specificity were predominating in Tunisia in 2005 and 2006, replaced by G2P[4] strains in 2007.
    Pathologie Biologie 11/2009; 59(4):e79-83. · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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. Were analyzed 278 rotavirus-positive specimens by PAGE and G/P-genotyped by multiplex semi-nested RT-PCR. Pearson's correlation tests were used for statistical analysis. 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).
    Pathologie Biologie 05/2009; 59(3):e43-8. · 1.67 Impact Factor