Molecular analysis of adenovirus strains responsible for gastroenteritis in children, under five, in Tunisia.

Purpose of work: Enteric Adenovirus (EAdV) is recognized as one of the most commonly identified agents responsible for severe acute gastroenteritis (AGEs) in the stools of infants.We sought to determine the rate of human adenovirus (HAdV) infections, and the genotypic characterization of circulating strains of HAdV in children under 5 years of age with AGEs in university and regional hospitals, located in the Center-East of Tunisia, from January 2014 to December 2016. Methods: A classic PCR was performed on 582 stool samples taken within 5 days of the onset of symptoms. Chosen positive samples were sequenced, and some of the results were confirmed by the Next Generation Sequencing technique (NGS). Partial nucleotide sequences of the Hexon gene obtained in this study were compared with the NCBI GenBank database using BLAST. Multiple sequence alignment and phylogenetic analysis were conducted using MEGA6 software. The phylogenetic tree was generated using the maximum-likelihood method and bootstrap analysis was performed with 1000 replications. Results: Out of 582 samples, 52 (8.93 %) cases were positive for HAdV, with a male predominance (57.4 %). Phylogenetic analyses showed that Tunisian HAdV strains clustered into five HAdV lineages corresponding to serotypes F41 (14/28), C2 (9/28), C5 (3/28), E4 (1/28), and A18 (1/28). HAdV was more frequent in children aged up to 12 months, as compared to the other age groups. The HAdV activity was noted in almost all the months of the year with a peak in autumn, in 2014 and 2015, and in winter in 2016. Conclusion: This study showed that infections with HAdV species were frequent in children suffering from AGE with the predominance of HAdV F41 and C2. This result underlines the importance of regular monitoring of circulating genotypes, and it could be useful for future epidemiological research.

Humoral and Cellular Immunogenicity of Six Different Vaccines against SARS-CoV-2 in Adults: A Comparative Study in Tunisia (North Africa).

BACKGROUND: The mass vaccination campaign against SARS-CoV-2 was started in Tunisia on 13 March 2021 by using progressively seven different vaccines approved for emergency use. Herein, we aimed to evaluate the humoral and cellular immunity in subjects aged 40 years and over who received one of the following two-dose regimen vaccines against SARS-CoV-2, namely mRNA-1273 or Spikevax (Moderna), BNT162B2 or Comirnaty (Pfizer-BioNTech), Gam-COVID-Vac or Sputnik V (Gamaleya Research Institute), ChAdOx1-S or Vaxzevria (AstraZeneca), BIBP (Sinopharm), and Coronavac (Sinovac). MATERIAL AND METHODS: For each type of vaccine, a sample of subjects aged 40 and over was randomly selected from the national platform for monitoring COVID-19 vaccination and contacted to participate to this study. All consenting participants were sampled for peripheral blood at 3-7 weeks after the second vaccine dose to perform anti-S and anti-N serology by the Elecsys® (Lenexa, KS, USA) anti-SARS-CoV-2 assays (Roche® Basel, Switzerland). The CD4 and CD8 T cell responses were evaluated by the QuantiFERON® SARS-CoV-2 (Qiagen® Basel, Switzerland) for a randomly selected sub-group. RESULTS: A total of 501 people consented to the study and, of them, 133 were included for the cellular response investigations. Both humoral and cellular immune responses against SARS-CoV-2 antigens differed significantly between all tested groups. RNA vaccines induced the highest levels of humoral and cellular anti-S responses followed by adenovirus vaccines and then by inactivated vaccines. Vaccines from the same platform induced similar levels of specific anti-S immune responses except in the case of the Sputnik V and the AstraZeneca vaccine, which exhibited contrasting effects on humoral and cellular responses. When analyses were performed in subjects with negative anti-N antibodies, results were similar to those obtained within the total cohort, except for the Moderna vaccine, which gave a better cellular immune response than the Pfizer vaccine and RNA vaccines, which induced similar cellular immune responses to those of adenovirus vaccines. CONCLUSION: Collectively, our data confirmed the superiority of the RNA-based COVID-19 vaccines, in particular that of Moderna, for both humoral and cellular immunogenicity. Our results comparing between different vaccine platforms in a similar population are of great importance since they may help decision makers to adopt the best strategy for further national vaccination programs.

[Infectious etiology of acute idiopathic intussusception in children]. / Les étiologies infectieuses des invaginations intestinales aiguës idiopathiques chez l'enfant.

The intussusception (IIA) is an invagination of the immediate part of the intestine. She is responsible for a syndrome with an occlusive venous compression and swelling that can rapidly progress to intestinal necrosis. Most cases occur in children aged 6 to 18 months and occur more frequently in boys than girls. There are two types of IIA: the IIA idiopathic representing 90-95% of invaginations of the child and the IIA secondary to local injury of the gastrointestinal tract or occurring in a particular context whose frequency are between 5 and 10%. The pathogenesis of the IIA remains uncertain, but the infectious origin is criminalized in most idiopathic invaginations. This component is dominated by viral agents including adenovirus, rotavirus, enterovirus, human herpesvirus 6 and 7, cytomegalovirus and Epstein-Barrvirus. Bacterial agents are rather found and include Yersinia enterocolitica, Staphylococcus aureus, Escherichia coli O157, H7, Salmonella and Campylobacter. In a small proportion parasitic agents may be reported in the IIA, the most frequently found are Entamoeba histolytica, Trichuris trichuira, Ascaris lumbricoides, Ankylostoma and Giardia.

Rotavirus infection and intussusception in Tunisian children: implications for use of attenuated rotavirus vaccines.

BACKGROUND: A licensed rotavirus vaccine was withdrawn from use because of an increased risk of intussusception. The association of rotavirus vaccination with intussusception raised concerns about a potential link between natural rotavirus disease and intussusception. The objectives of the present study were to determine whether an epidemiological association with natural rotavirus infection existed. METHODS: From 1984 to 2003, all children younger than 5 years with intussusception were retrospectively identified by medical charts, and from 1995 to 2003, a prospective surveillance study of rotavirus infection in children younger than 5 years was independently conducted. Epidemiological characteristics of intussusception and rotavirus infection were then compared. RESULTS: A total of 533 cases of intussusception and 146 cases of rotavirus infection were identified. The incidence of intussusception for infants younger than 1 year was 62/100,000 child-years. The age distributions of intussusception and rotavirus gastroenteritis overlapped, and a masculine predominance was noted in both cases. No significant association was observed between the monthly distribution of intussusception and rotavirus infection. CONCLUSION: The present study has not convincingly shown that rotavirus diarrhea plays a major role in intussusception. However, data about age and sex distributions supported the biologic plausibility of such an association.

Combined analysis of interferon-gamma and interleukin-10 gene polymorphisms and chronic hepatitis C severity.

Today there is increasing evidence concerning the contribution of pro-/anti-inflammatory cytokine balance and genetic factors in hepatitis C pathogenesis and interindividual heterogeneity of disease outcome. In the current study, we investigated the influence of functionally described single nucleotide polymorphisms (SNPs) present in interferon-gamma (IFNgamma) and interleukin-10 (IL-10) genes, on chronic hepatitis C severity. IFNgamma (+874T/A) and IL-10 (-1082G/A) genotypes were determined in 100 hepatitis C patients with different disease severities (chronic hepatitis, n = 42, liver cirrhosis [LC], and hepatocellular carcinoma in liver cirrhosis [HCC], n = 58) and 103 healthy controls using allele-specific polymerase chain reaction. No statistical differences in allele or genotype distributions of IFNgamma and IL-10 genes were observed between patients and controls. However, some significant differences in IFNgamma genotype frequencies were observed between the two groups of patients. IFNgamma(high producer) genotypes TT and TA were significantly more common in patients with LC and HCC (odds ratio = 2.65; p = 0.019). Although IL-10 genotypic frequencies were comparable between the different clinical forms of the disease, the combination of IFNgamma(low producer) and IL-10(high producer) genotypes was significantly associated with a lower risk of LC and HCC (odds ratio = 0.21; p = 0.015). In conclusion, our findings suggest that the imbalance between the pro-inflammatory and anti-inflammatory responses mediated by polymorphisms in the IFNgamma and IL-10 genes may influence the outcome of chronic HCV infection.

Recognition of coxsackievirus A by Enterovirus genus-specific immune and molecular markers in experimentally infected suckling mice.

OBJECTIVE: Most of coxsackieviruses A (CV-A) are difficult to isolate in cell culture and are responsible for flask paralysis in suckling mice. The aim of the present work was to analyze the ability of immune and RT-PCR techniques to detect viral components of three different serotypes, CV-A6, CV-A13, and CV-A14, in skeletal muscles of experimentally infected suckling mice. MATERIAL AND METHODS: The antigen detection was done by immunofluorescence technique on trypsinized muscular cells and by immunoperoxidase assay on frozen sections of skeletal muscle, using a monoclonal antibody directed towards a conserved epitope of the VP1 capsid protein among enteroviruses. The nested RT-PCR technique used primers located in the 5' non coding region of viral RNA. RESULTS: The group antigen was present in muscle cells of suckling mice infected by the three serotypes of CV-A which were assayed. Similarly, the muscle specimens were positive by nested RT-PCR. A kinetic study performed with CV-A13 and CV-A14 showed that the RT-PCR assay was positive as soon as 24 h after infection whereas the detection of VP1 antigen and symptoms of flask paralysis were observed only 48 and 72 h after infection, respectively. CONCLUSION: These results show that the tested serotypes of CV-A can be easily detected in muscle specimens of suckling mice by using antigenic and molecular techniques currently available for the diagnosis of enterovirus infections.