Dynamic of SARS-CoV-2 variants circulation in Tunisian pediatric population, during successive waves, from March 2020 to September 2022.

The emergence of SARS-CoV-2 variants has led to several cases among children. However, limited information is available from North African countries. This study describes the SARS-CoV-2 strains circulating in Tunisian pediatric population during successive waves. A total of 447 complete sequences were obtained from individuals aged from 13 days to 18 years, between March 2020 and September 2022: 369 sequences generated during this study and 78 ones, available in GISAID, previously obtained from Tunisian pediatric patients. These sequences were compared with 354 and 274 ones obtained from Tunisian adults and a global dataset, respectively. The variant circulation dynamics of predominant variants were investigated during the study period using maximum-likelihood phylogenetic analysis. Among the studied population, adolescents were the predominant age group, comprising 55.26% of cases. Twenty-three lineages were identified; seven of which were not previously reported in Tunisia. Phylogenetic analysis showed a close relationship between the sequences from Tunisian adults and children. The connections of sequences from other countries were variable according to variants: close relationships were observed for Alpha, B1.160 and Omicron variants, while independent Tunisian clusters were observed for Delta and B.1.177 lineages. These findings highlight the pivotal role of children in virus transmission and underscore the impact of vaccination on virus spread. Vaccination of children, with booster doses, may be considered for better management of future emergences.

SARS-CoV-2 excretion kinetics in nasopharyngeal and stool samples from the pediatric population.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for serious respiratory infections in humans. Even in the absence of respiratory symptoms, gastrointestinal (GI) signs were commonly reported in adults and children. Thus, oral-fecal transmission was suspected as a possible route of infection. The objective of this study was to describe RNA shedding in nasopharyngeal and stool samples obtained from asymptomatic and symptomatic children and to investigate virus viability. Methods: This study included 179 stool and 191 nasopharyngeal samples obtained from 71 children, which included symptomatic (n = 64) and asymptomatic (n = 7) ones. They were collected every 7 days from the onset of the infection until negativation. Viral RNA was detected by real-time RT-PCR, targeting the N and ORF1 genes. Whole-genome sequencing was performed for positive cases. Viral isolation was assessed on Vero cells, followed by molecular detection confirmation. Results: All cases included in this study (n = 71) were positive in their nasopharyngeal samples. SARS-CoV-2 RNA was detected in 36 stool samples obtained from 15 out of 71 (21.1%) children; 13 were symptomatic and two were asymptomatic. Excretion periods varied from 7 to 21 days and 7 to 14 days in nasopharyngeal and fecal samples, respectively. Four variants were detected: Alpha (n = 3), B.1.160 (n = 3), Delta (n = 7), and Omicron (n = 1). Inoculation of stool samples on cell culture showed no specific cytopathic effect. All cell culture supernatants were negative for RT-qPCR. Conclusion: Our study demonstrated nasopharyngeal and fecal shedding of SARS-CoV-2 RNA by children up to 21 and 14 days, respectively. Fecal shedding was recorded in symptomatic and asymptomatic children. Nevertheless, SARS-CoV-2 was not isolated from positive stool samples.

Whole genome analysis of hepatitis B virus before and during long-term therapy in chronic infected patients: Molecular characterization, impact on treatment and liver disease progression.

Hepatitis B virus (HBV) infection remains a serious public health concern worldwide despite the availability of an efficient vaccine and the major improvements in antiviral treatments. The aim of the present study is to analyze the mutational profile of the HBV whole genome in ETV non-responder chronic HBV patients, in order to investigate antiviral drug resistance, immune escape, and liver disease progression to Liver Cirrhosis (LC) or Hepatocellular Carcinoma (HCC). Blood samples were collected from five chronic hepatitis B patients. For each patient, two plasma samples were collected, before and during the treatment. Whole genome sequencing was performed using Sanger technology. Phylogenetic analysis comparing the studied sequences with reference ones was used for genotyping. The mutational profile was analyzed by comparison with the reference sequence M32138. Genotyping showed that the studied strains belong to subgenotypes D1, D7, and D8. The mutational analysis showed high genetic variability. In the RT region of the polymerase gene, 28 amino acid (aa) mutations were detected. The most significant mutations were the pattern rtL180M + rtS202G + rtM204V, which confer treatment resistance. In the S gene, 35 mutations were detected namely sP120T, sT126S, sG130R, sY134F, sS193L, sI195M, and sL216stop were previously described to lead to vaccine, immunotherapy, and/or diagnosis escape. In the C gene, 34 mutations were found. In particular, cG1764A, cC1766G/T, cT1768A, and cC1773T in the BCP; cG1896A and cG1899A in the precore region and cT12S, cE64D, cA80T, and cP130Q in the core region were associated with disease progression to LC and/or HCC. Other mutations were associated with viral replication increase including cT1753V, cG1764A/T, cC1766G/T, cT1768A, and cC1788G in the BCP as well as cG1896A and cG1899A in the precore region. In the X gene, 30 aa substitutions were detected, of which substitutions xT36D, xP46S, xA47T, xI88F, xA102V, xI127T, xK130M, xV131I, and xF132Y were previously described to lead to LC and/or HCC disease progression. In conclusion, our results show high genetic variability in the long-term treatment of chronic HBV patients causing several effects. This could contribute to guiding national efforts to optimize relevant HBV treatment management in order to achieve the global hepatitis elimination goal by 2030.

Overview of the epidemic history of Hepatitis C uncommon subtypes 2i and 4d in Tunisia and in the world.

The impressive improvements in qua therapy efficacy alone are not sufficient to substantially reduce the Hepatitis C Virus burden because of the usually very long asymptomatic phase of the infection. In turn, this renders prevention of infection of great importance. The value of learning how the virus has spread in the past is that this can provide clues as to what routes the virus likely spreads through today, which can feedback into prevention policy. In Tunisia, HCV subtypes 2i and 4d are minor circulating subtypes. Here, we applied a Bayesian Markov Chain Monte Carlo method for visualization of spatial and temporal spread of HCV-2i and 4d in Tunisia and some other countries in the world. Our analysis included sequences retrieved from Genbank and isolated from several countries in the world; 21 HCV-NS5B subtype 2i genome sequences obtained during the period 2002-2020 and 206 HCV-NS5B-4d sequences detected between 2000 and 2019. Phylogenetic analysis revealed that two geographical clusters could be identified in HCV-2i tree with two clearly distinguished clusters in HCV-4d Tree. The estimated time for the most recent common ancestor suggested that current HCV-2i strains emerged in 1963 [1930, 1995] and current HCV-4d strains emerged in 1992 [1988, 1996] in Tunisia and other countries from the world investigated in the present study.

SARS-CoV2 RT-PCR assays: In vitro comparison of 4 WHO approved protocols on clinical specimens and its implications for real laboratory practice through variant emergence.

INTRODUCTION: RT-PCR testing on nasopharyngeal swabs is a key component in the COVID-19 fighting, provided to use sensitive and specific SARS-CoV2 genome targets. In this study, we aimed to evaluate and to compare 4 widely used WHO approved RT-PCR protocols on real clinical specimens, to decrypt the reasons of the diverging results and to propose recommendations for the choice of the genome targets. METHODS: 260 nasopharyngeal samples were randomly selected among the samples tested between Week-16, 2020 and week-16 2021, in the Institut Pasteur de Tunis, Tunisia, one of the referent laboratories of COVID-19 in Tunisia. All samples were tested by Charité, Berlin protocol (singleplex envelop (E) and singleplex RNA-dependent RNA polymerase (RdRp)), Hong Kong Universiy, China protocol (singleplex nucleoprotein (N) and singleplex Open reading frame Orf1b), commercial test DAAN Gene® (using the CDC China protocol), (triplex N, Orf1ab with internal control) and Institut Pasteur Paris protocol (IPP) (triplex IP2(nsp9) and IP4 (nsp12) with internal control). For IPP, a selection from samples positive by IP2 but negative with IP4 was re-tested by exactly the same protocol but this time in singleplex. New results were described and analyzed. RESULTS: In vitro analysis showed discordant results in 29.2% of cases (76 out of 260). The most discordant protocol is DAAN Gene® due to the false positive late signals with N target. Discordant results between the two protocol's targets are more frequent when viral load are low (high Ct values). Our results demonstrated that the multiplexing has worsened the sensitivity of the IP4 target. CONCLUSION: We provide concise recommendations for the choice of the genome targets, the interpretation of the results and the alarm signals which makes suspect a gene mutation.

Sequencing Using a Two-Step Strategy Reveals High Genetic Diversity in the S Gene of SARS-CoV-2 after a High-Transmission Period in Tunis, Tunisia.

Recent efforts have reported numerous variants that influence severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral characteristics, including pathogenicity, transmission rate, and detectability by molecular tests. Whole-genome sequencing based on next-generation sequencing technologies is the method of choice to identify all viral variants; however, the resources needed to use these techniques for a representative number of specimens remain limited in many low- and middle-income countries. To decrease sequencing costs, we developed a primer set allowing partial sequences to be generated in the viral S gene, enabling rapid detection of numerous variants of concern (VOCs) and variants of interest (VOIs); whole-genome sequencing is then performed on a selection of viruses based on partial sequencing results. Two hundred one nasopharyngeal specimens collected during the decreasing phase of a high-transmission COVID-19 wave in Tunisia were analyzed. The results reveal high genetic variability within the sequenced fragment and allow the detection of first introductions in the country of already-known VOCs and VOIs, as well as other variants that have interesting genomic mutations and need to be kept under surveillance. IMPORTANCE The method of choice for SARS-CoV-2 variant detection is whole-genome sequencing using next-generation sequencing (NGS) technologies. Resources for this technology remain limited in many low- and middle-income countries, where it is not possible to perform whole-genome sequencing for representative numbers of SARS-CoV-2-positive cases. In the present work, we developed a novel strategy based on a first partial Sanger screening in the S gene, which includes key mutations of the already known VOCs and VOIs, for rapid identification of these VOCs and VOIs and to help better select specimens that need to be sequenced by NGS technologies. The second step consists of whole-genome sequencing to allow a holistic view of all variants within the selected viral strains and confirm the initial classification of the strains based on partial S gene sequencing.

Distribution of HCV Genotypes Among People Who Inject Drugs in Tunisia: New Evidence for Scaling Up Prevention and Treatment Toward National Elimination Goal.

Little is known about the distribution of hepatitis C virus (HCV) genotypes among people who inject drugs (PWID) in North African countries, including Tunisia. This study aims to describe HCV genotypes circulating among Tunisian PWID. A cross-sectional study was conducted, and 128 HCV-positive PWID were recruited between 2018 and 2019 from community-based harm reduction centers. After informed consent, sociodemographic characteristics and risk behavior data were obtained using an interviewer-administrated questionnaire. Blood samples were collected for further serological and molecular testing. Overall, five women and 123 men were included. The median age was 39.5 years. The majority of PWID (56.3%) had less than a secondary level of education, were single (57%), were unemployed (65.6%), were incarcerated at least once (93.0%), and had a history of residency in at least one foreign country (50.8%). During the previous 12 months, 82.0% reported having reused syringes at least once, 43.8% shared syringes at least once, while 56.2% had at least one unprotected sexual relation, and 28.1% had more than two different sexual partners. Tattooing was reported among 60.2%. All positive results for HCV-infection by rapid testing were confirmed by enzyme-linked immunosorbent assay (ELISA). HCV-RNA was detectable in 79.7%. Genotyping showed a predominance of genotype 1 (52%) followed by genotype 3 (34%) and genotype 4 (10%). Four patients (4%) had an intergenotype mixed infection. Subtyping showed the presence of six different HCV subtypes as follows: 1a (53.2%), 1b (6.4%), 3a (33.0%), 4a (3.2%), and 4d (4.3%). This is the first study describing circulating HCV genotypes among PWID in Tunisia. The distribution of HCV genotypes is distinct from the general population with a predominance of subtypes 1a and 3a. These findings can be used to guide national efforts aiming to optimize the access of PWID to relevant HCV prevention and treatment measures including pangenotypic regimens for patients infected with HCV genotype 3.

Whole genome sequencing and phylogenetic analysis of six SARS-CoV-2 strains isolated during COVID-19 pandemic in Tunisia, North Africa.

BACKGROUND: In Tunisia a first SARS-CoV-2 confirmed case was reported in March 03, 2020. Since then, an increase of cases number was observed from either imported or local cases. The aim of this preliminary study was to better understand the molecular epidemiology and genetic variability of SARS-CoV-2 viruses circulating in Tunisia and worldwide. METHODS: Whole genome sequencing was performed using NGS approach on six SARS. CoV-2 highly positive samples detected during the early phase of the outbreak. RESULTS: Full genomes sequences of six Tunisian SARS-CoV-2 strains were obtained from imported and locally transmission cases during the COVID-19 outbreak. Reported sequences were non-identical with 0.1% nucleotide divergence rate and clustered into 6 different clades with worldwide sequences. SNPs results favor the distribution of the reported Tunisian sequences into 3 major genotypes. These SNP mutations are critical for diagnosis and vaccine development. CONCLUSIONS: These results indicate multiple introductions of the virus in Tunisia and add new genomic data on SARS-CoV-2 at the international level.

Strong association of functional polymorphism in IL-12B with susceptibility to chronic hepatitis B in Tunisia.

BACKGROUND: The chronicity or clearance of hepatitis B virus (HBV) infection depends on viral and genetic variables. The immune response against HBV is thought to be responsible for viral persistence or clearance. Cytokines such as interleukin 1-2B (IL1-2B) involved in the T-helper 1 system are key mediators in the defence mechanisms against viral infection and play a role in the regulation of HBV clearance during infection. We aimed to examine whether the polymorphic variant TaqI polymorphism in the 3'-untranslated region (3'-UTR; rs3212227) suspected to modulate interleukin-levels of IL-12B has an influence on the risk of development of chronicity after HBV exposure. METHODS: Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism method for 236 patients with chronic hepatitis B (CHB) and 240 controls from different cities of Tunisia recruited in the Pasteur Institute of Tunisia between January 2017 and December 2018. RESULTS: We found that the IL-12B polymorphism was associated with a significantly increased risk of CHB in patients (p = 1 × 10-3 ; χ 2 = 10.31 and odds ratio [OR] = 2.14; 95% confidence interval [CI] = 1.30-3.52) when AC/CC variant genotypes were compared with the wild-type AA homozygote. Statistical significance was found when CHB-males were compared with CHB-females (p = 2 × 10-7 ; χ 2 = 26.62 and p = 1 × 10-3 ; χ 2 = 10.36, for genotypic and allelic frequencies, respectively). Also, CHB-patients carrying C-allele less than 50-years were at an increased risk of developing chronic HBV infection than patients more than 50-years (p = 6.1 × 10-5 ; χ 2 = 16.07). CONCLUSIONS: These results suggest that the C-allele would affect susceptibility to chronicity after HBV exposure in Tunisian patients especially for males less than 50-years. Age and sex have an influence on this polymorphism in CHB Tunisian patients.

Identification of two novel hepatitis C virus subtype 2 from Tunisia (2v and 2w).

BACKGROUND: Hepatitis C virus (HCV) has a high genetic diversity. Eight genotypes and 90 subtypes are currently described. Genotypes are clinically significant for therapeutic management and their determination is necessary for epidemiological studies. METHODS: Tunisian patients plasma samples (n = 6) with unassigned HCV-2 subtype using partial sequencing in the NS5B and Core/E1 regions were analyzed by realizing whole-genome sequencing analysis. Phylogenetic analyses were performed to assign subtypes. RESULTS: Phylogenetic analysis of the full genome sequences of Tunisian strains shows two subtypes within HCV-2. These later were genetically distinct from all previously established HCV-2 subtypes with nucleotide divergence greater than 15% (20% -31%). These two subtypes are proposed as new subtypes 2v and 2w. CONCLUSIONS: The discovery of two new HCV-2 subtypes circulating in the Tunisian population confirms the great diversity of HCV-2 viruses and increases the total number of HCV-2 subtypes from 21 to 23.

Focus on hepatitis C virus genotype distribution in Tunisia prior to elimination: a 16-year retrospective study.

With the introduction of direct-acting antiviral treatment (DAA), Tunisia has committed to achieving the international goal of eliminating viral hepatitis. Because the specific DAA prescribed depends on viral genotype, viral genotyping remains of great importance. The aim of the present study was to outline the trends in the distribution of HCV genotypes from 2002 to 2017 in the Tunisian general population in order to guide authorities towards the most appropriate therapeutic strategies for preventing HCV infection. A total of 2532 blood samples were collected over a 16-year period and from all regions of Tunisia. Genotyping showed that genotype 1 (subtype 1b) was the most prevalent genotype in the country (n = 2012; 79.5%), followed by genotype 2 (n = 339; 13.3%). Genotypes 3, 4 and 5 were detected in 4.8%, 2.2% and 0.1% of the country's population, respectively. Mixed infections with different HCV genotypes were detected in 0.1% of the population (one case each of genotypes 1b + 4, 1b + 2 and 2 + 4). Interestingly, a significant increase in genotypes 2, 3 and 4 was observed over time (p = 0.03). Sixteen different subtypes were detected over the study period, most of which were subtypes of genotype 2, and some of these subtypes appeared to be new. Patients infected with genotypes 1a, 3 and 4 were significantly younger than those infected with genotypes 1b and 2 (p < 0.01). Furthermore, genotypes 1b and 2 were detected more often in women than men, while genotypes 1a and 3 were detected mostly in men (P < 0.01). Our study confirms a large predominance of genotype1/subtype1b in Tunisia and shows a significant increase in the prevalence of other genotypes over time. These findings reinforce the need for an additional HCV genotype survey to improve the design of treatment strategies in Tunisia.

Interleukin IL-1B gene polymorphism in Tunisian patients with chronic hepatitis B infection: Association with replication levels.

Approaches based on association studies have proven useful in identifying genetic predictors for many diseases, including susceptibility to chronic hepatitis B. In this study we were interested by the IL-1B genetic variants that have been involved in the immune response and we analyzed their role in the susceptibility to develop chronic hepatitis B in the Tunisian population. IL-1B is a potent proinflammatory cytokine that plays an important role in inflammation of the liver. Polymorphic gene IL-1 (-511, +3954) was analyzed in a total of 476 individuals: 236 patients with chronic hepatitis B from different cities of Tunisia recruited in Pasteur Institute between January 2017 and December 2018 and 240 controls. Genomic DNA was obtained using the standard salting-out method and genotyping was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism. For -511C>T polymorphism a significant association was found between patients and controls when comparing the genotypic (P = 0.007; χ2 = 9.74 and odds ratio [OR] = 0.60; confidence interval [CI] = 0.41-0.89) and allelic (P = 0.001; χ2 = 10.60) frequencies. When the viral load was taken into account a highly significant difference was found (P = 9 × 10-4 ; χ2 = 10.89). For +3954C>T polymorphism a significant association was found between patients and controls when comparing genotypic (P = 0.0058; χ2 = 7.60 and OR = 1.67; CI = 1.14-2.46) and allelic (P = 0.0029; χ2 = 8.81) frequencies. T allele can be used as a strong marker for hepatitis B virus disease for both polymorphisms.

Hepatitis viruses take advantage of traditional practices to increase the burden of hepatocellular carcinoma in Tunisia.

Hepatocellular carcinoma (HCC) is a major public health issue in Africa. In Tunisia, hepatitis B virus (HBV) is known to be an important risk factor for HCC in the south of the country, but the role played by hepatitis C virus (HCV) still remains unclear. The aim of the current case-control study was to identify risk factors for HCC development in the northern part of the country. Clinical and biological data including viral hepatitis status (serological and molecular) and non-infectious risk factors from 73 patients with HCC and 70 control subjects without hepatic diseases were collected. The mean age of the patients was 63 ± 10 years, and the ratio of males to females was 1.1. HCC occurred in cirrhotic liver in 72.0% of the cases. HCV infection was the dominant risk factor (64.3% of cases); the presence of HBV was observed in 53.4% of the cases. Occult hepatitis B and C were implicated, respectively, in 30.1% and 9.6% of the cases. HCV genotype 1b was predominant. Patients originating from western Tunisia formed a homogeneous group, characterized by significantly higher rates of tattoos or scarifications (83%) and HCV infection (80%) than those from other parts of the country. Chronic HCV infection is currently the primary risk factor for HCC in Tunisia; HBV infection remains frequent in its overt or occult infection forms. Traditional esthetic practices apparently contribute to increasing the burden of terminal liver diseases in western Tunisia.

Hepatitis C virus epidemiology in Central-West Tunisia: a population-based cross-sectional study.

This study aimed to assess the seroprevalence, viraemia and genotype distribution of hepatitis C virus (HCV) in a region in Central-West Tunisia. A door-to-door cross-sectional study was conducted on a randomly selected sample. A total of 3178 individuals aged 5 to 74 years and members of 935 families were investigated. Seroprevalence of HCV was assessed using ELISA tests. The viral load was determined by real-time RT-PCR, and HCV genotyping was conducted by amplification and sequencing in the NS5b genomic region. The global prevalence of HCV antibodies was 3.32% (95% confidence interval [CI]: 2.72-4.00). It was significantly higher in women: 4.47% vs. 2.16% in men, p = 0.001. Seroprevalence increased with age, and the highest rates were found in the 50- to 59-year-old age group (12.90%, 95% CI: 9.45-16.86), suggesting a cohort effect with very low contribution of intrafamilial transmission. Genotyping showed a predominance of subtype 1b (84.6%), with cocirculation of subtypes 2c (9.6%), 1a (1.9%), 1d (1.9%) and 2k (1.9%), similar to the previously reported genotype distribution in Tunisia and with no genetic clusters specific to the study region. These results indicate a higher endemicity of HCV infection when compared to the previously reported nationwide surveillance data. This study provides valuable data that can contribute to current strategies to eliminate hepatitis C.

Phylogenetic Analysis and Epidemic History of Hepatitis C Virus Genotype 2 in Tunisia, North Africa.

HCV genotype 2 (HCV-2) has a worldwide distribution with prevalence rates that vary from country to country. High genetic diversity and long-term endemicity were suggested in West African countries. A global dispersal of HCV-2 would have occurred during the 20th century, especially in European countries. In Tunisia, genotype 2 was the second prevalent genotype after genotype 1 and most isolates belong to subtypes 2c and 2k. In this study, phylogenetic analyses based on the NS5B genomic sequences of 113 Tunisian HCV isolates from subtypes 2c and 2k were carried out. A Bayesian coalescent-based framework was used to estimate the origin and the spread of these subtypes circulating in Tunisia. Phylogenetic analyses of HCV-2c sequences suggest the absence of country-specific or time-specific variants. In contrast, the phylogenetic grouping of HCV-2k sequences shows the existence of two major genetic clusters that may represent two distinct circulating variants. Coalescent analysis indicated a most recent common ancestor (tMRCA) of Tunisian HCV-2c around 1886 (1869-1902) before the introduction of HCV-2k in 1901 (1867-1931). Our findings suggest that the introduction of HCV-2c in Tunisia is possibly a result of population movements between Tunisia and European population following the French colonization.

Genotype Distribution and Prevalence of Human Pegivirus among High-Risk Populations in Tunisia.

OBJECTIVE: A recently discovered non-A-E hepatitis virus has been designated as human Pegivirus (HPgV). HPgV is prevalent in high-risk groups such as patients with hepatitis C virus (HCV), and it is of interest for patients who are at risk for transmitted infections. The aim of this study was to evaluate the prevalence of HPgV as well as the genotype distribution among patients in the Tunisian population who are infected with HCV and also in multitransfused patients. METHODS: A total of 144 patients were screened using RTPCR/nested PCR of the 5'-untranslated region (UTR); 14 cases were sequenced and phylogenetically analyzed. RESULTS: Seven (14.9%) subjects from the multitransfused group and 7 (7.2%) patients infected with HCV, respectively, were found positive for HPgV RNA. Sequencing and phylogenetic analysis of the 14 cases revealed that genotype 2a was the main genotype circulating in Tunisian patients. Genotype 2b was found in the amplified samples of 2 HCV-infected patients. CONCLUSION: This study enriches the limited data on HPgV prevalence in Tunisia, and shows, for the first time, the molecular epidemiology of the circulating strains in this country.

Molecular epidemiology of hepatitis B and Delta virus strains that spread in the Mediterranean North East Coast of Tunisia.

BACKGROUND: Tunisia is classified as an area of middle endemic for hepatitis B virus (HBV) infection, however little is known about hepatitis Delta virus (HDV) infection. OBJECTIVES: This study aimed to address the prevalence of HDV infection, to identify possible risks factors, and to analyze the genetic diversity of HDV strains that are spreading in Tunisia. STUDY DESIGN: A retrospective large-scale study including 1615 HBsAg positive patients, native of the North East coast of Tunisia, recruited from Gastroenterology departments, was conducted. Demographic, epidemiological, ethnical, clinical and biological data were recorded. HBV and HDV serological analyses and DNA and RNA viral load quantification were performed. Genotyping of HBV and HDV strains was performed using nucleotide sequencing followed by phylogenetic analyses. RESULTS: The study population included 819 (50.7%) men and 796 (49.3%) women; aged 12-90 years (mean age 41±13 years). A very low prevalence of HDV infection, 2% was observed. No risk factor, except a history of hospitalization for surgery was found. All HDV strains belonged to genotype 1, with a wide distribution within the HDV-1 group. They all share the African amino acid marker, a serine at position 202 of the large Delta protein. HBV genotypes were distributed as follows: HBV/D1 (56.8%), HBV/D7 (40.9%), and HBV/A2 (2.3%). CONCLUSION: Tunisia is a low endemic region for HDV infection, due to an efficient policy of HBV infection control. HDV-1 is the sole genotype found, with a high diversity within this group. Further studies are ongoing in order to better characterize and manage the HBV/HDV-infected patients according to the genetic variability of the viral strains.

Subtyping genotype 2 hepatitis C viruses from Tunisia: identification of two putative new subtypes.

HCV variants were classified into six genotypes (1-6) subdivided into several subtypes with different geographic distribution worldwide. Previous studies conducted in Tunisia showed that genotype 1 counts for more than 80 % of circulating HCV genotypes and most of the isolates belong to subtype 1b. Genotype 2 comes in the second position, however, few sequences have been analyzed and published. In the present study, 89 isolates from Tunisian patients, typed as genotype 2 by the InnoLIPA commercial probe hybridization test, were sequenced in the NS5B and Core/E1 regions. All the isolates, clustered with the genotype 2 reference sequences, in the NS5B and in the Core/E1 region and the phylogenetic analyses in the two genomic regions were perfectly concordant: subtype 2c was the most frequent (58 out of 89, 65.1 %) and few isolates belonged to subtypes 2k(n = 10), 2i(n = 5), and 2b(n = 1). Fifteen isolates did not match with any of the reference sequences representing the genotype 2 subtypes, identified up-to-date. They divided into 2 separate clusters with high bootstrap values in both genomic regions. This study shows perfect concordance between the NS5B and the Core/E1 region suggesting that any of the two regions can be used for genotyping and that intergenotypic and intragenotypic recombinants are not very frequent, at least for HCV isolates from genotype 2. The present study also shows a predominance of subtype 2c among genotype 2 HCV isolates circulating in Tunisia, the co-circulation of minor subtypes (2k, 2i, and 2b) and proposes the possible existence of two other new subtypes.

Frequency and clinical significance of core promoter and precore region mutations in Tunisian patients infected chronically with hepatitis B.

Genetic variability of hepatitis B virus (HBV) in the C gene and its association with the different stages of chronic liver disease has been studied inadequately with controversial results. The objectives of the current study were to determine the frequency of core promoter and precore mutations in chronic hepatitis B in Tunisia and to evaluate their impact on viral replication and disease progression. Sequencing was performed in upstream regulatory sequence (URS), pre-core (PreC) and basal core promoter (BCP) regions for 123 chronic infected patients by HBV genotype D at different status of disease. Mutations were detected in 98.4% of cases, affecting URS, BCP and Pre-C in 95.1%, 95.9% and 87.8% respectively. Multi-mutations increased significantly from asymptomatic carrier to advanced liver disease status. G1896A (74.8%), G1764A/T/C (71.5%), G1899A (54.4%) and T1678C (52%) were the most common. Special attention should be paid to A1703T, T1678C/G-A1703T, and A1652G-A1679G mutations probably specific of Tunisians sequences; they were observed in 40.6%, 41.5% and 30.1% respectively. A1679G/C, T1753C/G/A, A1762T/G and A1762T-G1764A were more prevalent in older patients. High DNA levels were associated with G1899A or G1764T/C-C1766G-C1799G and advanced liver disease with mutations at positions 1762, 1764 and/or 1899 alone or in double or triple mutations. It was also shown that substitutions at nucleotides 1762, 1764 and 1899 have an impact on the disease progression. It is the first report for specific mutations in the URS region for genotype D. It should be completed by studying eventual correlation with clinical progression and the response to treatment.