Molecular analysis of HBV genotypes and subgenotypes in the Central-East region of Tunisia

Mapping hepatitis B virus genotypes on the African continent from 1997 to 2021: a systematic review with meta-analysis

Hepatitis B virus (HBV) has ten genotypes (A-J) and over 40 sub-genotypes based on the divergence of ≥ 8% and 4 to < 8% in the complete genome respectively. These genotypes and sub-genotypes influence the disease prognosis, response to therapy and route of viral transmission. Besides, infection with mixed genotypes and recombinant genotypes has also been reported. This study aimed at mapping the de novo genotypes and correlate them with the immigration trends in order to inform future research on the underlying reasons for the relative distribution of HBV genotypes from a large sample size pooled from many primary studies. Data was extracted from 59 full research articles obtained from Scopus, PubMed, EMBASE, Willy library, African Journal Online (AJOL) and Google Scholar. Studies that investigated the genotypes, sub-genotypes, mixed genotypes and recombinant were included. The Z-test and regression were used for the analysis. The study protocol is registered with PROSPERO under the registration number CRD42022300220. Overall, genotype E had the highest pooled prevalence significantly higher than all the other genotypes (P < 0.001). By region, genotype A posted the highest pooled prevalence in eastern and southern Africa, E in west Africa and D in north Africa (P < 0.0001). Regarding the emerging genotypes B and C on the African continent, genotype B was significantly higher in south Africa than C (P < 0.001). In contrast, genotype C was significantly higher in east Africa than west Africa (P < 0.0001). The A1 and D/E were the most diverse sub-genotypes and genotype mixtures respectively. Finally, we observed a general progressive decrease in the prevalence of predominant genotypes but a progressive increase in the less dominant by region. Historical and recent continental and intercontinental migrations can provide a plausible explanation for the HBV genotype distribution pattern on the African continent.

The role of quantitative HBsAg in the natural history of e antigen-negative chronic hepatitis B: A Tunisian prospective study

BACKGROUND/AIMS

During the natural course of Chronic Hepatitis B (CHB) infection, differentiation between inactive carrier (IC) and HBeAg negative CHB is a subject of ongoing debate. We studied the role of hepatitis B surface antigen (HBsAg) level as a means of differentiating between CHB and IC in a group of untreated chronic HBeAg-negative HBV-infected patients.

STUDY

A total of 115 HBeAg negative carriers were enrolled and followed up for>12 months; 78 as inactive carriers (IC), and 37 as active carriers (AC). Among ACs, patients were categorized according to the highest rate of viral load: AC1 (n=23), active carriers with persistent HBV-DNA<20,000 IU/mL; AC2 (n=14), active carriers with HBV-DNA>20,000 IU/mL.

RESULTS

HBsAg levels were higher in AC compared to IC patients (1607 IU/ml vs. 225 IU/ml respectively, P=0.001). Among the AC group, the 23 AC1 cases had HBsAg levels significantly lower than the 14 AC2 patients (1756 IU/mL vs. 3327 IU/mL respectively; P<10^-3). HBsAg showed weak correlation with HBV-DNA in the whole cohort (r=0.44, P<0.01). The suggested cutoff value of HBsAg titer to differentiate between the two groups was 938 IU/mL. Combined single-point quantification of HBsAg (938 IU/mL) and HBV DNA (2000 IU/mL) identified IC with 87.2% specificity and 91.7% positive predictive value.

CONCLUSION

This study confirms the predictability of a one-time combined HBsAg and HBV DNA measurement for true inactive carriers requiring neither strict follow-up nor antiviral treatment.

A Systematic Review of the Current Hepatitis B Viral Infection and Hepatocellular Carcinoma Situation in Mediterranean Countries

Viral hepatitis B is a global public health problem affecting nearly two billion subjects; 3.3% of whom are from the WHO (World Health Organization) Eastern Mediterranean Region (EMRO). It induces both acute and chronic hepatic disorders with subsequent liver cirrhosis and hepatocellular carcinoma (HCC) in a considerable percentage of patients based on the age of exposure. In this review, hepatitis B virus (HBV) and HCC prevalence, distribution and prevalence of different genotypes, and male/female infection frequencies in relation to the vaccination status in the Mediterranean countries were reported. Study Design. This systematic review describes the prevalence of hepatitis B infection, genotype distribution of hepatitis B virus, and prevalence and incidence of hepatocellular carcinoma in Mediterranean countries belonging to three different continents: Southern Europe (Spain, France, Italy, Croatia, and Greece), North Africa (Morocco, Algeria, Tunisia, Libya, and Egypt), and the Near East region (Syria, Lebanon, Turkey, Israel, and Palestine). We tried to collect new data from electronic databases: PubMed, ScienceDirect, ResearchGate, Google Scholar, and public health reports between 1980 and 2019. For each publication, we recorded reference, publication year, study characteristics (date, locations, sample size, and study population), and participant characteristics (population group, year, age, and sex). No language limitation was imposed, and articles or reports from non-peer-reviewed sources were not considered for this analysis. The main keywords were HBV prevalence, hepatitis B infection, HBV genotype, and HCC. Inclusion and Exclusion Criteria. Healthy population-based studies included the following sample populations: (i) voluntary blood donors, (ii) pregnant women, (iii) community studies, (iv) hemodialysis patients, (v) hospitalized patients, (vi) healthcare workers, (vii) sex workers, (viii) drug abusers, and (ix) prisoners. We excluded studies from the following special groups who were assumed to be at a special high risk: patients from sexually transmitted disease clinics and thalassemia clinics and professional or paid blood donors.

A systematic genotype and subgenotype re-ranking of hepatitis B virus under a novel classification standard

Background and aim

It is commonly noticed that chaotic and inefficient subgenotyping are universally used academically and clinically, a standardized HBV genotype/subgenotype classification criterion is urgently acquired. Sequence similarity, which was commonly used for the last three decades, should be upgraded by phylogenetic analysis in genotyping of recombinant-free HBV strains.

Methods

In this study, 4,429 HBV whole-genome sequences were employed to reconstruct the phylogeny of HBV using Bayesian inference. After excluding recombinant sequences, calculating partitioned evolutionary models, excluding recombinant sequences, reconstructing phylogenetic trees, and performing a correlation analysis of genetic distances, geographical distribution and serotypes, we systematically redefined the genotypes and subgenotypes of HBV.

Results

Compared to previous taxonomy, fourteen subgenotypes (A5-A7; B5-B9; C2-C4, C7; and D6-D7) were revised in the new standard. Now the HBV is divided into ten genotypes (A-J) and 24 subgenotypes (A1-A3; B1-B5; C1-C6; D1-D6; and F1-F4).

Conclusion

Our robust genotype/subgenotype new taxonomy has objectively re-molded the current shape of HBV classification. We believe that all future hepatitis B related researches or diagnosis will be benefited under the new HBV genotyping/subgenotyping standards.

The Epidemiology of Hepatitis D Virus in North Africa: A Systematic Review and Meta-Analysis

BACKGROUND

Hepatitis D virus (HDV) infection has been considered a serious neglected pandemic, particularly in developing countries. The virus causes a more severe disease than mono infection with hepatitis B virus (HBV). The epidemiology of HDV is not well documented in North Africa, which is known to be endemic for HBV. In this study, we explored the prevalence of HDV infection and also attempted to identify factors associated with hepatitis D positive status among chronic hepatitis B patients in North Africa.

METHODS

The electronic databases PubMed, Embase, Scopus, Science Direct, Web of Science, and Google Scholar were comprehensively searched for all papers published between January 1, 1998, and December 31, 2017, using appropriate strategies containing all related keywords, including North Africa, names of countries in the region, and all permutations of hepatitis D virus. The estimated prevalence of HDV in North Africa was calculated as an average of the pooled infection prevalence in each country weighted by the ratio of the country's hepatitis D virus population to the study's sample size in the survey data analysis.

FINDINGS

A total of 312 studies were identified and 32 were included in this study, with a total sample of 4907 individuals screened for HDV. There was considerable variability in the prevalence estimates of HDV within the countries of the region. The overall prevalence of HDV in the general population of North Africa was 5·01% (95% CI: 1·25-8·27) and in liver disease patients it was 20.7% (95% CI:9.87-44.53). Genotype-1 was the most prominent genotype reported in five published studies. Ten studies reported on HDV RNA in participants who were seropositive for HDV, and four studies highlighted the impact of demographic factors (sex and age). No study showed the impact of risk factors on the prevalence of HDV in North Africa.

INTERPRETATION

This review provides a comprehensive assessment of the burden of HDV in Northern Africa. There were significant differences in seroprevalence, study population, and diagnostic testing between the countries in the region. The results presented here will alert health professionals to implement clear policies based on evidence to diminish the burden of HDV infection. Such measures may include but are not restricted to improving the laboratory diagnostic tests and initiating patient data registries and blood screening. Further epidemiological and research studies are needed to explore the risk factors, coinfections, and approaches to increase testing for HDV, particularly in high-risk subpopulations, such as intravenous drug users and immigrants, and to define the consequences of HDV infection in North Africa.

Hepatitis B virus and hepatitis delta virus subtypes circulating in Algeria and seroprevalence of HDV infection

BACKGROUND

Little is known about molecular characteristics of HBV strains circulating in Algeria and there are few data regarding HDV infection.

OBJECTIVES

The aim of this study is to describe the genetic diversity of HBV and HDV strains existing in Algeria and to determine the seroprevalence of HDV infection.

STUDY DESIGN

Plasma samples from 134 patients were analyzed by enzyme immunoassay method for HBV and HDV serological markers. Genotyping of HBV and HDV strains were performed using direct sequencing followed by phylogenetic analyses of the PreS1 and R0 region of the HBV and HDV genome respectively.

RESULTS

The PreS1 gene was successfully amplified in 119 patients (82 males and 37 females). Phylogenetic analysis of HBV strains revealed the presence of genotypes D (86.5%) and A2 (11.76%). The subgenotypes D are distributed as follows: HBV/D7 (43.5%), HBV/D3 (24.75%), HBV/D1 (16.8%) and HBV/D2 (14.85%). A recombinant between genotypes A, E and D was found. The seroprevalence of HDV infection among HBV carriers was less than 5.35%. Only one isolate of HDV genotype 1 was identified.

CONCLUSIONS

Our data indicate the predominance of HBV subgenotype D7 and a low prevalence of HDV infection.

Molecular characterization of hepatitis B virus (HBV) in African children living in Australia identifies genotypes and variants associated with poor clinical outcome

Migration from sub-Saharan Africa is contributing to the rising incidence of chronic hepatitis B (CHB) infection and its complications in Australia. African CHB is associated with unique genotypes, such as E and A1, which are associated with reduced vaccine efficacy and early-onset hepatocellular carcinoma, respectively, although the prevalence of these genotypes outside Africa is poorly described. Treatment-naïve children of African origin with CHB were recruited at the Royal Children's Hospital Melbourne. Population-based sequencing of the complete HBV genome, or the clinically relevant basal core promoter (BCP)/precore (PC) region, was performed, and the HBV genotype/subgenotype assigned by phylogenetic analysis. HBV was characterized in serum from 67 children, median age 12.5 years. HBV genotype E was most frequent (70 %), with genotype D [25 %; subgenotypes D6 (formerly D7)/D3/D2)] and subgenotype A1 (5 %) also being identified. Despite their young age, over 50 % of the children were HBeAg-negative and had seroconverted to anti-HBe, with this being associated with canonical BCP/PC mutations in the majority of cases. The profile of HBV in African children living in Australia was characterized by early HBeAg seroconversion and infection with HBV variants associated with poor clinical outcome, as well as genotypes previously associated with reduced vaccine efficacy or rapid progression to liver cancer. These findings have important ramifications for patient monitoring and treatment guidelines in the Australian paediatric setting.

Untypable genotype restriction patterns and surface gene variants of hepatitis B virus isolates

Chronic hepatitis B is a global health problem, and is one of the leading causes of cirrhosis and hepatocellular carcinoma. Hepatitis B virus (HBV) genotyping helps in decision making for clinical management of HBV infection, and is important for epidemiological studies. The objectives of this study were to investigate the distribution of HBV genotypes circulating in the Philippines; molecularly characterize untypable genotype restriction patterns; and analyze the presence of surface gene variants. HBV genotypes were determined by restriction fragment length polymorphism (RFLP) and DNA sequencing. Three genotypes, HBV A (76%; 73/96), HBV B (10%; 10/96) and HBV C (14%; 13/96) were detected by RFLP. Out of the 96 isolates, 9% were untypable by RFLP analysis. DNA sequencing followed by phylogenetic analysis revealed that these isolates belonged to HBV genotypes A (67%; 6/9), B (11%; 1/9) and C (22%; 2/9). Out of the 9 isolates, 55% showed single or multiple variations which resulted to amino acid changes. Overall, the identification of untypable genotype can be resolved by sequence and phylogenetic analysis of the S gene and this approach can also be used to detect single or multiple variants. Our findings underscore the importance of accurate genotyping and detection of surface gene variants by DNA sequencing for optimal clinical management.

Molecular analysis of Hepatitis B virus sub-genotypes and incidence of preS1/preS2 region mutations in HBV-infected Egyptian patients from Mansoura

Hepatitis B virus (HBV) is one of the major causes of viral hepatitis worldwide. Despite the prevalence of HBV infection in Egypt, few studies have focused on sub-genotyping of the virus. Moreover, no studies are available regarding the mutational analysis of the preS1/preS2 region of the viral genome, or its impact on hepatocellular carcinoma (HCC) development in Egypt. In this study, we have analyzed the sub-genotypes and incidence of mutations in the preS1/preS2 region of HBV present in HBV-infected patients, from Mansoura city (located in the center of Nile Delta region of Egypt), via partial sequencing of this specific region. Moreover, we have investigated the impact of these mutations on HCC development by measuring serum alpha fetoprotein (AFP) level and abdominal ultrasound examination of the HBV-infected patients. According to our results, all samples were genotype D in which sub-genotype D1 was predominant. In addition, the results revealed mutations in the preS1/preS2 region, which could result in either immature preS1 protein or completely inhibit the translation of the preS2 protein. However, there was no incidence of HCC development in patients infected with mutated HBV in the preS1/preS2 region. In summary, for the first time our work has proved the predominance of sub-genotype D1 among HBV-infected Egyptian patients in Mansoura city, Nile Delta region, Egypt, and incidence of mutations in the preS1/preS2 region of HBV genome. This current study opens up research opportunities to discuss the impact of HBV mutations on the development of HCC in Egypt.

Evolutionary dynamics of HBV-D7 subgenotype in Tunisia

Hepatitis B virus (HBV) is the main cause of diseases liver related infecting more than 200 milion persons worldwide. HBV infection shows high level of prevalence in South-East Europe and in Mediterranean basin. In Tunisia, a country with an intermediate level endemicity, HbsAg prevalence ranges from 2 to 5%. Most of the HBV isolates from Tunisia were classified as subgenotype D7 whose circulation is restricted to a specific area of North Africa including Maghreb region. In this paper, the phylogeny of HBV-D7 isolated from 38 Tunisian patients was investigated by analyzing the S gene region of HBV. A Bayesian coalescent-based framework was used to estimate the origin of the HBV-D7 in the country. The Tunisian D7 isolates were found to share a common ancestor whose origin was traced back to 1958. Population dynamics indicated that HBV-D7 epidemic in Tunisia grew exponentially from 1960s to 1990s. After that, the curve reached a plateau around the years 2000 likely due to the implementation of the infant vaccination program in 1996. Epidemiological data suggested that the exponential growth phase was likely sustained by intra-familial transmission events occurring during infancy. Further characterization of HBV-D7 isolates should be performed to evaluate, in the post-vaccination era, the emergence of new transmission routes, and to monitor the efficacy of the vaccination program. J. Med. Virol. 89:469-475, 2017. © 2016 Wiley Periodicals, Inc.

Naturally Occurring Surface Antigen Variants of Hepatitis B Virus in Tunisian Patients

In Tunisia, the prevalence of naturally occurring surface (S) gene variants of hepatitis B virus (HBV) has not been determined. In the present study, the prevalence of these variants was examined in terms of the clinical and viral state in a series of 99 Tunisian patients with HBV infection. The S genes were amplified and directly sequenced. Genotype D was predominant (98%), 40.4% isolates belonged to subgenotypes D7 and 1 to subgenotype D2. The most common subtype was ayw2 (95.9%). In total, 60.6% of the studied strains harbored S mutations. Several novel mutation patterns were detected. Interestingly, the presence of S mutations was significantly correlated with the D7 subgenotype, low HBV DNA and advancing age (≥35 years), and tended to be higher in liver cirrhosis than in chronic infection. The global prevalence of the major hydrophilic region variants was 12.1%, with substitution S143L/T as the most frequent (4%). Only 33.9% of S substitutions produced amino acid changes in the polymerase gene. In conclusion, a high prevalence of naturally occurring HBsAg variants was observed among Tunisian HBV carriers. Natural viral variability in a geographical region and duration of infection are among the major factors associated with the occurrence of S mutations.

Impact and long-term protection of hepatitis B vaccination: 17 years after universal hepatitis B vaccination in Tunisia

Hepatitis B virus (HBV) vaccination has been part of the Expanded Programme of Immunization (EPI) in Tunisia since 1995. The aim of this study was to evaluate, for the first time, the impact of mass vaccination in Tunisia 17 years after this programme was implemented, and in parallel, assess the long-term persistence of anti-HBs antibody in the vaccinated Tunisian population. A total of 1422 students were recruited (703 vaccinated, 719 non-vaccinated). HBV seromarkers were checked. None of the students from either group had positive HBsAg. The overall prevalence of anti-HBc was 0·8%. A Significantly higher prevalence of anti-HBc was noted in unvaccinated students than in vaccinated (1·4% vs. 0·3%, P = 0·02). The overall seroprotection rate (anti-HBs titre ⩾10 mIU/ml) was 68·9% in vaccinated subjects. Seroprotection rates and geometric mean titres decreased significantly with increasing age, reflecting waning anti-HBs titre over time. No significant difference was detected between seroprotection rates and gender or students' area of origin. Incomplete vaccination was the only factor associated with an anti-HBs titre <10 mIU/ml. This study demonstrates the excellent efficacy of the HBV vaccination programme in Tunisia 17 years after its launch. However, a significant decline of anti-HBs seroprotection has been observed in ⩾15-year-old adolescents which places them at risk of infection. Additional studies are needed in hyperendemic regions in Tunisia.

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.

Epidemiology of HBV subgenotypes D

The natural history of hepatitis B virus infection is not uniform and affected from several factors including, HBV genotype. Genotype D is a widely distributed genotype. Among genotype D, several subgenotypes differentiate epidemiologically and probably clinically. D1 is predominant in Middle East and North Africa, and characterized by early HBeAg seroconversion and low viral load. D2 is seen in Albania, Turkey, Brazil, western India, Lebanon, and Serbia. D3 was reported from Serbia, western India, and Indonesia. It is a predominant subgenotype in injection drug use-related acute HBV infections in Europe and Canada. D4 is relatively rare and reported from Haiti, Russia and Baltic region, Brazil, Kenya, Morocco and Rwanda. Subgenotype D5 seems to be common in Eastern India. D6 has been reported as a rare subgenotype from Indonesia, Kenya, Russia and Baltic region. D7 is the main genotype in Morocco and Tunisia. D8 and D9 are recently described subgenotypes and reported from Niger and India, respectively. Subgenotypes of genotype D may have clinical and/or viral differences. More subgenotype studies are required to conclude on subgenotype and its clinical/viral characteristics.

Novel point mutations and mutational complexes in the enhancer II, core promoter and precore regions of hepatitis B virus genotype D1 associated with hepatocellular carcinoma in Saudi Arabia

In this study, a cohort of 182 patients [55 hepatocellular carcinoma (HCC) and 127 non-HCC] infected with hepatitis B virus (HBV) in Saudi Arabia was investigated to study the relationship between sequence variation in the enhancer II (EnhII), basal core promoter (BCP) and precore regions of HBV genotype D (HBV/D) and the risk of HCC. HBV genotypes were determined by sequencing analysis and/or enzyme-linked immunosorbent assay. Variations in the EnhII, BCP and precore regions were compared between 107 non-HCC and 45 HCC patients infected with HBV/D, followed by age-matched analysis of 40 cases versus equal number of controls. Age and male gender were significantly associated with HCC (p = 0.0001 and p = 0.03, respectively). Serological markers such as aspartate aminotransferase, albumin and anti-HBe were significantly associated with HCC (p = 0.0001 for all), whereas HBeAg positivity was associated with non-HCC (p = 0.0001). The most prevalent HBV genotype was HBV/D (94%), followed by HBV/E (4%), HBV/A (1.6%) and HBV/C (0.5%). For HBV/D1, genomic mutations associated with HCC were T1673/G1679, G1727, C1741, C1761, A1757/T1764/G1766, T1773, T1773/G1775 and C1909. Age- and gender-adjusted stepwise logistic regression analysis indicated that mutations G1727 [odds ratio (OR) = 18.3; 95% confidence interval (CI) = 2.8-118.4; p = 0.002], A1757/T1764/G1766 (OR = 4.7; 95% CI = 1.3-17.2; p = 0.01) and T1773 (OR = 14.06; 95% CI = 2.3-84.8; p = 0.004) are independent predictors of HCC development. These results implicate novel individual and combination patterns of mutations in the X/precore region of HBV/D1 as predictors of HCC. Risk stratification based on these mutation complexes would be useful in determining high-risk patients and improving diagnostic and treatment strategies for HBV/D1.

Identification of optimal target gene regions for hepatitis B virus genotyping by DNA sequencing

OBJECTIVES

DNA sequencing is the gold standard for hepatitis B virus (HBV) genotyping. We investigated the intergenotypic discriminatory capabilities of various target gene regions over the entire HBV genome, introducing a novel data evaluation approach generally applicable in viral genotyping.

METHODS

Complete genome sequences of seventy HBV variants obtained from the sera of 50 Syrian patients were determined and assigned GenBank accession No. from JN257148 to JN257217. Nucleotide sequence contigs were analyzed together with the NCBI reference genome set of HBV genotypes. Nine target gene regions were analyzed by phylogenetic and scored BLAST analyses. Thirty-one overlapping 300-bp sequence segments over the entire genome were also analyzed using a scored BLAST analysis, and intergenotypic discriminatory capabilities were statistically estimated for each.

RESULTS

Intergenotype discrimination was extremely significant when targeting either the complete genome, the entire coding sequence of either P or S genes, or any 300-bp sequence segment over the coding sequences of S protein or the polymerase N-terminal domain. Interestingly, intergenotypic discriminatory capability correlated negatively with intragenotype variation.

CONCLUSIONS

The intragenotypic conservation of certain target gene regions determines the intergenotypic discriminatory capability and allows reliable genotyping with relatively short segments. Our referential genome-wide tabulated guide allows for selecting candidate target gene regions for sequencing-based HBV genotyping. © 2013 S. Karger AG, Basel.

Hepatitis B virus in the Maghreb region: from epidemiology to prospective research

Hepatitis B virus (HBV) represents an important health problem in the Maghreb countries, Algeria, Libya, Mauritania, Morocco and Tunisia, but no detailed synthesis of its epidemiology is available. In this review, we systematically searched for data about HBV in the Maghreb in peer-reviewed databases and included in our analysis works written in English and French, as well as institutional reports and regional conference meeting abstracts. We estimated national and regional prevalence of chronic HBV infection. In addition, we discuss molecular features of the viral strains circulating in the region. Data analysis suggests that in the Maghreb region HBs antigen carriage concerns 1.8-4.9% of the population for an estimated number of 2.7 million persons. Genotype D, subtype D7, is predominant and mutations in the precore region of HBV genome are highly prevalent. This epidemiological situation requires obviously widespread active interventions for prevention and control. In addition, anti-hepatitis B vaccination programme should be applied with the utmost discipline in the five countries considered in this present review. This systematic review will, hopefully, increase knowledge at disposal of Public Health authorities, enabling better resource allocation and healthcare delivery. The present synthesis intends to stimulate policies aiming at preventing the spread of HBV, keeping in mind that eradication of the virus from Maghrebi populations should be the ultimate objective of Public Health authorities.

Global risk assessment of aflatoxins in maize and peanuts: are regulatory standards adequately protective?

The aflatoxins are a group of fungal metabolites that contaminate a variety of staple crops, including maize and peanuts, and cause an array of acute and chronic human health effects. Aflatoxin B1 in particular is a potent liver carcinogen, and hepatocellular carcinoma (HCC) risk is multiplicatively higher for individuals exposed to both aflatoxin and chronic infection with hepatitis B virus (HBV). In this work, we sought to answer the question: do current aflatoxin regulatory standards around the world adequately protect human health? Depending upon the level of protection desired, the answer to this question varies. Currently, most nations have a maximum tolerable level of total aflatoxins in maize and peanuts ranging from 4 to 20ng/g. If the level of protection desired is that aflatoxin exposures would not increase lifetime HCC risk by more than 1 in 100,000 cases in the population, then most current regulatory standards are not adequately protective even if enforced, especially in low-income countries where large amounts of maize and peanuts are consumed and HBV prevalence is high. At the protection level of 1 in 10,000 lifetime HCC cases in the population, however, almost all aflatoxin regulations worldwide are adequately protective, with the exception of several nations in Africa and Latin America.

Hepatitis B virus in the Arab world: where do we stand?

The epidemiology of viral hepatitis is of great importance for planning and managing health provision for all the countries in the Arab world. However, data on viral hepatitis are not readily available in a large percentage of Arab countries. Hepatitis B virus (HBV) is considered to be one of the most important causes of chronic hepatitis, cirrhosis and hepatocellular carcinoma. A systematic electronic search of published literature was conducted to extract data on epidemiology and risk factors for the analysis of HBV infection among the countries in the Arab world. The prevalence of chronic HBV infection was found to be decreasing in some Arab countries although it was still unacceptably high. This was particularly evident in the Arabian Gulf region, in Lebanon, Egypt and Libya. The age-specific prevalence varied from country to country with decline in prevalence being noted among children in the Gulf States and among Libyan women. These declines in prevalence are most likely to be related to the Expanded Immunization Programme. The alarmingly high prevalence of chronically infected patients in some areas and the widespread differences in HBV prevalence between Arab nations may be explained by the variation in risk factors involved. This situation calls for targeted approaches to tackle HBV-related mortality and morbidity. Precise HBV infection prevalence data are needed at the national and the sub-national level to estimate the disease burden, guide health intervention programmes and evaluate vaccine efficiency.

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.