O. Bahri

Human Bocaviruses Are Highly Diverse, Dispersed, Recombination Prone, and Prevalent in Enteric Infections

Abstract A new species of parvovirus, tentatively named human bocavirus 4 (HBoV4), was genetically characterized. Among 641 feces samples obtained from children and adults, the most commonly detected bocavirus species were, in descending order, HBoV2, HBoV3, HBoV4, and HBoV1, with an HBoV2 prevalence of 21% and 26% in Nigerian and Tunisian children, respectively. HBoV3 or HBoV4 species were found in 12 of 192 patients with non-polio acute flaccid paralysis in Tunisia and Nigeria and 0 of 96 healthy Tunisian contacts (P= .01). Evidence of extensive recombination at the NP1 and VP1 gene boundary between and within bocavirus species was found. The high degree of genetic diversity seen among the human bocaviruses found in feces specimens, relative to the highly homogeneous HBoV1, suggest that this worldwide-distributed respiratory pathogen may have recently evolved from an enteric bocavirus after acquiring an expanded tropism favoring the respiratory tract. Elucidating the possible role of the newly identified enteric bocaviruses in human diseases, including acute flaccid paralysis and diarrhea, will require further epidemiological studies.

A Novel Picornavirus Associated with Gastroenteritis

ABSTRACT A novel picornavirus genome was sequenced, showing 42.6%, 35.2%, and 44.6% of deduced amino acid identities corresponding to the P1, P2, and P3 regions, respectively, of the Aichi virus. Divergent strains of this new virus, which we named salivirus, were detected in 18 stool samples from Nigeria, Tunisia, Nepal, and the United States. A statistical association was seen between virus shedding and unexplained cases of gastroenteritis in Nepal (P = 0.0056). Viruses with approximately 90% nucleotide similarity, named klassevirus, were also recently reported in three cases of unexplained diarrhea from the United States and Australia and in sewage from Spain, reflecting a global distribution and supporting a pathogenic role for this new group of picornaviruses.

Combined analysis of interferon-γ 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.

Association of interleukin‐18 polymorphisms and plasma level with the outcome of chronic HCV infection

Hepatitis C virus (HCV) infection is the main cause of chronic liver disease throughout the world, and may progress to cirrhosis and hepatocellular carcinoma (HCC). Immunological factors, especially cytokines and some host genetic variations, rather than direct HCV action, seem to play an important role in the pathogenesis of HCV infection. Elevated levels of interleukin‐18 (IL‐18) were described previously for chronically (HCV)‐infected patients. This study is aimed at investigating IL‐18 promoter polymorphisms (−607C/A and −137G/C) in HCV‐infected patients with different disease severities (chronic hepatitis C, liver cirrhosis and HCC) and establishing an association between these polymorphisms and IL‐18 plasma concentration with the outcome of chronic HCV infection. The carriage of at least one C allele at position −607 (CC + CA) was associated with a higher risk of cirrhosis and HCC (P = 0.032). Compared with controls, HCV‐infected patients had significantly higher levels of IL‐18 (P = 0.0001) that correlate with disease severity (P = 0.01, P = 0.001, P = 0.0006, respectively). In conclusion, we supposed a possible implication of IL‐18 promoter polymorphisms in the pathogenesis of chronic HCV infection. J. Med. Virol. 80:607–614, 2008.

First multicenter study for risk factors for hepatocellular carcinoma development in North Africa

AIM To assess the role of the major risk factors for hepatocellular carcinoma (HCC) development in the western part of North Africa. METHODS A multicenter case control study was conducted in Tunisia, Morocco and Algeria in collaboration with Pasteur Institutes in these countries. A total of 164 patients with HCC and 250 control subjects without hepatic diseases were included. Prevalences of HBsAg, anti-hepatitis C virus (HCV) and diabetes were assessed. HCV and HBV genotyping were performed for anti-HCV and HBsAg positive patients. RESULTS The mean age of patients was 62 ± 10 years old for a 1.5 M:F sex ratio. Sixty percent of HCC patients were positive for anti-HCV and 17.9% for HBsAg. Diabetes was detected in 18% of cases. Odd ratio (OR) and 95% confidence intervals (CI) were 32.0 (15.8 - 65.0), 7.2 (3.2 - 16.1) and 8.0 (3.1 - 20.0) for anti-HCV, HBsAg and diabetes respectively. Multivariate analysis indicated that the three studied factors were independent. 1b HCV genotype and D HBV genotype were predominant in HCC patients. HCV was the only risk factor significantly associated with an excess of cirrhosis (90% vs 68% for all other risk factors collectively, P = 0.00168). Excessive alcohol consumption was reliably established for 19 (17.6%) cases among the 108 HCC patients for whom data is available. CONCLUSION HCV and HBV infections and diabetes are the main determinants of HCC development in North Africa. An active surveillance and secondary prevention programs for patients with chronic hepatitis and nutrition-associated metabolic liver diseases are the most important steps to reduce the risk of HCC in the region.

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

BackgroundIn Tunisia, country of intermediate endemicity for Hepatitis B virus (HBV) infection, most molecular studies on the virus have been carried out in the North of the country and little is known about other regions. The aim of this study was to determine HBV genotype and subgenotypes in Central-East Tunisia. A total of 217 HBs antigen positive patients were enrolled and determination of genotype was investigated in 130 patients with detectable HBV DNA. HBV genotyping methods were: PCR-RFLP on the pre-S region, a PCR using type-specific primers in the S region (TSP-PCR) and partial sequencing in the pre-S region.ResultsThree genotypes (D, B and A) were detected by the PCR-RFLP method and two (D and A) with the TSP-PCR method, the concordance between the two methods was 93%. Sequencing and phylogenetic analysis of 32 strains, retrieved the same genotype (D and A) for samples with concordant results and genotype D for samples with discordant results. The sequences of discordant genotypes had a restriction site in the pre-S gene which led to erroneous result by the PCR-RFLP method. Thus, prevalence of genotype D and A was 96% and 4%, respectively. Phylogenetic analysis showed the predominance of two subgenotypes D1 (55%) and D7 (41%). Only one strain clustered with D3 subgenotype (3%).ConclusionsPredominance of subgenotype D7 appears to occur in northern regions of Africa with transition to subgenotype D1 in the East of the continent. HBV genetic variability may lead to wrong results in rapid genotyping methods and sequence analysis is needed to clarify atypical results.

Molecular characterisation of a coxsackievirus A24 that caused an outbreak of acute haemorrhagic conjunctivitis, Tunisia 2003

This study reports the genetic characteristics of coxsackievirus A24 isolates from Tunisia, including a coxsackievirus A24 variant (CVA24v) that caused an outbreak of acute haemorrhagic conjunctivitis (AHC) between September and November 2003. The virus genome was detected by PCR from conjunctival swabs obtained from patients with AHC. Four virus isolates were obtained from PCR-positive samples and were serotyped by sequence analysis of the VP1 and VP4 genomic region and by seroneutralisation. Phylogenetic analysis of the VP1, VP4 and 3C genomic regions was performed. Other Tunisian CVA24 isolates from paralytic cases and healthy individuals were also amplified, sequenced and included in the phylogenetic analysis. The epidemic strain belonged to the CVA24 serotype. Phylogenetic analysis of the 3C region of the genome revealed a strong relationship between the Tunisian epidemic strain and strains that caused outbreaks in Korea (2002) and Guadeloupe and French Guiana (2003). Phylogenetic analysis of the VP1 and VP4 regions showed a clear distinction between serotype CVA24 isolates from conjunctivitis and non-conjunctivitis cases. This is the first study to report an outbreak of AHC caused by CVA24v in the North African region.

Hépatite virale B chez les femmes enceintes tunisiennes : facteurs de risque et intérêt de l’étude de la réplication virale en cas d’antigène HBe négatif

OBJECTIVE To evaluate the seroprevalence and the risk factors of hepatitis B virus (HBV) infection in 2303 Tunisian pregnant women and to estimate the risk of perinatal transmission in women positive for hepatitis B surface antigen (HBsAg) but negative for hepatitis B e-antigen (HBeAg). MATERIAL AND METHODS Positive samples were tested for HBeAg and anti-HBe antibody using enzyme immunoassays. Serum HBV-DNA was determined by real time PCR assay. RESULTS Overall, 4% of women were HBsAg positive and for the majority of them (96.8%) this status was unknown. Only 1.4% of studied population were vaccinated previously against hepatitis B. Study of risk factors revealed association between the HBsAg status and presence of intrafamilial hepatitis cases (p<0.05). Only four women were positive for HBeAg. Among patients with HBeAg negative status, only 11% were negative for HBV DNA. For the others, DNA level ranged from 34 to 10(8)copies/ml; it was greater than 10(4)copies/ml in 26.5% of them. CONCLUSION Hepatitis B virus (HBV) prevalence in pregnant women is of intermediate endemicity in Tunisia. Universal vaccination before pregnancy and antenatal screening is recommended. Pregnant women who are found to be HBsAg positive and HBeAg negative should be tested systematically for DNA level to evaluate the risk of perinatal infection and to prevent it by sero-prophylactic for babies or by treatment during the third trimester of pregnancy.

Heterogeneity of hepatitis B transmission in Tunisia: Risk factors for infection and chronic carriage before the introduction of a universal vaccine program☆

UNLABELLED A population-based sero-epidemiological study enrolled 9486 volunteers in two governorates, Béja in the north and Tataouine in the south of Tunisia, in order to assess the magnitude of HBV transmission heterogeneity between the north and the south and within the same governorate, as well as the risk factors associated with infection and chronic carriage. RESULTS The overall prevalence of anti-HBc, HBsAg and chronic carriage was 28.5, 5.3 and 2.9%, respectively. Significant differences were observed between the two governorates according to anti-HBc (32.1% in Béja and 27.8% in Tataouine; p=0.005) and HBsAg prevalence (4.2% in Béja and 5.6% in Tataouine; p=0.001). Significant differences were noticed between districts revealing important heterogeneity in HBV transmission within the same governorate (HBsAg ranged from 12 to <2% within the same governorate). At the individual level, the presence of a family member infected with HBV, scarification practices, needle practices in the Primary Care Center and gender (male) significantly increased the risk of anti-Hbc, HBsAg positivity and chronic carriage of infection while existence of sanitation in the house was found to be protective. The basic reproductive number and the force of infection confirmed the heterogeneity of transmission. Horizontal transmission within the family explains hyperendemic clusters in Tunisia.

Measles surveillance and control in Tunisia: 1979-2000.

BACKGROUND The aim of this study was to analyze measles epidemiology in Tunisia after the introduction of specific vaccine in 1979 and the results of the serological investigation of suspected cases, introduced as part of the National Program for Measles Elimination recently implemented. METHODS Available data were used to examine trends in measles epidemiology from 1979 to 2000: number of reported cases, patients age, reporting date, epidemiological link with similar cases and laboratory confirmation. Serological investigation included the detection, by ELISA, of measles and rubella IgMs in 542 suspected measles cases sampled from 1997 to 2000. RESULTS Measles coverage level increased gradually and was maintained to over 90% since 1992. In parallel, the annual incidence of reported cases declined and outbreaks became less frequent, the latest occurred in 1992. Measles-specific IgMs were detected in only nine patients who received measles vaccine few days before blood collection, anti-rubella IgMs were detected in 52% of cases. CONCLUSION Vaccination strategies including routine and supplemental immunizations, implemented in Tunisia, achieved a substantial decrease in measles incidence. Virological results highlight frequent confusion, at the clinical level, with the other etiologies of rash and fever and the importance of systematic serological confirmation of cases.