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


RESULTS
Three 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%).


CONCLUSIONS
Predominance 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.
Laboratoire de Microbiologie-Immunologie, UR02SP13, Hôpital Farhat Hached, Sousse, Tunisia. nhannachi@lycos.com
Naila
N
Hannachi
Nadia Ben
NB
Fredj
Olfa
O
Bahri
Vincent
V
Thibault
Asma
A
Ferjani
Jawhar
J
Gharbi
Henda
H
Triki
Jalel
J
Boukadida
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D017931:DNA Primers / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics*; D019353:Endemic Diseases; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000821:virology*; D006514:Hepatitis B Surface Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011498:Protein Precursors / Q000235:genetics; D017422:Sequence Analysis, DNA; D014416:Tunisia / Q000453:epidemiology; D055815:Young Adult
D017931:DNA Primers; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors