Molecular epidemiology and genotyping of hepatitis B virus of HBsAg-positive patients in Oman.
BACKGROUND
Hepatitis B virus (HBV) infection is a major global health burden with distinct geographic public health significance. Oman is a country with intermediate HBV carrier prevalence; however, little is known about the incidence of HBV variants in circulation. We investigated the HBV genotype distribution, the occurrence of antiviral resistance, and HBV surface antigen (HBsAg) escape mutations in HBsAg-positive patients in Oman.


METHODS
Serum samples were collected from 179 chronically HBV-infected patients enrolled in various gastroenterology clinics in Oman. HBV genotypes were determined by sequencing and phylogenetic analysis. Mutations in the HBV polymerase and the HBsAg gene were characterized by mutational analysis.


RESULTS
HBV genotypes D (130/170; 76.47%) and A (32/170; 18.28%) are predominant in Oman. The HBV genotypes C and E were less frequent (each 1.18%), while the HBV genotypes B, G, F, and H were not detected. Four patients revealed HBV genotype mixtures (HBV-A/D and D/C). The analyses of vaccine escape mutations yield that 148/170 (87.06%) HBV sequences were wild type. 22/170 (12.94%) HBV sequences showed mutations in the "a" determinant of the HBsAg domain. Two patients showed the described HBV vaccine escape mutation sP120T. 8/146 (5.48%) HBV isolates harbored mutations in the HBV polymerase known to confer resistance against antiviral therapy. Especially the lamivudine resistance mutations rtL180M/rtM204V and rtM204I were detected.


CONCLUSIONS
This study shows the distribution of HBV genotypes, therapy resistance, and vaccine escape mutations in HBV-infected patients in Oman. Our findings will have a major impact on therapy management and diagnostics of chronic HBV infections in Oman to control HBV infection in this intermediate HBV-endemic country.
Central Public Health Laboratory - Ministry of Health, Muscat, Oman.
Said Ali
SA
Al Baqlani
Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany; Vietnam Military Medical University, Ha Dong, Ha Noi, Viet Nam; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
Bui Tien
BT
Sy
Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany.
Boris A
BA
Ratsch
Armed Forces Hospital - Ministry of Defense, Muscat, Oman.
Khalid
K
Al Naamani
Office of the Undersecretary for Health Affairs - Ministry of Health, Muscat, Oman.
Salah
S
Al Awaidy
Central Public Health Laboratory - Ministry of Health, Muscat, Oman.
Suleiman Al
SA
Busaidy
Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany.
Georg
G
Pauli
Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany.
C-Thomas
CT
Bock
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000235:genetics; D017325:Hepatitis B Vaccines / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000453:epidemiology / Q000821:virology*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009154:Mutation; D009850:Oman / Q000453:epidemiology; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use; D055815:Young Adult
D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine