Hepatitis D virus infection in Thailand: HDV genotyping by RT-PCR, RFLP and direct sequencing.
BACKGROUND
Hepatitis D virus (HDV) is a degenerate RNA virus or virusoid that requires the surface coat of hepatitis B virus (HBV), i.e. hepatitis B surface antigen (HBsAg), in order to become infectious. Three distinct genotypes of the virus have been classified. In this study, HDV genotypes were determined by restriction fragment length polymorphism (RFLP) and direct sequencing. In Thailand, simultaneous HDV/HBV infections are particularly prevalent among intravenous drug users (IVDU).


METHODS
A total of 743 IVDU sera were screened for HBV infection. HBsAg-positive samples were subjected to serological analysis for anti-HDV. RFLP analysis using the endonucleases Xho I and Sma I was performed on the PCR amplified HDV genome to establish the prevailing HDV genotypes.


RESULTS
55 sera (7%) had detectable HBsAg; all 55 were subsequently subjected to serological analysis for anti-HDV, 12 (21.8%) of which were positive. Eight (66%) specimens had detectable HDV-RNA by RT-PCR. All polymorphisms were shown to be genotype I, a finding confirmed by direct sequencing. 36 HBsAg-positive sera obtained from the blood bank to serve as controls were negative for anti-HDV.


CONCLUSIONS
Our data show that HDV infection is still limited among IVDU and that the pattern of polymorphism closely resembles that of the western HDV genotype I.
Theamboonlers
A
A
Dept. of Pediatrics, Faculty of Medicine, Chulalongkorn University & Hospital, Bangkok, Thailand.
Hansurabhanon
T
T
Verachai
V
V
Chongsrisawat
V
V
Poovorawan
Y
Y
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005838:Genotype; D003699:Hepatitis D / Q000097:blood / Q000453:epidemiology* / Q000235:genetics*; D003698:Hepatitis Delta Virus / Q000235:genetics*; D006801:Humans; D015994:Incidence; D008297:Male; D012150:Polymorphism, Restriction Fragment Length; D012367:RNA, Viral / Q000032:analysis*; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D015819:Substance Abuse, Intravenous / Q000097:blood; D013785:Thailand / Q000453:epidemiology
D012367:RNA, Viral