"Defective" mutations of hepatitis D viruses in chronic hepatitis D patients.
OBJECTIVE
To verify whether "defective" mutations existed in hepatitis D virus (HDV).


METHODS
Hepatitis delta antigen (HDAg)-coding sequences were amplified using Pfu DNA polymerases with proof-reading activities from sera of five patients with chronic hepatitis D. Multiple colonies were sequenced for each patient. Pfu analyzed a total of 270 HDV clones. Three representative defective HDV clones were constructed in expression plasmids and transfected into a human hepatoma cell line. Cellular proteins were extracted and analyzed by Western blot.


RESULTS
Four of five cases (80%) showed defective HDV genomes in their sera. The percentage of defective genomes was 3.7% (10/270). The majority (90%) of the defective mutations were insertions or deletions that resulted in frameshift and abnormal stop translation of the HDAg. The predicted mutated HDAg ranged from 45 amino acids to >214 amino acids in length. Various domains of HDAg associated with viral replication or packaging were affected in different HDV isolates. Western blot analysis showed defected HDAg in predicted positions.


CONCLUSIONS
"Defective" viruses do exist in chronic HDV infected patients, but represented as minor strains. The clinical significance of the "defected" HDV needs further study to evaluate.
Wu
Jaw-Ching
JC
Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan, China. jcwu@vghtpe.gov.tw
Hsu
Sheng-Chieh
SC
Wang
Shen-Yung
SY
Huang
Yi-Hsiang
YH
Sheen
I-Jane
IJ
Shih
Hsuan-Hui
HH
Syu
Wan-Jr
WJ
D000595:Amino Acid Sequence; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D002908:Chronic Disease; D004279:DNA, Viral / Q000097:blood; D016368:Frameshift Mutation; D017353:Gene Deletion; D016679:Genome, Viral; D019701:Hepatitis D, Chronic / Q000821:virology*; D003698:Hepatitis Delta Virus / Q000235:genetics*; D035923:Hepatitis delta Antigens / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms; D008969:Molecular Sequence Data
D004279:DNA, Viral; D035923:Hepatitis delta Antigens