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Primary structure and variability of partial nonstructural gene 5 region of hepatitis G virus
1Institute of Hepatology, People's Hospital, Beijing Medical University, China.
Objective:
To sequence partial nonstructural 5 (NS5) gene of hepatitis G virus (HGV) in the sera of Chinese patients with chronic non-A-E hepatitis or hepatitis B virus (HBV) infection.
Methods:
Total nucleic acid was extracted from the sera of 35 patients with chronic non-A-E hepatitis and 20 patients with HBV infection, then it was subjected to reverse transcriptase-nested-polymerase chain reaction (RT-nested-PCR) with primers derived from the putative nonstructural gene 5 (NS5) region of HGV. The positive PCR products (994 bp in length) were directly sequenced using the Sang's method after purification.
Results:
HGV RNA was detected in 1 of the 35 patients (2.9%) with chronic non-A-E hepatitis and 5 of the 20 patients (25%) with HBV infection. All the 6 positive samples were sequenced. These 6 Chinese isolates exhibited 87.21% to 93.92% nucleotide sequence identities with 3 reported isolates (GBV-C, PNF2161, R10292) over the 994 nucleotides examined, while the nucleotide homologies among the 6 isolates were 90.09% to 93.82%. And 93.61% to 98.72% homologies were found at the deduced amino acid level in comparing the 6 isolates with 3 reported ones, while 93.61% to 98.40% amino acid identities were found among the 6 isolates. In the region sequenced, there existed 16 conserved proline residues and 8 conserved cysteine residues.
Conclusions:
Six isolates of HGV were obtained from different Chinese patients in this study. The partial nucleotide sequences, as well as amino acid sequences, of the putative NS5 region of HGV in Chinese patients are relatively conserved. The overall degree of nucleotide conservation (90.09% to 93.82%) among Chinese isolates may make this region of the genome suitable for the development of diagnosis reagents.