Detection of hepatitis G virus from serum and liver of a patient with long-term liver dysfunction after autologous bone marrow transplantation

Hepatitis G virus: molecular organization, methods of detection, prevalence, and disease association

This article reviews data on hepatitis G virus (HGV) prevalence and possible disease associations in various groups of patients. An important fraction of acute or chronic hepatitis cases probably have a viral etiology and are not attributable to known hepatitis viruses. Therefore, researchers continually are looking for new hepatitis viruses. Among the agents found are members of GB hepatitis viruses, including GB-C virus, or HGV. This review presents the history of the discovery of HGV, its molecular biology and some methods of detection; results of clinical and molecular studies of HGV infection also are discussed.

In vitro infection of human peripheral blood mononuclear cells by GB virus C/Hepatitis G virus

GB virus C (GBV-C), also known as hepatitis G virus, is a recently discovered flavivirus-like RNA agent with unclear pathogenic implications. To investigate whether human peripheral blood mononuclear cells (PBMC) are susceptible to in vitro GBV-C infection, we have incubated PBMC from four healthy blood donors with a human GBV-C RNA-positive serum. By means of (i) strand-specific reverse transcription-PCR, cloning, and sequencing; (ii) sucrose ultracentrifugation and RNase sensitivity assays; (iii) fluorescent in situ hybridization; and (iv) Western blot analysis, it has been demonstrated that GBV-C is able to infect in vitro cells and replicate for as long as 30 days under the conditions developed in our cell culture system. The concentration of GBV-C RNA increased during the second and third weeks of culture. The titers of the genomic strand were 10 times higher than the titers of the antigenomic strand. In addition, the same predominant GBV-C sequence was found in all PBMC cultures and in the in vivo-GBV-C-infected PBMC isolated from the donor of the inoculum. GBV-C-specific fluorescent in situ hybridization signals were confined to the cytoplasm of cells at different times during the culture period. Finally, evidence obtained by sucrose ultracentrifugation, RNase sensitivity assays, and Western blot analysis of the culture supernatants suggests that viral particles are released from in vitro-GBV-C-infected PBMC. In conclusion, our study has demonstrated, for the first time, GBV-C replication in human lymphoid cells under experimental in vitro infection conditions.

Identification of a novel GB type C virus/hepatitis G virus subtype in patients with hematologic malignancies

The existence of four GB C virus/hepatitis G virus (GBV-C/HGV) subtypes has been reported. The subtype was determined in 16 multitransfused GBV-C/HGV infected patients prior to bone marrow transplantation by comparing the 5' untranslated region (5' UTR) sequence with 39 available sequences. Phylogenetic and bootstrap analyses were carried out with PHYLIP package 3.5c. In the samples with undefined subtype, the whole 5' UTR was cloned and sequenced. Comparison of distances showed that the isolates from 12/16 and 4/16 patients belonged theoretically to subtypes 2a and 2b, respectively. The phylogenetic tree and bootstrap analyses confirmed this result in only 11/16 samples. Analysis of the entire 5' UTR from the remaining five samples with undefined GBV-C/HGV subtype revealed genomic variability within the isolates from each patient and between the isolates of different patients. Evolutionary distances, phylogenetic tree, and bootstrap showed that the isolates from these samples were grouped in a separate branch, different from the published subtypes. In conclusion, a novel GBV-C/HGV subtype was found in a group of multitransfused patients with GBV-C/HGV infection.