Digital PCR provides absolute quantitation of viral load for an occult RNA virus.

Using a multiplexed LNA-based Taqman assay, RT-digital PCR (RT-dPCR) was performed in a prefabricated microfluidic device that monitored absolute viral load in native and immortalized cell lines, overall precision of detection, and the absolute detection limit of an occult RNA virus GB Virus Type C (GBV-C). RT-dPCR had on average a 10% lower overall coefficient of variation (CV, a measurement of precision) for viral load testing than RT-qPCR and had a higher overall detection limit, able to quantify as low as three 5'-UTR molecules of GBV-C genome. Two commercial high-yield in vitro transcription kits (T7 Ribomax Express by Promega and Ampliscribe T7 Flash by Epicentre) were compared to amplify GBV-C RNA genome with T7-mediated amplification. The Ampliscribe T7 Flash outperformed the T7 Ribomax Express in yield of full-length GBV-C RNA genome. THP-1 cells (a model of monocytic derived cells) were transfected with GBV-C, yielding infectious virions that replicated over a 120h time course and could be infected directly. This study provides the first evidence of GBV-C replication in monocytic derived clonal cells. Thus far, it is the only study using a microfluidic device that measures directly viral load of mammalian RNA virus in a digital format without need for a standard curve.

Hepatitis G virus.

A number of new hepatitis viruses (G, TT, SEN) were discovered late in the past century. We review the data available in the literature and our own findings suggesting that the new hepatitis G virus (HGV), disclosed in the late 1990s, has been rather well studied. Analysis of many studies dealing with HGV mainly suggests the lymphotropicity of this virus. HGV or GBV-C has been ascertained to influence course and prognosis in the HIV-infected patient. Until now, the frequent presence of GBV-C in coinfections, hematological diseases, and biliary pathology gives no grounds to determine it as an "accidental tourist" that is of no significance. The similarity in properties of GBV-C and hepatitis C virus (HCV) offers the possibility of using HGV, and its induced experimental infection, as a model to study hepatitis C and to develop a hepatitis C vaccine.

Epidemiology of hepatitis B, C, D and G viruses and cytokine levels among intravenous drug users.

To investigate the features of various hepatitis virus infection in intravenous drug users (IVDU), we conducted an epidemiological survey of hepatitis viruses including hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV) and hepatitis G virus (HGV) in IVDU. The correlation of TH lymphocyte cytokine and hepatitis virus infection was examined. A study population of 406 IVDU consisted of 383 males and 23 females. HBV-DNA and HCV-RNA were detected by fluorescence quantitative polymerase chain reaction. HBsAg, HBeAg, anti-HBc, anti-HCV, HDV-Ag and anti-HGV were assayed by ELISA. The levels of cytokines of TH1 and TH2 were measured by ELISA. The similar indices taken from 102 healthy persons served as controls. The infection rate of each virus among IVDU was 36.45 % for HBV, 69.7 % for HCV, 2.22 % for HDV, and 1.97 % for HGV, respectively. The co-infection rate of HBV and HCV was detected in 113 of 406 (27.83 %). In contrast, among controls, the infection rate was 17.65 % for HBV and 0 % for the other hepatitis viruses. The levels of PHA-induced cytokines (IFN-gamma and IL-4) and the level of serum IL-2 were obviously decreased in IVDU. On the other hand, the level of serum IL-4 was increased. The IFN-gamma level was continuously decreased when the IVDU was infected with HBV/HCV. In conclusion, HBV and HCV infection were common in this population of IVDU and they had led to a high incidence of impaired TH1 cytokine levels.

HCV and HGV infection, iron overload and liver disease in multitransfused patients with thalassaemia and persistently normal or abnormal transaminase levels.

Prevalence and influence on liver disease of HCV and HGV infections, and HCV genotypes were studied in 28 HCV-Ab positive multitransfused thalassaemia patients with persistently normal ALT levels (group A) matched by sex and age with 28 patients with increased ALT levels (group B). Laboratory and virologic tests (all patients), liver biopsy (28 patients) and LIC by SQUID (30 patients) were performed. In group A, HCV-RNA was positive in 39%, genotype 2a was detected in 91%. In Group B, HCV-RNA was positive in 89%, prevalence of genotype 1b and 2a was 52% and 48% respectively; compared with group A, they had significantly increased values of gammaGT, AF, BA, TP, IgG, IgA, LIC (group B: 2,142 -/+ 1,524 microg/g liver; group A: 1,084 -/+ 610 microg/g liver). Overall prevalence of HGV-RNA was low (12.5%) and not significantly different between groups. Liver biopsies revealed no cirrhosis and severe fibrosis was found in 3 HCV viremic patients in group B. In 14 viremic patients examined both for LIC and liver histology, mild fibrosis was observed in 71%, in which iron overload was below 5 times the normal value. In conclusion, in patients with normal ALT levels, active HCV infection must be excluded by evaluation of HCV-RNA. Liver biopsy is indicated in HCV viremic patients, independent of ALT levels; in non-viremic patients, increased ALT levels may be due to iron overload and LIC measurement is indicated. Our data emphasise the crucial role of chelation therapy to maintain low LIC levels in order to prevent progression of fibrosis to cirrhosis in patients with HCV chronic hepatitis.

Effects of HAART on hepatitis C, hepatitis G, and TT virus in multiply coinfected HIV-positive patients with haemophilia.

In multiply coinfected human immunodeficiency virus (HIV)-positive patients, we investigated the effects of high-activity antiretroviral therapy (HAART) using HIV protease inhibitors on three other viruses: hepatitis C virus (HCV), hepatitis G virus (HGV), and TT virus (TTV). Viral concentrations were measured serially by polymerase chain reaction methods in five patients with quadruple infection (HIV, HCV, HGV, and TTV) and in two patients with triple infection (HIV, HCV, and HGV) before and during HAART. In addition, CD4+ cell counts and serum alanine aminotransferase (ALT) levels were measured serially. Generally we observed no difference in serum HCV RNA, HGV RNA, or TTV DNA concentrations between samples obtained before and after initiation of HAART, whereas HIV RNA concentration decreased and CD4 counts increased in most patients. However, two patients had markedly decreased concentrations of HCV RNA and HGV RNA, respectively, more than 12 months after beginning HAART. Normalization of serum ALT levels was observed in a patient with decline of HCV RNA concentrations. No interactions were observed among these four viruses. HAART had no apparent direct effects on HCV, HGV, or TTV. Further studies will be required to elucidate whether the restoration of immune status through suppression of HIV replication by HAART may affect HCV or HGV RNA concentrations.