Clinical Impact of GB Virus C Viremia on Patients with HIV Type 1 Infection in the Era of Highly Active Antiretroviral Therapy

BACKGROUND

The influence of GB virus C (GBV-C) viremia on clinical outcomes of patients with human immunodeficiency virus type 1 (HIV-1) infection remains controversial in the era of highly active antiretroviral therapy (HAART).

METHODS

A prospective observational study was conducted to describe the epidemiology of GBV-C viremia and assess its clinical impact on treatment responses to HAART in 385 HIV-1-infected patients during the period from January 1999 through June 2004.

RESULTS

A total of 59 patients (15.3%) had detectable GBV-C RNA viremia during a median observation of 3.6 years (range, 1.0-7.0 years); 47 patients (12.2%) had GBV-C viremia at enrollment, and 12 (3.1%) acquired GBV-C infection during follow-up. Thirty-two (68.1%) of the 47 patients with baseline GBV-C viremia had persistent GBV-C viremia. Compared with patients with clearance of GBV-C viremia (n=15) and patients without detectable GBV-C viremia (n=326), patients with persistent GBV-C viremia were more likely to be men who have sex with men (81.3% vs. 60.4%; P=.02), tended to have lower baseline plasma HIV RNA load (HIV RNA load > or =5 log(10) copies/mL, 31.3% vs. 49.4%; P=.05), and had a higher proportion of isolated anti-hepatitis B core antibody (37.5% vs. 17.2%; P=.005). There was no statistically significant difference in terms of virologic, immunologic, and clinical responses to HAART; occurrence of hepatic events; and mortality among the 3 groups.

CONCLUSIONS

Persistent GBV-C viremia is significantly associated with male-male sex in HIV-infected patients with advanced immunodeficiency, and persistent GBV-C viremia does not confer short-term benefit in patients receiving HAART.

GB virus type C NS5A sequence polymorphisms: association with interferon susceptibility and inhibition of PKR-mediated eIF2alpha phosphorylation

GB virus type C (GBV-C) causes persistent infection in humans, although the mechanism by which the virus avoids clearance by the host is unknown. To determine if amino acid polymorphisms in the GB virus type C (GBV-C) NS5A and E2 proteins alter response to interferon (IFN) therapy, we studied the sequence of GBVC NS5A and E2 obtained from people receiving IFN therapy. In addition, we expressed recombinant GBVC NS5A protein to determine if it interferes with RNA-activated protein kinase (PKR) function in vitro. GBVC NS5A amplified from a person whose virus was cleared by IFN therapy (IFN sensitive) demonstrated unique amino acid changes occurring in the region that aligns with the hepatitis C virus (HCV) IFN sensitivity-determining region (ISDR) compared with NS5A sequences from individuals who did not clear GBV-C (IFN resistant). There were no differences in the E2 sequences obtained from IFN-sensitive and IFN-resistant isolates. Using a yeast genetic system, IFN-resistant NS5A inhibited PKR-mediated phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha) in yeast, whereas IFN-sensitive NS5A did not inhibit PKR function. GBV-C NS5A amino acid polymorphisms appear to be involved in response to IFN therapy, and IFN-resistant GBV-C NS5A inhibited PKR-mediated eIF2alpha phosphorylation in a yeast genetic system, suggesting a mechanism by which GBV-C may evade clearance by naturally occurring host antiviral responses.

[HG-viral infection in adults]

AIM

To characterize the clinical and laboratory manifestations in patients with HG viral infection frequently concurrent with chronic HCV infection and the potentialities of their treatment.

MATERIALS AND METHODS

109 patients with suspected chronic hepatic disease were examined. The markers of HGV, HCV, HBV, and TTV infections were determined. The possible factors of infection, biochemical parameters, and the efficiency of antiviral therapy were assessed.

RESULTS

Hepatitis G virus RNK was detected in 32 cases, a combined variant of hepatitis G + C viruses RNA was found in 77 patients with chronic viral hepatitis (CVH). Among the presumed routes of contamination in the mixed variant of CVH, there were most common intravenous injection of narcotic drugs; in monoinfection (HGV), there were parenteral interventions in medical facilities and blood transfusion. Antiviral treatment of 13 patients with chronic HGV + HCV infection yielded a positive result in 5 patients after 3-month therapy.

CONCLUSION

In patients with CVH, HG virus infection was more frequently observed in combination with CVHC, less frequently as monoinfection. In HG virus monoinfection, biochemical studies revealed the enhanced activity of transaminases and hyperbilirubinemia that was absent in the mixed variant of HGV + HCV. The financial capacities of patients should be taken into account while choosing therapy.

GB virus C/hepatitis G virus infection in chronic hepatitis C patients with and without interferon-alpha therapy

GB virus C/hepatitis G virus (GBV-C/HGV) RNA, detected by polymerase chain reaction, and antibodies to the GBV-C/HGV envelope protein (anti-E2), detected by an enzyme-linked immunosorbent assay, were used to evaluate both the impact of GBV-C/HGV on the coexistent hepatitis C virus (HCV) infection and the course of GBV-C/HGV infection in chronic hepatitis C patients with and without interferon-alpha (IFN-alpha) treatment. Of the 162 chronic hepatitis C patients treated with INF-alpha, 17.9% were GBV-C/HGV RNA-positive and 18.5% anti-E2-positive (total exposure, 35.2%). Neither present nor past GBV-C/HGV infection had impact on the clinical features, HCV virological characteristics and response to IFN-alpha treatment in chronic hepatitis C patients. Among patients with ongoing HCV/GBV-C/HGV coinfection, 20.7% (6/29) in IFN-alpha-treated patients lost GBV-C/HGV RNA concomitant with anti-E2 seropositivity, which was significantly higher than 4.8% (2/42) in patients without INF-alpha treatment (P<0.05). Based on multivariate analyses, the significant factors associated with clearance of GBV-C/HGV viremia combined with anti-E2 seropositivity were baseline anti-E2 seropositivity and IFN-alpha treatment. In summary, GBV-C/HGV did not alter the course of coexistent HCV. IFN-alpha treatment was effective in some patients against GBV-C/HGV and might facilitate anti-E2 seroconversion in chronic hepatitis C patients with GBV-C/HGV viremia.

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.