Analysis of Chemokine and Cytokine Expression in Patients with HIV and GB Virus Type C Coinfection

Human pegivirus type 1 infection in Asia-A review of the literature

The human pegivirus type 1 (HPgV-1)-as known as hepatitis G virus and GB virus C-is a common single-stranded RNA flavivirus. Because few studies have demonstrated an association between HPgV-1 infection and disease, screening for HPgV-1 is not performed routinely. Nonetheless, a beneficial impact of HPgV-1 infection on HIV disease progression has been reported in multiple studies. Given the burden of HIV in Asia and the complex interactions between viral co-infections and the host, we provide a comprehensive overview of the existing data from Asia on HPgV-1 infection, including the prevalence and circulating genotypes in all Asian countries with data reported. This review highlights the research conducted thus far and emphasizes the need for additional studies on HPgV-1 across the Asian continent.

Cytokine/chemokine expression associated with Human Pegivirus (HPgV) infection in women with HIV

A beneficial impact of the Human Pegivirus (HPgV)-formerly called GB virus C (GBV-C)-on HIV disease progression has been reported previously. One possible mechanism by which HPgV inhibits HIV replication is an alteration of the cytokine/chemokine milieu. Their expression has not been specifically evaluated in women despite their influence on disease progression and the possibility of gender-based differences in expression. Moreover, the impact of HPgV genotype on cytokine/chemokine expression is unknown. Sera levels of IL-2, IL-4, IL-7, IL-8, IL-10, IL-12p70, IL-13, IFNγ, TNFα, IP-10, MIP-1α, MIP-1β, and TGF-β₁ were quantified in 150 HIV-positive women based on HPgV RNA status. Cytokines/chemokines with detection rates of at least 50% included IL-2, IL-4, IL-8, IL-10, IL-12p70, IFNγ, TNFα, IP-10, MIP-1α, MIP-1β, and TGF-β₁ . Absolute values were significantly higher for HPgV positive compared to HPgV negative women for IL-7, IL-13, IL-12p70, and IFNγ. Absolute values were significantly lower for HPgV positive women for IL-4, IL-8, TGF-β₁ , and IP-10. IFNγ values were higher for HPgV genotype 2 than for genotype 1 (P = 0.036). Further study of cytokine/chemokine regulation by HPgV may ultimately lead to the development of novel therapeutic agents to treat HIV infection and/or the design of vaccine strategies that mimic the "protective" effects of HPgV replication.

Inhibition of HIV strains by GB virus C in cell culture can be mediated by CD4 and CD8 T-lymphocyte derived soluble factors

OBJECTIVE

A number of studies concerning the pathogenesis of GB virus C (GBV-C) in HIV-infected people suggest a beneficial effect and improved survival for dually infected individuals. However there has remained controversy regarding the clinical relevance of these findings, as some studies have not confirmed these observations. To address the possibility of direct inhibitory mechanisms, we studied the impact of GBV-C on HIV-1 replication in vitro.

METHODS

Peripheral blood mononuclear cells (PBMC) were infected with sera from GBV-C positive individuals or transfected with GBV-C specific RNA and superinfected with HIV. Replication kinetics of HIV were studied by quantification of HIV-p24 release. Induction of soluble antiretroviral factors were monitored with an HIV infection assay and by quantification of chemokine secretion. Changes in chemokine receptor expression were analysed by flow cytometry.

RESULTS

We demonstrate that GBV-C infection of PBMC leads to significant replication inhibition of R5- and X4-HIV isolates representing eight HIV clades. The inhibitory effect is mediated by GBV-C infection and also by expression of GBV-C structural glycoproteins and/or of non-structural proteins NS2/NS3. Upon GBV-C infection CD4 and CD8 T lymphocytes produce soluble HIV-suppression factors. Induction of stromal cell-derived factor (SDF)-1 and subsequent internalization of CXCR4 was not observed.

CONCLUSIONS

CD4 and CD8 T lymphocytes are stimulated by GBV-C to secrete antiretroviral factors, inhibiting R5- and X4-HIV strains. As no induction of SDF-1 and no down-regulation of the respective receptor CXCR4 could be observed, it is likely that additional unidentified factors causing inhibition of X4-HIV strains are induced by GBV-C.