Kaposi's sarcoma-associated herpesvirus-specific immune reconstitution and antiviral effect of combined HAART/chemotherapy in HIV clade C-infected individuals with Kaposi's sarcoma

Kaposi's sarcoma-associated herpesvirus (KSHV) is endemic in South Africa and the clinical manifestation of AIDS-associated Kaposi's sarcoma (KS) represents a significant clinical problem. Whereas the positive effects of HAART on the regression of KS have been well established, less is known about the role of herpesvirus-specific cellular immunity in disease improvement. Thirty-three treatment-naive HIV clade C-infected individuals with KS were randomly assigned into two treatment arms (HAART plus systemic chemotherapy versus HAART alone). KSHV-specific cellular immune responses, viral loads and clinical outcome were evaluated. KSHV, Epstein-Barr virus and HIV-specific cellular immunity was measured using an IFN-gamma enzyme-linked immunospot assay in samples obtained at baseline and up to 11 months after treatment initiation. Cell-associated KSHV viremia was determined by real-time polymerase chain reaction. Robust increases in CD4 cell counts and suppressed HIV viral loads were seen in parallel with significant increases in the KSHV-specific cellular immune responses over time. Although slowly increasing after 5 months, KSHV-specific T-cell responses were significantly elevated only after 11 months, with both lytic and latent antigens being more frequently targeted. A trend towards better clinical outcome with HAART plus chemotherapy treatment was observed compared with HAART alone, and was accompanied by a significant reduction in cellular KSHV viral load in the HAART plus chemotherapy-treated subjects but not those treated with HAART alone after 11 months of treatment. The data show a temporal association between the clinical improvement of KS and the re-appearance of KSHV-specific cellular immunity, and demonstrate an effective suppression of KSHV viral replication using combination therapy.