A method for treating a subject infected with a Kaposi's sarcoma-associated herpesvirus (KSHV), comprising administering a therapeutically effective amount of a monoclonal antibody that specifically binds Kaposi's sarcoma-associated herpesvirus (KSHV) interleukin-6 (vIL-6), wherein the monoclonal antibody is produced by a hybridoma deposited as American Type Culture Collection (ATCC) Deposit No. PTA-2217 PTA-2218, PTA-2219, or PTA-2220 or a humanized form of the monoclonal antibody, in a pharmaceutically acceptable carrier.