A specific binding agent is provided, wherein the specific binding agent specifically binds Kaposi's sarcoma-associated herpesvirus (KSHV) interleukin-6 (vIL-6), and the specific binding agent neutralizes an activity of vIL-6. In one embodiment, the specific binding agent is an antibody. Methods are provided for using a specific binding agent that binds vIL-6, and neutralizes a biological activity of vIL-6. Methods of treatment for a KSHV-associated disorder are also provided. Methods for diagnosing a KSHV-associated disorder are provided, as are kits that include a specific binding agent of the invention. A method is also provided for testing an agent for effectiveness in treating a KSHV-associated disorder. The method includes incubating the agent with a cell free system comprising a vIL-6 receptor component and vIL-6, and comparing the binding of vIL-6 and the receptor component in the presence of the agent to binding of vIL-6 to the receptor component in the absence of the agent. A decrease in the binding of vIL-6 to the receptor component in the presence of the agent indicates that the agent is effective for treating the KSHV-associated disorder.