Generation and Evaluation of KSHV VLPs as Vaccines

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DESCRIPTION (provided by applicant): This proposal is being submitted in response to the Announcement RFA-OD-09-004 under ARRA Research Grand Opportunities for Exploratory Research in the Development of Vaccines for AIDS-Associated Malignancies (RC2 mechanism). This is designed to stimulate early stage innovative research efforts in either preventative or therapeutic vaccine development for infectious causes of cancer. Kaposi's sarcoma (KS) was one of the original defining opportunistic infections in the AIDS epidemic, when these highly angiogenic skin lesions first appeared in an aggressive often disseminated form in young gay men in New York and San Francisco. In 1994, both classic and epidemic KS were found out to be caused by a previously unknown human herpesvirus called Kaposi's Sarcoma Associated Herpesvirus (KSHV or sometimes HHV8). Today in Southern Africa, KS has become the most prevalent of all tumors because of the spread of HIV into a population that was already nearly universally endemically infected by KSHV. In contrast, in Western countries, KSHV infections are very uncommon, except in AIDS-patients with promiscuous life-style factors, where this combined with HIV-induced immunosuppression produces KS at high frequency. Fortunately, the use of HAART and related therapies has reduced the problem of KS, but there is still a subset of patients with stable reconstituted immune function, in which KS reappears and becomes increasingly non-responsive over time. We believe that preventative vaccines against KSHV should be seriously considered as a potential way to control KSHV infection in Western countries and possibly in future in Africa also. However, little is known as yet about immune responses to KSHV infection in either KS or non-KS patients, and vaccines did not appear attractive previously because of the large size and complexity of this virus, as well as the fact that as a tumor forming virus the viral genome and oncogenes would have to be absent or removed. Based on recent success with prophylactic HPV subunit vaccines to prevent cervical carcinoma, and the demonstration that virus-like particles (VLP) of small viruses such as influenza can be effective in inducing a variety of immune responses, the vaccine prospects for other AIDS malignancies now need to be reassessed. Here we propose initial exploratory steps to both develop a DNA-free VLP-based preventative vaccine for KSHV/KS, and to develop a revolutionizing high-throughput global proteome approach to measuring viral antibody and neutralization responses in KSHV-positive patients with and without KS, as well as the responses induced by VLP vaccination. These will be assessed in experimental inocculated mice, as well as in existing collections of AIDS and KS patient sera. The global proteome approach has the additional advantage of not only likely providing much new data discovery about novel KSHV antigens and epitopes, but also potentially of being used as a Pan-herpesvirus immune assessment test chip for both humoral and T-cell mediated immunity in all relevant patients. PUBLIC HEALTH RELEVANCE: Narrative: This project responds to an RFA OD-09-004 for early exploratory research on the development of vaccines for AIDS Malignancies. We propose to attempt to assemble in insect cell culture DNA-free virus-like particles (VLP) as potential preventative vaccines against Kaposi's sarcoma, which is caused by the herpesvirus KSHV. The immune responses to these experimental VLP will be assessed with the first steps in development of an innovative new global high-throughput assay approach for identifying and measuring viral proteins as targets for humoral (neutralizing antibodies) and T-cell-mediated immune responses to KSHV and other human herpesviruses in AIDS patients.