ROLE OF CONFORMATIONAL EPITOPES EXPRESSED BY HUMAN PAPILLOMAVIRUS MAJOR CAPSID PROTEINS IN THE SEROLOGIC DETECTION OF INFECTION AND PROPHYLACTIC VACCINATION

Human papillomaviruses (HPVs) cause a variety of cutaneous warts, muco sal condylomata, and dysplasias and are etiologic in cervical cancer. Papillomavirus (PV) conformational epitopes on the surface of virions are type-specific and are the target of neutralizing antibodies. In th is study, we describe two methods of in vitro expression of HPV major capsid (L1) proteins which mimicked conformational epitopes and demons trate their type specificity and ability to react with neutralizing an d/or conformation-dependent antibodies. The L1 open reading frames (OR Fs) for HPV-1, 6, 11, and 16 were molecularly cloned into a SV 40 expr ession vector and the encoded gene products were expressed in mammalia n (cos) cells. Similarly, the L1 ORFs for HPV-6, 11, 16, and 18 were m olecularly cloned into recombinant baculovirus and the encoded gene pr oducts were expressed in insect (SF9) cells. The expressed L1 proteins reacted by immunofluorescence and immunoprecipitation with polyclonal and monoclonal antibodies generated against their corresponding nativ e virions and by Western blotting with antibodies that recognized nonc onformational epitopes of denatured virions. The recombinant L1 protei ns expressed conformational epitopes in both cos and Sf9 cells that we re type-specific and displayed neutralizing epitopes. The ability to e xpress, purify, and qualitate the reactivity of recombinant L1 protein s will now permit the serologic analysis of host response to HPV infec tion and the development of prophylactic PV subunit vaccines. (C) 1994 Academic Press, Inc.