Sera from cattle that had been inoculated with BPV-1 virions or with recombinant L1 proteins and serum from a rabbit that had been immunized with SDS-denatured virions were evaluated for their reactivity with 466 overlapping synthetic peptides corresponding to 95% of the BPV-1 L1 protein. The late serological response of cattle to both intact virions and recombinant L1 proteins exhibited a similar profile of reactivity with approximately 70% (7 of 10) of L1 antigenic sites. However, the L1 serological response of the rabbit to SDS-denatured virions exhibited a significant difference from bovine serum antibodies in the profile of epitopes recognized, including a relative lack of response to major bovine epitopes located between L1 amino acids (AAs) 300-400. Importantly, only the sera from animals inoculated/immunized with intact virions was capable of neutralizing BPV-1 infectivity of murine C127 cells, suggesting that nonlinear epitopes are important for papillomavirus neutralization.

Four of five groups of Holestine by Angus calves (5 calves/group) were immunized with different formulations of a recombinant BPV-1 DNA vaccine using a BPV-1 major capsid:B-galactosidase fusion protein as the immunogen. Group 5 was not vaccinated. Vaccinated calves received the vaccine on days 0 and 21 of the trial, and calves from all five groups were challenged intradermally with 10(10) BPV-1 particles at each of two different sites on day 56. All calves were bled on days 3, 24, 55, 77, and 104 of the trial, and the sera were tested for reactivity with intact and disrupted BPV-1 particles by ELISA. At the time of challenge with BPV-1 virions (day 56), 19 of 20 vaccinated calves were seropositive for disrupted BPV-1 particles; sera from 3 of 20 calves reacted with intact BPV-1 virions. By day 77, 11 of 19 vaccinated calves had developed antibody titers to intact BPV-1 virions; only 1 calf in group 5 developed antibodies (transiently) against BPV-1 capsid epitopes. After challenge, 24 of 25 calves from the five groups developed intradermal fibromas, the biological end point of this study. Fibromas appeared to increase in size in group 5 (unvaccinated, inoculated controls), whereas most tumors from the four vaccinated groups (1-4) stabilized or decreased in size. Although the calves developed fibromas, 90% of calves (in groups 1-4) developed antibodies against disrupted BPV-1 capsid proteins whereas 58% developed antibodies that reacted with intact virions. The immunologic response of vaccinated calves to intact and disrupted BPV-1 particles appeared to be determined in large part by the various formulations of the vaccine, particularly the adjuvant.

Monoclonal (MAbs) and polyclonal antibodies were produced against the major capsid protein of detergent-disrupted, purified bovine papillomavirus type 1 (BPV-1). The precise locations of the corresponding epitopes were identified by the reactivity of MAbs and selected polyclonal antibodies with synthetic, overlapping, hexameric peptides corresponding with 95% of the BPV-1 major capsid protein. The topography of these epitopes was determined by reactivity of antibodies with intact (conformational and nonconformational surface epitopes) and disrupted (external or internal nonconformational epitopes) BPV-1 virions. The distribution of epitopes in various papillomaviruses of 13 different species was determined by reactivity of the MAbs and polyclonal sera with productively infected, formalin-fixed papillomas, fibropapillomas, and fibromas. Epitope scanning, using MAbs and polyclonal antisera, resulted in the precise location of BPV-1 hexameric epitopes that could be correlated with their topography on the capsid and distribution in papillomatous lesions of various species.

Thirty plantar warts were analyzed for the presence of HPV‐1 type‐specific and PV genus‐specific capsid antigens by immunofluorescence (IF) using monoclonal and polyclonal antibodies and type‐specific HPV‐1 DNA employing in situ hybridization methods. Fifteen of 30 plantar warts were positive by IF for PV genus‐specific structural viral antigens. Thirteen of the 15 productively infected plantar warts expressed intranuclear HPV‐1 type‐specific capsid antigens and viral DNA, which were detected in the same distribution in each individual wart. The 2 productively infected plantar warts that did not react with HPV‐1 type‐specific MoAbs did not react with HPV‐1 type‐specific DNA by in situ hybridization. Thus, serotyping of HPV‐1 capsid antigens by monoclonal antibodies is concordant with genotyping of HPV‐1 viral DNA by in situ hybridization in productively infected plantar warts.

Monoclonal antibodies against SDS-disrupted bovine papillomavirus type 1 (BPV1) were obtained from hybridomas prepared by fusing mouse myeloma cell line P3X63Ag8U1 with spleen cells from immunized BALB/c mice. Six hybridoma cell lines were obtained after testing supernatant fluids for positivity by the enzyme-linked immunosorbent assay using the immunogen as antigen and by indirect immunofluorescence (IF) on frozen sections of BPV1-induced bovine fibropapillomas. Monoclonal antibodies (AU1-AU6) from these hybridomas were then tested for reactivity by IF tests on BPV2-induced fibropapillomas and on human plantar warts and vulvar condylomas and by avidin-biotin complex tests on sections of formalin-fixed cervical dysplasias. One monoclonal antibody (AU1) was reactive with all tissues, four (AU3-AU6) were reactive with both BPV1 and BPV2 fibropapillomas, and the remaining antibody (AU2) was only reactive with BPV1-induced fibropapillomas. All monoclonal antibodies reacted with the major capsid protein (mol. wt. 54,000) of BPV1, whereas five (AU1, AU3-AU6) reacted with the major capsid protein of BPV2. These results indicate that papillomavirus genus-specific, cross-reactive, and type-specific antigenic determinants are located on the major capsid protein of BPV1.

HPVs are associated with a variety of proliferative squamous lesions. 27 different types of HPV have been identified by DNA molecular hybridization studies. Genus- and type-specific HPV structural antigens can be detected in approximately half of benign warts and condylomata by immunocytochemistry; positive lesions are considered infectious. Genus- and type-specific putative HPV DNA sequences replicating as episomes can be recovered from the majority of benign (exophytic and flat condylomata) and malignant squamous lesions of the cervix and anogenital area. The type of HPV determines, in part, the anatomic site, clinical appearance, and natural history (including potential malignant conversion) of the lesion.