Mapping of linear B cell epitopes on capsid proteins of bovine papillomavirus: identification of three external type-restricted epitopes

Abstract

Immunodominant, conserved and type-restricted external epitopes of bovine papillomavirus (BPV) major (L1) capsid protein have been identified using BPV particles and synthetic peptides. Antisera to disrupted BP¥-I recognized BPV-1 and BPV-2 particles in immune electron microscopy (IEM) studies and inhibited BPV-2-induced focus formation of NIH/3T3 cells. Thus BPV-1/BPV-2 cross-reactive epitopes occur on the surface of virions. The L1 protein appeared to be immunodominant as the antisera reacted with three dominant BPV-1/BPV-2 conserved B cell epitopes (amino acids 111 to 125, 131 to 145 and 191 to 205) in Pepscan assays of BPV-1 L1, whereas no common epitopes and less frequent antibody binding to peptides were detected in Pepscans of the L2 protein of BPV-1.Four discrete variable regions were identified in the sequences of L1 proteins of BPV-1 and BPV-2. Antisera against synthetic peptides corresponding to three of the four variable regions (amino acids 42 to 56, 435 to 449 and 485 to 499) of BPV-2 L1 caused clumping of BPV-2, but not of BPV-1, particles as examined by IEM, and antisera to one peptide (amino acids 485 to 499) inhibited BPV-2-induced focus formation of NIH/3T3 cells. These data suggest that these regions are typespecific BPV-2 L1 epitopes and that they occur on the virion surface. Although conformation-dependent epitopes remain to be identified on papillomaviruses, the linear epitopes identified in this study may be worthy of further study as constituents of experimental prophylactic vaccines.

Human papillomavirus type 16 capsids expose multiple type-restricted and type-common antigenic epitopes

“…The staining pattern of these monoclonal antibodies was type-restricted, although cross-reactivity with HPV-2 was found. Our antipeptide antibodies directed at the corresponding region of L1 (peptides 20, 21 and 22 at positions 287-306, 302-321 and 317-336) stained most genital HPV types tested and did not stain the skin warts, indicating that the epitopes recognized by our sera are not the same as those studied by Cason et al In a subsequent study, four unconjugated synthetic peptides derived from L1 of BPV type 2 were injected into rabbits, whereafter 3/4 (75 %) rabbit sera were found to induce clumping of viral particles (Cason et al, 1993). None of the regions thus identified as potentially surface-exposed correspond to the major surface-exposed regions identified in this study.…”

The immunology of animal papillomaviruses

“…The focus-forming ability of 220 bovine papillomaviruses in NIH/3T3 cell cultures has been used to confirm and map the neutralising abilities of anti-221 BPV antibodies (Cason et al, 1993). A cottontail rabbit epidermal cell line was used to demonstrate type-specific 222 neutralising activity by monoclonal antibodies to CRPV, but not HPV-11 (Angell et al, 1992).…”

Detection of E5 oncoprotein in human papillomavirus type 16-positive cervical scrapes using antibodies raised to synthetic peptides

“…1; Kyte & Doolittle, 1982). Fmoc amino acids (Milligen) were coupled on UltraSyn-C resin (Novabiochem), cleaved using trifluoroacetic acid with appropriate scavengers and freeze dried, as previously described (Cason et al, 1993). Before their use as immunogens, peptides were conjugated to keyhole limpet haemocyanin (Sigma) using carbodiimide (Doolittle, 1986).…”