Identification of two cross-neutralizing linear epitopes within the L1 major capsid protein of human papillomaviruses.
The neutralizing activities of polyclonal antibodies and monoclonal antibodies (MAbs) obtained by immunization of mice with L1 virus-like particles (VLPs) were investigated by using pseudovirion infectivity assays for human papillomavirus type 16 (HPV-16), HPV-31, HPV-33, HPV-45, HPV-58, and HPV-59 to obtain a better definition of cross-neutralization between high-risk HPVs. In this study, we confirmed and extended previous studies indicating that most genital HPV genotypes represent separate serotypes, and the results suggest that the classification of serotypes is similar to that of genotypes. In addition, three cross-neutralizing MAbs were identified (HPV-16.J4, HPV-16.I23, and HPV-33.E12). MAb HPV-16.J4 recognized a conserved linear epitope located within the FG loop of the L1 protein, and HPV-16.I23 recognized another located within the DE loop. The results suggested that reactivity of MAb HPV-16.I23 to L1 protein is lost when leucine 152 of the HPV-16 L1 protein is replaced by phenylalanine. This confirmed the existence of linear epitopes within the L1 protein that induce neutralizing antibodies, and this is the first evidence that such linear epitopes induce cross-neutralization. However, the cross-neutralization induced by L1 VLPs represents less than 1% of the neutralizing activity induced by the dominant conformational epitopes, and it is questionable whether this is sufficient to offer cross-protection in vivo.
Combita
Alba-Lucia
AL
Laboratoire de Virologie Moléculaire, INSERM EMIU 00-10 and USC INRA, Philippe Maupas Faculté des Sciences Pharmaceutiques, 31 Avenue Monge, 37200 Tours, France.
Touzé
Antoine
A
Bousarghin
Latifa
L
Christensen
Neil D
ND
Coursaget
Pierre
P
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology; D002213:Capsid / Q000737:chemistry / Q000276:immunology*; D003429:Cross Reactions; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology; D006801:Humans; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D009856:Oncogene Proteins, Viral / Q000737:chemistry / Q000276:immunology*; D027383:Papillomaviridae / Q000145:classification / Q000276:immunology*; D014771:Virion / Q000276:immunology
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D009856:Oncogene Proteins, Viral