Human papillomavirus type 16 E2- and L1-specific serological and T-cell responses in women with vulval intraepithelial neoplasia

Abstract

Human papillomavirus type 16 (HPV-16)-associated vulval intraepithelial neoplasia (VIN) is frequently a chronic, multifocal high-grade condition with an appreciable risk of progression to vulval cancer. The requirement to treat women with VIN has recently stimulated the use of immunotherapy with E6/E7 oncogene vaccines. Animal models have shown that E2 may also be a useful vaccine target for HPV-associated disease; however, little is known about E2 immunity in humans. This study investigated the prevalence of HPV-16 E2-specific serological and T-cell responses in 18 women with HPV-16-associated VIN and 17 healthy volunteers. E2 responses were determined by full-length E2-GST ELISA with ELISPOT and proliferation assays using E2 C-terminal protein. As positive controls, HPV-16 L1 responses were measured using virus-like particles (VLPs) and L1-GST ELISA with ELISPOT and proliferation using VLPs as antigen. The VIN patients all showed a strong serological response to L1 compared with the healthy volunteers by VLP (15/18 vs 1/17, P<0?001) and L1-GST ELISA (18/18 vs 1/17, P<0?001). In contrast, L1-specific cellular immune responses were detected in a significant proportion of controls but were more prevalent in the VIN patients by proliferation assay (9/17 vs 17/18, P<0?02) and interferon-c ELISPOT (9/17 vs 13/18, P=not significant). Similar and low numbers of patients and controls were seropositive for E2-specific Ig (2/18 vs 1/17). In spite of previous studies showing the immunogenicity of E2 in eliciting primary T-cell responses in vitro, there was a low prevalence of E2 responses in the VIN patients and controls (2/18 vs 0/17).

Distinct regulation and impact of type 1 T‐cell immunity against HPV16 L1, E2 and E6 antigens during HPV16‐induced cervical infection and neoplasia

“…Analysis of HPV16 L1 peptide-specific immunity in patients with HPV161 CIN II/III also revealed that the vast majority of these subjects displayed strong type 1 T-cell immunity against this antigen, corroborating the data of others. [21][22][23]34 In addition, this study shows that strong HPV16 L1 peptide-specific type 1 T-cell immunity is also present in the majority of patients with an HPV161 cervical carcinoma. These responses were covering a broad range of peptides within L1, suggesting that during persistent or repeated exposure to HPV16 L1, the immune system maximizes its efforts to counter the viral challenge.…”

“…[21][22][23]33,34 To obtain more detailed information about the magnitude, specificity and functionality of T-cell responses against HPV16 L1, we incubated PBMC isolated from the blood of a group of 20 healthy donors with an overlapping set of 30-mer peptides covering the entire HPV16 L1 sequence and tested T-cell reactivity by IFNg ELISPOT assay. In addition, PBMC were incubated with HPV16 E6 peptides to relate the reactivity against L1 with our previous findings for early antigens.…”

Identification of B-Cell Epitopes on Virus-Like Particles of Cutaneous Alpha-Human Papillomaviruses

“…This screening strategy might have favored the selection of hybridoma clones producing MAbs that preferentially recognize linear epitopes. However, the GST-L1 capture ELISA was previously demonstrated to be equivalent to VLP ELISA (19,46). Moreover, Rizk et al previously showed that MAbs raised against VLPs and that recognize conformation-dependent epitopes also bind to GST-L1 fusion proteins, suggesting that they display most conformational and neutralizing epitopes (41).…”

Human papillomavirus in cervical screening and vaccination

“…Most studies have concentrated on measuring HPV16 E6-and/or E7-specific immune responses, since these antigens are continuously expressed throughout the full spectrum of HPV-associated disease development [32]. More recently, E2-specific T-cell responses have been reported in patients and healthy volunteers alike, although the relationship between the measured immunity and disease outcome is unclear [25,33,34]. Taking all of these results together, it appears that the specific type(s) of cellular immunity that an individual mounts in response to an HPV infection may influence its outcome.…”