Serologic response to human papillomavirus 16 among Australian women with high-grade cervical intraepithelial neoplasia

This study evaluated the detection of human papillomavirus (HPV) 16 antibody in HPV 16-associated cervical intraepithelial neoplasia (CIN) in Australian women. Seroreactivity to HPV 16 L1 virus-like particles was assessed in patients with CIN 2 (n = 169) and CIN 3 (n = 229) lesions previously tested for the presence of HPV DNA. Seropositivity was significantly commoner in women with HPV 16 DNA-positive lesions (98/184) than in women with no HPV DNA in the lesion (15/47) or with HPV of types other than 16 in the lesion (43/167) (P = 0.0004). In addition, seropositivity was observed in 33% (55/169) of women with CIN 2 and 46% (106/229) of women with CIN 3, in keeping with the lower fraction of CIN 2 (57/169) than CIN 3 (127/229) biopsies positive for HPV 16 DNA. HPV 16 seropositivity is most common in women with HPV 16-associated CIN, but many patients with HPV-associated CIN 3 are seronegative, and HPV 16 seropositivity is common in women with CIN associated with other HPV types. Overall, HPV 16 serology is a poor predictor of presence of HPV 16-associated CIN 3 in patient population studied.

Assembly of Human Papillomavirus Type-16 Virus-Like Particles: Multifactorial Study of Assembly and Competing Aggregation

Pentameric capsomeres of human papillomavirus capsid protein L1 expressed in Escherichia coli self-assemble into virus-like particles (VLPs) in vitro. A multifactorial experimental design was used to explore a wide range of solution conditions to optimize the assembly process. The degree of assembly was measured using an enzyme-linked immunosorbent assay, and a high-throughput turbidity assay was developed to monitor competing aggregation. The presence of zinc ions in the assembly buffer greatly increased the incidence of aggregation and had to be excluded from the experiment for meaningful analysis. Assembly of VLPs was optimal at a pH of about 6.5, calcium and sodium ions had no measurable effect, and dithiothreitol and glutathione inhibited assembly. Tryptophan fluorescence spectroscopy demonstrated that an increase in urea concentration reduced the rate of VLP formation but had no effect on the final concentration of assembled VLPs. This study demonstrates the use of the hanging-drop vapor-diffusion crystallization method to screen for conditions that promote aggregation and the use of tryptophan fluorescence spectroscopy for real-time monitoring of the assembly process.