Serological differentiation of human papillomavirus types 11, 16 and 18 using recombinant virus-like particles.

The L1 major capsid protein-coding sequences of human papillomavirus (HPV) types 11, 16 and 18 were expressed in the baculovirus system. Virus-like particles (VLPs) were purified from recombinant-infected Spodoptera frugiperda Sf9 cells and cell-free culture supernatants. Rabbits immunized with purified VLPs developed antibodies that reacted only with the specific VLP type used as the immunogen. In addition, rabbit antibodies raised against infectious HPV-11 virions only reacted with HPV-11 L1 VLPs and not with VLPs derived from either HPV-16 or HPV-18. These results suggest that HPV-11, HPV-16 and HPV-18 virions are antigenically distinct from one another. This observation should be considered in future studies of immune responses to HPV.

Evaluation of temperature sensitivity of human papillomavirus type 11 by using the human xenograft severe combined immunodeficiency mouse model.

The temperature sensitivity of human papillomavirus type 11 was evaluated by using a human xenograft severe combined immunodeficiency mouse model. Incubation of the virus for 1 h at a temperature higher than 56 degrees C but lower than 72 degrees C was sufficient to inhibit the virally induced growth of infected human tissue. However, 100 degrees C was necessary to completely inactivate HPV type 11 genome expression.

Propagation of human papillomavirus type 11 in human xenografts using the severe combined immunodeficiency (SCID) mouse and comparison to the nude mouse model.

We report propagation of human papillomavirus (HPV) type 11 in human xenografts in the severe combined immunodeficiency (SCID) mouse and compare this new animal model for HPV infection to the previously established athymic nude mouse model. HPV-11-infected foreskin fragments grafted under the renal capsule of SCID mice formed large epithelial cysts that had the histologic and immunocytochemical features of HPV infection. This infection was successfully passaged to nude mice. Viral particles that reacted to an antibody directed to HPV-11 virions were identified from samples recovered from the SCID and nude mice. Viral DNA sequence analysis confirmed that the passaged virus was HPV-11. In a comparative experiment of the nude mouse and SCID mouse models, the latter produced HPV-11-infected xenografts that were larger and more often positive for HPV by immunocytochemistry and presence of viral mRNA than those propagated in the former model. Finally, we observed that growth of HPV-11-infected foreskin fragments in the SCID mouse model is not restricted to the kidney as in the nude mouse, but also can occur in the subcutis and the peritoneum.

Evolution of the antibody response to human papillomavirus type 11 (HPV-11) in patients with condyloma acuminatum according to treatment response.

To evaluate the variation over time of seroreactivity to human papillomavirus type 11 (HPV-11) according to disease outcome, we selected a sample of 42 condyloma acuminatum patients from a group of subjects enrolled in a placebo-controlled trial of three alpha-interferon preparations administered parenterally for the treatment of condyloma acuminatum. This sample included 14 subjects who were cured by the end of follow-up (cured group) and 28 subjects who were not (failed group). For each individual, the first and last sera collected in the study were tested with an intact HPV-11 virion-based enzyme linked immunosorbent assay (ELISA). The sera of 20 nuns with no lifetime sexual exposure served as controls. The median optical density (OD) value of the first serum samples (as well as that of the last samples) from the patients, 0.155, was higher than that of the control sera, 0.073 (P = 2 x 10(-4)). Sensitivity of the assay was 50%. To test if evolution of seroreactivity in the seropositive patients was related to disease outcome after treatment, we examined the average percentage of daily change in OD between the two serum collections. The median OD in the cured group (n = 7) dropped by 0.05% a day whereas in the failed group (n = 11) it increased by 0.07% a day, a highly statistically significant difference (P = 0.006). It is concluded that changes in the seroreactivity to HPV-11 virions are related to outcome of condyloma acumination after treatment. Therefore, improved serological assays may eventually contribute to the monitoring of HPV disease activity.

Use of human papillomavirus type 11 virions in an ELISA to detect specific antibodies in humans with condylomata acuminata.

Human papillomavirus types 6 and 11 (HPV-6 and HPV-11) are the major aetiological agents of condylomata acuminata. Serological studies of this disease have been difficult to perform and interpret because native, type-specific antigens have not been available. In particular, since these viruses have not been propagated in vitro and sufficient quantities of virions are not present in lesions, virus particles have been difficult to obtain. In the present study, we used HPV-11 particles, obtained from human tumours produced in athymic mice, as antigen in an ELISA to compare antibody responses between 46 patients with biopsyproven condylomata acuminata and 44 controls. The median [interquartile range] of the absorbance values for the condylomata acuminata and the control groups were respectively 0.324 [0.183, 1.029] and 0.118 [0.047, 0.286] (P = 0.0001). Thirty-three per cent of the absorbance values in the condylomata acuminata group were higher than any of those of the control group. Sera from patients whose biopsies contained the papillomavirus common antigen were more reactive than sera from patients whose biopsies did not contain it (P = 0.0014). This study demonstrates the presence of specific antibodies directed at native HPV-11 viral particles in the sera of patients with condylomata acuminata, and describes a test which can be used in future serological studies of this common sexually transmitted disease.