Richard J. Jewers

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

Polyclonal antibodies were raised to partial and full-length synthetic peptides of human papillomavirus type 16 (HPV-16) E5. Antisera specificity for HPV-16 E5 was demonstrated by their ability to recognize not only their peptide immunogens but also full-length peptide and a glutathione S-transferase-E5 fusion protein. The most reactive antiserum, PE-6, raised to a full-length peptide, was used in Western blot analysis to identify HPV-16 E5 protein from exfoliated cervical cells. A strong, single band at approximately 20K was detected in two of six HPV-16-positive samples from women with a history of low-grade cervical intraepithelial neoplasia. The apparent M(r) by SDS-PAGE suggests that HPV-16 E5 forms homodimers in vivo, but not through cysteine linkage.

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

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 BPV-1 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 type-specific 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.

Detection of Class-Specific Antibodies to Baculovirus-Derived Human Papillomavirus Type 16 (HPV-16) Capsid Proteins

Seroepidemiological. studies on the prevalence of HPV16 infections are not possible as HPVs cannot be grown in conventional. cell cultures and premalignant and malignant cervical. lesions contain few intact HPV-16 particles and only low levels of native viral. proteins. Whilst HPV-31b has been propagated in vitro 1 and HPV-16 virions have been produced in nude mice2, virus yields are low. Peptides and prokaryotic fusion proteins have therefore been used as antigens for serological. studies3,4. As such constructs probably represent poor imitations of native viral. proteins5, we have expressed the L1 and L2 proteins of HPV-16 in insect cells (via recombinant Autographa californica nuclear polyhedrosis virus: AcMNPV) for serological. studies.

Cancer-Associated Human Papillomaviruses: Perinatal Transmission and Persistence

OBJECTIVE To demonstrate the perinatal transmission and persistence of the cancer associated human papillomavirus types 16, 18, 31 and 33. DESIGN Cervical swabs were taken from pregnant women between 20 and 38 weeks of gestation. Buccal and genital swabs were taken from infants at 24 h and at six weeks after delivery and examined for HPV-16, -18, -31 and -33 DNA by the polymerase chain reaction. SETTING Maternity Unit at St Thomass Hospital, London. SUBJECTS Thirty-one pregnant women, 16 with a previous history of cervical intraepithelial neoplasia or genital warts, or both, and their 32 infants (one set of twins). RESULTS Twenty of the 31 (65%) women were positive for HPV-DNA prior to delivery. Twelve of 32 (38%) and eight of 31 (26%) infants were HPV-DNA positive at 24 h and six weeks respectively. Swabs taken at 24 h demonstrated HPV type 16 in five mother-infant pairs and HPV type 18 in two mother-infant pairs. Dual infections with HPV types 16 and 18 were demonstrated in swabs from three mother-infant pairs. At six weeks, HPV-16 was demonstrated in swabs from six infants and HPV-18 in swabs from two infants. CONCLUSIONS Perinatal transmission of human papillomavirus types 16 and 18 occurred in 55% cases. Persistent human papillomavirus infection was demonstrated at six weeks of age. Whether acquisition of human papillomavirus during the perinatal period predisposes to an increased risk of cervical intraepithelial neoplasia among female infants in later life remains to be established. Information on the persistence of perinatally acquired human papillomavirus is required before rational vaccination programmes can be considered.

Perinatal Transmission and Persistence of the Cancer Associated Human Papillomaviruses

There is currently an increasing interest in developing prophylactic and therapeutic vaccines against the human papillomavirus types (HPV 16, 18, 31, 33) associated with cervical. cancer. 1 Although techniques are available to produce such HPV-16 vaccines, knowledge of the natural. history of these infections is required before rational. vaccination programmes can be designed. Perinatal. transmission of HPV types 6 and 11 has been demonstrated.2 This may occasionally lead to the development of the juvenile respiratory papillomatosis. However, the perinatal. acquisition and possible persistence of the cancer associated HPV types have been largely ignored.