Professional Services

Our laboratories can provide medium to high throughput HPV typing, HPV16/18 antibody determinations by ELISA and neutralization assays. Our laboratory can thus participate to world-wide or regional studies.

HPV typing with the PGMY-CHUV assay

The PGMY-CHUV assay associates polymerase chain reaction (PCR) amplification of HPV DNA from cervical samples with reverse blot hybridization of biotinylated amplicons and DNA sequencing. PCRs are performed with the PGMY09/11 primers for HPV and with HLA dQ primers for human DNA detection as an internal positive control. Reactions are analyzed by gel electrophoresis, and positives hybridized against 32 HPV type-specific probes covalently bound as an array of parallel lines on a reusable membrane. For hybridization, heat-denatured amplicons are diluted in hybridization buffer and maintained on the membrane using a miniblotter so that they cross each probe perpendicularly. Hybrids are then revealed by chemiluminescence. Typing of HPV PCR-positives that are hybridization-negative is done by sequencing of the amplicon using the PGMY11 cocktail of primers, and comparison to public databases. This technique is part of our accredited set of diagnostic procedures. The method is accessible in chapter 5 of the WHO HPV Laboratory Manual available online ( 2.5 Mo) at the WHO web site. Its description and validation is in press.

HPV16 and 18 specific antibody detection

Conformational VLP-specific antibodies (IgG or IgA) can be measured in the serum and cervical secretions by ELISA. Our assay is based on the direct coating of VLPs on ELISA plates. There is good correlation between the presence of anti-VLP conformational antibodies and their neutralizing activity, however neutralization assays are the gold standard to assess the protective potential of the antibodies induced by the HPV vaccine. Neutralization assays determine the ability of such antibodies to inhibit infection of target cells by type-specific pseudovirions (type specific VLPs that have encapsidated a reporter DNA) according to the method of Dr. J. Schiller. Briefly, neutralization assays are performed with secreted alkaline phosphatase (SEAP) HPV16 or HPV18 pseudoviruses. Optiprep-purified SEAP HPV16 or 18 pseudoviruses are incubated with two-fold serial sample dilutions, and the pseudovirus-antibody mixtures are used to infect 293TT cells for 3 days. The SEAP content in clarified cell supernatant is then determined.