A global proficiency study of Human Papillomavirus genotyping.

Internationally comparable quality assurance of Human Papillomavirus (HPV) DNA detection and typing methods is essential for evaluation of HPV vaccines and effective monitoring and implementation of HPV vaccination programs. Therefore, the World Health Organisation (WHO) HPV Laboratory Network (LabNet) designed an international proficiency study. Following announcement at the WHO website, responding laboratories performed HPV typing using one or more of their usual assays on 43 coded samples composed of titration series of purified plasmids of sixteen HPV types (HPV 6, 11, 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68). A detection of at least 50 International Units (IU) of HPV16 or HPV18 DNA and of 500 genome equivalents (GE) of the other 14 HPV types (in samples with single and multiple HPV types) was considered proficient. Fifty-four laboratories worldwide submitted a total of 84 data sets. There were more than 21 HPV genotyping assays used. Commonly used methods were Linear Array, Lineblot, Inno-LiPa, Clinical-Array, type-specific real-time PCR, PCR-Luminex and microarray assays. The major oncogenic HPV types (HPV16 and 18) were detected in 89.7% (70/78) and 92.2% (71/77) of data sets, respectively. HPV types 56, 59 and 68 were the least commonly detected types (in less than 80 % of data sets). Twenty-eight data sets reported multiple false positive results and were considered non-proficient. In conclusion, we found that international proficiency studies, traceable to International Standards, allow a standardised quality assurance of different HPV typing assays and enables a comparison of data generated from different laboratories worldwide.