The performance of three line blot assays (LBAs), the Linear Array HPV genotyping assay (LA) (Roche Diagnostics), INNO-LiPA HPV Genotyping Extra (LiPA) (Innogenetics), and the reverse hybridization assay (RH) (Qiagen), was evaluated using quantitated whole genomic human papillomavirus (HPV) plasmids ( T he introduction of human papillomavirus (HPV) vaccines has highlighted the need for standardized accurate HPV genotyping assays to ensure comparability of results in laboratories worldwide, both before and after vaccine introduction. A large variety of assays, using both in-house methods and commercial kits, are available for HPV detection and typing (6), and more can be anticipated. International proficiency testing organized by the WHO HPV LabNet has documented significant differences in sensitivity, specificity, and reproducibility between different laboratories using a variety of testing platforms (2). Variation in performance for laboratories using the same assay implicates laboratory practice; however, the results also indicated differences between assays. The WHO HPV LabNet has further recognized the need for HPV typing assays that can easily be standardized, require minimal equipment for assay performance and interpretation, and can be used in a variety of laboratory settings. Following its meeting on the standardization of HPV assays and the role of the WHO HPV LabNet in supporting vaccine introduction (WHO, Geneva, Switzerland, 23 to 25 January 2008 [http://www.who.int/biologicals /publications/meetings/areas/vaccines/human_papillomavirus /HPV%20Jan%20meeting%20report_20080909%20_Clean _.pdf]), it was agreed that commercial assay kits should be evaluated in collaborative studies for proficiency.Reverse line blot assays (LBAs), based on consensus amplification of conserved regions of HPV followed by hybridization to type-specific probes on line blot strips, have been widely used. Available LBAs differ in the primer set (1, 3, 4) used in the amplification phase and in the number and sequences of the detection probes. Beyond thermocyclers for target amplifications, only temperature control water baths and visual inspection are required to carry out these assays. Therefore, the LBA platforms have the potential to meet the needs of the WHO for high-performance genotyping that does not involve expensive equipment.Studies have been conducted previously to compare and evaluate the performance of these HPV typing assays. Typically, these were restricted to DNA extracts from patient-collected anogenital specimens, which cannot be validated independently and limit the analysis to relative comparisons and assessments of type prevalence found by the individual assays (5,7,10). The use of plasmid standards offers clear advantages for more objective evaluations beyond that level. Cloned, full-length HPV genomic DNA (gDNA) provides complete control over genotype identity as well as copy number input and eliminates the need for a gold standard test.We selected three commercial LBAs using different primer sets and subjec...