The original SPF10 LiPA25 algorithm is more sensitive and suitable for epidemiologic HPV research than the SPF10 INNO-LiPA Extra

Abstract

Two commercial HPV tests target the same 65 bp fragment of the human papillomavirus genome (designated SPF10): the original HPV SPF10 PCR-DEIA-LiPA25 system, version 1, (LiPA25) and the INNO-LiPA HPV Genotyping Extra (INNO-LiPA). The original SPF10 LiPA25 system was designed to have high analytical sensitivity and applied in HPV vaccine and epidemiology studies worldwide. But due to apparent similarities, this test can be easily confused with INNO-LiPA, a more recent assay of which the intended use, i.e., epidemiological or clinical, is currently unclear. The aim was to compare the analytical sensitivity of SPF10 LiPA25 to that of INNO-LiPA on the level of general HPV detection and genotyping. HPV testing by both assays was performed on the same DNA isolated from cervical swab (n = 365) and biopsy (n = 42) specimens. In cervical swabs, SPF10 LiPA25 and INNO-LiPA identified 35.3% and 29.3% multiple infections, 52.6% and 51.5% single infections, and no HPV type in 12.1% and 19.2%, respectively. Genotyping results were 64.7% identical, 26.0% compatible and 9.3% discordant between both methods. SPF10 LiPA25 detected significantly more genotypes (p < 0.001). The higher analytical sensitivity of SPF10 LiPA25 was confirmed by the MPTS123 genotyping assay. HPV positivity by the general probes in SPF10 DEIA was significantly higher (87.9%) than by those on INNO-LiPA (77.0%) (kappa = 0.592, p < 0.001). In cervical biopsies, SPF10 LiPA25 and INNO-LiPA identified 21.4% and 9.5% multiple types, 76.2% and 81.0% single types, and no type in 2.4% and 9.5%, respectively. Between both tests, the identification of genotypes was 76.3% identical, 14.3% compatible and 9.5% discordant. Overall, significantly more genotypes were detected by SPF10 LiPA25 (kappa = 0.853, p = 0.022). HPV positivity was higher by the SPF10 DEIA (97.6%) than by the INNO-LiPA strip (92.9%). These results demonstrate that SPF10 LiPA25 is more suitable for HPV genotyping in epidemiologic and vaccine-related studies, due to its higher analytical sensitivity.

Keywords: Epidemiology; Genotyping; Human papillomavirus; INNO-LiPA; LiPA(25); SPF(10).