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Impact of HPV Assay on Observed Population Prevalence

Unger, Elizabeth R. PhD, MD; Steinau, Martin PhD; Lin, Jin-Mann S. PhD; Patel, Sonya S. BS; Swan, David C. PhD

Diagnostic Molecular Pathology: June 2011 - Volume 20 - Issue 2 - p 101–104
doi: 10.1097/PDM.0b013e3181f56fa5
Original Articles

Type-specific surveillance of human papillomavirus (HPV) has been proposed as an early indicator of vaccine impact. Longitudinal comparison of HPV typing results requires stable assays with high type-specific reproducibility. Assays are evolving and the impact of even minor changes in the assay format may be difficult to anticipate. We initiated a population-based study of HPV with the prototype line blot (PLB) assay. These reagents were replaced by the research use only Linear Array (LA) HPV Genotyping kit. The assays are similar in principle and earlier comparisons found increased sensitivity and detection of more types per sample with LA; however, in samples from women with cervical abnormalities, the overall concordance was good. Slight changes in sensitivity may be more significant in samples from a general population with lower viral loads in the samples. Residual extracts from 3001 self-collected vaginal swabs from women in the general US population originally tested with PLB were retested with LA. With LA, all the samples were hybridized. PLB hybridization was restricted to samples with probable amplicon in gel electrophoresis. For HPV detection, the agreement between the 2 assays was 78.6% (κ=0.55) with a positive concordance of 52.8%. However, this masks the observation that repeat testing with LA led to the detection of HPV in nearly twice as many samples. Agreement improves if comparison was restricted to the samples hybridized. These results emphasize that assay comparisons should consider the clinical-epidemiologic context of sample collection. Studies designed to examine temporal trends in type-specific prevalence should archive residual material to permit retesting if assays change.

Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic, Infectious Diseases (proposed), Chronic Viral Diseases Branch Atlanta, GA

Disclaimer: The findings and conclusions in this report are hose of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

Reprints: Elizabeth R. Unger PhD, MD, Centers for Disease Control and Prevention, MS G41, Atlanta, GA (e-mail:

© 2011 by Lippincott Williams & Wilkins.