title: Human papillomavirus type 16 viral load measurement as a predictor of infection clearance.
abstract: Viral load measurements may predict whether human papillomavirus (HPV) type 16 infections may become persistent and eventually lead to cervical lesions. Today, multiple PCR methods exist to estimate viral load. We tested three protocols to investigate viral load as a predictor of HPV clearance. We measured viral load in 418 HPV16-positive cervical smears from 224 women participating in the Ludwig-McGill Cohort Study by low-stringency PCR (LS-PCR) using consensus L1 primers targeting over 40 known HPV types, and quantitative real-time PCR (qRT-PCR) targeting the HPV16 E6 and L1 genes. HPV16 clearance was determined by MY09/11 and PGMY PCR testing on repeated smears collected over 5 years. Correlation between viral load measurements by qRT-PCR (E6 versus L1) was excellent (Spearman's rank correlation, ρ = 0.88), but decreased for L1 qRT-PCR versus LS-PCR (ρ = 0.61). Viral load by LS-PCR was higher for HPV16 and related types independently of other concurrent HPV infections. Median duration of infection was longer for smears with high copy number by all three PCR protocols (log rank P<0.05). Viral load is inversely related to HPV16 clearance independently of concurrent HPV infections and PCR protocol.
authors.affiliation: Laboratoire de santé publique du Québec, Institut national de santé publique, 20045, Chemin Sainte-Marie, Sainte-Anne-de-Bellevue, Québec, H9X 3R5, Canada.|Ludwig Institute for Cancer Research, R. João Julião, 245, 01323-903 São Paulo, SP, Brazil.
authors.forename: Andrea
authors.initials: A
authors.lastname: Trevisan
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Nicolas F
authors.initials: NF
authors.lastname: Schlecht
authors.affiliation: Division of Cancer Epidemiology, McGill University, 546 Pine Avenue West, Montreal, Quebec, H2W 1S6, Canada.
authors.forename: Agnihotram V
authors.initials: AV
authors.lastname: Ramanakumar
authors.affiliation: HPV Institute, School of Medical Sciences, Santa Casa de São Paulo, 01223-001 São Paulo, SP Brazil.|Dept of Radiology and Basic Oncology, School of Medicine, University of São Paulo, ICESP, Av Dr Arnaldo 251, 8th floor, 01246-000 São Paulo, SP, Brazil.|Ludwig Institute for Cancer Research, R. João Julião, 245, 01323-903 São Paulo, SP, Brazil.
authors.forename: Luisa L
authors.initials: LL
authors.lastname: Villa
authors.affiliation: Division of Cancer Epidemiology, McGill University, 546 Pine Avenue West, Montreal, Quebec, H2W 1S6, Canada.
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: Franco
authors.affiliation: See acknowledgments for details.
authors.lastname: The Ludwig-McGill Study Group
mesh_terms: D005260:Female; D052162:Human papillomavirus 16 / Q000302:isolation & purification*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods; D030361:Papillomavirus Infections / Q000175:diagnosis / Q000821:virology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D019562:Viral Load / Q000379:methods*