title: Genotype-specific incidence and clearance of human papillomavirus in oral mucosa of women: a six-year follow-up study.
abstract: BACKGROUND
  There are no previous longitudinal studies on genotype-specific natural history of human papillomavirus (HPV) infections in oral mucosa of women.
  
  
  METHODS
  In the Finnish Family HPV Study, 329 pregnant women were enrolled and followed up. HPV-genotyping of oral scrapings was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). Incidence and clearance times and rates for each HPV-genotype identified in oral mucosa were determined. Predictors for incident and cleared HPV infections for species 7/9 genotypes were analyzed using Poisson regression model.
  
  
  RESULTS
  Altogether, 115 baseline HPV-negative women acquired incident oral HPV infection, and 79 women cleared their infection. HPV16 and multiple HPVs most frequently caused incident infections (65% and 12%) in 13.3 and 17.1 months respectively, followed by HPV58, HPV18 and HPV6 (close to 5% each) in 11-24 months. HPV58, HPV18 and HPV66 were the most common to clear. HPV6 and HPV11 had the shortest clearance times, 4.6 months and 2.5 months, and the highest clearance rates, 225.5/1000 wmr and 400/1000 wmr, respectively. The protective factors for incident oral HPV-species 7/9 infections were 1) new pregnancy during follow-up and 2) having the same sexual partner during FU. Increased clearance was related with older age and a history of atopic reactions, whereas previous sexually transmitted disease and new pregnancy were associated with decreased clearance.
  
  
  CONCLUSIONS
  HPV16 was the most frequent genotype to cause an incident oral HPV-infection. Low risk HPV genotypes cleared from oral mucosa more quickly than high risk HPV genotypes. Pregnancy affected the outcome of oral HPV infection.
authors.affiliation: Department of Oral Pathology, Institute of Dentistry, Faculty of Medicine and Medicity Research Laboratory, University of Turku, Turku, Finland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Louvanto
authors.forename: Jaana
authors.initials: J
authors.lastname: Rautava
authors.forename: Jaana
authors.initials: J
authors.lastname: Willberg
authors.forename: Lilli
authors.initials: L
authors.lastname: Wideman
authors.forename: Kari
authors.initials: K
authors.lastname: Syrjänen
authors.forename: Seija
authors.initials: S
authors.lastname: Grénman
authors.forename: Stina
authors.initials: S
authors.lastname: Syrjänen
mesh_terms: D000328:Adult; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D005814:Genes, Viral; D005838:Genotype; D052162:Human papillomavirus 16 / Q000235:genetics; D006801:Humans; D015994:Incidence; D009061:Mouth Mucosa / Q000821:virology*; D027383:Papillomaviridae / Q000235:genetics* / Q000378:metabolism; D030361:Papillomavirus Infections / Q000175:diagnosis / Q000378:metabolism*; D016012:Poisson Distribution; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000821:virology; D012725:Sexual Behavior