title: Prevalence, genotype distribution and persistence of human papillomavirus in oral mucosa of women: a six-year follow-up study.
abstract: BACKGROUND
  Human papillomavirus (HPV) infections have been linked to a subset of oral and oropharyngeal cancers. However, little is known on the natural history of oral HPV infections. We designed the prospective Finnish HPV Family Study to assess the dynamics of HPV infections in parents and their infants. This study reports HPV genotype distribution and virus persistence in oral mucosa of the mothers.
  
  
  METHODS
  Totally, 324 pregnant women were enrolled at the 3(rd) trimester of pregnancy and followed-up for 6 years. Oral scrapings taken with a brush were collected and HPV-genotyping was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). The predictors of persistent oral HPV species 7/9 infections were analyzed using generalized estimating equation models.
  
  
  RESULTS
  The point prevalence of oral HPV varied from 15% to 24% during the 6-year follow-up. Altogether, 18 HPV genotypes were identified either as single or multiple-type oral infections. HPV16 was the most prevalent type at 9.7%-18.4%, followed by HPV18, HPV6, and multiple infections. Altogether, 74 women had persistent oral HPV infection determined as at least two consecutive samples positive with the same HPV genotype. HPV16 and HPV6 were the two most frequent types to persist (76% and 9%) for a mean of 18.6 and 20.2 months, respectively, followed by multiple infections (8%) for 18.3 months. An increased risk for persistent oral HPV infection with species 7/9 was associated with being seropositive for low-risk (LR)-HPV-types at baseline, whereas the use of oral contraceptives and a second pregnancy during follow-up were protective. Clinical oral lesions were detected in 17% of these women, one-third of whom had persistent oral HPV-infections.
  
  
  CONCLUSIONS
  HPV16 and HPV6 were the most common genotypes in oral HPV-infections and were also most likely to persist. Use of oral contraceptives and a second pregnancy protected against oral HPV persistence.
authors.affiliation: Department of Oral Pathology, Institute of Dentistry, and Medicity Research Laboratory, Faculty of Medicine, University of Turku, Turku, Finland.
authors.forename: Jaana
authors.initials: J
authors.lastname: Rautava
authors.forename: Jaana
authors.initials: J
authors.lastname: Willberg
authors.forename: Karolina
authors.initials: K
authors.lastname: Louvanto
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: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005192:Family Health; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D005814:Genes, Viral; D005838:Genotype; D052162:Human papillomavirus 16 / Q000235:genetics; D052163:Human papillomavirus 6 / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D018811:Maternal Exposure; D008875:Middle Aged; D009035:Mothers; D009061:Mouth Mucosa / Q000821:virology*; D027383:Papillomaviridae / Q000235:genetics*; D030361:Papillomavirus Infections / Q000453:epidemiology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies