title: Human papillomavirus types 16 and 18 DNA load in relation to coexistence of other types, particularly those in the same species.
abstract: BACKGROUND
  Infection with multiple human papillomavirus (HPV) types is common. However, it is unknown whether viral DNA load is related to the coexistence of other types.
  
  
  METHODS
  Study subjects were 802 and 303 women who were positive for HPV16 and HPV18, respectively, at enrollment into the Atypical Squamous Cells of Undetermined Significance and Low-Grade Squamous Intraepithelial Lesion Triage Study. HPV16 and HPV18 E7 copies per nanogram of cellular DNA in cervical swab samples were measured by real-time PCR in triplicate.
  
  
  RESULTS
  Concurrent coinfection was common in this population of women with minor cervical lesions; multiple HPV types were detected in 573 (71.4%) of 802 HPV16-positive women and 227 (74.9%) of 303 HPV18-positive women. The adjusted odds ratio associating coinfection with per 1 log unit increase in HPV16 DNA load was 0.78 (95% confidence interval, 0.68-0.89); it was 0.64 (95% confidence interval, 0.52-0.79) for a similar analysis of HPV18 DNA load. Women with, compared with without, coinfection of A9 species types possessed a significantly lower HPV16 DNA load (P < 0.001), whereas women with, compared with without, coinfection of A7 species types possessed a significantly lower HPV18 DNA load (P = 0.001). A trend of decrease in HPV16 DNA load with increasing number of the coexisting non-HPV16 A9 species types was statistically significant (P(trend) = 0.001).
  
  
  CONCLUSIONS
  Coinfection with other types was associated with lower HPV16 and HPV18 DNA load. The extent of reduction was correlated to phylogenetic distance of the coexisting types to HPV16 and HPV18, respectively.
authors.affiliation: Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, USA. longfu@u.washington.edu
authors.forename: Long Fu
authors.initials: LF
authors.lastname: Xi
authors.forename: Zoe R
authors.initials: ZR
authors.lastname: Edelstein
authors.forename: Craig
authors.initials: C
authors.lastname: Meyers
authors.forename: Jesse
authors.initials: J
authors.lastname: Ho
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Cherne
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
mesh_terms: D004279:DNA, Viral / Q000097:blood*; D055088:Early Detection of Cancer; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics* / Q000302:isolation & purification; D052161:Human papillomavirus 18 / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D030361:Papillomavirus Infections / Q000453:epidemiology / Q000821:virology*; D014481:United States / Q000453:epidemiology; D002577:Uterine Cervical Diseases / Q000453:epidemiology / Q000821:virology*; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000821:virology; D019562:Viral Load; D002578:Uterine Cervical Dysplasia / Q000453:epidemiology / Q000821:virology
chemical_list: D004279:DNA, Viral
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