title: Higher human T lymphotropic virus (HTLV) provirus load is associated with HTLV-I versus HTLV-II, with HTLV-II subtype A versus B, and with male sex and a history of blood transfusion.
abstract: BACKGROUND
  High human T lymphotropic virus (HTLV)-I provirus load (VL) has been associated with an increased risk of HTLV-associated myelopathy, but little is known about variation in HTLV-I or -II VLs by demographic characteristics and risk behaviors.
  
  
  METHODS
  We measured HTLV-I and HTLV-II VLs in a large cohort of 127 HTLV-I-seropositive and 328 HTLV-II-seropositive former blood donors, by use of real-time polymerase chain reaction using tax primers. Multivariable linear regression was used to control for confounding by relevant covariates.
  
  
  RESULTS
  The mean VLs were 3.28 log(10) copies/10(6) peripheral blood mononuclear cells (PBMCs) (range, 0.5-5.3 log(10) copies/10(6) PBMCs) for HTLV-I and 2.60 log(10) copies/10(6) PBMCs (range, 0.05-5.95 log(10) copies/10(6) PBMCs) for HTLV-II (P<.0001). HTLV-II VLs were higher in those subjects with subtype A infection (mean, 2.82 log(10) copies/10(6) PBMCs) than in those with subtype B infection (mean, 2.29 log(10) copies/10(6) PBMCs) (P=.005). Higher HTLV-I VL was associated with previous receipt of a blood transfusion (P=.04), and lower HTLV-II VL was associated with female sex (P=.007). These associations persisted in virus-specific multivariate linear regression models controlling for potential confounding variables.
  
  
  CONCLUSIONS
  VL was significantly higher in HTLV-I than in HTLV-II infection and was higher in HTLV-II subtype A than in HTLV-II subtype B infection. Chronic HTLV VLs may be related to the infectious dose acquired at the time of infection, with higher VLs following acquisition by blood transfusion and lower VLs following sexual acquisition.
authors.affiliation: Department of Laboratory Medicine, University of California, San Francisco 94118, USA. murphy@itsa.ucsf.edu
authors.forename: Edward L
authors.initials: EL
authors.lastname: Murphy
authors.forename: Tzong-Hae
authors.initials: TH
authors.lastname: Lee
authors.forename: Daniel
authors.initials: D
authors.lastname: Chafets
authors.forename: Catharie C
authors.initials: CC
authors.lastname: Nass
authors.forename: Baoguang
authors.initials: B
authors.lastname: Wang
authors.forename: Katharine
authors.initials: K
authors.lastname: Loughlin
authors.forename: Donna
authors.initials: D
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D001782:Blood Donors; D001803:Blood Transfusion; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000097:blood; D005260:Female; D015490:HTLV-I Infections / Q000453:epidemiology / Q000821:virology; D015491:HTLV-II Infections / Q000453:epidemiology / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D015367:Human T-lymphotropic virus 2 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000821:virology; D008297:Male; D008875:Middle Aged; D011533:Proviruses / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D012307:Risk Factors; D012737:Sex Factors; D019562:Viral Load
chemical_list: D004279:DNA, Viral