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.
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.
Murphy
Edward L
EL
Department of Laboratory Medicine, University of California, San Francisco 94118, USA. murphy@itsa.ucsf.edu
Lee
Tzong-Hae
TH
Chafets
Daniel
D
Nass
Catharie C
CC
Wang
Baoguang
B
Loughlin
Katharine
K
Smith
Donna
D
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
D004279:DNA, Viral