Clonality of HTLV-2 in natural infection.

Human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) both cause lifelong persistent infections, but differ in their clinical outcomes. HTLV-1 infection causes a chronic or acute T-lymphocytic malignancy in up to 5% of infected individuals whereas HTLV-2 has not been unequivocally linked to a T-cell malignancy. Virus-driven clonal proliferation of infected cells both in vitro and in vivo has been demonstrated in HTLV-1 infection.

Polygenic control of human T lymphotropic virus type I (HTLV-I) provirus load and the risk of HTLV-I-associated myelopathy/tropical spastic paraparesis.

Human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is one outcome of infection with HTLV-I. A population association study of 229 patients with HAM/TSP and 202 healthy carriers of HTLV-I in southern Japan showed that this outcome of HTLV-I infection and the HTLV-I provirus load are under polygenic control. Of 58 polymorphic sites studied in 39 non-HLA candidate gene loci, 3 new host genetic factors that influenced the risk of HAM/TSP or the provirus load of HTLV-I were identified.