A New Subtype of Human T-Cell Leukemia Virus (HTLV-II) Associated with a T-Cell Variant of Hairy Cell Leukemia

TLDR

Human T‑cell leukemia virus (HTLV) is a type‑C RNA retrovirus isolated from patients with T‑cell leukemias or lymphomas, with closely related US and Japanese isolates linked to acute mature T‑cell malignancies, and the prototype is HTLV‑I while the virus from patient Mo is designated HTLV‑II. The authors classify individual HTLV subgroups by patient‑specific subscripts, such as HTLV‑I(CR), HTLV‑I(MB), and HTLV‑II(Mo). In patient Mo with a T‑cell variant of hairy cell leukemia, a distinct HTLV‑II virus was identified, evidenced by anti‑p24 antibodies, expression of HTLV antigens in a splenic T‑cell line, and significant immunological divergence from prior HTLV isolates.

Abstract

Human T-cell leukemia virus (HTLV) is a human type-C RNA tumor virus (retrovirus) previously identified in and isolated from several patients with T-cell leukemias or lymphomas. The known virus isolates from the United States and Japan are closely related and are found in adults with an acute malignancy of mature T cells. A related retrovirus has been found in a patient (Mo) with a somewhat different disease (a T-cell variant of relatively benign hairy cell leukemia). Serum from Mo contains antibodies to the major internal core protein (p24) of HTLV. A T-cell line established from the spleen of Mo expresses HTLV antigens. However, HTLV from Mo is significantly different from all previous HTLV isolates in immunological cross-reactivity tests of p24. The usual prototype HTLV isolate is represented as HTLV-I, and the HTLV from Mo is represented as HTLV-II. Individual members of each subgroup may then be identified by subscript initials of the patient [for example, HTLV-I(CR), HTLV-I(MB), and HTLV-II(Mo)].