Human T-Cell Lymphotropic Virus Type II, strain C3-44/Mo (HTLV-II). Family: Retroviridae, subfamily: Oncovirinae. Single-stranded, positive-sense enveloped RNA virus.

HTLV-I, strain MT-2 (Human T-Cell Lymphotropic Virus - 1), Family: Retroviridae, subfamily: Oncovirinae, genus C retrovirus.
Purified virus made from clarified, virus infected tissue culture harvest fluids that are concentrated and cleaned of debris by a combination of ultracentrifugation, ultrafiltration and selection of viral band from a sucrose density gradient. This preparation contains live virus; however, it is not known to infect any cells commonly used in tissue culture without using transfection techniques.