ISOLATION, CHARACTERIZATION, AND TRANSMISSION OF HUMAN T-LYMPHOTROPICVIRUS TYPE-I AND TYPE-II IN CULTURE

Highly sensitive coculture methods were developed both for isolation o f human T-lymphotropic virus types I and II (HTLV-I and HTLV-II) from infected individuals and for productive infection of lymphoid cells. M itogen-activated peripheral blood mononuclear cells (PBMC) from 13 HTL V-I- and 20 HTLV-II-positive specimens were cocultured with an equal n umber of mitogen-activated PBMC from HTLV-seronegative individuals, an d culture supernatants were tested for the presence of soluble p24gag antigens at weekly intervals for 4 weeks. Eleven of 13 (85%) HTLV-I an d 14 of 20 (70%) HTLV-II cultures were positive for p24 antigens. None of the 17 HTLV-seroindeterminate or six HTLV-seronegative specimens w ere positive for the presence of p24 antigen. The isolation rates for HTLV-I and HTLV-II by an alternative whole-blood lysis procedure were comparable to those obtained by standard PBMC cultures. Furthermore, c ocultivation of PHA-stimulated PBMC from healthy donors with lethally irradiated HTLV-I- and HTLV-II-infected cell lines (SP and Mo-T, respe ctively) resulted in productive viral infection, as reflected by the a ppearance of p24gag antigens concomitant with specific genomic amplifi cation of HTLV proviral DNA after 3 weeks of cocultivation. Thus, the cocultivation technique provides a highly sensitive and specific proce dure both for HTLV isolation and for infection of target cells.