Effect of phospholipids on adsorption and penetration of human T-cell leukemia virus type I

A human B-lineage dendritic cell line, HBM-noda and its potential role in human T-cell leukemia/lymphoma virus type I infection

An Epstein-Barr virus-transformed B-cell line, HBM-Noda (Noda), that has a dendritic morphology as well as several characteristic features of dendritic cells (DC) has been established. We therefore refer to Noda as B-lineage DC. Although human T-cell leukemia/lymphoma virus type I (HTLV-I) exhibit substantial cellular tropism, the roles of DC in HTLV-I infection remain unknown. To further clarify the characteristics of Noda cells, we performed infection experiments using a concentrated HTLV-I fraction from the adult T-cell leukemia cell line, HPB-ATL-2. Noda, as well as other cell lines examined, were sensitive to HTLV-I infection as detected by proviral DNA using polymerase chain reaction, but most infected Noda cells underwent necrosis within 7 days. The most striking feature of Noda cells was the abundant expression of viral antigen (p19) on the cell surface following infection (approximately day 4), probably due to strong viral adsorption. In cocultivation experiments using Noda cells at day 1 of post-infection and peripheral blood activated T cells, we detected a few (1.3%) viral antigen expressing T cells after 5 days of coculture by flow cytometry. These results suggest that B-lineage DC such as Noda cells play a role in the establishment of HTLV-I infection at an early phase.

Identification of membrane antigens important for adsorption of human T-cell leukaemia virus type I

We isolated three monoclonal antibodies (mAbs), H3e, H11b and H16h, which were capable of inhibiting syncytium formation induced in a human T-cell line MOLT-4 or a human glioma line U251 MG by coculture with human T-cell leukaemia virus type I (HTLV-I)-positive human T-cell lines. The mAbs partially inhibited the plating of pseudotypes of vesicular stomatitis virus (VSV) bearing envelope antigens of HTLV-I. Formation of proviral DNA was also inhibited when indicator cells were treated with the mAbs before adsorption of HTLV-I, but not after its adsorption. They did not inhibit syncytium formation induced by human immunodeficiency virus type 1. Flow cytometry revealed that H16h hardly reacted with various HTLV-I-positive T cells, while H3e and H11b reacted with HTLV-I-positive human cells as well as HTLV-I-negative human cells. H11b and H16h immunoprecipitated the membrane antigen with a molecular weight of 20 and 110-130 kDa, respectively. Western blot analysis showed that H3e, H11b and H16h bound to the protein of 20, 20 and 110-130 kDa, respectively. Thus, these findings suggest that the 20- and 110-130-kDa cell surface proteins may play a role at the early stage of HTLV-I infection.