Toru Chosa

Expression of HTLV-specific polypeptides in various human T-cell lines.

The adult T-cell leukemia(ATL)-associated antigen complex (ATLA) was first discovered with indirect immunofluorescence by Hinuma et al. (1981). Biochemical analysis with MT-2 cells revealed that ATLA consisted mainly of human T-cell leukemia virus (HTLV) structural polypeptides and their precursors (Yamamoto and Hinuma 1982a; Schneider et al. 1984). In this study, we have investigated the molecular nature of the ATLA antigen complex in various HTLV-positive human cell lines established by different methods including independently established HTLV-infected HUT 102 cells. We found that HTLVs infecting these cell lines have similar core polypeptides, p24 and p19, as well as an envelope glycopolypeptide, gp46, in all these cells. The intracellular gp61 and p53 appear to be precursors of the viral envelope and core polypeptides, respectively. Interestingly, MT-2 and MT-2 related T-cell lines contain two different species of envelope proteins, gp68 and gp61, whereas cell lines not related to MT-2 express only gp61.

Risk of poliomyelitis importation and re-emergence in Laos

The declaration of poliomyelitis eradication in the western pacific region is scheduled for Oct 29, 2000, in Kyoto, Japan. Our survey in the border areas of the southeast Asia region, however, revealed that there remains a risk of re-emergence and importation of poliomyelitis into Laos. We report the evidence based on our border area investigations during the past 4 years under the bilateral supervision of the governments of Laos and Japan.

Human Adult T-Cell Leukaemia Virus Is Distinct from a Similar Isolate of Japanese Monkeys

We have compared the structural polypeptides of an adult T-cell leukaemia (ATL) virus (ATLV) isolate from a Japanese patient with ATL with those of a similar virus derived from a Japanese macaque monkey. Both are distinct but related entities. Their core polypeptides p19 could not be distinguished, but p24, another core polypeptide, and their envelope glycopolypeptides differ. The human virus directs the synthesis of a single intracellular glycopolypeptide, gp68, while the macaque virus specifies two such glycopolypeptides, gp57 and gp50. Furthermore, the glycopolypeptides of both viruses are serologically distinct. Thus, these viruses represent subtypes of the ATLV family and the macaque virus is apparently not involved in human ATL.

Binding of adult T-cell leukemia virus to various hematopoietic cells

A newly found human retrovirus, adult T-cell leukemia virus (ATLV) was shown by means of membrane immunofluorescence to bind to various hematopoietic cells including T-, B- and non-T, non-B-cell lines. Partially purified viral gp46 from culture fluids of ATL virus producer lines also bound efficiently to an ATLV-negative T-cell line, CCRF-CEM cells. When the viruses were pre-incubated with anti-ATLV-positive human sera, ATLV binding to the cells was clearly inhibited but not by pre-incubation with anti-ATLV-negative sera. These data suggest that: (1) ATLV binds not only to T-cells but also to multiple types of cells of hematopoietic origin; (2) anti-ATLV antibody-positive human sera have the blocking antibody for the binding of ATLV to lymphoid cells.

Nature of Adult T-Cell Leukemia-Associated Membrane Antigen on the Surface of Adult T-Cell Leukemia Virus-Carrying Cells as Revealed by Membrane Immunofluorescence

Adult T‐cell leukemia‐associated membrane antigen (ATLMA) expressed on the surface of living ATL virus (ATLV)‐carrying cells was investigated by an indirect membrane immunofluorescence method using natural antibodies to ATLV in human sera. All the ATLV‐positive cell lines tested that had cytoplasmic ATL‐associated antigen (ATLA) detectable in acetone‐fixed cell smears were also positive for ATLMA, but ATLMA was not detected in any ATLV‐negative cell lines. The frequencies of ATLA‐ and ATLMA‐bearing cells in seven cell lines tested were roughly parallel. The frequency of expression of both ATLMA and ATLA in cultures of MT‐1 cells increased in the presence of 5‐iodo‐2′‐deoxyuridine. All human sera having ATLA antibody had ATLMA antibody and the titers of the two were similar in most of the sera. The anti‐ATLMA titers of human sera determined by using an ATLV‐bound non‐ATL T‐cell line as antigen were also similar to the anti‐ATLA titers. Absorption of anti‐ATLMA‐positive sera with living MT‐2 cells, in which almost 100% of the cells express ATLA and ATLMA, caused parallel decreases in the anti‐ATLA and anti‐ATLMA titers. Analysis of the 125I‐labeled surface of MT‐2 cells by immunoprecipitation with anti‐ATLMA‐positive human serum followed by gel electrophoresis revealed that p19, p24, p28, and p46 polypeptides were specifically precipitated. These data suggest that ATLMA on the cell surface is not distinguishable from ATLA in the cytoplasm.