Increased production of viral proteins by a 3'-LTR-deleted infectious clone of human T-cell leukemia virus type 1

We previously reported that a full-length provirus of HTLV-1 was directly constructed from the HTLV-1-transformed cell line MT-2 using overlapping polymerase chain reaction (PCR) and cloned into a plasmid vector (pFL-MT2). 293T cells transfected with pFL-MT2 alone did not produce virus particles because there was no expression of the viral transactivator protein Tax, whereas cells transfected with pFL-MT2 plus a Tax expression vector produced virus-like particles. In the process of constructing the HTLV-1 provirus by overlapping PCR, we also constructed an incomplete molecular clone, in which the 3' long terminal repeat (LTR) was replaced with the endogenous human gene, which resulted in the expression of a tax gene shorter by 43 bp. This incomplete molecular clone alone expressed Tax and produced the viral protein in transfected cells. Various clones were then constructed with different lengths of the 3' LTR and lacking the reverse-direction TATA box. The clones contained over 113 bp of the 3' LTR, with no reverse-direction TATA box, which might express the full-length tax gene, and did not produce the viral antigen. These results suggest that Tax in which the C-terminal portion is deleted is more strongly expressed than the wild-type protein and has transcriptional activity

Low CD4/CD8 T-Cell Ratio Associated with Inflammatory Arthropathy in Human T-Cell Leukemia Virus Type I Tax Transgenic Mice

Human T-cell leukemia virus type I (HTLV-1) can cause an aggressive malignancy known as adult T-cell leukemia/lymphoma (ATL) as well as inflammatory diseases such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). A transgenic mouse that expresses HTLV-1 Tax also develops T-cell leukemia/lymphoma and an inflammatory arthropathy that resembles rheumatoid arthritis. The aim of this study was to identify the primary T-cell subsets involved in the development of arthropathy in Tax transgenic mice. mRNA was strong in the spleen and joints of arthropathic mice, with a 40-fold increase compared with healthy transgenic mice.Our findings reveal that Tax transgenic mice develop rheumatoid-like arthritis with proliferating synovial cells in the joints; however, the proportion of different splenic T-cell subsets in these mice was completely different from other commonly used animal models of rheumatoid arthritis. The crucial T-cell subsets in arthropathic Tax transgenic mice appear to resemble those in HAM/TSP patients rather than those in rheumatoid arthritis patients

Stevens-Johnson syndrome/toxic epidermal necrolysis-like disease in human T-cell leukemia virus type 1 Tax transgenic mice

Human T-cell leukemia virus type 1 (HTLV-1) can cause adult T-cell leukemia/lymphoma (ATLL) and inflammatory diseases such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). My research group established a transgenic (Tg) mouse model of HTLV-1 infection using the distal promoter of Lck to induce tax expression in mature thymocytes and peripheral T lymphocytes. The major disease phenotypes in this model were mature T cell leukemia/lymphoma, similar to ATLL, and inflammatory arthropathy. While expanding Tax-Tg mouse colony, my group found that about 2% of the Tg mice developed Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)-like disease. SJS/TEN-like lesions were characterized by a rash and diffuse exfoliation of large areas of the skin, similar to second-degree burns. The pathology of Tg mice with SJS/TEN-like disease included epidermal necrosis and detachment at the dermoepidermal junction. Serum soluble Fas ligand levels were significantly increased in Tax-Tg mice with SJS/TEN-like disease

Effects of expressing human T-cell leukemia virus type 1 (HTLV-I) oncoprotein Tax on DOK1, DOK2 and DOK3 gene expression in mice

Transgenic mice expressing the tax gene from human T-cell leukemia virus type 1 (HTLV-I) genome developed T-cell leukemia or histiocytic sarcoma after at least 12 months. The transgenic mice showed low expression of the downstream of tyrosine kinase (DOK) family members, DOK1, DOK2 and DOK3, which were recently reported to be tumor suppressor genes. Mice showed low DOK2 expression at 5–6 months of age, before disease onset. The expression of DOK1 and DOK3 was not significantly reduced at any age tested. These results suggest that downregulation of DOK2 by the expression of the viral tax gene is the first step in the development of T-cell leukemia or histiocytic sarcoma

ROLE OF ADHERENT MONONUCLEAR CELLS DERIVED FROM ADULT PIGS AND SUCKLING PIGLETS IN RESPONSE TO POKEWEED MITOGEN-INDUCED IMMUNOGLOBULIN PRODUCTION

The effect of monocytes as an activator of a function of lymphocytes in pigs was studied using an in vitro Ig production system with pokeweed mitogen (PWM). When mononuclear cells (lymphocytes) from adult pigs were stimulated by PWM, optimal number of adherent cells (monocytes) collected from serum coated plastic Petri dishes were required for the generation of Ig producing cells, whereas the production was suppressed by the addition of excessive adherent cells. In neonatal and suckling piglets up to 6 weeks of age, PWM induced B lymphocyte differentiation was enhanced by addition of adherent cells from peripheral blood of adult pigs. On the other hand, adherent cells derived from piglets did not have the effect of increasing Ig production in the in vitro Ig production system with lymphocytes (non-adherent) derived from adult pigs

LYMPHOCYTE TRANSFORMATION OF PERIPHERAL BLOOD LYMPHOCYTES AND PLAQUE FORMING CELLS OF THE SPLEEN AND THE MESENTERIC LYMPH NODE IN SUCKLING PIGLETS WITH AND WITHOUT IMMUNOPOTENTIATORS

Lymphocyte transformation with mitogen, phytohemagglitinin (PHA) and concanavalin A (conA) was tested in peripheral blood lymphocytes from suckling piglets aged 1,2,3,4 and 5 weeks old respectively. A study was also made to observe plaque forming cells with sheep red blood cells (SRBC) in the spleen and nucleated cells of the mesenteric lymph nodes (MLN) of piglets aged 2,3 and 4 weeks respectively. Reratively high levels of lymphocyte responses were seen in the 1 week-old piglets. Differences of stimulation indexes (SI) of lymphocyte responses of the piglets were not significant in the animals aged from 1 to 5 weeks. The effect of administration of peptidoglycan and chemical composites of cultural supernates derived from Streptomyces olivaceogriseus sp. nov (FR41565) on the lymphocyte responses was investigated. The value of SI among the piglets treated with and without peptidoglycan and FR41565 was not significant. On the other hand, the count of plaque forming cells (PFC) of the splenic and MLN's cells with SRBC in the piglets aged 2 to 4 weeks was low in spite of the SRBC injections, and the count of PFC of MLN was fewer than that of the spleen of any age. The count of PFC was the highest in the piglets treated with the rapid acting immunopotentiator (FR41565) at 2 weeks of age while the highest count was seen in the piglets administered the slow acting substance (peptidoglycan) at 4 weeks of age. These results indicated that differentiation of B lymphocyte in suckling age piglets seems to be restrained by a certain suppressive activity which leads to poor production of immunoglobulin