The tax protein from the primate T-cell lymphotropic virus type 3 is expressed in vivo and is functionally related to HTLV-1 Tax rather than HTLV-2 Tax.

Human T-cell leukemia virus and simian T-cell leukemia virus (STLV) form the primate T-cell lymphotropic viruses group. Human T-cell leukemia virus type 1 and type 2 (HTLV-1 and HTLV-2) encode the Tax viral transactivator (Tax1 and Tax2, respectively). Tax1 possesses an oncogenic potential and is responsible for cell transformation both in vivo and in vitro. We and others have recently discovered the existence of human T-cell lymphotropic virus type 3. However, there is currently no evidence for the presence of a Tax protein in HTLV-3-infected individuals. We show that the serum of an HTLV-3 asymptomatic carrier and the sera of two STLV-3-infected monkeys contain specific anti-Tax3 antibodies. We also show that tax3 mRNA is present in the PBMCs obtained from an STLV-3-infected monkey, demonstrating that Tax3 is expressed in vivo. We further demonstrate that Tax3 intracellular localization is very similar to that of Tax1 and that Tax3 binds to both CBP and p300 coactivators. Using purified Tax3, we show that the protein increases transcription from a 4TxRE G-free cassette plasmid in an in vitro transcription assay. In all cell types tested, including transiently transfected lymphocytes, Tax3 activates its own promoter STLV-3 long terminal repeat (LTR), which contains only two Tax Responsive Elements (TREs), and activates also HTLV-1 and HTLV-2 LTRs. In addition, Tax3 also activates the NF-kappaB pathway. We also show that Tax3 possesses a PDZ-binding sequence at its C-terminal end. Our results demonstrate that Tax3 is a transactivator, and that its properties are more similar to that of Tax1, rather than of Tax2. This suggests the possible occurrence of lymphoproliferative disorders among HTLV-3-infected populations.

Cutaneous leishmaniasis: an increasing threat for travellers.

Analysis of the literature on cutaneous leishmaniasis in low-prevalence countries suggests an increase in imported cases that is attributable to the growing phenomenon of international tourism, migration and military operations in highly endemic regions. Cases of imported cutaneous leishmaniasis are often missed initially, but diagnosis can be made non-invasively by PCR using skin scrapings of lesions as starting material. Cutaneous leishmaniasis is an emerging threat for travellers and should be considered in all patients presenting with slow-to-heal ulcers.

Long-term remission of Kaposi sarcoma-associated herpesvirus-related multicentric Castleman disease with anti-CD20 monoclonal antibody therapy.

Kaposi sarcoma-associated herpesvirus (KSHV)-related multicentric Castleman disease (MCD) is potentially lethal. Growing evidence indicates that, as in Epstein-Barr virus-driven lymphoproliferative disorders after transplantation, KSHV DNA burden in peripheral blood mononuclear cells (PBMCs) may represent the most accurate marker of disease activity. This report describes a patient with human immunodeficiency virus who was followed up clinically and by quantitative polymerase chain reaction for KSHV DNA sequences in PBMCs for more than 3 years following the diagnosis of KSHV-related MCD. Therapy with the antiherpesvirus agent cidofovir, antihuman interleukin-6 antibody BE-8, antiblastic chemotherapy, and combination antiretroviral agents did not achieve durable clinical or virologic remission of the disease. By contrast, administration of the anti-CD20 monoclonal antibody rituximab was well tolerated and allowed a 14-month remission of clinical symptoms and KSHV viremia. Rituximab should be added to the therapeutic armamentarium for KSHV-related MCD.

Role of PCR in diagnosis and prognosis of visceral leishmaniasis in patients coinfected with human immunodeficiency virus type 1.

A group of 76 consecutive human immunodeficiency virus (HIV)-positive patients with fever of unknown origin (n = 52) or fever associated with pulmonary diseases was evaluated in order to assess the usefulness of PCR with peripheral blood in the diagnosis and follow-up of visceral leishmaniasis. We identified 10 cases of visceral leishmaniasis among the 52 patients with fever of unknown origin. At the time of diagnosis, all were parasitemic by PCR with peripheral blood. During follow-up, a progressive decline in parasitemia was observed under therapy, and all patients became PCR negative after a median of 5 weeks (range, 6 to 21 weeks). However, in eight of nine patients monitored for a median period of 88 weeks (range, 33 to 110 weeks), visceral leishmaniasis relapsed, with positive results by PCR with peripheral blood reappearing 1 to 2 weeks before the clinical onset of disease. Eight Leishmania infantum and two Leishmania donovani infections were identified by PCR-restriction fragment length polymorphism analysis. PCR with peripheral blood is a reliable method for diagnosis of visceral leishmaniasis in HIV-infected patients. During follow-up, it substantially reduces the need for traditional invasive tests to assess parasitological response, while a positive PCR result is predictive of clinical relapse.