HTLV-1 Associated Neurological Disorders

Abstract

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus which is endemic to certain regions of the world and infects around 10-20 million people. HTLV-1 is the etiologic agent of Adult T cell leukemia/lymphoma and HTLV-1 associated neurological disorders including mainly HTLV-1 associated myelopathy/Tropical spastic paraparesis. The involvement of the central nervous diseases occurs among: HTLV-1 infected patients from endemic areas, HIV positive individuals and drug users. The ability of HTLV-1 to cause associated neuropathies starts with the virus crossing the blood brain barrier (BBB), then entering and infecting the cells of the central nervous system. As a consequence, to the viral attack, HTLV-1 infected lymphocytes produce pro-inflammatory cytokines like tumor necrosis factor alpha, Interleukin 1 beta and interleukin 6 which further disrupts the BBB. Different serological tests have been used in the diagnosis of HTLV-1. These include: ELISA, Western Blotting (WB), Immunofluorescence, Particle Agglutination and Polymerase Chain Reaction which is used as a confirmatory test. Danazol, pentoxifylline, azathioprine and vitamin C have been used in the treatment of the HTLV-1 associated neurological disorders. Other antiviral drugs (lamivudine, zidovudine), monoclonal antibodies (Daclizumab) and therapeutic agents (valporic acid, interferons) have also been evaluated. No known drug, so far, has been shown to be efficacious. The aim of this review is to present the complexities of HTLV-1 associated neurological disorders and their current ongoing treatment. In addition to discussing future possible therapeutic strategies, by targeting HTVL-1 viral components and gene/s products, for the treatment of those neurological conditions.

Keywords: Antiviral drugs; Blood brain barrier; HTLV-1; Neurological disorders; New drugs discovery; Pathogenesis; Reteroviradae.