Tropical Spastic Paraparesis - Vaccine Development

Vaccine Development

Currently, there is no licensed vaccine to protect against HTLV-1 or HTLB-2 in the US. At least 500,000 of the individuals infected with HTLV-1 eventually develop an often rapidly fatal leukemia, while others will develop a debilitative myelopathy, and yet others will experience uveitis, infectious dermatitis, or another inflammatory disorder. HTLV-2 is associated with milder neurologic disorders and chronic pulmonary infections. The novel HTLV-3 and HTLV-4 have been isolated only in a few cases. Human T cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world. They cause two life-threatening diseases, adult T cell leukaemia/lymphoma and tropical spastic paraparesis. A vaccine is needed because in developing countries there are no other feasible preventive interventions against these diseases and in Western countries intravenous drug users at high risk for HTLV-I and HTLV-II infections and the health workers in contact with such populations must be protected. A recombinant adenovirus vector that expresses the HTLV-I envelope glycoprotein env in HeLa cells in the clinical trial stage. A pneumococcalpolysaccharide vaccine has elicited significant increases in concentrations of IgG against all 5 serotypes tested at 1 and 6 months after immunization. While there is no present licensed vaccine, there are many factors which make a vaccine against HTLV-1 feasible. The virus displays relatively low antibody production variability, natural immunity does occur in humans, and experimental vaccination using envelope antigens has been shown to be successful in animal models.