Presence of HTLV DNA and antibodies in sporadic amyotrophic lateral sclerosis

In order to investigate the possible association between retroviruses and Amyotrophic Lateral Sclerosis (ALS) we evaluated the presence of antibodies toward the Human T-lymphotropic viruses (HTLV-I and HTLV-II) in the sera of 29 ALS patients and in control sera of 30 healthy individuals and of 20 HIV infected yet HTLV seronegative subjects. In addition, we searched for HTLV tax/rex and pol DNA sequences in the peripheral blood mononuclear cells (PBMCs) of 14 ALS patients, 20 healthy controls and 20 HIV positive but HTLV negative subjects using a sensitive nested polymerase chain reaction (PCR). Antibodies to one or more HTLV proteins have been found using the Western Immunoblotting (WIB) assay in the sera of 19 ALS cases (65%), while all healthy controls were negative and only one HIV seropositive subject demostrated antibodies against HTLV gp21. HTLV tax/rex DNA sequences have been found in the PBMCs of 5 ALS patients (36%) while controls were negative. All 14 ALS cases and both control groups were negative for HTLV pol DNA, indicating that only the most conserved region of the HTLV nucleotide sequence could be detected. These data indicate that in some ALS patients an infection by an unidentified HTLV-related endogenous or exogenous retrovirus, or a novel type of reactivation of retroviral genomic sequence may have occurred in this sporadic motor neuron degeneration.