LACK OF EVIDENCE FOR HTLV TAX-REX DNA IN MOTOR-NEURON DISEASE

It has recently been claimed (Ferrante et al., 1995, HTLV tax-rex DNA and antibodies in idiopathic amyotrophic lateral sclerosis. J. Neurol. Sci. 129 (Suppl.) 140-144) that human T-lymphotropic virus (HTLV) tax -rex sequences are detectable in the peripheral blood mononuclear cell s (PBMCs) of 40% of patients with motor neurone disease (MND). In an a ttempt to confirm this we employed a highly sensitive 'nested' polymer ase chain reaction (PCR) assay, capable of detecting single molecules of HTLV proviral DNA, to look for tax-rex sequences in the PBMCs of 43 patients with MND. We were unable to detect the presence of HTLV tax- rex in any of 43 MND patients tested, using three different PCR primer sets under both high and low stringency conditions. Using the same DN A samples we were able to detect the presence of the single-copy pyruv ate dehydrogenase gene, thus demonstrating that the extracted DNA was indeed amplifiable by PCR. To further exclude the possibility that the extracted DNA samples contained unrecognised inhibitory factors we co nducted spiking experiments with trace amounts (approximately 10 copie s) of HTLV proviral DNA. Spiked samples yielded PCR products of the ex pected size. We are therefore unable to confirm the presence of HTLV t ax-rex sequences in this disease. (C) 1997 Elsevier Science B.V.