The neurotoxin-like sequence of human immunodeficiency virus gp120: a comparison of sequence data from patients with and without neurological symptoms.

A region of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp 120 has been claimed previously to be homologous to parts of snake venom neurotoxins and rabies virus glycoprotein ("the neurotoxic loop"). We have determined DNA sequences directly from a polymerase chain reaction amplified fragment corresponding to this region of HIV-1 gp 120 and have translated these to protein sequences. This was performed with the prototype HIVSF2 isolate and several Swedish HIV-1 strains, which were precultivated from blood cells or cerebrospinal fluid (CSF) or were directly obtained from CSF cells of patients with and without neurological symptoms. The results show that there are sequence similarities between a short segment of gp120 of clinical HIV-1 strains and the neurotoxic loop. The strains of patients with neurological symptoms did not, however, show a genetic shift of their sequences towards a greater similarity to the sequences of snake venom neurotoxins and rabies virus glycoprotein as compared to the strains of asymptomatic individuals.