ANTIGENIC CHARACTERIZATION OF HIV-1 GP41 BINDING-PROTEINS

The envelope protein HIV-1 gp41 has been shown to exert various effect s on human T-cells, B-cells and monocytes like inhibition of cell prol iferation, modulation of MHC expression and cytokine production. In co ntrast to gp120, where several receptor molecules have been identified , the receptor for gp41 is still unknown. Using a sepharose column, co upled with recombinant soluble gp41, (rsgp41; Env amino acids 539-684) , five gp41-binding proteins of 37, 45, 50, 62 and 100 kDa had been is olated from lysates of the B-cell line Raji. Two mouse antiserums were generated against the proteins P45 and P62 and were tested against th e binding specificity of both antiserums. In Western blot analysis the antiserums recognized two protein bands of 45 and 62 kDa in complete Raji cell lysates, as well as the purified proteins P45 and P62, respe ctively, but did not show any cross-reaction, indicating that the two proteins do not share any immunological epitopes. Besides, the polyclo nal antiserums did not recognize the other gp41-binding proteins P37, P50 and P100. Using the P62 antiserum proteins of the same size as in Raji cell lysates were stained in the lysates of the monocytic cell li ne U937 and the T-cell line H9, demonstrating distribution of P62 in d ifferent blood cells. P45 seems not to be identical to HLA-C which had been shown to bind to gp41. These results indicate, that P45 and P62 are two separate gp41-binding proteins without homology to each other or to the other gp41-binding proteins. Published by Elsevier Science B .V. All rights reserved.