IMMUNE RECOGNITION OF BOTULINUM NEUROTOXIN TYPE-A - REGIONS RECOGNIZED BY T-CELLS AND ANTIBODIES AGAINST THE PROTECTIVE H-C FRAGMENT (RESIDUE-855-1296) OF THE TOXIN

Botulism toxicity is caused by botulinum neurotoxins (BoNTs), a group of protein neurotoxins produced by Clostridium botulinum. Recent studi es have shown that immunization with a C-terminal fragment (H-C, resid ues 855-1296) of BoNT type A (BoNT/A) affords excellent protection aga inst BoNT/A toxicity. The present work was carried out in order to map the molecular and cellular immunological recognition of H-C. We have previously described the synthesis of 31 overlapping peptides encompas sing the entire H-C-fragment of BoNT/A. These peptides were employed i n this study to localize the continuous regions recognized by T cells and by antibodies (Abs) generated in two mouse strains against H-C. T cells from SJL that had been primed with H-C gave a strong proliferati ve response to challenge in vitro with each of the six peptides spanni ng residues 897-985 and a lower response to peptide 1051-1069. While H -C-primed T cells of BALB/c recognized three regions residing within r esidues 939-957, 1009-1027 and 1135-1153 (strong). Recognition regions by Abs in SJL or BALB/c anti-H-C antisera essentially overlapped. How ever, the level of Abs bound to each region differed between the two s trains. These common or similar recognition regions by the two strains were: 855-915 (SJL) or 855-901 (BALB/c); 939-957; 967-1013 (BALB/c) o r 981-1013 (SJL); 1051-1069; 1079-1111 (BALB/c) or 1093-1125 (SJL); 11 77-1195; and 1275-1296. In addition, BALB/c recognized region 1135-115 3. Some of these regions show considerable sequence similarity in BoNT types B and E and, therefore, H-C of these two BoNTs might offer prot ection against the correlate clostridial toxins. (C) 1997 Elsevier Sci ence Ltd. All rights reserved.