Dstl, Chemical and Biological Sciences, Porton Down, Salisbury, Wiltshire SP4 0JQ, United Kingdom.
The immunogenicity and protective efficacy of overlapping regions of the protective antigen (PA) polypeptide, cloned and expressed as glutathione S-transferase fusion proteins, have been assessed. Results show that protection can be attributed to individual domains and imply that it is domain 4 which contains the dominant protective epitopes of PA.