THE SALMONELLA OMPC GENE - STRUCTURE AND USE AS A CARRIER FOR HETEROLOGOUS SEQUENCES

The Salmonella typhi (St) ompC gene codes for a major outer membrane p rotein (OMP) that is highly expressed in both low and high osmolarity. By hybridization studies with the entire gene or with segments thereo f, ompC was found to be highly conserved within 11 different Salmonell a serotypes, with the exception of S. arizonae. The study included sev eral St isolates from Mexico and Indonesia, Variation was only detecte d in two (e and f) of the seven regions previously found to vary betwe en St and E. coli ompC. Chimeric OmpC proteins, carrying a rotavirus V P4 capsid protein epitope, are well recognized by a specific monoclona l antibody (mAb) against this epitope, either in OMP preparations (by enzyme-linked immunosorbent assay; ELISA) or intact cells (by ELISA an d immunogold-labelling), indicating that regions c and f are oriented towards the cell surface and are probably exposed. As has been shown b efore for other regulated OMP, this experimental approach could be use ful for the presentation of heterologous epitopes in order to gain kno wledge about porin topology, for testing the effect of altered porin s urface epitopes on bacterial physiology, or else, in the development o f multivalent vaccines.