EFFICIENT SECRETION OF THE MODEL ANTIGEN-M6-GP41E IN LACTOBACILLUS-PLANTARUM NCIMB-8826

Four Lactobacillus strains (Lb. plantarum NCIMB 8826, Lb. paracasei Lb TGS1.4, Lb. casei ATCC 393 and Lb. fermentum KLD) were tested for thei r ability to produce and secrete heterologous proteins. These strains were first screened with an a-amylase reporter under the control of a set of expression or expression/secretion signals from various lactic acid bacteria. With most of the constructions tested, the lever of ext racellular production was highest in Lb. plantarum NCIMB 8826, and low est in Lb. paracasei LbTGS1.4. These two strains were next assayed usi ng a model antigen consisting of the N-terminal part of the M6 protein from Streptococcus pyogenes fused to the linear epitope ELDKWAS from human immunodeficiency virus gp41 protein. Secretion of this heterolog ous protein was inefficient in Lb. paracasei LbTGS1.4 which accumulate d a large intracellular pool of the unprocessed precursor. whereas Lb. plantarum NCIMB 8826 was able to secrete the antigen to a revel as hi gh as 10 mg l(-1).