A SALMONELLA-TYPHIMURIUM HTRA LIVE VACCINE EXPRESSING MULTIPLE COPIESOF A PEPTIDE COMPRISING AMINO-ACIDS-8-23 OF HERPES-SIMPLEX VIRUS GLYCOPROTEIN-D AS A GENETIC FUSION TO TETANUS TOXIN FRAGMENT-C PROTECTS MICE FROM HERPES-SIMPLEX VIRUS-INFECTION

Multiple tandem copies of an immunogenic epitope comprising amino acid s 8-23 of glycoprotein D of herpes simplex virus (HSV) were expressed as C-terminal fusions to tetanus toxin fragment C (TetC) in different Salmonella typhimurium live vaccine strains. Expression of the longer fusions was best in strains harbouring a lesion in htrA, a stress prot ein gene. SL3261, an aroA strain, did not effectively express the long er fusions. Mice immunised with an S. typhimurium C5 htrA mutant expre ssing fusions with two or four copies of the peptide made an antibody response to both the peptide and TetC, whereas constructs expressing o ne copy of the peptide only elicited antibody to TetC. A non-immunogen ic octameric fusion underwent rearrangements in vivo resulting in a pr edominantly monomeric fusion. In contrast, the S. typhimurium SL3261 a roA vaccine expressing the TetC-tetrameric fusion did not elicit antib ody to the peptide. Sera from mice immunised with a single dose of the dimer and tetramer fusions in the htrA strain neutralised HSV in vitr o, and the mice were protected from HSV infection as measured by a red uction in virus load in the ear pinna. We have previously shown that m ice vaccinated with salmonella expressing TetC are protected against t etanus toxin and virulent salmonella challenge. These results suggest that it may be possible to develop a multivalent vaccine against salmo nellosis, tetanus and HSV.