Partial protection to respiratory syncytial virus (RSV) elicited in mice by intranasal immunization using live staphylococci with surface-displayed RSV-peptides

• A live bacterial vaccine-delivery system based on the food-grade bacterium Staphylococcus carnosus was used for delivery of peptides from the G glycoprotein of human respiratory syncytial virus, subtype A (RSV-A). Three peptides, corresponding to the G protein amino acids, 144-159 (denoted G5), 190-203 (G9) and 171-188 (G4 S), the latter with four cysteine residues substituted for serines, were expressed by recombinant means as surface-exposed on three different bacteria, and their surface accessibility on the bacteria was verified by fluorescence-activated cell sorting (FACS). Intranasal immunization of mice with the live recombinant staphylococci elicited significant anti-peptide as well as anti-virus serum IgG responses of balanced IgG1/IgG2a isotype profiles, and upon viral challenge with 10(5) tissue culture infectious doses(50) (TCID50), lung protection was demonstrated for approximately half of the mice in the G9 and G4 S immunization groups. To our knowledge, this is the first study in which protective immunity to a viral pathogen has been evoked using food-grade bacteria as vaccine-delivery vehicles.

Nyckelord

live bacterial vaccine delivery

respiratory syncytial virus

Staphylococcus carnosus

recombinant lactococcus-lactis

streptococcal protein-g

albumin-binding region

g fusion protein

g-glycoprotein

cell-wall

klebsiella-pneumoniae

antibody-responses

oral vaccination

balb/c mice

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