The Journal of Medical Microbiology, Vol 46, Issue 2 129-138, Copyright © 1997 by Society for General Microbiology
Immune response to a Murray Valley encephalitis virus epitope expressed in the flagellin of an attenuated strain of Salmonella
B. L. Whittle, E. Lee, R. C. Weir and N. K. Verma
Division of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, Australia.
Recent developments in vaccine construction include the use of attenuated,
avirulent strains of Salmonella as carriers of foreign antigens. These
recombinant strains can elicit a heterologous immune response when injected
into animals, demonstrating potential for their use in the construction of
many vaccines. In the present study, a B-cell epitope of Murray Valley
encephalitis virus (MVE) was identified and expressed in a Salmonella
strain to evaluate its potential to induce a specific immune response to
MVE. A synthetic oligonucleotide encoding the B-cell epitope (residues
E201-224) of the envelope protein of MVE was inserted into the cloned
flagellin gene of the Salmonella strain. The construct was sequenced to
ensure correct orientation of the epitope. Expression of the epitope was
demonstrated by Western blot analysis and immunogold electron microscopy
with monoclonal antibody specific to the epitope. Electron microscopy
analysis revealed multiple copies of the epitope along the flagella. The
recombinant Salmonella carrying the hybrid flagellin gene elicited an
immune response to the MVE epitope in a mouse model. The MVE-specific
antibodies partially neutralised the virus in vitro. The significance of
this system for engineering vaccines for other medically important
flaviviruses is discussed.
