Candidate vaccine against botulinum neurotoxin serotype A derived from a Venezuelan equine encephalitis virus vector system.
A candidate vaccine against botulinum neurotoxin serotype A (BoNT/A) was developed by using a Venezuelan equine encephalitis (VEE) virus replicon vector. This vaccine vector is composed of a self-replicating RNA containing all of the VEE nonstructural genes and cis-acting elements and also a heterologous immunogen gene placed downstream of the subgenomic 26S promoter in place of the viral structural genes. In this study, the nontoxic 50-kDa carboxy-terminal fragment (H(C)) of the BoNT/A heavy chain was cloned into the replicon vector (H(C)-replicon). Cotransfection of BHK cells in vitro with the H(C)-replicon and two helper RNA molecules, the latter encoding all of the VEE structural proteins, resulted in the assembly and release of propagation-deficient, H(C) VEE replicon particles (H(C)-VRP). Cells infected with H(C)-VRP efficiently expressed this protein when analyzed by either immunofluorescence or by Western blot. To evaluate the immunogenicity of H(C)-VRP, mice were vaccinated with various doses of H(C)-VRP at different intervals. Mice inoculated subcutaneously with H(C)-VRP were protected from an intraperitoneal challenge of up to 100,000 50% lethal dose units of BoNT/A. Protection correlated directly with serum enzyme-linked immunosorbent assay titers to BoNT/A. The duration of the immunity achieved was tested at 6 months and at 1 year postvaccination, and mice challenged at these times remained refractory to challenge with BoNT/A.
Lee
J S
JS
Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702-5011, USA. John.Lee@det.amedd.army.mil
Pushko
P
P
Parker
M D
MD
Dertzbaugh
M T
MT
Smith
L A
LA
Smith
J F
JF
D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D019274:Botulinum Toxins, Type A / Q000235:genetics / Q000276:immunology*; D001906:Botulism / Q000517:prevention & control*; D002460:Cell Line; D003014:Clostridium botulinum / Q000276:immunology / Q000378:metabolism; D004685:Encephalomyelitis, Venezuelan Equine / Q000235:genetics* / Q000378:metabolism; D005822:Genetic Vectors; D051379:Mice; D008807:Mice, Inbred BALB C; D012093:Replicon / Q000235:genetics*; D014611:Vaccination; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology
D001428:Bacterial Vaccines; D014614:Vaccines, Synthetic; D019274:Botulinum Toxins, Type A