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J. Virol., 10 1997, 7442-7447, Vol 71, No. 10
G Ward, E Rieder and PW Mason
DNA vaccine candidates for foot-and-mouth disease (FMD) were engineered to
produce FMD virus (FMDV) particles that were noninfectious in cell culture
or animals. The prototype plasmid, pWRM, contains a cytomegalovirus
immediate-early promoter-driven genome-length type A12 cDNA followed by the
bovine growth hormone polyadenylation site. BHK cells transfected with this
plasmid produced virus, but the specific infectivity of pWRM was much lower
than that achieved with in vitro- generated RNA genomes. To improve the
infectivity of the plasmid, a cDNA encoding the hepatitis delta virus
ribozyme was added to the 3' end of the FMDV cDNA. The resulting plasmid,
pWRMH, exhibited slightly increased infectivity in cell culture and
produced virus when inoculated into suckling mice. A third plasmid, pWRMHX,
was created by removal of the sequences encoding the cell binding site
found in capsid protein VP1 of pWRMH. Although cells transfected with
pWRMHX produced viral capsids, this plasmid was not lethal in suckling
mice, indicating that particles lacking the cell binding site were not able
to initiate secondary infectious cycles. Swine inoculated with pWRMHX did
not show any signs of disease and produced neutralizing antibodies to FMDV,
and 20% of the vaccinated animals were protected from challenge. A
derivative of pWRMHX, pWRMHX-pol-, harboring a mutation designed to
inactivate the viral polymerase was much less immunogenic, indicating that
immunogenicity of pWRMHX resulted, in part, from amplification of the viral
genome in the animal.
Copyright © 1997, American Society for Microbiology
Plasmid DNA encoding replicating foot-and-mouth disease virus genomes induces antiviral immune responses in swine
Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, North Atlantic Area, Greenport, New York 11944, USA.
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