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J. Virol., Jun 1996, 3770-3780, Vol 70, No. 6
JM Torres, C Alonso, A Ortega, S Mittal, F Graham and L Enjuanes
The infection of epithelia] swine testicle and intestinal porcine
epithelial (IPEC-1) cell lines by adenovirus type 5 (Ad5) has been studied
in vitro by using an Ad5-luciferase recombinant containing the firefly
luciferase gene as a reporter. Porcine cell lines supported Ad5
replication, showing virus titers, kinetics of virus production, and
luciferase expression levels similar to those obtained in human 293 cells,
which constitutively express the 5'-end 11% of the Ad5 genome. The tropism
of Ad5-based vectors in swine and its ability to induce an efficient immune
response against heterologous antigens expressed by foreign genes inserted
in these vectors has been determined. Ad5 vectors replicate and express
heterologous antigens in porcine lungs and mediastinal and mesenteric lymph
nodes. Significant levels of heterologous antigen expression were also
demonstrated in the small intestine (jejunum and ileum), but Ad5
replication in this organ was very poor, suggesting that Ad vectors undergo
an abortive replication in the porcine small intestine. The tissues
infected by Ad5 were dependent on the inoculation route. The oronasal route
appeared to be best for inoculation of bronchus-associated lymphoid tissue
infection, while the intraperitoneal route was best for gut-associated
lymphoid tissue infection. Epithelial cells of bronchioles, macrophages,
type II pneumocytes, and follicular dendritic cells were identified as
targets for Ad5, while epithelial cells of the intestine were not infected
by Ad5. Viruses with a deletion from 79.5 to 84.8 map units in the E3
region, with or without heterologous inserted genes, replicated to lower
levels in porcine tissues than did wild-type Ad5. It was also shown that an
Ad5 recombinant expressing the four antigenic sites (A, B, C, and D) of
transmissible gastroenteritis coronavirus (TGEV) spike protein induced in
swine immune responses which neutralized TGEV infectivity. In addition,
porcine serum from Ad-TGEV-immune animals provide passive protection when
mixed with fully virulent TGEV and orally administered to highly
susceptible newborn piglets. These results taken together indicate that
swine may be a good animal model for human Ad5 lung infection to aid in the
evaluation of candidate adenovirus vaccines and that Ad5 may be suitable as
a recombinant viral vaccine or for other applications in swine.
Copyright © 1996, American Society for Microbiology
Tropism of human adenovirus type 5-based vectors in swine and their ability to protect against transmissible gastroenteritis coronavirus
Department of Molecular and Cell Biology, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.
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