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Journal of Virology, September 1999, p. 7607-7618, Vol. 73, No. 9
Centro Nacional de Biotecnología,
Received 8 March 1999/Accepted 5 June 1999
Targeted recombination within the S (spike) gene of transmissible
gastroenteritis coronavirus (TGEV) was promoted by passage of helper
respiratory virus isolates in cells transfected with a TGEV-derived
defective minigenome carrying the S gene from an enteric isolate. The
minigenome was efficiently replicated in trans and packaged
by the helper virus, leading to the formation of true recombinant and
pseudorecombinant viruses containing the S proteins of both enteric and
respiratory TGEV strains in their envelopes. The recombinants acquired
an enteric tropism, and their analysis showed that they were generated
by homologous recombination that implied a double crossover in the S
gene resulting in replacement of most of the respiratory, attenuated
strain S gene (nucleotides 96 to 3700) by the S gene of the enteric,
virulent isolate. The recombinant virus was virulent and rapidly
evolved in swine testis cells by the introduction of point mutations
and in-phase codon deletions in a domain of the S gene (nucleotides 217 to 665) previously implicated in the tropism of TGEV. The helper virus,
with an original respiratory tropism, was also found in the enteric
tract, probably because pseudorecombinant viruses carrying the spike
proteins from the respiratory strain and the enteric virus in their
envelopes were formed. These results demonstrated that a change in the
tropism and virulence of TGEV can be engineered by sequence changes in the S gene.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Targeted Recombination Demonstrates that the Spike
Gene of Transmissible Gastroenteritis Coronavirus Is a Determinant
of Its Enteric Tropism and Virulence
*
Corresponding author. Mailing address: Centro Nacional
de Biotecnología, CSIC, Dept. of Molecular and Cell Biology,
Campus Universidad Autonoma, Cantoblanco, 28049 Madrid, Spain. Phone: 34-91-585-45-55. Fax: 34-91-585-45-55. E-mail:
L.Enjuanes{at}cnb.uam.es.
Journal of Virology, September 1999, p. 7607-7618, Vol. 73, No. 9
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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