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Journal of Virology, September 2000, p. 7952-7962, Vol. 74, No. 17
Enterovirus Research Laboratory, Department
of Pathology and Microbiology,1 and
Department of Pathology and
Microbiology,2 University of Nebraska Medical
Center, Omaha, Nebraska 68198
Received 17 December 1999/Accepted 8 June 2000
We cloned the sequence encoding murine interleukin-4 (mIL-4),
including the secretory signal, into the genome of CVB3/0, an artificially attenuated strain of coxsackievirus B3, at the junction of
the capsid protein 1D and the viral protease 2Apro. Two strains of
chimeric CVB3 were constructed using, in one case, identical sequences
to encode 2Apro cleavage sites (CVB3/0-mIL4/47) on either side of the
inserted coding sequence and, in the other case, nonidentical sequences
that varied at the nucleotide level without changing the amino acid
sequences (CVB3-PL2-mIL4/46). Transfection of HeLa cells yielded
progeny viruses that replicated with rates similar to that of the
parental CVB3/0 strain, although yields of mIL-4-expressing strains
were approximately 10-fold lower than those of the parental virus.
Western blot analysis of viral proteins isolated from HeLa cells
inoculated with either strain of chimeric virus demonstrated that the
chimeric viruses synthesized capsid protein 1D at approximately twofold-higher levels than the parental virus. mIL-4 protein was detected by enzyme-linked immunosorbent assay (ELISA) in HeLa cells
inoculated with either strain of chimeric virus. Lysates of HeLa cells
inoculated with either chimeric virus induced the proliferation of the
mIL-4-requiring murine MC-9 cell line, demonstrating biological
activity of the CVB3-expressed mIL-4. Reverse transcription (RT)-PCR
analysis of viral RNA derived from sequential passaging of
CVB3/0-mIL4/47 in HeLa cells demonstrated deletion of the mIL-4 coding
sequence occurring by the fourth passage, while similar analysis of
CVB3-PL2-mIL4/46 RNA demonstrated detection of the mIL-4 coding
sequence in the virus population through 10 generations in HeLa cells.
mIL-4 protein levels determined by ELISA were consistent with the
stability and loss data determined by RT-PCR analysis of the passaged
viral genomes. Studies of insert stability of CVB3-PL2-mIL4/46 during
replication in mice showed the presence of the viral mIL-4 insert in
pancreas, heart, and liver at 14 days postinfection. Comparison of the
murine antibody responses to CVB3-PL2-mIL4/46 and the parental CVB3/0
strain demonstrated an increased level of CVB3-binding serum
immunoglobulin G1 in mice inoculated with CVB3-PL2-mIL4/46.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Coxsackievirus Expression of the Murine Secretory
Protein Interleukin-4 Induces Increased Synthesis of Immunoglobulin
G1 in Mice
and
*
Corresponding author. Mailing address: Enterovirus
Research Laboratory, Department of Pathology and Microbiology,
University of Nebraska Medical Center, 986495 Nebraska Medical Center,
Omaha, NE 68198. Phone: (402) 559-7735. Fax: (402) 559-4077. E-mail: nchapman{at}unmc.edu.
Present address: Transfusion Service, Stanford University Hospital,
Stanford, CA 94303.
Present address: Path Logic, Inc., Dixon, CA 95620.
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