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Cloning and expression of FECV spike gene in vaccinia virus. Immunization with FECV S causes early death after FIPV
S Klepfer1, A P Reed, M Martinez
1Department of Molecular Biology, Smithkline Beecham Animal Health, King of Prussia, Pennsylvania, USA.
Abstract:
The spike gene of the feline enteric coronavirus (FECV), strain FECV-1683, was PCR amplified from total RNA extracted from FECV-infected cells and its sequence determined. A primary translation product of 1454 amino acids is predicted from the nucleotide sequence, containing a N-terminal signal sequence, a C-terminal transmembrane region and 33 potential N-glycosylation sites. The sequence shares 92% homology with the previously published feline infectious peritonitis virus, strain WSU-1146; however, several regions were identified that distinguished FECV from Feline Infectious Peritonitis virus, FIPV. The full length FECV S gene was cloned and expressed in vaccinia virus. Recombinants produced a 200 kD protein which was recognized by sera from cats infected with FIPV. When kittens were immunized with the vaccinia/FECV S recombinant, neutralizing antibodies to FIPV were induced. After challenge with a lethal dose of FIPV, the recombinant vaccinated animals died earlier than control animals immunized with vaccinia virus alone.
Insights
Researchers sequenced the feline enteric coronavirus (FECV) spike gene, finding it distinct from feline infectious peritonitis virus (FIPV). Expression in vaccinia virus induced antibodies but did not protect kittens from FIPV challenge.
Area of Science:
- Veterinary Virology
- Molecular Biology
- Immunology
Background:
- Feline enteric coronavirus (FECV) causes enteric disease in cats.
- Feline infectious peritonitis virus (FIPV) causes a fatal systemic disease.
- The spike (S) protein is a key determinant of coronavirus tropism and immunogenicity.
Purpose of the Study:
- To characterize the FECV spike gene sequence.
- To evaluate the potential of the FECV S protein as a vaccine candidate against FIPV.
Main Methods:
- PCR amplification and sequencing of the FECV S gene.
- Cloning and expression of the FECV S gene in vaccinia virus.
- Immunization of kittens with the recombinant vaccinia virus.
- Challenge of vaccinated kittens with FIPV.
Main Results:
- The FECV S gene sequence was determined and predicted to encode a 1454 amino acid protein.
- The FECV S sequence shared 92% homology with FIPV but contained distinct regions.
- Recombinant vaccinia virus expressing FECV S produced a 200 kDa protein recognized by FIPV-infected cat sera.
- Vaccination with the recombinant induced neutralizing antibodies to FIPV but did not prevent mortality upon FIPV challenge.
Conclusions:
- The FECV S protein is antigenically related to FIPV S protein.
- While FECV S elicits neutralizing antibodies, it does not confer protection against lethal FIPV infection.
- Further research is needed to identify protective epitopes of FIPV.