Replicons of pestviruses that do not express C and or E1 protein and infectious viral particles containing same, that can be used in vaccines
The present invention provides new Pestiviral RNA genomes (replicons) that are able to replicate, and can be packaged into infectious viral particles in cells that complement the missing protein(s), but do not produce infectious progeny virus. Such replicons can be useful for vaccine purposes.
1. A replicon of a pestivirus which is incapable of expressing one or more structural proteins of the virus, characterized in that said replicon expresses all structural proteins of a pestivirus except for a functional C protein, but wherein the coding sequences encoding a signal sequence within the C protein essential for post translational processing are retained or replaced by a coding sequence encoding analogous signal sequences from another pestiviral species.
2. The replicon according to claim 1 , characterized in that at least part of the coding sequence of the C protein has been deleted from said replicon.
3. The replicon according to claim 1 , characterized in that said replicon is of a Bovine Viral Diarrhea Virus (BVDV).
4. The replicon according to claim 3 , characterized in that the coding region encoding amino acid positions 201-243 of a BVDV strain NCP-7 polyprotein have been deleted.
5. An infectious viral particle of pestivirus, characterized in that it contains a replicon according to claim 1 .
6. A method for the production of infectious viral particles of a pestivirus, characterized in that said method comprises the following steps:
a. providing cells that are permissive for the pestivirus and express pestiviral C protein,
b. transfecting said cells with in-vitro transcribed RNA of a replicon according to claim 1 ,
c. culturing transfected cells obtained in step b,
d. harvesting the viral particles from the cultured cells.
7. The method according to claim 6 , characterized in that said pestivirus is BVDV.
8. The method according to claim 7 , characterized in that said cells express the C protein of BVDV.
9. A vaccine containing infectious viral particles according to claim 5 and a pharmaceutically acceptable carrier.