|VELAZQUEZ-SALINAS, LAURO - Oak Ridge Institute For Science And Education (ORISE)|
|RISATTI, GUILLERMO - University Of Connecticut|
|O'DONNELL, VIVIAN - University Of Connecticut|
|CARLSON, JOLENE - Kansas State University|
|ALFANO, MARIALEXIA - Oak Ridge Institute For Science And Education (ORISE)|
|CARRILLO, CONSUELO - Animal And Plant Health Inspection Service (APHIS)|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2016
Publication Date: 7/4/2016
Citation: Velazquez-Salinas, L., Risatti, G.R., Holinka-Patterson, L.G., O'Donnell, V.K., Carlson, J., Alfano, M., Rodriguez, L.L., Carrillo, C., Gladue, D.P., Borca, M.V. 2016. Recoding classical swine fever virus (CSFV) structural glycoprotein E2 produces complete virus attenuation in swine and protects infected animals against disease. Virology. 494:178-189. doi: 10.1016/j.virol.2016.4.007.
Interpretive Summary: Controlling classical swine fever (CSF) involves vaccination in endemic regions and preemptive slaughter of infected swine herds during epidemics. Generally, live attenuated vaccines induce solid immunity. Here we present data in the use of a special methodology called codon de-optimization to develop attenuated strains of viruses. The methodology, already used with other viruses, consists includes in the massive introduction of nucleotide changes in the genome of the viruses without altering their amino acid sequence. We present here the production of four different classical swine fever viruses (CSFV) developed in that way. One of these viruses was completely attenuated and, importantly, induced protection when used as vaccine against the infection with virulent CSFV. This is the first report describing the use of this methodology in CSFV.
Technical Abstract: Controlling classical swine fever (CSF) involves vaccination in endemic regions and preemptive slaughter of infected swine herds during epidemics. Generally, live attenuated vaccines induce solid immunity. Using diverse approaches, reverse genetics has been useful in developing classical swine fever virus (CSFV) experimental attenuated strains. Here we present data on the effect of codon de-optimization in the major CSFV structural glycoprotein in virus attenuation in swine. Four different mutated constructs were designed using various mutational approaches based on the genetic background of the highly virulent strain Brescia (BICv). Three of these constructs produced infectious viruses; CSFm2v, CSFm3v, and CSFm4v and presented similar growth characteristics to the parental BICv in vitro. Swine intranasally infected with CSFm3v or CSFm4v developed a clinical disease indistinguishable from that presented by animals infected with BICv, including viremia levels and replication kinetics closely resembling those of BICv. Animals infected with CSFm2v presented with reduced and extended viremia but did not display any CSF-related clinical signs. Interestingly, the replication ability of CSFm2v was markedly reduced compared with the parental BICv when assessed in primary swine macrophage cell cultures, the main target cell type during the infection in vivo. Importantly, animals infected with CSFm2v were completely protected against CSF disease and infection after challenge with the virulent parental BICv. This is the first report describing the development of an attenuated CSFV experimental vaccine by codon usage de-optimization, and one of the few examples of virus attenuation using this methodology that is assessed in a natural host.