Expression of Porcine Fusion Protein IRF7/3(5D) Efficiently Controls Foot-and-Mouth Disease Virus Replication

Abstract

Several studies have demonstrated that the delivery of type I, II, or III interferons (IFNs) by inoculation of a replication-defective human adenovirus 5 (Ad5) vector expressing IFNs can effectively control foot-and-mouth disease (FMD) in cattle and swine during experimental infections. However, relatively high doses are required to achieve protection. In this study, we identified the functional properties of a porcine fusion protein, poIRF7/3(5D), as a biotherapeutic and enhancer of IFN activity against FMD virus (FMDV). We showed that poIRF7/3 ( IMPORTANCEFMD remains one of the most devastating diseases that affect livestock worldwide. Effective vaccine formulations are available but are serotype specific and require approximately 7 days before they are able to elicit protective immunity. We have shown that vector-delivered IFN is an option to protect animals against many FMDV serotypes as soon as 24 h and for about 4 days postadministration. Here we demonstrate that delivery of a constitutively active transcription factor that induces the production of endogenous IFNs and potentially other antiviral genes is a viable strategy to protect against FMD.

Constitutively Active IRF7/IRF3 Fusion Protein Completely Protects Swine against Foot-and-Mouth Disease

“…In our previous studies, we showed that administration of Ad5-poIRF7/3(5D) prevents mortality in an FMD mouse model (20). Therefore, we investigated whether Ad5-poIRF7/3(5D) administration could prevent FMD in swine, an FMD natural host.…”

“…Groups of three pigs each were treated with different doses of Ad5-poIRF7/3(5D) (10 9 PFU/animal or 10 10 PFU/animal) or with Ad5-Blue (10 10 PFU/animal) as a control. All doses were adjusted with Ad5-Blue in order to administer a total of 10 10 PFU of Ad5 per animal and account for the possible baseline antiviral effect induced by the vector alone (20,30). Twenty-four hpi, animals were challenged with FMDV A24 (Fig.…”

“…7A). The dose of Ad5-poIRF7/3(5D) selected (10 8 PFU/mouse) was based on previous data (20) and accounted for the fact that Ad5-poIRF7/3(5D) does not induce as high a level of antiviral activity in murine cells as it does in porcine cells. Forty-eight hours after Ad5 treatment, all mouse groups were challenged with FMDV A24 Cruzeiro at the lethal dose of 5 ϫ 10 4 PFU/mouse.…”

“…Forty-eight hours after Ad5 treatment, all mouse groups were challenged with FMDV A24 Cruzeiro at the lethal dose of 5 ϫ 10 4 PFU/mouse. Challenge with FMDV A24 was conducted at 48 hpi as previously reported, to minimize the effect of the antiviral activity induced by the adenoviral vector alone (20,30). Serum samples were collected at specified days (see Fig.…”

“…In turn, IFNs are secreted and, in an endocrine and autocrine manner, bind to specific receptors, triggering the activation of hundreds of IFN-stimulated genes (ISGs) that mediate cellular antiviral pathways (17,19). Recently, we have demonstrated that a constitutively active fusion protein of porcine IRF3 and IRF7 [poIRF7/3(5D)] strongly induces type I IFN and antiviral genes in swine cells and protects mice from FMD mortality (20). In this study, we demonstrated that pigs inoculated with an Ad5 expressing poIRF7/3(5D) [Ad5-poIRF7/3(5D)] and challenged at 24 h postinoculation (hpi) with FMDV are fully protected against FMD clinical signs, had no viremia or virus shedding, and did not develop antibodies against FMDV nonstructural proteins.…”