| Summary: | Classical swine fever virus (CSFV) causes a serious disease of pigs that is a major threat to pork production industries worldwide. Due to the limitations of available vaccines there is a need for alternative strategies to aid (SF outbreak control. One such alternative could be through the use of type I interferon (IFN ). During the acute phase of CSFV infection, high levels of systemic porcinelFNα (Po IFNα) are detected in pigs and one recombinant Pol FNα subtype has been reported to have anti-viral activities against CSFV in vitro. The aim of this study was to express and characterize the full panel of recombinant PoIFN-α subtypes and to establish an in vitro model to assess their anti-CSFV activity if given prophylactically. All 17 PoIFN-α subtypes were cloned, expressed in Chinese hamster ovary cells and purified. The biological activity of each subtype was confirmed using a VSV bioassay. Following the optimisation of an infection model using a commercial preparation of PoIFNα, differential activity was observed between subtypes following treatment of porcine monocytes prior to infection with CSFV. The subtypes were subsequently grouped as having high, medium or low anti-CSFV activity. The potency of representative members of the active subtypes was investigated over a 72hr pre-treatment assay which confirmed PoIFNα12 as the most potent subtype against CSFV in vitro. An additive effect was observed when equal ratios of subtypes with in an activity group were used in combination. The expression of each subtype was then assessed du ring the course of a primary CSFV infection in vivo. When comparing the relative patterns of expression of the PolFNα subtypes in individual pigs, several subtypes appeared to be expressed at higher levels. However, the only consistent increase post CSFV infection was that of PoIFNα12, In conclusion, this study has shown that PolFNα subtypes possess differential anti-CSFV activities in vitro, and that PoIFNα12 represents a possible candidate for investigation as a me◦taphylactic treatment against CSFV infection.
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