%0 Journal Article %A Overend, C. %A Mitchell, R. %A He, D. %A Rompato, G. %A Grubman, M. J. %A Garmendia, A. E. %T Recombinant swine beta interferon protects swine alveolar macrophages and MARC-145 cells from infection with Porcine reproductive and respiratory syndrome virus %D 2007 %J Journal of General Virology, %V 88 %N 3 %P 925-931 %@ 1465-2099 %R https://doi.org/10.1099/vir.0.82585-0 %I Microbiology Society, %X Swine beta interferon (swIFN-β) produced in HEK 293 cells infected with a recombinant, replication-defective human adenovirus 5 (Ad5) encoding the swIFN-β gene was tested for antiviral activity against Porcine reproductive and respiratory syndrome virus (PRRSV). MARC-145 cells were incubated overnight with dilutions of supernatant fluids from HEK 293 cells infected with Ad5-swIFN-β or with an Ad5 control virus (Ad5-Blue). Treated cells were infected with PRRSV; MARC-145 cells incubated with Ad5-Blue supernatants developed cytopathic effects (CPE), whereas those incubated with swIFN-β showed no CPE. To confirm the antiviral activity of swIFN-β, culture fluids from Ad5-swIFN-β-infected cells were affinity-purified on a Sepharose–anti-swIFN-β matrix, and the resulting fractions exhibited antiviral activity upon infection with PRRSV. The antiviral effects were specific, as they were blocked by mAbs against swIFN-β. Additional cultures of MARC-145 cells treated with swIFN-β-containing supernatants or affinity-purified swIFN-β were infected with PRRSV and tested by real-time RT-PCR for viral RNA in culture supernatants at various times post-inoculation. These experiments confirmed the protective effects of swIFN-β. swIFN-β was also tested for antiviral activity on porcine alveolar macrophages (PAMs) obtained by bronchoalveolar lavage from PRRSV-negative swine. PAMs were treated with dilutions of swIFN-β or Ad5-Blue culture fluids, infected with PRRSV and tested for viral RNA by real-time RT-PCR. The viral load data showed a dose-dependent protection in swIFN-β-treated PAMs, whereas no protection was evident from Ad5-Blue culture fluids. The data demonstrate that swIFN-β protects both MARC-145 cells and PAMs from PRRSV infection. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.82585-0