Development of a fluorescent ASFV strain that retains the ability to cause disease in swine

Authors: Borca, Manuel; O'DONNELL, VIVIAN - University Of Connecticut; Holinka-Patterson, Lauren; SANFORD, BRENT - Us Deparment Of Homeland Security; AZZINARO, PAUL - Oak Ridge Institute For Science And Education (ORISE); RISATTI, GUILLERMO - University Of Connecticut; Gladue, Douglas

Submitted to: Nature Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2017
Publication Date: 4/24/2017
Citation: Borca, M.V., O'Donnell, V., Holinka-Patterson, L.G., Sanford, B., Azzinaro, P.A., Risatti, G., Gladue, D.P. 2017. Development of a fluorescent ASFV strain that retains the ability to cause disease in swine. Nature Scientific Reports. 7:46747. doi: 10.1038/srep46747.

Interpretive Summary: It is very difficult to see virus under a normal microscope, without using complex labeling procedures. In this manuscript we add a fluorescent tag, originally discovered in jelly fish, that naturally fluoresces on its own a green color, this tag is commonly known as Green fluorescent protein (GFP) allowing us to easily visualize African Swine Fever Virus (ASFV), a swine virus that is devastating to the swine industry. Often when you tag a virus in a similar way, the virus loses its ability to function or to cause disease. In this manuscript our GFP tag does not interfere with the ability of ASFV to cause disease in swine. This will allow us or others to use this fluorescent tagged protein to monitor ASFV replication and pathogenesis without the need for complex labeling procedures, something that is required for large scale studies, such as antiviral screening procedures.

Technical Abstract: African swine fever is a contagious and often lethal disease for domestic pigs with a significant economic impact for the swine industry. The etiological agent, African swine fever virus (ASFV), is a highly structurally complex double strain DNA virus. No effective vaccines or antiviral treatment are currently commercially available. We present here the development of a strain of ASFV that has been shown to retain its ability to cause disease in swine, efficiently replicate in swine macrophage and that is fluorescently tagged. The insertion of an EGFP cassette replacing the reading frames for two neighboring genes, MGF360-13L and MGF360-14L, in highly virulent field isolate Georgia/2007, did not affect virus replication in cell cultures and did not affect disease progression in swine, the natural host for ASFV. A virulent fluorescently tagged ASFV is a suitable tool to conduct pathogenesis studies in swine, study on virus-macrophage interaction and to run large scale screens that require a sensitive high throughput output. Utilizing an EGFP reporter system for observing ASFV replication and infectivity can circumvents the time and labor-intensive steps associated with viral antigen-based assays, observation of hemadsorption or cytopathic effect.