#15-125

Complete

Date Full Report Received

02/09/2018

Date Abstract Report Received

02/09/2018

Investigation

Institution:
Primary Investigator:

African swine fever (ASF) is a highly lethal and contagious disease of domestic and wild pigs caused by the ASF virus. ASF is commonly found in Africa, but in 2007 spread to Russia and Eastern Europe, and continues to spread within domestic pigs and wild boar populations. ASF is a serious risk to the global pig population and a challenge for the animal health sector in other countries including the U.S. There is no vaccine available for ASF; therefore, rapid and accurate diagnostic tools will be critical for control and surveillance in the event of an outbreak in the U.S. Oral fluid-based diagnostics provide a possible solution by allowing rapid pen-based sampling to monitor disease progression and intervention measures during disease outbreaks. Oral fluids are an aggregate sample collected from a group of pigs using rope chew sampling. Oral fluid sampling of groups is simple, inexpensive, safe, and less labor and animal intensive than individual sampling methods. This sampling method is user-friendly and the technology is easily transferrable to farmers and animal care specialists.

The purpose of this project was to compare and validate oral fluids (pooled sample) for the laboratory diagnosis of ASF infections in pigs. In doing so, we evaluated commercially-available diagnostic tests for detecting antibodies to the ASF virus and virus DNA. In the event of the detection of ASF in North America, the demand for testing will rapidly overwhelm national testing capacity. The only way to deal with this anticipated demand is through the use of commercial kits. The second aim of this project was to compare different specimen types, including oral fluids, to assess their suitability for diagnostic testing using our tests.

In order to produce diagnostic specimens to test in the laboratory, we infected pigs experimentally with the ASF virus within a high biocontainment animal facility. Blood samples, along with oral fluids were collected at various time points to test for virus and antibodies. We found that the appearance of antibodies and virus in oral fluids occurred at a similar time to blood, which is a traditional diagnostic specimen, but invasive to collect. Therefore, our results indicate that oral fluids have the potential to serve as a cheap and rapid sample type for diagnosing ASF infections. We also identified the best commercial kits available for sensitive antibody and DNA testing. Importantly, antibody tests were shown to be less sensitive than a non-commercial reference test, highlighting the need for more research and development in this area.

The results from this study have enabled us to identify sensitive diagnostic tools that are available commercially and can be applied to a variety of scenarios, such as diagnosis of infection during an outbreak, surveillance, and proof of freedom from ASF. The information we have generated will assist the swine industry and animal health decision makers concerning the tools and surveillance strategies available to deal with the potential emergence of ASF in North America. The results derived from this project have also underlined the need for future research on improved ASFV diagnostics.