Applying Bioportal in a PRRS Regional Disease-Control Program: case study

Introduction of gilts into a swine farm always conveys the risk of disease introduction into the recipient herd and, consequently, from a regional perspective, disease introduction into clusters of neighboring farms. In several areas in North, Central and South America, the swine industry is organized in projects of PRRS (Porcine Reproductive and Respiratory Syndrome) control by regions. These projects allow for coordinated actions to control PRRS and for sharing of information regarding swine diseases circulating in the area. Information related to diseases present in the different regions can be analyzed simultaneously in time, space and genomics applying a program called Bioportal which was originally developed at UC Davis to understand the dynamics of Foot and Mouth Disease worldwide.

In this case, 500 replacement gilts imported into the country tested PCR and ELISA negative to PRRS virus (PRRSv) upon shipment, arrival and seven days into quarantine. Three weeks after arrival, the gilts tested PCR PRRSv positive. When sequenced, a 1-26-2 RFLP cut pattern was detected. In order to assess if this PRRSv isolate was a new introduction to the region or a resident virus, those nucleotide sequences were compared against the available regional database. Bioportal was applied to generate a dendrogram linking sequences on it to a map of their corresponding sites of origin. The swine industry usually applies a threshold of ≥2% difference on the ORF5 region of the PRRSv to determine similarity among sequences.

The resultant dendrogram showed three different branches: one at > 6% difference –heterology-, another at between 2 and 6%, and one more at < 2% heterology from the case’s sequence. Sixty eight (n=68) isolates were included in the branch showing < 2% heterology to the case’s isolate. The map in that report showed that those 68 isolates were located in the same sub-region within the project’s area.

The agreements reached to share diagnostic data among participants from projects of regional control of PRRS have shown great value when investigating questions related to the dynamics of pathogens’ presentation and distribution in those regions. In this case, the availabilty of such data and the application of a powerful tool as Bioportal allowed the management of large amounts of data (e.g., geographic location, nucleotide sequences, different points in time, etc.) to generate analytical and visual/descriptive reports in a fast, timely approach. Once determined that the PRRSv isolate from the quaratined gilts was a regional resident virus, an investigation was conducted to understand routes of lateral introduction.

Disclosure of Interest: None Declared.