The swine group was well represented at the 2017 MVMA meeting. Ms. Alyssa Anderson and Dr. Karine Ludwig Takeuti both gave a presentation on diagnostic tools to detect Mycoplasma hyopneumoniae infections. Drs. Jorge Garrido Mantilla and Fabian Chamba Pardo shared the latest update on swine influenza. Dr. Amy Kinsley explained how the structure of a swine farm can influence disease persistence. Dr. Talita Resende shared the advantages of a fairly recent diagnostic technique: in situ hybridization. Congratulations to Ms. Alyssa Anderson who also received a $5,000 Food Animal Scholarship from the MVM Foundation!
Today, we are very pleased to report that a new indirect ELISA to identify Senecavirus A antibodies has been validated at the University of Minnesota and is now available for our Veterinary Diagnostic Laboratory clients. This ELISA targets specifically antibodies against Viral Protein 2 (VP2) and has a sensitivity of 94.2% and a specificity of 89.7%. The test does not cross react with antibodies against Foot-and-Mouth Disease allowing for a quick differentiation between a Senecavirus A outbreak and a costly foreign animal disease.
Fig 1: Different ELISA types (Source: nptel.ac.in)
Abstract
Background: Senecavirus A (SVA), a member of the family Picornaviridae, genus Senecavirus, is a recently identified single-stranded RNA virus closely related to members of the Cardiovirus genus. SVA was originally identified as a cell culture contaminant and was not associated with disease until 2007 when it was first observed in pigs with Idiopathic Vesicular Disease (IVD). Vesicular disease is sporadically observed in swine, is not debilitating, but is significant due to its resemblance to foreign animal diseases, such as foot-and-mouth disease (FMD), whose presence would be economically devastating to the United States. IVD disrupts swine production until foreign animal diseases can be ruled out. Identification and characterization of SVA as a cause of IVD will help to quickly rule out infection by foreign animal diseases.
Methods: We have developed and characterized an indirect ELISA assay to specifically identify serum antibodies to SVA. Viral protein 1, 2 and 3 (VP1, VP2, VP3) were expressed, isolated, and purified from E. coli and used to coat plates for an indirect ELISA. Sera from pigs with and without IVD symptoms as well as a time course following animals from an infected farm, were analyzed to determine the antibody responses to VP1, VP2, and VP3.
Results: Antibody responses to VP2 were higher than VP1 and VP3 and showed high affinity binding on an avidity ELISA. ROC analysis of the SVA VP2 ELISA showed a sensitivity of 94.2% and a specificity of 89.7%. Compared to IFA, the quantitative ELISA showed an 89% agreement in negative samples and positive samples from 4–60 days after appearance of clinical signs. Immune sera positive for FMDV, encephalomyocarditis virus, and porcine epidemic diarrhea virus antibodies did not cross-react.
Conclusions: A simple ELISA based on detection of antibodies to SVA VP2 will help to differentially diagnose IVD due to SVA and rule out the presence of economically devastating foreign animal diseases.
Next week-end will start the 48th American Association of Swine Veterinarians (AASV) meeting in Denver, CO. As usual, numerous UMN-CVM faculty and graduate students will be attending and presenting the results of their latest research. We hare looking forward to seeing you there!
Pre-conference seminars:
Doug Marthaler: Porcine rotaviruses: what we know and what we are still missing
Maria Pieters: Current tools to approach Mycoplasma hyopneumoniae diagnostic cases
Research topics:
Michael Murtaugh: Broadly neutralizing antibodies to recent, virulent type 2 PRRSV isolates
Michael Rahe: Characterization of the memory immune response to PRRSV infection
Fabian Chamba Pardo: Effect of influenza prevalence at weaning on transmission, clinical signs and performance after weaning
Talita Resende: Mycoplasma hyorhinis associated with conjunctivitis in pigs
Antibiotic session:
Peter Davies: Antibiotic use metrics
Managing the reproductive herd for high health and productivity
Maria Pieters: A pig’s early challenges
Student session:
Alyssa Anderson: Use of molecular characterization tools to investigate Mycoplasma hyopneumoniae outbreaks
Hunter Baldry: Evaluation of positive pressure filtration to reduce aerosol transmission of PRRSV during an experimental challenge of farm access points
Chris Deegan: Dynamics of Mycoplasma hyopneumoniae colonization, seroconversion and onset of clinical signs in a population of gilts under field conditions
Zhen Yang: Investigating Porcine Circovirus Associated Disease (PCVAD) in commercial swine herd by next generation sequencing
Posters:
Fabian Chamba Pardo: Influenza A virus prevalence and seasonality in midwestern US breeding herds
Donna Drebes: Trends in Lawsonia intracellularis PCR to the submissions to the UMN-VDL over a 10-year period
Kevin Gustafson: B-cell tetramer monitoring of the memory immune response to PRRSV
Taylor Homann: Characterizing piglet loss from PRRS outbreak
