In today’s post, we would like to highlight the value of flu surveillance in swine as well as to acknowledge the University of Minnesota Veterinary Diagnostic Laboratory (UMN-VDL) as a long-standing and committed contributor to the USDA Voluntary Influenza A Virus (IAV) in Swine Surveillance program. Thanks to this surveillance program, the U.S. swine industry has ample information available for analysis and to support influenza-related research, vaccinology and diagnostics.
The emergence of antimicrobial resistance in humans, animals
and the environment is a major global public health threat to both human and
veterinary medicine. Efforts to address
this important issue involve government, industry, academia, and most notably,
veterinary diagnostic laboratories (VDLs).
These efforts include surveillance to assess the extent resistance in
human and animal pathogens and the development of policies to monitor and
control antimicrobial resistance.
A collaborative effort involving the stakeholders listed above is the key to addressing this emerging threat of antimicrobial resistance and VDLs play major roles in these collaborative efforts. As reported in a Commentary by GK Hendrix in the Journal of Veterinary Diagnostic Investigation in 2018, VDLs are the “nexus in the battle against antimicrobial resistance” (1). The University of Minnesota VDL Bacteriology Section performs almost 30,000 bacterial cultures annually, and most of the pathogenic isolates are archived for future use. These uses include further testing (subtyping, virulence gene assays, serotyping, etc.), use in disease control efforts (autogenous vaccines, etc.), various research projects, and surveillance studies. Almost 5,000 of these pathogenic bacteria are subjected to antimicrobial resistance testing annually, and these antimicrobial minimum inhibitory concentration data are archived for decades for further use.
Performing one of many antimicrobial susceptibility tests in the University of Minnesota Veterinary Diagnostic Laboratory, Bacteriology Section.
For our part in this aforementioned collaborative effort in
antimicrobial stewardship, the University of Minnesota VDL is actively involved
in two collaborative government-organized antimicrobial resistance projects as
well as several collaborative academic research projects on antimicrobial
resistance. The common goal of the
collaborative government projects is to determine the population and
distribution of resistant bacteria in the U.S.
The first of these projects is the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service National Animal
Health Laboratory Network (NAHLN) project (2).
This project has 19 AAVLD-accredited laboratories throughout the U.S.
and Canada participating with the objective of monitoring antimicrobial
resistance profiles in animal pathogens routinely isolated from VDLs. Ultimately, this project will result in a national
centralized data collection and reporting process, using harmonized methods and
antimicrobial resistance interpretation and reporting standards. It aims to monitor data for trends in
antimicrobial resistance phenotypes (and eventually genotypes) by identifying
new or emerging resistance profiles, monitoring usefulness of antimicrobials
over time, and reporting these trends to facilitate antimicrobial stewardship
efforts.
This USDA project
began in January, 2018, and initially involved collection of isolates and
antimicrobial resistance data from Escherischia
coli (all species), Salmonella
enterica (all species), Mannheimia
haemolytica (cattle) and Staphylococcus
intermedius group (companion animals) from routine VDL submissions. A target of about 3,000 isolates will be collected
from the participating VDLs annually and archived for further testing. The antimicrobial testing data will be
tracked and stored by USDA for each
isolate and an annual report will be prepared for stakeholders. This report will include antimicrobial
resistance trends for antibiotics important for human and animal health and the
distribution of minimum inhibitory concentrations for each antimicrobial
monitored for each bacterial pathogen for each animal species included in the
study.
The second of these collaborative antimicrobial resistance projects
is the Food and Drug Administration
(FDA), Center for Veterinary
Medicine, Veterinary-Laboratory Investigation and Response Network (Vet-LIRN)
project (3). This project has 21 AAVLD-accredited laboratories participating
with the objective of performing surveillance of antimicrobial susceptibility
testing results and whole genome sequencing of pathogens from the National
Antimicrobial Resistance Monitoring System scope of interest (4).
This FDA project began in January, 2017, and initially involved collection of isolates and data for three zoonotic bacterial pathogens, with several other bacterial species added to the project in July, 2018. About 2,000 isolates have been collected since project inception, and the FDA has randomly selected about 200 of these isolates for whole genome sequencing. The remaining isolates have been archived for future studies. As an additional benefit related to this project, the University of Minnesota VDL received funds from FDA to purchase an Illumina iSeq Sequencer and participate in a collaborative project designed to increase the number and capabilities of network laboratories involved in the whole genome sequencing portion of this FDA project. Standardization and harmonization of these bacterial genome sequencing abilities among participating laboratories is further designed to increase the network capacity and facilitate future outbreak investigations.
In summary, in support of antimicrobial stewardship efforts, the University of Minnesota VDL Bacteriology Section provides clinical isolates and antimicrobial susceptibility testing data for two collaborative government-initiated projects, one in collaboration with the USDA and the other with the FDA. Further, the VDL as a whole provides leadership in antimicrobial stewardship on a daily basis, cooperating with disease outbreak investigations, collaborating with academic and industrial researchers, and educating veterinarians, clients and the public on issues of antimicrobial stewardship (1).
This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
Antimicrobial resistance has been a preoccupying topic for the past few years. We talked before about what the definition of antibiotic resistance is and how it can be interpreted in two different manners. This week, Dr. Alvarez from the STEMMA lab is reporting the trends in antimicrobial susceptibility observed in strains of Streptococcus suis and Pasteurella multocida isolated at the Minnesota Veterinary Diagnostic Laboratory over the past 10 years. S. suis and P. multocida are common swine pathogens that can cause severe economic losses. Knowing which antibiotics are more likely to be efficient against those bacteria can help in tackling the disease faster.
Key Points:
MN-VDL data was analyzed to study antibiotic susceptibility in clinical isolates of Pasteurella multocida and Streptococcus suis from 2006 to 2016.
Isolates were highly susceptible to Ampicillin, Ceftiofur, Enrofloxacin and Florfenicol throughout the study period.
There were no changes in antibiotic susceptibility against the antibiotics tested routinely across the study period.
The Veterinary Diagnostic Laboratory’s mission is to protect and promote animal and human health through early detection and monitoring of animal diseases.
The 2016 report was published last month and we are compiling here the highlights related to swine. We can also read the full 2016 UMN VDL report.
In April 2016, the VDL welcomed its new director Dr. Jerry Torrison.
More than 50% of the procedures in the VDL were related to the porcine species last year.
A new multiplex PCR test that combines Porcine Epidemic Diarrhea Virus (PEDv), Porcine Deltacoronavirus (PDCoV) and Transmissible Gastroenteritis Virus (TGEV) into one assay was implemented into the Molecular Diagnostic clinical testing schedule effective October 31st, 2016. The new assay provides clients with timely, quality results for all three viruses at the same time. The VDL ran 40,131 PEDv and PDCoV Multiplex Real Time PCR tests and 5,238 Triplex (PEDv/TGE/PDCoV) RT-PCR tests.
Additionally, the Serology lab conducted intensive testing in collaboration with Zoetis for validation of PED antibody test kit which they are planning to release on the market soon.
Seneca Valley Virus PCR was validated and is part of routine testing. 3,205 Senecavirus A EZ Real time RT-PCR tests were run. An ELISA test for antibodies to Seneca Valley Virus in pigs is also available.
The IHC lab participated in the 2016 AAVLD/NVSL Program for Inter-laboratory Comparison, and scored 100% in its detection of Porcine Circovirus type 2 in the test samples provided.
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.
