Veterinary Diagnostic Laboratory

We have been testing for porcine lymphotropic herpesviruses (PLHV; also referred to as porcine gammaherpesviruses) here at UMN VDL using a conventional gel-based assay, which provides a positive or negative result but does not differentiate between PLHV-1, PLHV-2, or PLHV-3. 

We've recently developed a new PLHV multiplex real-time PCR assay and will start running this new assay this week as our routine PLHV test. The gel-based assay will still be available by special request for a period of time but will eventually be retired. If you need the gel-based assay for specific research projects or for any other reason, please contact me and let me know the details. Also, when submitting for the gel-based test please specify/write-in "PLHV gel-based PCR" on your submission forms. The latest version of the Swine Health Test Chart is on our website (Link to current form) There is a checkbox to request the real-time PLHV PCR. 

Improvements incorporated into this new assay include the utilization of real-time reagents so that non-negative results will now include a Cycle Threshold (Ct) value, use of differential primers and probes so that PLHV-1, PLHV-2, and PLHV-3 are being reported separately, and the addition of an internal control reaction to ensure that the PCR reaction within each well is functioning as expected. 

For our accreditation purposes, the PLHV-2 component of this triplex assay is considered to be in the research/validation phase because we haven't been able to find/acquire PLHV-2 positive field samples. Based on in-silico testing with the primers and probes against sequences in GenBank and actual testing using a synthetic plasmid created based on GenBank sequences, this assay is capable of detecting PLHV-2. Once we reach the minimum number of PLHV-2 positive samples and confirm them with Sanger sequencing, there will no longer be a disclaimer applied to that portion of the test. 

Based on comparisons of detection for 154 samples tested with the new real-time assay as compared to the same samples on the gel-based assay (previous gold standard for us), the sensitivity was 100% (90/90 gel-based PCR positives tested positive on the real-time test) and specificity was 98.46% (out of the 64 gel-based PCR negative samples, one tested positive on the real-time test with a Ct 33 for PLHV-1; this was confirmed by repeat testng and gB Sanger sequencing). The consistent limit of detection for all three types based on triplicate dilutions tested on three different testing days was 93 copies per reaction, with frequent detection in the Suspect range (Ct >=36 but <40) down to 10 copies per reaction.

Please contact us if you have questions. 

Avian Metapneumovirus (aMPV) Real-Time PCR Subgroups A, B and C is now tested at the Minnesota Poultry Testing Lab Monday - Friday.  Testing will be completed the next business day after receipt in the lab.  For same day testing, pre-arrangement must be made with the lab and samples must arrive at 8AM when MPTL opens.

Avian Metapneumovirus (aMPV) ELISA Subgroup A,B,C  is now the default aMPV ELISA test at the Minnesota Poultry Testing Laboratory (MPTL).  This is replacing the UMN  Avian Metapneumovirus (aMPV) ELISA Subgroup C test.  The  Avian Metapneumovirus (aMPV) ELISA Subgroup C test can still be requested by noting "Subgroup C ELISA only" on the submission form, or by contacting the lab directly.

The official screening test in swine and cattle (including Cervids and Camelids) for brucellosis conducted at the VDL is the Buffered Acidified Plate Antigen (BAPA) test. The Card test is used specifically to fulfill testing requirements for exports and/or show pigs testing.

The Minnesota Veterinary Diagnostic Laboratory is returning the Actinobacillus suis (A. suis) PCR as a test option for a variety of sample types. An improved real time PCR test was developed for the detection of A. suis from porcine oral fluids, lung, joint, joint swabs, pooled tissues, pleura, pericardium, peritoneum, tonsil scrapings, biopsies, nasal swabs, oropharyngeal swabs, tonsil swabs, bone swabs, serum, bacterial isolates, fetal tissues, and subcutaneous skin swabs (ear/other skin lesions).  The test will be run weekly on Monday at a cost of $27.00. As with most tests, samples should be at the lab by noon the day before the test is scheduled to run ( by noon Friday for the A.suis PCR). Off schedule/emergency testing may be possible after consultation with a food animal diagnostician.
 

The A. suis primers and probe target the 23S ribosomal gene and are adapted from the reference article Kariyawasam, Subhashinie, et al.  “Development of a Real-Time Polymerase Chain Reaction Assay for Detection of Actinobacillus Suis in Porcine Lung.”  Updates were made to modernize the enzyme kit used in the assay as well as the probe prior to the start of validation.  The sequence of the primers and probe remained the same as the publication.  The A. suis PCR test has a detection limit of 50 copies/reaction.   The assay also has an exogenous internal control added during extraction.