Laboratory Diagnostic Tests

The following examples of diagnostics tests represent the tests available through Prairie Diagnositic Services (PDS) and are not meant to be an exhaustive list of the techniques available to diagnose Bovine Coronavirus and Rotavirus.

Prices and turnaround times are estimates and are given only for comparison purposes.

1.  Fluorescent Antibody Test (FAT)

Description: The coronavirus or rotavirus group A antigens are identified in the FA test by a specific antibody that has been conjugated to a fluorescent dye (4).  The dye is washed over the sample and excess is washed away (4).  The sample is then viewed under a fluorescence microscope (4).  A positive sample will fluoresce and a negative sample will not (4). 

Advantages:

-        Most commonly used when an individual case diagnosis is required (16)

-       Rapid, simple (16)

-       Less expensive than TEM ($20.00) (16)

-       Turnaround time is 1 day (16)

Disadvantages:

-       Less sensitive than TEM due to non-specific fluorescence or fading fluorescence (16)

-       Requires rapid transport of fresh samples (16)

Sample Submission: Fecal or Tissue (Jejunum or Ileum) (16)

Available for:
Bovine Coronavirus and Rotavirus Group A antigens (16)

 

2.  Transmission Electron Microscopy (TEM)

  Description: A transmission electron microscope works on the same principles as a light microscope except it uses an electron beam as a light source (16).  The low frequency of the electron beam allows the microscope to achieve the resolution required to examine microorganisms such as coronavirus and rotavirus (16). Samples are determined to be positive by actually seeing virus present in the sample (16).

Advantages:

-         Most sensitive of the available tests from PDS (6)

-         Preferred test for mature animals with suspected winter dysentery (16)

Disadvantages:

-         More expensive than FAT or ELISA ($49.50) (16)

-         After onset of diarrhea, viral shedding may drop below sensitivity levels of TEM (6)

-         Turnaround time is 2-4 days (16)

Sample Submission: Fecal (16)

Available for:
Bovine Coronavirus (16)

3.  Enzyme-Linked Immunosorbent Assay (ELISA) 

Description:
This test also relies on the Antibody/Antigen interaction principles (4).  An antibody specific for coronavirus antigen is linked to an enzyme and added to the serum sample (4).  Excess antibody is washed away (4).  A substrate for the enzyme is then added to the sample and a visible reaction should occur
if the sample is positive for viral antigen (4).  In a negative sample the reaction will not occur (4). 

Advantages:

-Rapid, and simple. Can test a large number of samples in a short amount of time (6)

-Inexpensive ($15.00) (16)

Disadvantages:

-Lack sensitivity (6)

-Turnaround time is 2-5 days (16)

Sample Submission: Serum (16)

Available for: Bovine Coronavirus (16)

calves (23)

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