Comparison of sample types and location of skin biopsies for BVDV detection using antigen capture ELISA Testing

1
Comparison of sample types and location of skin
biopsies for BVDV detection using antigen capture
ELISA Testing

• Dr. Brian Vander Ley
• BVD Symposium January 26, 2009
• Phoenix, Arizona

2
Introduction

• We are looking for ways to screen for PI animals
  more effectively
• Sample choices
• Assay evaluation
• Assay development

3
Overview

• 2 Projects
• Sample project
• 40 PIs
• Several different samples evaluated
• Hide project
• 3 PIs
• Involved systematic evaluation of whole hides for
  BVDV antigen

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Sample Project

• 40 PI calves in 2 stocker operations in Oklahoma
• Identified by ACE
• Segregated from non-PI herdmates

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Skin Samples

• 3 ear notches
• IHC
• ACE
• One was archived for future use
• 1 tail fold biopsy

Above Ear notcher with ear notch. Below tail
fold
Photo from www.drugs.com/vet/images/1136000a.png
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Swab Samples

• Nasal
• Oral
• Conjuctival
• Vaginal/Preputial
• Rectal

Collecting an oral swab
Photo from www.puritanmedproducts.com
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Sample Processing

• Skin Samples
• Placed in dry tubes and frozen until testing
• Incubated in 1 mL PBS for 24 hours at 4C prior
  to using ACE
• Swab Samples
• Collected and place immediately in 1 mL PBS then
  frozen
• Thawed and allowed to incubate for 24 hours 4C
  prior to ACE

8
Results

• Accuracy reported as a percentage positive of
  sample type divided by positive IHC.
• Accuracies
• Ear notch-98
• Tail biopsy-98
• Nasal swab-98
• Vaginal/Preputial swab-90
• Conjunctival swab-63
• Rectal swab-10
• Oral swab-8

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Sample Conclusions

• Nasal swabs could be a good sample for detecting
  PI cattle.
• Simple
• Non-invasive
• Other samples could also be good, but would pose
  some challenges
• More work would need to be done to validate any
  of these samples

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Hide Project

• 3 PIs selected based on previous diagnosis as PI
  by ACE
• Each animal was euthanized and the skin was
  removed in its entirety

A complete hide
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Hide Project

• Each hide was quartered in the field and packed
  on ice
• The hides were frozen until processing

Quarter division of hides
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Hide Processing

• Each quarter was thawed and divided into 10 cm by
  10 cm sections
• A 4 mm punch biopsy was taken from each section
  and placed in a dry microcentrifuge tube.

Hide section schematic
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Sample Evaluation

• All samples were incubated in 1 mL PBS at 4C for
  the same amount of time.
• All steps were performed the same way on each
  plate and in sequential order from plate 1 to
  plate 7.
• Multiple controls were used in each plate
• Kit positive control
• Kit negative control
• Titered BVDV infected cell culture
• Titered BVDV infected cell culture diluted 110
  in PBS

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Results

• All sections were positive by ACE
• No significant differences in S/P ratios were
  found
• Between one particular quarter in all three hides
• Between quarters on an individual
• Between animals

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Conclusions

• Large amounts of sample material are available
  for evaluation/development of diagnostic assays
  aimed at detecting PI cattle.
• The whole hide can be utilized as a source of
  samples for running the ACE.

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Overall Conclusions

• BVDV Antigen can be recovered from a variety of
  places.
• Many swabs
• Essentially any haired skin sample
• There are large amounts of material that can be
  harvested from an individual animal for
  evaluation or development of diagnostic assays,
  especially those that use skin.
• More research needs to be done to validate any of
  the samples.

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References

• Idexx Herdchek Bovine Virus Diarrhea Antigen
  Test Kit. U.S. Vet. License No. 313. 2007.

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• Questions?

Thank You