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

ELISA Testing

Dr. Brian Vander LeyBVD Symposium January 26, 2009

Phoenix, Arizona

Introduction

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

Overview

• 2 Projects– Sample project

• 40 PIs• Several different samples evaluated

– Hide project• 3 PIs• Involved systematic evaluation of whole hides for BVDV

antigen

Sample Project

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

Skin Samples

• 3 ear notches– IHC– ACE– One was archived for

future use

• 1 tail fold biopsyAbove: Ear notcher with ear notch. Below: tail fold

Photo from: www.drugs.com/vet/images/1136000a.png

Swab Samples

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

Photo from: www.puritanmedproducts.com

Collecting an oral swab

Sample Processing

• Skin Samples– Placed in dry tubes and frozen until testing – Incubated in 1 mL PBS for 24 hours at 4°C prior to

using ACE

• Swab Samples– Collected and place immediately in 1 mL PBS then

frozen – Thawed and allowed to incubate for 24 hours 4°C

prior to ACE

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%

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

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

Hide Project

• Each hide was quartered in the field and packed on ice

• The hides were frozen until processing

Quarter division of hides

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

Sample Evaluation

• All samples were incubated in 1 mL PBS at 4°C 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 1:10 in PBS

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

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.

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.

References

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

Questions?

Thank You