Sensitivity and specificity of multiple technologies for the detection of confirmed persistently BVDV infected cattle from a feed yard in South Texas

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1 Sensitivity and specificity of multiple technologies for the detection of confirmed persistently BVDV infected cattle from a feed yard in South Texas Lalitha Peddireddi 1, Richard Hesse 1, Gregg Hanzlicek 1, Jeff Baxter 2, Ivan Leyva-Baca 2 1 Kansas State Veterinary Diagnostic Laboratory, Kansas State University, 2005 Research Park Circle Manhattan, KS Animal Health Group at Thermo Fisher Scientific, 2130 Woodward St, Austin, TX 78744, USA The world leader in serving science

2 Etiology: Bovine Viral Diarrhea Virus (BVDV) Etiology: Bovine Viral Diarrhea Virus (BVDV) is an pathogen that belongs to the genus Pestivirus of the family Flaviviridae BVDV is an enveloped, single stranded RNA virus Economic Relevance: Bovine Viral Diarrhea leads to major economic loss in both beef and dairy industries estimated to be ~ $2-3 billion annually in the US alone History: It was first reported in 1946 in Ithaca New York by researchers from Cornell University in one-cow herd with subsequent outbreaks of the disease with morbidity 33-88% and mortality of 4-8% Genome: Has a positive sense single stranded RNA genome (ss (+) RNA). Size of approximately 12.3 Kb. The genomic RNA has one open reading frame of about 4000 codons flanked with 2 untranslated regions (5 - and 3 -UTR) Vet. Res. 41 (6) 44 (2010) DOI: /vetres/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License ( which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly cited. 2

3 Classification of BVDV Cattle are the natural host of the BVDV but infection has been demonstrated in other species: Sheep, goats, wild ruminants, pigs, bison, alpacas, mouse deer, mountain goats, and white-tailed can also be infected... The virus is divided in to two main genotypes: BVDV-1, is considered the most prevalent genotype BVDV-2, historically is considered more virulent causing severe disease Most recently BVDV-3 or HoBi-like pestivirus that has been classified as an atypical pestivirus Other pestivirus are: Classical Swine fever, Borders Disease Virus Note: More recent data has demonstrated that both genotypes (BVDV-1 and BVDV-2) can cause the same damage at respiratory and reproductive level Further classification based on isolates non-cytopathogenic (ncp): do not induce apoptosis and is the main source is PI cattle. NCP account for 95% of the isolated BVDV cytopathogenic (cp): induces apoptosis. The ncp biotype is the main frame to generate cp biotype through mutations and reconventions Vet. Res. 41 (6) 44 (2010) DOI: /vetres/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License ( which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly cited. ncp cp Virol J Feb 25;8:83. doi: / X-8-83 Copyright Policy open access 3

4 BVDV Presence and Epidemiology Presence: BVD has a world-wide presence Prevalence of seropositive cattle varies among countries and is influenced by vaccine use and management practices In USA, seropositive rates range between 40 and 90% Unvaccinated herd-level prevalence with unvaccinated cattle varies from 28 to 53% depending on the region PI prevalence is ~0.2% in the USA Epidemiology: From an epidemiological point of view BVDV is very talented It has a combination of strategies to remain in a herd for extended periods of time Persistent infection provides a unique ability to BVDV to survive by inducing immune tolerance trough evasion of both innate and acquired immunity in utero Laboratory techniques are the best way to detect the presence of BVDV and distinguish the form of the disease 4

5 BVDV-Persistently Infected (PI) Creation embrionic death return to estrus Vet. Res. 41 (6) 44 (2010) DOI: /vetres/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License ( which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly cited. 5

6 The Impact of BVDV PI Animals on BRD Although the prevalence of PI-BVDV cattle in the USA is very low, the presence of only one PI-BVDV animal is well documented (Hay et al, 2016) to be a risk factor in feed yards for an increased rate of BRD, cost of vaccination, antibiotic therapy and mortality of unresolved BRD infections BVDV-PI cattle are more likely to become chronically ill or die than non-bvdv-pi cattle. Also, the probability for initial treatment with respiratory disease was 43% greater for cattle exposed to BVDV-PI cattle in the same pen or an adjoining pen. Loneragan; Journal of the American Veterinary Medical Association,

7 BVD: Control and Management Biosecurity Vaccinations Diagnostics 7

8 Study Rationale & Objectives Rationale: There was a request from the Kansas Farm Bureau in South East Kansas to regulate BVDV in their region by making it a reportable disease. SNAP BVDV Antigen Test was getting some discrepant results when compared to testing in VDLs The application of highly sensitive and specific diagnostic technologies is fundamental to accurately identify those low prevalent PI-BVDV animals for implementation of control strategies Objective: To compare the sensitivity and specificity performance of: BVDV Test Methods Immunochromatographic strip Antigen Capture ELISA Applied Biosystems RT-PCR VetMAX TM Gold BVDV PI Detection Kit 8

9 Materials and Methods Two samplings with three weeks apart of previously confirmed PI-BVDV (n=37) and BVDV-negative (n=20) cattle were performed from a feed yard located in South Texas, USA holding 24,000 cattle and keeping PI- BVDV in a single pen until slaughter time (~n=48) During the first sampling five ear notches from each animal were collected in a single day shipped out overnight to the Kansas State Veterinary Diagnostic Laboratory (KSVDL) in order to be processed immediately after arrival with the following diagnostic technologies: Ear Notch No Testing Method Sample Prep Testing Location VetMAX Gold BVDV PI Detection Kit AM1836 MagMAX TM -96 Viral Isolation Kit SNAP BVDV Antigen Test ACE BVDV Kit IHC/BVDV RNA Sequencing KSVDL, Manhattan, KS Two weeks later, resampling of the same set of animals (n=57) was carried out to be tested with IHC and BVDV RNA sequencing as the gold standard methods True positive or true negative based on the combined results from at least 1 out of the 2 methods was implemented 9

10 Results Table 1. Result of the real-time PCR testing, SNAP test and Antigen Capture ELISA Gold standard/tested technology Total Diagnstic technology P/P P/N N/P N/N count Se Sp SNAP ACE VetMAX-Gold BVDV PI Detection Kit VetMAX-Gold BVDV PI Detection Kit is more sensitive than the other methods. Missing some of the PI-BVDV animals when utilizing technologies with low sensitivity will generate false-negative results, allowing PI-BVDV cattle to be undetected and continue comingling with BVDV-negative cattle which is very detrimental for the health status of a herd 10

11 Discussion and Conclusions All of the diagnostic technologies tested in this study offered a good but different level of sensitivity and equal level of specificity However, the real-time PCR technology tested was more sensitive than the antibody-based methods The practical implication of using diagnostic technologies with low sensitivity e.g. (91.67% and 94.44%) with a disease of very low prevalence (0.2%-0.4%) such as PI-BVDV in the US is of significant importance SNAP Test ACE VetMAX TM Gold BVDV PI Detection Kit The current study reveals substantial practical differences in diagnostic methods that can be used as management tools in controlling BVDV and ultimately reducing the incidence of BRD. 11

12 Acknowledgments KSVDL South Texas Feed Yard Thermo Fisher Scientific For Veterinary Use Only. For In Vitro Use Only. Regulatory requirements vary by country; products may not be available in your geographic area Thermo Fisher Scientific Inc. All rights reserved. All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. IDEXX SNAP is a trademark of IDEXX LtD 12