sensitivity and specificity of multiple technologies for ... · etiology: bovine viral diarrhea...
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Sensitivity and specificity of multiple technologies for the detection of confirmed persistently BVDV infected cattle from a feed yard in South Texas Lalitha Peddireddi1, Richard Hesse1, Gregg Hanzlicek1, Jeff Baxter2, Ivan Leyva-Baca2
1Kansas State Veterinary Diagnostic Laboratory, Kansas State University, 2005 Research Park Circle Manhattan, KS 66506 2Animal Health Group at Thermo Fisher Scientific, 2130 Woodward St, Austin, TX 78744, USA
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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: 10.1051/vetres/2010016
This is an Open Access article distributed under the terms of the
Creative Commons Attribution-Noncommercial License
(http://creativecommons.org/licenses/by-nc/3.0/), which permits
unrestricted use, distribution, and reproduction in any
noncommercial medium, provided the original work is properly
cited.
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: 10.1051/vetres/2010016
This is an Open Access article distributed under the terms of the
Creative Commons Attribution-Noncommercial License
(http://creativecommons.org/licenses/by-nc/3.0/), which permits
unrestricted use, distribution, and reproduction in any
noncommercial medium, provided the original work is properly cited.
ncp cp
Virol J. 2011 Feb 25;8:83. doi: 10.1186/1743-422X-8-83
©Copyright Policy – open access http://openi.nlm.nih.gov/index.php
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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
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BVDV-Persistently Infected (PI) Creation
embrionic death
return to estrus
Vet. Res. 41 (6) 44 (2010) DOI: 10.1051/vetres/2010016
This is an Open Access article distributed under the terms of the
Creative Commons Attribution-Noncommercial License
(http://creativecommons.org/licenses/by-nc/3.0/), which permits
unrestricted use, distribution, and reproduction in any noncommercial
medium, provided the original work is properly cited.
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, 2005
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• Biosecurity
• Vaccinations
• Diagnostics
BVD: Control and Management
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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 VetMAXTM Gold BVDV PI Detection Kit
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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:
• 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
Ear Notch No. 1 2 3 4 5
Testing Method
VetMAX™Gold
BVDV PI
Detec t ion Kit
SNAP BVDV Antigen Test
ACE BVDV Kit
IHC/BVDV RNA
Sequencing
Sample Prep AM1836
MagMAXTM-96 Viral Isolation Kit
- - - -
Testing Location
KSVDL, Manhattan, KS
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Results
• 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
Diagnstic technology P/P P/N N/P N/N
Total
count Se Sp
SNAP 33 3 0 21 57 91.67 100.00
ACE 34 2 0 21 57 94.44 100.00
VetMAX-Gold BVDV PI Detection Kit 36 0 0 21 57 100.00 100.00
Table 1. Result of the real-time PCR testing, SNAP test and Antigen Capture ELISA
Gold standard/Tested technology
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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 VetMAXTM 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.
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Acknowledgments
• KSVDL
• South Texas Feed Yard
• Thermo Fisher Scientific
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