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New Diagnostic Approaches and
Diagnostic Tools for Bovine Viral Diarrhea Control
First reported in 1946, bovine viral diarrhea virus (BVDV) has became
one of the most important pathogenic viruses in cattle, causing
considerable economic losses in both the dairy and beef industries
worldwide. When pregnant cows get infected with a noncytopathic BVDV
strain between days 30–150 of gestation, it results in
persistently infected (PI) calves. PI cattle often die from mucosal
disease, caused by mutation of the virus or super-infection with a
cytopathic BVDV strain. Because these PI cattle are the main source of
BVDV transmission, eradication programs are focused on the elimination
of PI cattle, and preventing the transmission of BVDV to other healthy
cattle in the herd.
Due to the economic impact of the disease, BVDV eradication and
control programs have been initiated in many countries. IDEXX
Laboratories has developed a set of diagnostic tools for detection of
BVDV antigen and antibodies to BVDV. The use of these highly sensitive
and specific, user-friendly HerdChek* BVDV diagnostics have helped
veterinarians and farmers worldwide to be successful in the control of
BVDV.
The HerdChek* BVDV Ag/Serum is an antigen-capture
ELISA designed for detecting Erns, a pestivirus protein (gp
44–48), which is secreted extracellularly during virus
replication. This assay has been validated for use in testing serum,
plasma†, whole blood† and ear-notch
tissue samples. In disease control programs Erns based
ELISAs allow user-friendly and high throughput testing.
More
information >
Enzyme-labeled immunodetection methods have proven to be useful to
detect BVDV antigens in skin biopsies for in-vivo diagnosis of
persistent BVDV infection.1 Both skin and ear-notch tissue
samples are commonly tested in the U.S.2, Canada3
and Europe4 by immunohistochemistry (IHC)5 and
BVDV antigen-capture ELISA.6 Additionally, ear-notch tissue
samples can be easily obtained by farmers or veterinarians without the
additional costs associated with blood sampling. In the United States,
"ear notchers" are used for collection of ear-tissue samples. In
Europe, a protocol has been developed that combines cattle ear-tagging
(mandatory in many countries) with the sampling and testing of
2–3-mm diameter ear-tissue samples for BVDV with the HerdChek
BVDV Ag/Serum Plus ELISA.†
Commercially available ear tag/tissue samplers can be used for
collecting 2–3-mm diameter ear-tissue samples. During the ear tag
application, a small ear tissue sample is punched into a collection
device for later testing. Advantages of these systems are the
combination of ear tagging and tissue-sampling in one step without
contamination of the sample or the sampling tool.
The method for testing ear tissue samples involves a simple soaking
step in buffer. This soaking buffer can then be tested with the
HerdChek BVDV Ag/Serum assay in the same way as a serum sample. There
is some indication that maternal antibodies in calves after receiving
colostrum do not interfere with the detection of BVDV antigen from
ear-notch tissue samples.5,7 This potentially allows the
detection of BVDV very early in the life of the calf.
More
information >
Other IDEXX Diagnostic Tools
for BVDV Detection
Ear-notch collection tubes: IDEXX provides tubes with
soaking buffer for collection and transportation of ear-notch tissue
samples to the testing lab.††
Anti-BVDV E0 monoclonal antibody for
Immunohistochemistry.††
The HerdChek BVDV Ag/Leukocytes†
is an antigen-capture ELISA that detects the nonstructural protein 2/3
of BVDV in peripheral blood leukocytes, tissue homogenates, cell
culture and nasal swabs. This kit also has utility in detecting PI
calves among dairy and beef herds.
More
information >
The HerdChek* BVDV Antibody Test†
is an indirect ELISA for detection of BVDV antibodies in bovine serum,
plasma, milk and bulk milk samples. The assay detects antibody to BVDV
type I and type II strains, and shows a good correlation to virus
neutralization assays. Detection of antibodies to BVDV in cattle herds
is indicative of BVDV infection or vaccination against BVDV. This test
can be used for initial testing of the BVDV status of a herd,
maintenance of the herd's BVDV negative status or vaccine-compliance
testing.
More
information >
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IDEXX Laboratories Customer
Workshop Held in Scotland
IDEXX Laboratories provides diagnostic tools, software for result
interpretation and data management, as well as guidelines and
consultation in disease control. For training and further education
of our global customers, IDEXX offers workshops and seminars on a
regular basis.
On August 31, 2004, in collaboration with Moredun Institute and
Scottish Agricultural Colleges, IDEXX Laboratories held a workshop
in Penicuik, Scotland on BVDV control. Speakers from England,
Scotland, Austria and Germany presented BVDV control methods.
Dr. George Caldow, from the Scottish Cattle
Health Scheme, presented different BVDV control programs from
Scotland, and concluded the need for fewer programs, but with more
commitment for those programs from the farmers and veterinarians.
View the abstract of this presentation.
Dr. Walter Obritzhauser, from Styria, Austria,
presented the BVDV program of Styria, which is part of the mandatory
BVDV eradication program in Austria. This program is based on
identification of BVDV-positive herds by testing bulk milk for the
herd BVDV status, with detection and removal of PI animals from
positive herds.
View the abstract of this
presentation.
Dr. Peter Nettleton, from Moredun Institute,
presented data evaluating two IDEXX BVDV antigen-capture ELISAs for
the detection of BVDV and border disease virus (BDV) strains from
sheep.
View the abstract of this
presentation.
Dr. Carsten Schroeder, from IDEXX Laboratories,
presented information on the detection of BVDV antigen from ear
tissue samples and data validating the IDEXX HerdChek BVDV Ag/Serum
Plus ELISA† for testing ear-notch tissue samples
obtained with ear tag/tissue sampler combinations.
View the abstract of this
presentation.
If you would like IDEXX to perform a training seminar for you and
your customers, please contact your local IDEXX representative or send
us an e-mail.
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† Available from IDEXX
Europe only.
††Available in the U.S. only.
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TECHNICAL
TIP
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Avian Leukosis Antigen Wash Procedure
When testing samples for ALV-Ag, there are two different wash
procedures that should be used, depending on the sample type.
For albumin samples, you must use the wash concentrate included
in the kit. Make up your wash solution by diluting the concentrate 1
to 20 with distilled water. This diluted wash solution is to be used
for all wash steps when albumin samples are being tested.
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For the first wash step, aspirate the
controls and albumin samples out of the wells, dispense the wash
solution and allow the wells to soak for two minutes. At the end of
the two-minute soak, wash the wells four more times without the
soak between washes.
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For the second wash step, i.e., after
conjugate incubation, repeat the procedure as above. Aspirate the
conjugate out of the wells, dispense the wash solution and allow
the wells to soak for two minutes. At the end of the soak, wash the
wells four more times without the soak between washes.
For serum or cloacal swab samples, wash the plates with distilled
water 3–5 times at each wash step.
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