avian
& livestock assay data sheet
Ovine herpesvirus 2 (malignant catarrhal fever)
Test code:
S0176
- Ultrasensitive detection of ovine herpesvirus 2 by real time PCR
Malignant
catarrhal fever (MCF) is a frequently fatal disease of cattle
and other ungulates such as deer, antelope, buffalo and bison.
It is caused by two viruses which cause inapparent infection in
their reservoir hosts: most frequently by ovine herpesvirus 2
(OvHV-2) carried by sheep, and less frequently by
Alcelaphine
herpesvirus 1 (AlHV-1) carried by wildebeest. Although the
diseases induced in susceptible species by these viruses are
indistinguishable, there are some fundamental differences
between the two viruses in disease development.
Young
animals are most susceptible to MCF. However, studies have shown
that under natural conditions, the majority of lambs are not
infected by OvHV-2 until after 2 months of age. Placental
transmission only rarely occurs in sheep, and colostrum and milk
from infected dams play little role in viral transmission, even
though they contain virus-infected cells. Both lambs and adult
sheep are likely to be infected via horizontal short-distance
transmission.
Passively
acquired maternal immunity does not affect the rate of
infection. Although OvHV-2 DNA can be detected continuously in
nasal secretions of most infected sheep, the highest levels of
viral DNA predominantly occur between 6 and 9 months of age,
suggesting this adolescent period as the time when most virus is
shed into the environment. Like other herpesviruses, OvHV-2
infection may result in latent infection which can be
reactivated again at any time to shed the virus.
Culture
detection of the virus is not very useful because it is very
difficult to propagate OvHV-2 in vitro. Diagnosis of the disease
by serological methods has low sensitivity and may not be
possible because of widespread prior exposure of animals to the
virus. However, molecular detection by polymerase chain reaction
is rapid, highly sensitive and specific (Mϋller-Doblies et al.,
1998).
Utilities:
-
Help confirm the disease causing agent
-
Identify
OvHV-2 carriers
-
Help ensure that flocks, herds and wild populations are free of
OvHV-2
-
Early prevention of spread of this virus among animals
-
Minimize human exposure to the virus
-
Safety monitoring of biological products that derive
from susceptible animals
References:
Mϋller-Doblies, U.U., Li, H., Hauser, B., Adler, H. and
Ackermann, M.(1998) Field Validation of Laboratory Tests for
Clinical Diagnosis of Sheep-Associated Malignant Catarrhal
Fever. J. Clin. Microbiol. 36:2970-2972.
Specimen requirements:
0.2 ml
whole blood in EDTA (purple top) tube, or
nasal swab, or 0.2 ml fresh, frozen or fixed
tissue.
Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.
For all
specimen types, if there will be a delay in shipping, or during
very warm weather, refrigerate specimens until shipped and ship
with a cold pack unless more stringent shipping requirements are
specified. Frozen specimens should be shipped so as to remain
frozen in transit. See
shipping instructions
for more information.
Turnaround time:
2 business days
Methodology:
Qualitative real time PCR
Normal range:
Nondetected
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