Equine herpesvirus type IV (EHV-4)
Ultrasensitive qualitative detection of equine herpesvirus type IV by
polymerase chain reaction.
included in P0013 - equine
herpesvirus I (EHV-1) and EHV-4 comprise two genetically and
antigenically distinct groups of viruses that can cause viral
rhinopneumonitis in horses. Both viruses are ubiquitous in horse
populations worldwide. Each produces an acute febrile
respiratory disease on primary infection, characterized by
rhinopharyngitis and tracheobronchitis. Outbreaks of respiratory
disease occur annually among foals in areas with concentrated
horse populations; elsewhere, episodes are sporadic. Most of
these outbreaks in weanlings are caused by strains of EHV-4. The
age, seasonal, and geographic distributions vary and probably
are determined by immune status and concentration of horses. In
individual horses, the outcome of exposure is determined by
viral strain involved, immune status, pregnancy status, and
possibly age. Infection of pregnant mares with EHV-4 strains
rarely results in abortion.
mechanisms of EHV-1 and EHV-4 infections are significantly
different. EHV-4 infections are restricted to respiratory tract
epithelium and associated lymph nodes, while EHV-1 strains have
a predilection for vascular endothelium, especially in the nasal
mucosa, lungs, adrenal, thyroid, and CNS. Of additional
significance is the leukocyte-associated viremia that occurs in
EHV-1 infections, which may result in abortion or neurologic
rhinopneumonitis cannot be clinically differentiated from equine
influenza, equine viral arteritis, or certain other equine
respiratory infections solely on the basis of clinical signs.
Confirmation can be achieved by virus isolation, preferably from
nasopharyngeal swabs and citrated blood samples taken very early
in the course of the infection and by serologic testing of acute
and convalescent sera. However, culture identification of the
virus is slow and not very sensitive. Serological testing
requires 3 to 4 weeks to complete. Molecular detection by PCR is
the most sensitive and specific method of identifying EHV-4
infection (Varrasso et al., 2001).
Help confirm the disease causing agent
Shorten the time required to confirm a clinical
diagnosis of EHV-4 infection
Help ensure that horse populations are free of EHV-4
Early prevention of spread of this virus
Minimize personnel exposure to this virus
Safety monitoring of biological products that derive
Varrasso, A., Dynon, K., Ficorilli, N., Hartley, C.A., Studdert,
M.J. and Drummer, H.E. (2001) Identification of equine
herpesviruses 1 and 4 by polymerase chain reaction. Aust. Vet.
Nasopharyngeal swab, or 0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml fresh, frozen or fixed
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.
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.
2 business days
Qualitative real time PCR