avian & livestock assay data sheet
Porcine hemagglutinating encephalomyelitis (PHE) virus
Ultrasensitive qualitative detection of porcine
hemagglutinating encephalomyelitis (PHE) virus by reverse
transcription coupled real time PCR
Coronaviruses are divided into at least three serogroups (I–III)
based on serology and nucleotide differences. Porcine
hemagglutinating encephalomyelitis virus (PHE) belongs to group
II, and it is the etiological agent of hemagglutinating
encephalomyelitis. This disease primarily affects pigs <3 weeks of age. Currently only a single
strain of the virus is known and is the only known neurotropic
coronavirus in pigs.
piglets usually exhibits vomiting, anorexia and depression;
hence the disease was known as "vomiting and wasting disease"
(VWD) in the past. In severe cases infected piglets will develop
encephalomyelitis. The mortality rate in infected piglets under
3 weeks old is nearly 100%, but the incidence of infection is
small as most piglets are protected by maternal antibodies.
However, the risk of PHE outbreaks has increased due to the use
of pathogen-free pigs which have no antibodies to the virus.
PHE has been reported in many countries, including mainland
China and Taiwan, since it first appeared in Canada in 1958. The
primary sign of disease outbreak is repeated retching and
vomiting in piglets, although there may be mild respiratory
signs initially. Piglets huddle and are listless, and there may
be a transient fever. Young nursing piglets often become
severely dehydrated and die. Older nursing or weaned piglets
suffer from physical wasting with loss of weight and muscle mass
due to inadequate feed intake. They may persist in a wasting
state for several weeks before dying. The abdomen may be
distended due to gaseous distension of the stomach and
The virus is
transmitted via nasal secretions (Sasseville et al., 2001) and
replicates in epithelial cells of the nasal mucosa, tonsils,
lungs, and small intestine. After local replication, the virus
spreads from the peripheral nervous system to the central
nervous system. Virus can be isolated from the tonsils and
respiratory tract during the incubation period, which lasts
about 5 days. Isolation of virus may be attempted on tonsil,
brain, and lung samples from affected piglets. However, culture
sensitivity is low unless samples are collected from acute cases
within 1 or 2 days of the onset of clinical signs. Serological
diagnosis is neither sensitive nor specific enough to quickly
identify the virus during the initial outbreak. Molecular
detection by reverse transcription coupled real time PCR enables
rapid, sensitive and specific detection of the virus and is
useful in identifying and isolating infected pigs.
Help confirm the disease causing agent
Identify PHEV carriers
Help ensure that animal colonies and populations are free of
Early prevention of spread of the virus among animals
Minimize human exposure to the virus
Safety monitoring of biological products that derive
Sasseville, A.M., Gelinas, A.M., Sawyer, S., Boutin, M. and Dea,
S. (2001) Biological and molecular characteristics of an HEV
isolate associated with recent acute outbreaks of
encephalomyelitis in Quebec pig farms. Adv Exp Med Biol.
Nasal swab or 0.2 ml fresh or frozen tissue.
types other than those listed here, please call 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 reverse transcription coupled real time PCR