avian & livestock assay data sheet
St. Louis encephalitis
Ultrasensitive qualitative detection of St.
Louis encephalitis virus by reverse
transcription coupled real time polymerase chain
West Nile (WN) and St. Louis encephalitis (SLE)
viruses are both arthropod-borne viruses within
the Japanese encephalitis virus serocomplex
(Murphy et al., 1995). They belong to the family
Flaviviridae, genus Flavivirus. This group of
viruses possesses a single positive strand of
RNA genome of approximately 11 kb. Like West
Nile virus and Japanese encephalitis virus, SLE
is transmitted primarily through Culex species
mosquitoes and birds. Humans, primates and other
mammals are thought to be incidental hosts (Monath
and Heinz, 1996).
Unlike WN, endemic SLE virus transmission in
nature is silent, with no reports of avian
mortality. Nevertheless, significant endemic
spread of SLE in United States and in several
South American countries has been reported. Over
the past 70 years, SLE virus has been
responsible for numerous epidemics throughout
the United States; the largest occurred in 1975,
with approximately 2,000 cases reported (Monath
and Heinz, 1996).
Detection of this SLE virus by virus isolation
followed by identification through
immunofluorescence assays can take over a week
to complete. Immunoglobulin M (IgM) capture and
IgG enzyme-linked immunosorbent assays (ELISAs)
are also used to detect this virus. However,
confirmation of the infection can only be
inferred by a fourfold or greater rise in
virus-specific neutralizing antibody titers in
either cerebrospinal fluid (CSF) or serum by
performing the plaque reduction neutralization
assay (PRNT) with several flaviviruses. Virus
culture from CSF or serum has generally been
unsuccessful due to the low level and
short-lived viremia. PCR detection of this
virus, thus, represents a rapid, specific and
sensitive approach to detection of this virus.
Help confirm the disease causing agent
Help ensure that flocks are free of SLE virus
Early prevention of spread of the virus among a flock
Minimize human exposure to the virus
Safety monitoring of biological products and vaccines
that derive from birds
Monath, T.P. and Heinz, F.X. (1996) Flaviviruses,
p. 978-984. In B.N. Fields (ed.), Fields
virology, vol. 1, 3rd ed. Lippincott-Raven
Publishers, Philadelphia, Pa.
Fauquet, C.M., Bishop, D.H.L., Ghabrial, S.A.,
Jarvis, A.W., Martelli, G.P., Mayo, M.A. and
Summers, M.D. (1995) Virus taxonomy,
classification and nomenclature of viruses.
Arch. Virol. 10 (Suppl): 1-586.
Specimen requirements: 0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml fresh or frozen CNS
tissue, or 0.2 ml CSF, serum or plasma.
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.
2 business days
Qualitative reverse transcription coupled real