6,502
edits
Changes
Jump to navigation
Jump to search
→Laboratory Tests
Laboratory testing is required to confirm a diagnosis of classical swine fever. As well as collection of tissues for histopathology, samples of tonsils, spleen, lymph nodes, kidney and distal ileum are taken for virus detection. Virus may be detected by fluorescent antibody detection, ''in situ'' hybridisation, immunoperoxidase staining or virus isolation.
Laboratory testing is required to confirm a diagnosis of classical swine fever. As well as collection of tissues for histopathology, samples of tonsils, spleen, lymph nodes, kidney and distal ileum are taken for virus detection. Virus may be detected by fluorescent antibody detection, ''in situ'' hybridisation, immunoperoxidase staining or virus isolation.
Although much progress had been made in the development of new methods for the
direct detection of CSFV, the `gold standard' is still the isolation of the virus in cell culture.
CSFV can be isolated from buffy coat cells or organ suspensions of viraemic animals.
Suitable organs are spleen, tonsils, lymph nodes, parotid glands and kidneys (Anonymous,
1980, 1996). The samples are incubated on susceptible cell cultures of porcine origin. Since
CSFV is noncytopathogenic, CSFV speci®c antibodies are used for detecting the virus in
cell culture. Differentiation of the CSFV from ruminant pestiviruses is usually done using
monoclonal antibodies (mAbs) (Anonymous, 1980, 1996; Cay et al., 1989). Virus isolation
takes about 3 days and is labour intensive. A rapid, though less sensitive test for CSFV
is based on the demonstration of viral antigen in organ tissue sections using ¯uorescent
antibodies. For the screening of large numbers of animals in herds suspect of being
recently infected by CSFV, virus antigen capture enzyme-linked immunosorbent assays
(AgC-ELISAs) may be used. This test is also less sensitive compared with virus isolation.
Recently, detection of viral RNA has become an additional option for laboratory
diagnosis (Paton et al., 2000b). In particular, the 5'nontranslated region of the genome
has been used for ampli®cation by the reverse transcriptase polymerase chain reaction
(RT-PCR). Subsequent nucleotide sequencing of the respective region allows discrimination
between different CSFV isolates (Hofmann et al., 1994; Lowings et al., 1996;
Greiser-Wilke et al., 1998). The EU/OIE Reference Laboratory for CSF in Hannover,
Germany, keeps a large computer data base on CSF virus isolates including
epidemiological and virus type information data (Greiser-Wilke et al., 2000).
5.2. Serology
Considering the progress in antigen detection methods the importance of serology in
the control of acute outbreaks has somewhat decreased. However, serological diagnosis of
CSF is still important for surveys and the detection of hidden clusters of CSF, especially
in wild boar.
V. Moennig / Veterinary Microbiology 73 (2000) 93±102 97
The virus neutralisation test is the most sensitive and speci®c method for CSF antibody
detection. Porcine serum samples are incubated with a CSF reference virus. In case the
serum contains antibodies to CSFV the test virus will be neutralised. However, crossneutralising
antibodies speci®c for ruminant pestivirus infections of pigs are often also
registered by this test. Differential diagnosis for ruminant pestiviruses should therefore be
carried out using a second neutralisation test using ruminant pestiviruses. The
neutralisation test takes at least 2±3 days or longer if comparative testing is required
and it is labour intensive. Large numbers of serum samples are, therefore, processed using
ELISA tests. Positive or unclear results should be retested using the neutralisation test
==Treatment==
==Treatment==