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| − | a) Complement fixation
| + | *Complement fixation: to avoid anti-complementary effects, sera should be separated from the blood as soon as possible. |
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| + | *Haemagglutination inhibition: titres of 1/10 and 1/20 are suspect, titres of 1/40 and above are positive. |
| − | To avoid anticomplementary effects, sera should be separated from the blood as soon as possible. Positive and negative control sera should be used in the test.
| + | *ELISA may be used to detect viral-specific IgM to the surface glycoprotein of Venezuelan EEV, from 3 days post-onset of clinical signs up to 21 days post-infection. This is useful in acute infections where convalescent serum samples are unobtainable. |
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| + | *The PRN test is very specific and can be used to differentiate between EEE and WEE infections. It is performed in duck embryo fibroblast, Vero, or BHK-21 cell cultures. Serum used in the PRN assay is tested against 100 plaque-forming units of virus. Endpoints are based on a 90% reduction in the number of plaques compared with the virus control flasks. |
| − | b) Haemagglutination inhibition
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| − | Titres of 1/10 and 1/20 are suspect, and titres of 1/40 and above are positive.
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| − | c) Enzyme-linked immunosorbent assay
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| − | Viral-specific IgM to the surface glycoprotein of Venezuelan EEV may be detected by ELISA, from 3 days post-onset of clinical signs up to 21 days post-infection. The ELISA is useful in acute VEE infections where convalescent serum samples are unobtainable. The ELISA is performed by coating flat-bottomed plates with anti-equine IgM capture antibody (11). A test sample is considered to be positive if the absorbance of the test sample in wells containing virus antigen is at least twice the absorbance of negative control serum in wells containing virus antigen and at least twice the absorbance of the sample tested in parallel in wells containing control antigen.
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| − | d) Plaque reduction neutralisation
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| − | The PRN test is very specific and can be used to differentiate between EEE and WEE virus infections. The PRN test is performed in duck embryo fibroblast, Vero, or BHK-21 cell cultures. Endpoints are based on a 90% reduction in the number of plaques compared with the virus control flasks.
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| | ======Clinical Pathology====== | | ======Clinical Pathology====== |