Page 910 - Veterinary Immunology, 10th Edition

VetBooks.ir Serology of Viral Diseases

Tests to Detect and Identify Viruses

Historically, serological tests were used to identify the presence of
viruses within tissues The tests commonly employed for this
purpose included fluorescent antibody tests, enzyme-linked

immunosorbent assay (ELISA), hemagglutination inhibition, virus
neutralization, complement fixation, and gel precipitation. The
precise tests employed depended on the nature of the unknown
virus. The development of the polymerase chain reaction (PCR) has
made many of these techniques obsolete. Exquisitely sensitive, the

PCR can be used to detect viral DNA. A reverse transcriptase PCR
can be used to detect RNA viruses. The PCR is best suited for use in
well-equipped laboratories. For animal-side testing or in situations

in which the equipment is not available, a more suitable technique
for the detection of viral antigen or antiviral antibodies is the
membrane filter ELISA test or lateral chromatography tests
(Chapter 42). These tests have the advantage that both positive and
negative controls can be incorporated with the test serum in one

well. In addition to serum, whole blood, plasma, or saliva may be
employed as a source of antigen or antibody.

Tests to Detect and Identify Antiviral

Antibodies

In general, the most widely employed techniques for detecting
antibodies to viruses are hemagglutination inhibition, indirect
ELISA, immunofluorescence, gel diffusion, Western blotting,

complement fixation, and virus neutralization. The first four of
these are technically simple and are thus preferred (Chapter 42).
Complement fixation and virus neutralization tests are complex,
restricting the circumstances in which they may be used. Virus
neutralization tests are also extremely specific, which as discussed

earlier tends to reduce their value as screening tests.

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