1. Introduction
Antibodies are produced by the immune systems of animals in response to
the presence of foreign substances. Antibodies raised against regions of the
viral coat protein (CP) (epitopes) can be exploited for virus detection; in 1977
Clark and Adams described the use of antibodies in ELISA to rapidly test a
large number of plant sap samples for the presence of virus (1). Antibodies
produced against virus particles can also be used in Western blots (see Chapter
45) to assay CP expression in transformed plants (2,3).
Originally, all antibodies were derived from the serum of animals following
immunization with the virus of interest. These polyclonal antibodies (PAbs)
are essentially a heterogeneic mixture of molecules that will recognize several
epitopes on the target protein. The main advantage of PAbs is that their broad
specificity may give a more robust test, perhaps allowing detection of most
strains of a virus or even all members of a virus group. Paradoxically, the relative
lack of specificity is also their main limitation, because they sometimes
produce crossreactions with plant proteins that can give false positives in
assays. Additionally, because they are produced on a batch basis, variable reactions
may be encountered between bleeds from the same animal and between
individual animals.
.。。。。。 antibody production