New Test: ELISA for Actinobacilluspleuropnemoniae
An ELISA (enzyme-linked immuno-sorbent assay) for
1, 3, 5, and 7 using phenol extracted capsule antigen has
been developed at the ADDL Bacteriology Laboratory, ADDL.
There are 12 serotypes of APP prevalent in different parts
of the world. Serotypes 1, 3, 5, and 7 have been reported
in the United States.
Published information suggests that serotype specific antigens
are present in the bacterial capsules. However, during the
process of extraction and purification, it is very difficult
to keep other cell wall components of bacteria from contaminating
the capsule antigen. Thus, low levels of cross reactivity
among serogroups and with other gram-negative pathogens
may occur. At ADDL, we have included additional purification
steps to minimize cross reactivity among serogroups in order
to enhance the specificity and accuracy of the test. Due
to the lack of serum sources, cross reactivity against Actinobacillussuis
or other common gram-negative bacteria has not been evaluated.
Therefore, accurate and detailed herd history is essential
for interpretation of the serological results for APP by
The ELISA test is available for $8.00 per sample ($2.00
per serotype). It is highly recommended to test for all
four APP serotypes. The report transmitted to the veterinarian
will contain estimated antibody titers against each APP
serotype and interpretation of the titers. The titers are
estimated by comparison against a known positive control
for each serotype.
The ELISA test is valuable in screening and understanding
herd status with APP. It can be used to monitor the health
of swine herds periodically for the presence ofsubclinical
or chronic infections with APP. It is important not to introduce
chronically infected pigs into non-immune healthy herds.
Early detection of subclinicalor chronic infection could
greatly aid in the prevention and control of the disease.
- byChingChingWu, DVM, PhD