Objective—To use antibodies produced by calves in
response to infection with Mannheimia haemolytica
in immunoaffinity chromatography for the identification
and subsequent isolation of the dominant
immunogenic antigens from bacteria grown in irondeficient
Sample Population—Serum from 10 calves actively
infected with M haemolytica.
Procedure—An outer membrane protein fraction was
obtained from sonicated salt-extracted M haemolytica
cells by extraction with N-lauroyl sarcosinate. The
immunoglobulin fraction of serum from calves actively
infected with M haemolytica was used to prepare
an immunoaffinity column. The immunoaffinity column
was used to isolate the dominant immunogenic
proteins from the outer membrane protein fraction.
The resultant immunogenic protein fraction was subjected
to ELISA and immunoblot methods as well as
carbohydrate quantification. Sequencing of the N-terminal
was performed on the most prominent protein.
Results—5 immunogenic proteins with molecular
weights of 42, 30, 24, 20, and 15 kd were isolated.
The immunogenic protein fraction was found to contain
51% carbohydrate. The immunoaffinity column
capacity was 1 µg of immunogenic protein/mL of gel.
The N-terminal sequence of the 42-kd protein was Tyr-Gln-Thr-Tyr-Gln-Ser-X-Leu-Gln, where X could not be
Conclusions and Clinical Relevance—Immunogenic
proteins were isolated by use of immunoaffinity chromatography.
A substantial amount of carbohydrates
was co-purified in the process. Additional experiments
are needed to determine whether the carbohydrates
would hinder or enhance development of
vaccine preparations. This method could potentially
allow a more rapid production of antigens for use in
vaccines. (Am J Vet Res 2002;63:1634–1640)
Objective—To determine the predictive ability of a
commercially available lateral-flow immunoassay
used for determining passive transfer of immunoglobulins
Animals—204 male Holstein calves ranging from 4 to
8 days old.
Procedure—Serum samples were obtained from
each calf. Results of refractometry, zinc sulfate turbidity
technique, and the lateral-flow immunoassay
were determined. Sensitivity, specificity, accuracy,
and predictive ability were calculated on the basis of
IgG concentrations determined by turbidimetric
Results—Mean IgG concentration in the study was
10.9 mg/ml as determined by TIA. Rate of failure of
passive transfer in this study population was 56%.
Associations between the values for the refractometry
and zinc sulfate turbidity techniques were established
by regression analysis. Accuracy for the lateral-flow
immunoassay, refractometry, and zinc sulfate
turbidity methods was 95, 80, and 73%, respectively.
Conclusions and Clinical Relevance—The lateral-flow
immunoassay was better at determining the status
of passive transfer of immunoglobulins, compared
with the refractometry or zinc sulfate turbidity methods.
The ability of the lateral-flow immunoassay to
provide accurate results should enable clinicians to
make immediate management or intervention decisions.
(Am J Vet Res 2002;63:247–250)