Ref.CDVB022
48 tests/kit
DIGESTIVE SCREEN
Bovine
General information
Diarrhea is a major cause of mortality in young cattle under six
months.
Bovine neonatal gastroenteritis is a multifactorial disease. It can be
caused by viruses : Coronavirus or rotavirus, by bacteria :
Salmonella, pathogenic strains of E. Coli or by protozoan microorganisms
such as Cryptosporidium parvum.
Coronavirus and Rotavirus are often associated with episodes of neonatal
diarrhea.
Cryptosporidium parvum is also frequently isolated in feces, where it can
be present in very high quantities. It can persist for a long period in
the environment. In calves younger than three days, K 99 positive
enterotoxigenic E. Coli are frequently isolated, particularly in colostrum-deprived
calves or in calves feeded with colostrum free of anti - K 99 specific
antibodies.
The diagnosis of the etiologic agent of diarrhea can only be performed in the laboratory because of clinical signs which do not allow to differentiate between these different microorganisms. It is possible to identify these agents by means of different techniques including culture, staining, electron microscopy and floating techniques. However, these techniques are labor intensive, unpractical and time consuming.
These classical techniques have rapidly been replaced by the Elisa technology because of its simplicity and the limited requirements in laboratory equipment.
The sensitivity and specificity of the Elisa technique for the detection of these pathogens is at least as good as that of the more classical techniques, results are very similar. The Elisa technique is rapid and reliable and is particularly suited to the analysis of important numbers of samples.
Principle of the test
Anti - pathogens responsible of digestive disease specific antibodies
have been immobilized in alternate rows of 8 x 12 wells microtiter plate.
These antibodies allow specifically the capture of the corresponding
pathogens which are present into the feces samples. Rows A,C,E and G have
been sensitized with these antibodies and rows B,D,F and H are containing
non specific biological material. These rows allow the differentiation
between specific immunological reaction and non specific bindings to get
rid of false positives.
Feces are diluted in dilution buffer and incubated on the microplate for 1 hour at room temperature.
Rows B,D,F and H are coated with non specific antibodies as control. After this first incubation step, the plate is washed, then conjugates - peroxidase labeled anti - pathogen monoclonal antibodies - are added to the wells. The plate is incubated for 1 hour at room temperature.
After a second incubation step, the plate is washed again and the enzyme substrate (hydrogen peroxide) and the chromogen (Tetramethyl Benzidine - TMB) are added. This chromogen has the advantage of being more sensitive than the other peroxidase chromogens and not being carcinogenic.
If specific pathogens are present in the tested feces, conjugates remain bound to the corresponding microwells and the enzyme catalyses the transformation of the colorless chromogen into a pigmented compound. The intensity of the resulting blue color is proportionate to the titre of specific pathogens in the sample. Enzymatic reaction can be stopped by acidification and resulting optical density at 450 nm can be recorded using a photometer. The signals recorded for the negative control microwells are subtracted from the corresponding positive microwells.
The positive antigens supplied with the kit gives the reference values. From these values and specific coefficients it is possible to determine a limit of positivity for each pathogen.
Rev.11.95
