Ref. CDVB021
24 tests/kit
RESPIRATORY SCREEN
Bovine
General information
Respiratory disorders are a major concern for bovidae, given the
frequency of such infections and the high number of animals affected.
These infections occur in all countries that practice intensive livestock
farming in which large numbers of animals are confined to small areas. The
etiology of these diseases is multifactorial. This complicates the
treatment as well as the diagnosis. Viruses and bacteria combined with
stress due to transport in overcrowded vans or dirty or poorly ventilated
stabling, for example, play a key role in triggering acute respiratory
infections. These infections are particularly common among the young
animals, although they also affect the adult animals.
In most cases the animals that show signs of respiratory ailments harbor several pathogens, some of which may act synergistically. So, it is generally recognized that viruses are the first pathogens to intervene, whereas bacteria act as second invaders to worsen the animal’s condition. Shipping fever is a good example of the synergism that can exist between a virus(PI 3) and a bacterium, such as Pasteurella, in the respiratory tract.
The Respiratory Elisa Screen kit consequently enables one to evaluate the humoral immune response of cattle to five pathogens commonly implicated in bovine respiratory infections. These are the virus causing infectious bovine rhinothracheitis (IBR) (BHV - 1), bovine virus diarrhea virus (BVDV), which is also responsible for mucosal disease, bovine respiratory syncytial virus (BRSV), parainfluenza 3 virus (PI 3) and Adenovirus 3.
Principle of the test
The test uses 96 - well microtitration plates sensitized by monoclonal
antibodies specific to the five pathogens listed above. These antibodies
are used to trap the pathogens as well as to purify them from the lysates
of the cells in which the viruses were grown. The distribution of these
pathogens on the microtitration plate is as follows : Columns 1 & 7 :
IBR ; Columns 2 & 8 : BVDV ; Columns 3 & 9 : BRSV ; Columns 4
& 10 : PI 3 ; Columns 5 & 11 : Adenovirus 3 ; Columns 6 & 12 :
negative control antigens for the viruses.
Columns 6 & 12 contain a lysate of the bovine kidney cell line that was used as a substrate to propagate the viruses. We thus have a genuine negative control to differentiate the virus - specific antibodies from the antibodies against the antigenic determinants of the kidney cells used for their replication. Using such a control reduces the number of false positives considerably. The test sera are diluted 1 : 100 in an appropriate buffer, then incubated on the plate for one hour at room temperature. The plate is washed, then the conjugate - a peroxidase - labeled anti - bovine IgG - monoclonal antibody - is added to the wells. The plate is re - incubated at room temperature for 1 hour. After this second incubation, the preparation is washed and the enzyme substrate (hydrogen peroxide- and the chromogen tetramethylbenzidine (TMB) are added. This chromogen has the advantages of being more sensitive than the other peroxidase chromogens and not being carcinogenic. If specific immunoglobuling are present in the test sera the conjugate remains bound to the corresponding microwell 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 antibody in the sample. The signals recorded for the negative control microwells are subtracted form the corresponding positive microwells, while the positive sera supplied with the kit give the reference values for each of the antigens. From these values it is possible to rank the positivity of unknown sera form 0 to ++++.
Rev.12.95
