Diagnostic tools for bacterial, viral, parasitic, and other sorts of infections in animals are known as "vet infectious disease diagnostics," and they are used to identify and find these infections in animals. The market for veterinary infectious diseases diagnostics, which was valued at USD 1.76 billion in 2021, is expected to grow to USD 3.80 billion by 2030, a promising CAGR of 8.9% over the forecasted period of 2021–2030.
The various Immunological technologies
Utilizing methods including viral neutralization, ELISA, complement fixation, and agar gel immunodiffusion, traditional immunoassays for disease diagnosis have been predicated on detecting antibodies to the pathogen of interest. These tests typically include the interaction of serum polyclonal antibodies with the target agent, followed by the application of a detection method such as the cytopathic effect, hemolysis, or color change of a reaction medium. Creating particular proteins or peptides has been made possible by new biotechnological techniques such as gene cloning, immunogen overexpression, utilization of expression vectors, and peptide synthesis.
The sensitivity or specificity of immunoassays may enhance with the use of these upgraded antigens. The immunological methods, such as western blotting, immunofluorescence, immunoperoxidase/enzyme immunohistochemistry, flow cytometry, confocal laser microscopy techniques, etc., are frequently employed for determining the expression pattern of different genes or for the diagnosis of various disorders.
a.) FAT or Fluorescent antibody technique
The idea behind fluorescent antibody approaches is the interaction between antigen and antibody. It entails the direct or indirect detection of an antigen or protein utilizing certain antibodies that have been attached to fluorescent dyes like fluorescein isothiocyanate (FITC), phycoerythrin (PE), etc. The primary antibody used in the FAT method is tagged with a fluorescent dye, whereas the secondary antibody used in the IFAT method is labeled with a fluorescent dye and produced against the species from which the initial antibody was originally obtained. The primary antibody used in the indirect technique is specific for the antigen, whereas the secondary antibody is specific for the first antibody. The detection of expressed proteins after transfection and microbial antigen in infected cell culture, tissue sections, clinical samples, etc., can be done using immunofluorescence techniques.
b.) IPT or the Immune Peroxidase technique
IPT is conceptually identical to FAT, except that an antibody is coupled to an enzyme, such as horse radish peroxidase (HRPO). When H2O2 is added to a substrate solution containing diaminobenzidine hydrochloride (DAB) and oxygen, the HRPO first catalyzes the reaction to produce nascent oxygen and a water molecule. Thusly created, nascent oxygen oxidizes DAB, resulting in the brown color. As a result, IPT also provides the ability to detect expressed antigens in tissue slices, impression smears, and cultured mammalian cells. It offers advantages to FAT in that slides can be preserved for a long time without altering the results, and a fluorescent microscope is not required. IPT is carried out using the direct and indirect approaches, just like FAT.
Traditional diagnostic methods are the mainstay of diagnosing livestock zoonotic pathogens and infectious illnesses. However, the development of new biotechnology tests in recent years has resulted in a significant change. These novel assays produce highly specialized antigens by using recombination, expression vectors, and synthetic peptides. The sensitivity and specificity of various conventional diagnostic assays have been greatly enhanced by the use of these assays along with monoclonal antibodies. In veterinary laboratories, various PCR techniques have been used as standard diagnostic methods for both precise typing and quick screening of large quantities of samples during disease outbreaks. With proteomics, examining more aspects of a pathogen of interest's protein expression may be possible.