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Title: Antigen detection systems

Author
item Pantin Jackwood, Mary
item ROSENBERGER, SANDRA - AVISERVE, LLC

Submitted to: Isolation and Identification of Avian Pathogens
Publication Type: Book / Chapter
Publication Acceptance Date: 3/25/2007
Publication Date: 6/15/2008
Citation: Pantin Jackwood, M.J., Rosenberger, S.S. 2008. Antigen detection systems. In: Dufour-Zavala, L., Swayne, D.E., Glisson, J.R., Pearson, J.E., Reed, W.M., Jackwood, M.J., Woolcock, P.R., editors. Isolation, Identification, and Characterization of Avian Pathogens. Fifth edition. Athens, GA: American Association of Avian Pathologists Inc. p. 233-240.

Interpretive Summary: Infectious agents or their components (antigens or nucleic acids) can be detected in fresh, frozen, or fixed tissue using a variety of direct or indirect assays. A particular assay is chosen based on the nature of the sample, availability of equipment, quality of reagents, time, cost, and technical expertise of the diagnostician. Viruses or bacteria can be visualized directly using electron microscopy. This procedure can be performed quickly; however, it is insensitive and requires expensive equipment and technical support. Some tests such as agglutination reactions or immunodiffusion assays are simple and inexpensive but they can only be used to identify a particular pathogen possessing agglutinative or soluble antigens, respectively. Other techniques such as antigen-capture enzyme-linked immunosorbent assay, immunohistochemical staining, or in situ hybridization offer increased sensitivity and specificity but require a higher level of technical training. It is as important to become familiar with the use and limitations of the antigen detection assays available.

Technical Abstract: Infectious agents or their constituent parts (antigens or nucleic acids) can be detected in fresh, frozen, or fixed tissue using a variety of direct or indirect assays. The assays can be modified to yield the greatest sensitivity and specificity but in most cases a particular methodology is chosen based on the nature of the sample, availability of equipment, quality of reagents, time, cost, and technical expertise. Whole virions or bacteria can be visualized directly using electron microscopy. Although this procedure can be performed quickly, it is insensitive and requires specialized equipment and technical support. Some tests such as agglutination reactions or immunodiffusion assays are simple and inexpensive but they can only be used to identify a particular etiologic agent possessing agglutinative or soluble antigens, respectively. The more cumbersome techniques such as antigen-capture enzyme-linked immunosorbent assay, immunohistochemical staining, or in situ hybridization offer increased sensitivity and specificity but may require better quality reagents, additional pretreatment procedural steps prior to testing, and a higher level of technical training. To optimize antigen detection systems for diagnostic and research purposes it is as important to become familiar with the limitations of the assays as it is to understand the pathogenesis of the suspected etiologic agent in selecting the timing and type of tissue samples for testing.