Spotting proteins for an ELISA-type microarray assay

Researchers in the groups of Professor David Barnes and Max Lagally at the University of Wisconsin have fabricated an enzyme-linked immunosorbent assay (ELISA)-type, or sandwich, microarray for detection of the presence of the Newcastle Disease Virus (NDV), a common avian pathogen.

NDV antigen solution was deposited using the microplotter in several grids on a poly-l-lysine-coated glass slide. The slide was blocked and then exposed to negative sera in one part and positive sera in another. Positive sera is simply solution containing antibodies for NDV, indicating an immune response to the presence of NDV in the avian host. These antibodies should bind to the probe antigen deposited on the glass slide surface.

The slide was then rinsed, placed a water bath, and then exposed to a fluorescently tagged anti-chicken IgY secondary antibody. The slide was rinsed again, placed in a water bath, dried, and scanned.

Even at relatively low concentrations of positive sera, the grids of 70 µm spots fluoresced strongly, while only a very small amount of flourescence (from nonspecific binding of the secondary antibody to the antigen spots) was seen in the negative controls.