Detection of bacterial antigens using immuno-PCR

A new and very sensitive antigen detection technique, immuno-polymerase chain reaction (immuno-PCR), was developed. This method is basically similar to the enzyme-linked immunosorbent assay which detects an antigen-antibody reaction, but instead of an enzyme being conjugated to an antibody, a DNA fragment is used and this DNA can be amplified by PCR. We applied this method to the detection of the fish pathogen, Pasteurella piscicida, in naturally infected yellowtail. Using immuno-PCR, 3.4 cfu ml(-1) of bacteria could be detected. In comparison, ELISA detected only 3.4 x 10(4) cfu ml(-1). Immuno-PCR is a powerful method for detection of pathogens in host tissues.