Application of the polymerase chain reaction for the diagnosis of fowl poxvirus infection.

The polymerase chain reaction (PCR) was used to amplify a 578-bp fragment of the fowl poxvirus (FPV) genome and with a set of primers framed a region within the gene coding for 4b core protein. An amplified product was detected with six strains of FPV, whereas none was obtained from uninfected cell cultures, skin tissue or four unrelated avian pathogens. The sensitivity of PCR was tested with nucleic acids from the FPV-infected cell cultures. The detection limit was 10(-1) TCID50 in an ethidium bromide-stained gel. In addition, this assay system was used to detect FPV in tissue specimens of skin and respiratory swabs collected from commercially reared chickens. The identity of the amplification products from the tissue specimen preparations was determined further by using a simple, rapid procedure in which an internally nested, end-labeled probe was used.