Detection of circovirus infection in pigeons by in situ hybridization using cloned DNA probes

Degenerate primers were designed based on known sequence information for th e circoviruses psittacine beak and feather disease virus and porcine circov irus and applied by polymerase chain reaction (PCR) to known virus-infected bursa of Fabricius (BF) from a pigeon. A 548-bp DNA fragment was amplified and shown to be specific to a novel circovirus, named pigeon circovirus (P iCV), and was used to produce sensitive and specific probes for detection o f circovirus DNA by in situ hybridization (ISH). Using ISH on BF from 107 p igeons submitted for necropsy, infection was detected in 89%, compared with a histologic detection rate of 66%. Using the ISH technique, infected cell s were also found in liver, kidney, trachea, lung, brain, crop, intestine, spleen, bone marrow, and heart of some birds. Large quantities of DNA were present in some of these tissues, and in the absence of BF, liver in partic ular is identified as a potentially useful organ to examine for presence of PiCV. This high prevalence of infection in diseased birds is noteworthy, e mphasizing the need for studies to determine the precise role of this virus as a disease-producing agent.