The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholar Program

2003 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Vanessa Lester University of Georgia Class of 2005	Dr. Branson Ritchie

Testing Parameters for the Control of Pigeon Circovirus

Pigeon Circovirus (PiCV) is a tentative member of the family Circoviridae, a family of small (15-17 nm), nonenveloped, icosahedral viruses containing a circular single stranded DNA genome. This family also includes Chicken Anemia Virus (CAV), the Porcine Circoviruses (PCV-1, PCV-2) and Psittacine Beak and Feather Disease virus (PsCV). Since its original description in 19931, PiCV has been a recognized cause of squab mortality in flocks of Columbiformes. Although PCR assays have been validated to detect circovirus nucleic acid in samples from live psittacines2, diagnosis of a PiCV infection has required histologic examination of tissues collected at necropsy.

Circoviruses are thought to be immunosuppressive and it is damage of the immune system that is theorized to result in PiCV associated fatalities in young Columbiformes. Intranuclear inclusion bodies and associated atrophy of lymphoid tissue are typical in circovirus infected birds. Chicken Anemia Virus and PsCV are both associated with thymic and bursal atrophy in young chicks. In addition, CAV is associated with bone marrow hypoplasia, and viral infection has been shown to suppress a chicken’s immune response to vaccination against Newcastle disease. Severe lymphoid atrophy and inclusion bodies have also been reported in PiCV diseased pigeons. Pigeons with PiCV are frequently reported with concurrent infections including Chlamydophila psittaci, Salmonella sp., Aspergillus sp., E.coli, PMV-1, Pigeon Herpesvirus and various parasitic agents.

Because of the flock impact associated with PiCV infections and the variability in presentations among infected pigeons, a molecular test to determine the PiCV status of subclinical pigeons is necessary to establish and maintain healthy flocks of Columbiformes. Using a flock of approximately 200 pigeons with a history of PiCV associated disease, we developed and tested a screening protocol to accomplish the following: determine if viral nucleic acid was present in tissues collected from live birds, determine if and when positive pigeons could clear nucleic acid to undetectable levels, determine if positive adults produced positive offspring and determine if selecting negative adults could be used to establish and maintain a disease, and viral nucleic acid free, flock. A nested PCR protocol specific for PiCV was used to test the samples for viral nucleic acid. We compared results from whole blood, isolated white blood cells, and lymphoid tissue to determine the most appropriate samples for testing. [Supported by the National Aviary]