Particles Resembling Circovirus in the Bursa of Fabricius of Pigeons

Abstract

Histological examination of the bursae from 12 pigeons under 4 months old revealed basophilic globular inclusion bodies, 5 to 25 microns in diameter, in the cytoplasm and the nuclei of the various bursal follicular cells. Electron microscopy of these inclusions revealed large electron-dense areas containing non-enveloped icosahedral viral particles, 14-19 nm in diameter, either loosely arranged or in paracrystalline array. Similar basophilic globular inclusion bodies were seen in the spleen and cecal tonsils of a few pigeons and in the duodenum of one pigeon. There were various degrees of lymphoid depletion in the bursa, spleen, and bone marrow. The morphology of the inclusions in the bursa and size of the viral particles are most consistent with circovirus. Preliminary studies on the bursae of two pigeons were negative for psittacine beak and feather disease (PBFD) viral antigen and nucleic acid by immunoperoxidase staining, DNA in situ hybridization, and polymerase chain reaction techniques, suggesting that this virus differs from PBFD virus. Most of the pigeons had concurrent infections such as paramyxovirus-1, salmonellosis, herpesvirus, and hepatic and cerebral trichomoniasis associated with adenovirus.

Molecular characterization of novel circoviruses from finch and gull

“…One of the characteristic histological features of circovirus infections of young birds is the occurrence of cytoplasmic globular or botryoid inclusions, which are commonly found in mononuclear inflammatory cells in the bursa of Fabricius. The most studied avian viruses of the circovirus genus are BFDV, which causes feather and beak abnormalities in a wide range of psittacine birds, and PiCV, infections with which are associated with a variety of clinical signs including lethargy, weight loss, respiratory distress, diarrhoea and poor race performance (Woods et al ., 1993;Shivaprasad et al ., 1994). Infections with BFDV and PiCV are both associated with lymphoid depletion and immunosuppression, which appears to increase the severity of secondary infections.…”

Pigeon circovirus infection: Pathological observations and suggested pathogenesis

“…Circoviruses are tiny non-enveloped icosahedral viruses (15-24 nm in diameter) with a single-stranded circular DNA of 1.76 kb to 2.31 kb (Bassami et al, 1998;Niagro et al, 1998). Like most other members of the newly proposed Circoviridae family, PiCV is characterized by typical basophilic globular inclusions in light microscopy (Woods et al, 1993;Shivaprasad et al, 1994;Woods et al, 1994).…”

Circovirus-like infection in a southern black-backed gull (Larus dominicanus)

“…Further circovirus-like infections in pigeons have subsequently been identi® ed in the US, as well as in Australia, Canada, Northern Ireland and England (Woods et al, 1994;Shivaprasad et al, 1994;Smyth & Carroll, 1995;Smyth, 1995;Gough & Drury, 1996).…”