Raymond P. Campagnoli

Circovirus-Like Infection in a Pigeon:

4,7,10-13 These viruses are similar in that they are small (15-17 nm), icosahedral, and nonenveloped and contain single-stranded circular DNA. Each virus, however, has distinct DNA sequences and antigenicity. Psittacine beak and feather disease virus has the largest host range and has been reported in over 35 species of Old World and New World psittaciforms but has never been reported in other avian families. 4 This is the first case report of circovirus-like infection in a pigeon (Columbiformes). A young female racing pigeon was submitted for necropsy to the Davis branch of the California Veterinary Diagnostic Laboratory System in the fall 1990. The owner had 50 birds (adult and young), and mortality in the squabs was 100%. Three to 5 birds had died per week. Squabs exhibited anorexia and lethargy and died 3-4 days after clinical signs appeared. On gross examination, the pigeon was emaciated, with pectoral muscle atrophy. The mucosal wall of the intestinal tract was slightly red, and luminal contents were foamy and yellow-green. The spleen was enlarged. Air sacs were edematous, and there were caseous cores within the primary bronchi of both lungs. The right lung was consolidated and red. A defined bursa of Fabricius was not evident on gross examination of the site dorsal to the cloaca. The lung and liver were cultured aerobically on blood agar. A Pasteurella sp. was isolated from the lung. Bacteria were not isolated from the liver. Air sacs cultured on selective media for Mycoplasma sp. exhibited no growth. Chlamydia was not identified in Gimenez-stained impression smears of the liver, air sac, and spleen nor in liver, air sac, and spleen impression smears stained with fluorescence-labeled monoclonal antibody specific for Chlamydia a and examined with ultraviolet light. However, Chlamydia psittaci was isolated in a McCoy cell culture system from an organ pool of liver, air sac, and spleen. Viruses were not isolated from pooled tissue homogenates of liver, spleen, lung, brain, and intestine

A retrospective study of circovirus infection in pigeons: nine cases (1986-1993)

Circovirus infections were diagnosed in 12 pigeons from the United States, 4 pigeons from Australia, and 1 pigeon from Canada (1986-1993). Circovirus was identified by electron microscopic examination of basophilic botryoid cytoplasmic inclusions that had a histologic appearance similar to that of psittacine beak and feather disease virus inclusions. Inclusions were seen in splenic, bursal, gut-associated, and bronchus-associated lymphoid tissue macrophages and in bursal epithelial cells. Inclusions were composed of paracrystalline arrays of tightly packed, nonenveloped icosahedral virions 14-17 nm in diameter. Histologic changes in the spleens ranged from lymphofollicular hyperplasia with mild discrete lymphocellular necrosis to lymphoid depletion and diffuse histiocytosis. Lesions in the bursa of Fabricius ranged from mild lymphocellular necrosis to severe cystic bursal atrophy. Remaining histologic findings coincided with concurrent bacterial, viral, fungal, and parasitic infections. Immunoperoxidase staining and DNA in situ hybridization demonstrated that pigeon circovirus is distinct from psittacine beak and feather disease virus; however, both viruses apparently share some homologous DNA sequences. Clinical and diagnostic findings indicate that pigeon circovirus may be similar to psittacine beak and feather disease virus with respect to acquired immunodeficiency and subsequent multiple secondary infections.

Histologic Evaluation of the Crop for Diagnosis of Proventricular Dilatation Syndrome in Psittacine Birds

Histologic sections of crop tissue were evaluated for the presence of lymphoplasmacytic infiltrates within mesenteric ganglia. All birds with proventricular dilatation syndrome that had lymphoplasmacytic infiltrates in crop ganglia had similar infiltrates in the proventricular and/or ventricular ganglia. False-negative crop biopsy results occurred approximately 24% of the time. More invasive procedures, such as proventricular or ventricular biopsy, may be necessary if the crop biopsy is nondiagnostic in a bird with clinical signs of proventricular dilatation syndrome.

Particles Resembling Circovirus in the Bursa of Fabricius of Pigeons

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.

Detection and confirmation of reptilian adenovirus infection by in situ hybridization

Adenovirus infections are documented in at least 12 different species of reptiles. In contrast to their mammalian and avian counterparts reptilian adenoviruses are not well characterized as to their pathogenic potential and their ability to cause primary disease. In the diagnostic setting, fresh tissues are often not available for virus isolation, and the confirmation of reptilian adenovirus infections is dependent largely upon electron microscopy for the identification of intranuclear viral inclusions associated with histopathologic changes. The diagnosis of adenovirus infection in 2 different species of snake was confirmed by the application of DNA in situ hybridization. Using an aviadenovirus specific oligoprobe, adenoviral DNA was observed in the nuclei of hepatocytes, Kupffer cells, endothelial cells, and enterocytes. Electron microscopy of the liver confirmed the presence of intranuclear viral particles morphologically consistent with an adenovirus. DNA in situ hybridization on formalin-fixed tissues can serve as a suitable alternative to electron microscopy in the diagnosis of reptilian adenovirus infections. Both affected snakes had other concurrent diseases, suggesting that the adenovirus may not have been the primary pathogen.

Diagnosis of Avian Adenovirus Infections Using DNA In Situ Hybridization

Three DNA oligonucleotide probes designated FN-23, FN-48, and FN-96 were evaluated for the diagnosis of aviadenovirus infections by DNA in situ hybridization. Paraffin-embedded tissues were obtained from birds with confirmed adenovirus infection, birds with putative adenovirus infections, and birds with intranuclear inclusions caused by herpesvirus and polyomavirus. In birds with confirmed adenovirus infection, probes FN-23 and FN-96 identified 78% and 72% of diseased individuals, respectively. Only probe FN-48 detected chickens with group II adenovirus infection. In birds with putative adenovirus infection, the DNA probes confirmed aviadenovirus infections in 76% of the population. Probes FN-23, FN-96, and FN-48 detected 85%, 74%, and 18% of adenovirus-infected birds, respectively. None of the DNA probes cross-hybridized with tissues from polyomavirus-infected psittaciform birds or with tissues from a chicken with infectious laryngotracheitis. In contrast, probe FN-23 did cross-hybridize to herpesvirus-infected tissues from two of eight psittaciform birds with Pachecos parrot disease. Probes FN-48 and FN-96 did not react with these tissues.

Detection of Eastern Equine Encephalomyelitis Virus RNA in Formalin-Fixed, Paraffin-Embedded Tissues using DNA in Situ Hybridization

Eastern equine encephalomyelitis (EEE) virus was detected in infected formalin-fixed horse and emu tissues and in infected chicken embryo fibroblasts. Results of in situ hybridization using a digoxigenin-labeled 40-base DNA probe complementary to a conserved region of the EEE virus RNA compared favorably with results of both virus isolation and serum neutralization tests. This technique may be useful for diagnosis of EEE virus infection in various animal species, especially when fresh tissues are not available for analysis, and also will provide a means for studying the involvement of alphaviruses in pathogenesis studies.

Metastatic Renal Carcinoma in an African Grey Parrot (Psittacus Erithacus Erithacus)

populations of bacilli. Various numbers of rod-shaped bacteria were present in the sinusoids of the liver. Lymphocytic depletion was evident in splenic sections. All bursal sections were affected with moderate to severe lymphoid atrophy. The affected flocks in this report were suffering environmental insults, including overcrowding, high humidity, and poor litter conditions. The bursal and splenic lymphocytic atrophy was suggestive of the birds being immunodeficient. Poor environmental conditions and immunodeficiency have been implicated as contributing factors in the occurrence of GD associated with C. septicum. 2-4,7,10,11 In addition, the periodic recurrence of GD in a single broiler unit as described in this report suggests a possible dose relationship. Clostridial organisms are generally accepted to be ubiquitous, even in locations where the presence of animals is rare. Although work has been done on the population dynamics of C. septicum in various soils, little is known about the relative populations of the organism in modem poultry production facilities. Specific housing units may be contaminated with unusually high numbers of organisms. The possible contribution of high levels of environmental contamination should be considered when evaluating an increased incidence of GD. Intensive cleaning efforts in specific housing units might limit the occurrence of GD when management is unable to control contributing factors such as immunosuppression and overcrowding.

Polyomavirus Encephalopathy in a Ducorps Cockatoo (Cacatua Ducorpsii) with Psittacine Beak and Feather Disease

Necropsy tissues were examined from an adult wild-caught Ducorps cockatoo (Cacatua ducorpsii) with progressive neurologic signs. Of the tissue specimens selected for histologic evaluation, only the brain contained rare amphophilic, glassy intranuclear inclusions within astrocytes and some neurons. Astrocyte and neuronal degeneration and necrosis also were observed. Scattered astrocytes, with and without discernable inclusions, contained avian polyomavirus (APV) nucleic acid, as determined by DNA in situ hybridization. In addition, endothelial cells and intravascular leukocytes contained psittacine beak and feather disease viral nucleic acid, as determined by DNA in situ hybridization, indicating dual viral infection. Electron microscopic examination of formalin-fixed brain tissue revealed typical intranuclear APV particles in some astrocytes. Encephalopathy ultimately was attributed to APV infection.

DNA In Situ Hybridization for the Rapid Diagnosis of Massive Necrotizing Avian Adenovirus Hepatitis and Pancreatitis in Chicks

The present study describes the use of DNA in situ hybridization for the rapid diagnosis of massive necrotizing adenovirus hepatitis and pancreatitis in broiler chicks. A light microscope and DNA probes were used to identify avian adenovirus in replicate sections of formalin-fixed paraffin-embedded liver and pancreas from field and experimental chicks. Avian adenovirus infection was confirmed by transmission electron microscopy and virus isolation.