Abstract. An unidentified, pleomorphic, gram-negative rod (PGNR) bacterium has been isolated from domestic fowl with respiratory disease. The PGNR was isolated in 5% of turkey accessions and 3% of chicken accessions, primarily from the respiratory tract. Preliminary characterization of this organism included reviewing accession records, conducting cultural and biochemical tests, and analyzing cellular fatty acids. The PGNR was also compared with other bacteria capable of inhabiting the avian respiratory system. Biochemical and cellular fatty acid analysis failed to identify the organism, however all 14 isolates were similar.Respiratory disease has been and continues to be a significant problem for the poultry industry. The large number of primary and secondary agents involved in respiratory disease, including viral, bacterial, mycotic, and parasitic agents, contributes to its complexity. The avian diagnostician is responsible for compiling information from a variety of sources and disciplines and for correlating the respiratory disease with an etiology. The significance of many secondary agents is often uncertain. A pleomorphic gram-negative rod-shaped bacterium is isolated with some frequency from fowl with respiratory disease at California Veterinary Diagnostic Laboratory System (CVDLS) laboratories. This report is a preliminary characterization of this unidentified bacterium. Materials and methodsCase material. Accessions were submitted to the Fresno and Turlock Branch Laboratories of the CVDLS from July 1, 1990 to July 1, 1991. Accessions consisted of one or more birds submitted for a standard necropsy, including a bacteriologic workup.Necropsy procedures. A complete necropsy was performed on bird(s) from each accession. Tissues were plated onto 5% sheep blood agar (BA) and MacConkey agar plates and incubated at 37 C in 7.0% CO 2 . When indicated, cultures for mycoplasma were performed. Significance of bacterial isolates was determined based on quality of tissues, quantity and quality of bacterial growth, and consideration of the Received for publication February 27, 1992. clinical history. Significant isolates from each case were harvested after 18 hr of growth, mixed with 20% skim milk, and stored at -70 C. Bacterial strains. Pleomorphic gram-negative rods (PGNRs) were initially identified from necropsy cases based on growth on BA plates, no growth on MacConkey agar plates, Gram's stain reaction and morphology, positive oxidase test, positive ß-galactosidase (ONPG) test, and negative catalase test. Detailed characterization was performed on 14 stored isolates of the PGNR, 1 field isolate of Actinobacillus salpingitidis (obtained from R. Walker, CVDLS), and 6 American Type Culture Collection strains of bacteria encountered in the avian respiratory system (Bordetella avium, Haemophilus paragallinarum, Moraxella anatipestlfer, Pasteurella gallinarum, P. avium, and P. langaa).Cultural characterization of isolates. Standard methods of cultural and biochemical examination were used: 2 Gram's stain reaction, g...

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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.

Various diagnostics techniques were compared for their ability to detect infectious laryngotracheitis (ILT) during an outbreak in chickens aged between 4 and 21 wk. Gross lesions ranged from excess mucus to accumulation of fibrinonecrotic exudate in the larynx and trachea. Syncytial cells with intranuclear inclusion bodies were found in sinus, conjunctiva, larynx, trachea, lung, and air sac. Virus isolation in chicken embryos was attempted in every case. Negative-stain electron microscopy detected herpesvirus in only 6% of the cases. Yet, isolation of ILT virus in the chorioallantoic membrane was presumed by histology in >20% of the samples and confirmed by fluorescent antibody (FA) in 35% of the embryos inoculated with conjunctivas or tracheas from affected birds. Overall, results from histology and FA tests were highly correlated. FA test has the advantage over histology of being diagnostically specific for ILT virus. Polymerase chain reaction was the most sensitive test and detected the viral DNA even in cases where histology and FA were negative. ILT virus DNA was quantified by real-time polymerase chain reaction (Re-Ti ILTV). Histologic and FA results from larynx and trachea were negative if the concentration of the viral DNA was < or =4 of log10. A viral DNA concentration higher than log10 4, as determined by Re-Ti ILTV, was required for clinical ILT to be manifested.