M. Goryo

Isolation of an agent inducing chicken Anaemia

A condition showing anaemia with asplasia of the bone marrow and atrophy of the lymphoid organs occurred in young layer chickens on a poultry farm. An agent (tentatively designated TK-5803 strain) was isolated in specific-pathogen-free (SPF) chicks from livers of the field cases. The agent was severely pathogenic when inoculated into 1-day-old SPF chicks, but the chicks developed age resistance to the agent. The agent produced no cytopathic effect nor alterations in chick embryo fibroblasts and chick kidney cells. Antisera to the agent had neutralising antibodies but no activity against other infective agents. The agent was resistant to ether, chloroform and pH 3.0, passed through a 25 nm membrane filter, and was inactivated partially after heating for 30 min at 80 degrees C and completely after 15 min at 100 degrees C. These characteristics of the agent were similar to those of the chicken anaemia agent reported by other workers.

Histopathology of chicks inoculated with chicken anaemia agent (MSB1-TK5803 strain).

One-day-old chicks, inoculated intramuscularly with the MSB1-TK5803 strain of chicken anaemia agent (CAA), showed a decrease of haematocrit value and inhibition of body weight gain, particularly between days 12 and 20 post inoculation (pi). Macroscopically, yellowish bone marrow, atrophy of the thymus and bursa of Fabricius, enlargement and discoloration of liver were observed in most chicks at the peak of infection. Histologically, the lesions appeared first in bone marrow and thymus on day 6 pi, and then in the bursa, spleen and liver. Swelling and intranuclear inclusion bodies in the haematopoietic precursor cells, thymocytes and reticular cells of the thymus were considered to be characteristic lesions. Hypoplasia or aplasia of bone marrow, depletion of lymphocytes in the lymphoid organs and swelling of hepatocytes occurred during the anaemic phase. Repopulation of the haematopoietic cells and lymphocytes occurred between days 16 and 24 pi, and most tissues of the surviving chicks recovered by day 32 pi.

Cryptosporidial infection in chickens

Cryptosporidial infection was found in 25 layer and four broiler chickens, aged 40 to 80 days, from 11 flocks on six poultry farms. The infection appeared in 1975 in broiler chickens and in 1976 in layers. On one of the poultry farms the infection occurred over a period of 2.5 years. Tissues most frequently affected with cryptosporidia were the bursa of Fabricius (85%), followed by the respiratory tract (nasal cavity, infraorbital sinus, larynx and trachea) (41%) and caeca (11%). Cryptosporidia in various stages of its life cycle were demonstrated histologically and electron microscopically attached to the host cells, and they were identical to those previously reported in other animals and humans. Hypertrophy and hyperplasia of the lining epithelial cells were noted in both the bursa of Fabricius and the respiratory tract. The histological alterations in the respiratory tract, especially the trachea, were sufficient to consider cryptosporidia as a primary cause of respiratory disease.

Serial propagation and purification of chicken Anaemia agent in mdcc‐MSB1 cell line

The TK-5803 strain of an agent which induces chicken anaemia was propagated and titrated in cultures of the MDCC-MSB1 cell line. When the isolates (tentatively designated MSBI-TK-5803 strain) from the original material were inoculated into 1-day-old susceptible chicks, they showed a severe pathogenicity, inducing anaemia with aplasia of the bone marrow and atrophy of the lymphoid organs. On density gradient separation, the peak of their infectivity titre appeared at a density of 1.35 to 1.36 g/cm(3) and numerous virus particles were demonstrated in the same fraction. The agent was resistant to heating for 30 min at 60 degrees C and 50% chloroform for 15 min at 4 degrees C, and passed through a 25 nm membrane filter, but it was completely inactivated after heating for 30 min at 70 degrees C or more. The purified virus particles were spherical or hexagonal in shape and 19.1 +/- 0.2 nm in diameter.

Histopathology of monensin‐tiamulin myopathy in broiler chicks

Thirty-six 7-day-old broiler chicks were simultaneously given food containing monensin, and water containing tiamulin, both drugs being at normal levels of usage. Equal numbers of chicks on a basal diet and plain water served as the controls. Anorexia, depression, drowsiness, leg weakness and a decrease in body weight appeared on days 2 to 3 of administration in several treated chicks. These clinical signs and growth retardation were prevalent and severe on days 4 to 7, at which time some chicks became recumbent. From day 9, chicks showed gradual recovery from the clinical signs and growth retardation. Histopathologically, the neck and leg skeletal muscles examined were severely affected in treated chicks, but cardiac and pectoral muscles were intact. Besides hyalinisation and floccular change which appeared infrequently in early stage of the experiment, muscle fibres showing an enlargement of the nuclei and a distention of a pale to basophilic sarcoplasm, suggestive of partial myofibrillar lysis and subsequent reparative change, dominated all affected muscles. These degenerative and reparative changes were considered to be distinctive for monensin-tiamulin myopathy in chicks.

Inclusion body hepatitis due to adenovirus in pigeons

Inclusion body hepatitis (IBH) occurred on a pigeon farm of Japan. Basophilic and/or eosinophilic inclusion bodies were found in nuclei of many hepatocytes of all the four pigeons examined pathologically. The same inclusions were seen in epithelial cells of the uriniferous tubules and enterocytes of the small intestine. Ultrastructurally, the hepatic inclusions had viral particles morphologically identical to adenoviruses. The inoculum prepared from the affected liver produced neither cytopathic effects in chick embryo fibroblasts nor pock lesions on chorioallantoic membranes of developing chick embryos.

Ultrastructure of the thymus in chicks inoculated with chicken anaemia agent (MSB1-TK5803 strain).

Mild depletion of thymocytes, with swelling of thymic lymphoblasts was observed 1 week post inoculation (pi). The affected cells had irregular nuclei and frequently contained intranuclear inclusion bodies consisting of fine granular or homogenous materials. Electron-opaque regions, microtubules and autophagosomes were also present in the cytoplasm of affected cells. Aggregation of virus-like particles of 14 to 18 nm in diameter was rarely observed in the degenerative cells. The reticular cells with elaborate cytoplasmic meshwork were prominent 2 weeks pi. Repopulation of thymic lymphoblasts was marked in the cortex 3 weeks pi. The fine structure of the thymic cortex is also described.

Ultrastructure of cryptosporidial life cycle in chicken host cells

Ultrastructural studies were conducted on cryptosporidia in various stages of the life cycle, attached to the epithelial cell surface of the bursa of Fabricius, caecum and trachea in six 5 and 6-week-old chickens fed faeces containing cryptosporidial oocysts. The stages observed were sporozoites or merozoites penetrating the host cells, trophozoites, schizonts, macrogametocytes, microgametocytes and oocysts. The cryptosporidia in the chickens were morphologically and developmentally similar to those reported previously in other animals and humans. All the life cycle stages were recognised in each organ examined and sporulating oocysts were found adherent to the host cells. Trophozoites, schizonts and macrogametocytes were common in each organ examined, while oocysts were found only occasionally and microgametocytes and sporozoites or merozoites were uncommon.

Ultrastructure of bone marrow in chicks ioculated with chicken aaemia agent (MSB1‐TK5803 strain)

Ultrastructural changes of the bone marrow in chicks inoculated with chicken anaemia agent (CAA: MSB1-TK5803 strain) and age-matched controls are described. Erythropoiesis in the lumen of the intravascular spaces (sinuses) of unaffected bone marrow were classed into four consecutive stages according to cell morphology: proerythroblasts, basophilic erythroblasts, polychromatophilic erythroblasts and erythrocytes. In the early stage of infection, haematopoietic cells showed irregular plasma membrane, vacuolisation, formation of pseudopods and electron-opaque regions in the cytoplasm as well as intranuclear inclusions consisting of fine granular or homogeneous materials. Aggregation of virus-like particles, of 14 nm in diameter, was rarely observed in the degenerative haematopoietic cells. Subsequently, an increase in numbers of macrophages with engulfed degenerative and necrotic haematopoietic cells and plasma cells with prominent Golgi complex and well developed rough endoplasmic reticulum was observed in the anaemic stage. Although immature cells were rarely seen on day 12 of postinoculation (pi), active erythropoiesis resumed on day 20 pi or later.

Ultrastructural changes of monensin‐oleandomycin myopathy in broiler chicks

Light microscopical and ultrastructural changes of skeletal muscles were described in chicks treated with monensin and oleandomycin in the food and water for 3 to 6 days. Simultaneously, or slightly subsequent to necrosis of some myofibres on days 3 and 4 of treatment, many myofibres exhibited reversible alterations initiated by focal myofibrillar lysis and degeneration of mitochondria. Reparative changes appearing on day 6 of treatment showed proliferation of the mitochondria, marked increase of ribosomes and polysomes, and enlargement of the Golgi apparatus in the sarcoplasm of degenerated myofibres. The morphological findings of monensin-oleandomycin myopathy in chicks were indistinguishable from monensin-tiamulin myopathy. Possible factors contributing to the unique morphology of this myopathy were discussed.