C. Itakura

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.

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.

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.

Fine structure of inclusion bodies in hepatic cells of chickens naturally affected with inclusion body hepatitis

The fine structure of intranuclear inclusion bodies in the hepatic cells of chickens naturally affected with inclusion body hepatitis was studied comparing them with the inclusions seen with light microscopy. Ultra-structurally the inclusions were classified into two types depending on whether they contained virus particles or not. The first type consisted of virus particles, granular material and loose granular material, and sometimes concentric-circular lamellae enclosing the virus core. It is suggested that the virus particles are adenoviruses. This type corresponded to the basophilic inclusions seen with light microscopy. The second type was without virus particles and was subdivided into two forms, one consisting of fibrillar-granular material and the other of crystals composed of filaments. These corresponded to the eosinophilic inclusions seen with light microscopy. Eosinophilic inclusions were present in all 20 cases of inclusion body hepatitis, whereas the basophilic inclusions were present in only six. The presence of adenovirus particles might suggest that they are the aetiology of this condition, although they were present in only six of the 20 cases examined. The significance of the inclusions without viral particles was not adequately elucidated, but it was suggested they are degenerating material present in cells dying from the effects of the viral infection.

Pathology of experimental vitamin D deficiency rickets in growing chickens. I. Bone

Experiments were done to determine the characteristics and to study the development of avian rachitic lesions caused by vitamin D deficiency, and to investigate the cause of rickets which occurred in growing broiler chickens from 1974 to 1975 in Japan. Two kinds of vitamin D3 deficient diets, and feed of the same formula as that in use during outbreaks of rickets, were fed to day-old commercial broiler chicks until they were 7 weeks of age. Bones from the birds were examined for pathological changes at weekly intervals. Pathological changes caused by the three experimental diets were identical in character though somewhat variable in degree. The main gross lesions were marked retardation of body growth, enlargement of the ends of the long bones, hypertrophy of the bones, widening of the epiphyseal plate, thickening of the cortical bone, softening of the bone, and enlargement of the parathyroid gland. Histologically, changes at the epiphyseal plate started with widening of both proliferating and hypertrophic zones. After that, the latter became paramount, but this was soon replaced by osteoid trabeculae resulting from accelerated endochondral ossification. Finally, the epiphyseal plate consisted mostly of a conspicuously widened proliferating zone. In the metaphysis and diaphysis, abnormal endosteal and periosteal osteogenesis appeared in the fairly early stages. The porosity of the cortical bone with osteogenous tissue was due to dilatation of the canal systems and demineralisation on the walls of Haversian canals. In brief, it was observed that lesions of vitamin D deficient rickets in growing chickens varied with time and that the entire bone including the cortical bone as well as the epiphyseal plate and metaphysis was involved. From the experimental results, it appeared that the rickets which occurred in Japanese commercial flocks was due to a vitamin D deficiency. The possibility that enlargement of the parathyroid gland, hyperparathyroidism, might play an important role in the development of this disease is discussed.

Comparative pathology of gizzard lesions in broiler chicks fed fish meal, histamine and copper.

In order to elucidate the histopathogenesis of gizzard lesions occurring with various diets and in particular with fish meals, comparative studies were made on the gizzard and proventriculus of broiler chicks fed a diet containing 15% of a suspect batch of fish meal (group A), and normal fish meal containing diets to which were added 0.4% of histamine (group B) or 1,000 parts/10(6) of copper (group C). The gizzard lesions in group A were widespread and consisted of thickening and loosening of the lining, frequently with erosions and ulcerations. The lesions in group B were almost identical to those in group A, but were less severe and less associated with erosions and ulceration. The lesions in group C were widespread and consisted of a markedly thickened lining with numerous desquamated surface cells, sometimes with erosions. The surface and chief cells were swollen in most glands of groups A and C and in the cells of those glands under the altered lining in group B. A poorly-staining secretion was shown to be excreted into the lining. The proventriculus in the three experimental groups showed increased secretion in direct proportion to the severity of the gizzard lesions. It was suggested that the gizzard lesions caused by dietary fish meal might have originated from hyperactivity of the gizzard glands, followed by erosion and ulceration.

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.

Enhanced myotoxicity and involvement of both type I and II fibers in monensin-tiamulin toxicosis in pigs.

Simultaneous administration of monensin and tiamulin to pigs resulted in enhanced myotoxicity. Skeletal muscles of tongue, diaphragm and legs were preferentially affected, whereas the masseter, longissimus thoracis and cardiac muscles, including the left auricle, were spared. Histochemical examination revealed an involvement of both type I and II fibers of skeletal muscles.