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Biomedical subjects

Y Otaki

Publications and source records attributed to Y Otaki.

27 records · Page 2Linked to original sources
PubMedDate not supplied

Occurrence of acute infectious bursal disease with high mortality in Japan and pathogenicity of field isolates in specific-pathogen-free chickens.

Highly virulent infectious bursal disease virus (IBDV) was isolated from field cases, and the pathogenicity of the isolates was examined in specific-pathogen-free chickens. Chickens inoculated with the isolates developed severe clinical disease with a high mortality rate. Histopathologically, infectious bursal disease was characterized by bursal and thymic necrosis, aplastic anemia, acute hepatitis with fatty change, and systemic inflammatory response. In addition to functional abnormalities in the liver, a hypoxic state was induced by aplastic anemia and severe inflammation in the pulmonary air capillary walls. These pathological changes appeared to be closely related to the cause of death.

Animals↗
PubMedDate not supplied

Immunosuppressive effect of a highly virulent infectious bursal disease virus isolated in Japan.

The immunosuppressive effect of infectious bursal disease virus (IBDV) on vaccination against Newcastle disease (ND) was compared among 2-, 3-, and 4-week-old chickens inoculated with the highly virulent IBDV field isolate 90-11 and the reference serotype 1 strain GBF-1. In all age groups, isolate 90-11 severely suppressed antibody response to ND vaccination and protective vaccinal immunity against ND. In contrast, chickens inoculated with strain GBF-1 and vaccinated with ND vaccine were well protected from the ND virus challenge. The mitogenic response to phytohemagglutinin of splenic lymphocytes from chickens inoculated with isolate 90-11 or strain GBF-1 was significantly lower than that of uninoculated controls. There was no difference between the two inoculated groups in responsiveness, although lymphocyte depletion in the thymus was more severe in chickens inoculated with isolate 90-11 than in chickens inoculated with strain GBF-1.

Animals↗
PubMedDate not supplied

Pathogenesis of abnormal feathers in chickens inoculated with reticuloendotheliosis virus.

Abnormal feathers, characterized by thinness and increased transparency of the calamus and rachis, and loss of barbs, were induced at a high frequency by inoculating day-old chicks with reticuloendotheliosis virus (REV) propagated in chicken-embryo fibroblast (CEF) cultures. The few birds that survived inoculation with oncogenic stock of REV derived from liver tissue of an infected chick developed similar abnormalities. Lesions of an inflammatory-degenerative type were observed in close association with the presence of viral antigen and numerous c-type virus particles, characteristic of REV, in the intermediate and cylindrical cell layers of all abnormal feathers examined. These findings, first detected in the intermediate and cylindrical cell layers of developing feathers 6--9 days after infection, suggest that degeneration and necrosis of feather-forming cells result from productive infection of REV, resulting in the development of the abnormal feathers.

Animals↗
PubMedDate not supplied

Direct correlation between the titer of infectious bursal disease virus VP2-specific antibody and protection.

The titer of antibody specific to infectious bursal disease virus (IBDV) was measured by a new method and correlated with protection. Challenge was carried out in chickens with various antibody titers, which were measured using a latex agglutination-inhibition (LI) test, a rapid and easy technique for measuring IBDV VP2-specific antibody. When actively immunized chickens had LI titers of 1:2 or more, almost all were protected from subsequent challenge with highly virulent IBDV. In contrast, even when chickens passively immunized with maternally derived antibody had LI titers of 1:4, half were susceptible to the same challenge.

Agglutination Tests↗
PubMedDate not supplied

Rapid and quantitative assay system for measuring anti-infectious bursal disease virus antibody using monoclonal antibody bound to polystyrene latex microspheres.

A monoclonal antibody (MAb) to infectious bursal disease virus (IBDV) that has virus-neutralizing activity was bound to polystyrene latex microspheres The microspheres agglutinated with extracts of bursae from chickens infected with IBDV. Agglutination was inhibited in a competitive manner by adding serum obtained from IBDV-infected chickens. The level of agglutination-inhibition depended on the serum antibody titer against IBDV. The reaction was visually accomplished within 5 minutes. The titer of this rapid assay showed a close relationship with that of the virus-neutralization test.

Animals↗
PubMedDate not supplied

Sequence comparisons of a highly virulent infectious bursal disease virus prevalent in Japan.

Variable cDNA regions in the VP2 gene of five highly virulent infectious bursal disease viruses (IBDVs) isolated in Japan were amplified by polymerase chain reaction (PCR) and sequenced. The nucleotide sequences of five highly virulent IBDVs were identical. Comparisons of the nucleotide and the deduced amino acid sequences with those of other strains of IBDV indicated that Japanese highly virulent IBDV is different from all other strains of IBDV that were compared. The number of amino acids that differed between strains (substitution score) showed that highly virulent IBDV is more closely related to European virulent strain 52/70 than to Japanese conventional strains. These results strongly suggest that a single strain of highly virulent IBDV that might have originated from a European strain is prevalent in Japan.

Amino Acid Sequence↗