Proventricular dilatation disease associated with avian bornavirus infection in a Citron-crested Cockatoo that was born and hand-reared in Japan

A 5-month-old female Citron-crested Cockatoo (Cacatua sulphurea citrinocristata) that was born and hand-reared in Japan died with suspected proventricular dilatation disease (PDD). Macroscopic and microscopic examinations of the bird revealed characteristic features of PDD, i.e., distention of the proventriculus and infiltration of lymphocytes and plasma cells in ganglia of various organs and in central and peripheral nerves. A linkage of this PDD case to infection with avian bornavirus (ABV) was documented by RT-PCR amplification of the virus genomes from the affected bird. Phylogenetic analysis revealed that the ABV identified in this study clustered into the genotype 2, which is one of the dominant ABV genotypes worldwide. To the best of our knowledge, this is the first report of a natural case of PDD associated with ABV infection in Japan.     

Identification of putative defense-related genes in Japanese pear against <Emphasis Type="Italic">Alternaria alternata</Emphasis> infection using suppression subtractive hybridization and expression analysis

The Japanese pear pathotype of Alternaria alternata, a toxin-dependent necrotrophic pathogen, causes black spot of Japanese pear by producing the host-specific AK-toxin. Pre-inoculation with nonpathogenic A. alternata or pretreatment with an elicitor prepared from A. alternata reduced disease symptoms caused by the pathogen. Salicylic acid- and jasmonic acid-dependent signaling pathways are not involved in the induced resistance to infection by the pathogen. The expression of multiple defense-related genes in Japanese pear leaves inoculated with nonpathogenic A. alternata was examined using suppression subtractive hybridization. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank database as accessions DC993229–DC993535.     

Immunosuppressive effect of infectious pancreatic necrosis virus on rainbow trout (Oncorhynchus mykiss)

The infectivity of infectious pancreatic necrosis virus (IPNV) for rainbow trout (Oncorhynchus mykiss) mononuclear leukocyte subpopulations was investigated to determine the mechanisms of immunosuppression caused by the virus. IPNV was recovered from nylon wool-adherent, surface immunoglobulin (Ig)-positive leukocytes of head kidney, spleen and peripheral blood collected from virus-inoculated fish with higher titers than non-adherent, Ig-negative cells. Non-adherent cell population showed mitogenic response to phytohemagglutinin and concanavalin A but not to lipopolysaccharide. Conversely, the responses of adherent cells to these mitogens were weak. Mitogenic response and non-specific cytotoxicity of head kidney leukocytes significantly decreased by the inoculation of fish with the virus. These results suggest that the suppression of immune responses is involved in the establishment of carrier state in fish after infection with IPNV.     

Identification of virus-specific antigens in cultured cells infected with Marek's disease virus serotype 2 and CVI-988 strain

For the identification of serotype-specific antigens of Marek's disease virus (MDV) serotype 1 (MDV1) or serotype 2 (MDV2), a total of 24 hybridoma clones, secreting monoclonal antibodies (MAbs) against CVI-988 (MDV1) or HPRS-24 (MDV2) strain, were established and characterized by immunofluorescence assay, virus neutralization and immunoprecipitation analysis. Based upon the molecular weights (mol. wt.) of the immunoprecipitated polypeptides, the MAbs were subdivided into 7 groups. Among them, two groups of MAbs reacted with antigens that have not been reported, were identified. MAbs belonging to the first group reacted with CVI-988- and MDV2-specific antigens with mol. wt. ranging from 29 K to 34 K (29/34 K). This antigen was not found in cells infected with Md/5 and JM strains of MDV1, and the results of kinetic analysis of antigen expression showed this antigen appeared to be related to late membrane antigens. MAbs belonging to the second group immunoprecipitated MDV2-specific antigens with mol. wt. of 37 K, 33 K and 31 K from HPRS-24-infected cells or with those of 37 K, 34 K and 31 K from SB-1(MDV2)-infected cells, and these antigens appeared to be related to early antigens. MAbs belonging to the other 5 groups included those which recognized similar antigens reported previously or the antigens characterized insufficiently in this study.     

Inhibition of turkey herpesvirus replication by anti-cellular serum

Quail embryo fibroblasts were used to investigate how rabbit and chicken antisera against chicken erythrocytes carrying different B alleles of the major histocompatibility antigens affect the neutralization of herpesvirus of turkeys (HVT). Although the neutralizing activities of these antisera were rather low, the HVT propagated in chicken embryo fibroblasts (CEF) from certain genotypic embryos was neutralized more by the antisera to the corresponding erythrocytes. After absorption of these antisera with homologous erythrocytes, the neutralizing activity of the absorbed sera was reduced slightly. These results reveal that the virion antigens of HVT might be partially associated with the host cell antigens of the fibroblast infected with the virus. The virus grown in these cells might incorporate the host cell antigens, including histocompatibility antigens, into the virion envelope.     

Isolation of serotype 2 Marek's disease virus from birds belonging to genus Gallus in Japan

Serotype 2 of Marek's disease virus (MDV) was isolated from apparently healthy birds belonging to genus Gallus that had no history of vaccination with MDV or herpesvirus of turkeys (HVT). Buffy-coat cells from these birds were inoculated onto chicken embryo fibroblast (CEF) cultures for primary isolation. Thirteen isolates from one golden pheasant and three white silky fowls, three black silky fowls, three Japanese long crowers, and three Japanese bantams produced herpes-like cytopathic effects (CPE) in the CEF cultures. Using serotype-specific monoclonal antibodies to MDV and HVT, 11 isolates were identified as serotype 2 MDV by indirect fluorescent antibody tests. The other two isolates were complicated with serotypes 1 and 3 of MDV-related viruses. Of 13 isolates, three cloned by the limiting-dilution method were further characterized as serotype 2 MDV biologically, genetically, and serologically. The results showed that the birds of the genus Gallus were naturally infected with serotype 2 MDV. This is the first report ever published about the distribution of serotype 2 MDV among healthy birds of the genus Gallus.     

Protection of neonatal calves against fatal enteric colibacillosis by administration of egg yolk powder from hens immunized with K99-piliated enterotoxigenic Escherichia coli.

The protective effects of egg yolk powder prepared from hens vaccinated with heat-extracted antigens from K99-piliated enterotoxigenic Escherichia coli (ETEC) strain 431 were evaluated in a colostrum-fed calf model of ETEC-induced diarrhea caused by a heterologous strain (B44). The antibody powder was obtained by spray-drying the water-soluble protein fraction of egg yolks after removing the lipid and fatty components by precipitation with hydroxypropylmethylcellulose phthalate. A total of 16 colostrum-fed calves were studied to determine whether the orally administered antibody powder would prevent fatal bovine colibacillosis caused by a virulent ETEC strain. Clinical response of individual calves was monitored and evaluated in the context of these variables: fecal consistency score, intestinal colonization, weight loss, and mortality. Control calves that were treated with vehicle (milk with egg yolk powder from nonimmunized hens) had severe diarrhea and dehydration and died within 72 hours after infection was manifested. In contrast, calves fed milk containing egg yolk powder with antipili agglutinin titers of 1:800 and 1:1,600 had transient diarrhea, 100% survival, and good body weight gain during the course of the study. Results indicate that the orally administered egg yolk powder protected against ETEC-induced diarrhea in neonatal calves and that the protective components may have been the antibodies raised by vaccination of chickens against ETEC.     

The early pathogenesis in chicken inoculated with non-pathogenic serotype 2 Marek's disease virus.

A newly cloned serotype 2 Marek's disease virus (MDV), strain ML-6, was inoculated via the nasal cavity in specific-pathogen-free chicks to examine early virus replication and the expression of Marek's disease (MD)-related antigens. Following inoculation, viral intracellular antigens (VIAs) were detected in lymphoid organs (bursas and spleens) between 5 and 14 days post inoculation (PI), in feather follicles between 14 and 30 days PI, and in lungs at 3 days PI by the immunohistopathological staining of avidin-biotin-peroxidase complex method. But, very few VIAs were expressed in the thymuses between 5 and 14 days PI. However, MD tumor-associated surface antigens were not detected in any organs. Viruses were isolated from separated spleen cells at 14 and 30 days PI. Fluorescent antibodies of convalescent sera were also detected after 10 days PI. As most of the VIAs were detectable in B-cells in bursas and spleens. B-cells were considered to be the main first target cells for the serotype 2 MDV infection.