Spontaneous regression of bovine cutaneous leukosis

Biopsies of skin from a 2-year-old heifer with spontaneously regressing dermal leukosis were examined. The heifer was not infected with bovine leukemia virus and was negative for tumor-associated antigens of enzootic bovine lymphosarcoma. By hematological standards for bovine leukemia, the heifer was positive at about 60 days post-occurrence of the disease (POD). At 53 days POD, lymphoblastic neoplastic cells in the dermis reacted with anti-T lymphocyte monoclonal antibody by the avidin biotin peroxidase complex method. The cells had intracytoplasmic clustered dense bodies under electron microscopy. From 53 to 83 days POD, figures of the transepithelial elimination (TE) against neoplastic cells and perivascular infiltration of small lymphocytes were in the dermis. Small lymphocytes reacted with anti-T lymphocyte monoclonal antibody. At necropsy there were no neoplastic lesions; there were flat lymph node-like tissues in the subcutis. Many germinal centers were seen in the lymphatic organs. Blood lymphocytes at 46 days POD were stimulated by phytohemagglutinin-P and concanavalin A. Sera, taken until 75 days POD and at necropsy, showed an inhibitory effect on mitogen-induced blastogenesis of normal bovine lymphocytes. These results suggested the existence of a spontaneous regressive mechanism against neoplastic lesions by TE and tumor immunity.     

Need for flagella for complete virulence of Pseudomonas syringae pv. tabaci: genetic analysis with flagella-defective mutants ?fliC and ?fliD in host tobacco plants

The flagellins purified from Pseudomonas syringae pv. tabaci induce a hypersensitive reaction in nonhost tomato cells. To investigate the role of flagella and flagellin in the compatible interaction, we generated two types of flagella-defective mutant. The fliC mutant lost the fliC gene that encodes flagellin protein, whereas the fliD mutant lost the fliD gene that encodes HAP2-capping protein. The two mutants had markedly reduced ability to cause disease symptoms in tobacco leaves. Furthermore, propagation of the mutants in tobacco leaves was less than that in wild-type pv. tabaci. Compared to the inoculation with wild-type pv. tabaci, inoculation with the two mutants did not markedly induce the expression of typical defense response-related genes such as PAL and hsr203J. Complementation of each fliC and fliD gene to the corresponding deficient mutant restored motility and virulence. These results indicate that flagella of P. syringae pv. tabaci are indispensable organelles for complete virulence on host tobacco plants.     

Establishment of a potency test by ELISA for a rabies vaccine for animal use in Japan

The ELISA we developed was able to determine the antigen content and was suitable for a potency test, and we described a relative potency assay method which determines the potency of test vaccines by comparing the ELISA value of a test vaccine to that of a reference vaccine. In the present study, we standardized the reference vaccine used for determining the potencies of test vaccines, and established a potency test by ELISA. We evaluated the proposed reference vaccine by the neutralizing antibody responses in dogs after vaccination, by the challenge protection test in guinea pigs (GP potency test), which is the earlier official potency test used in Japan, and by the NIH potency test, which is widely used throughout the world. The results showed that a 4-fold dilution of the proposed reference vaccine induced sufficient immunity in dogs. A 3-fold dilution of the proposed reference vaccine passed the GP potency test. The international units (IU) calibrated by the NIH potency test were 3.7 IU/dose. From the results and the WHO recommendation that veterinary rabies vaccines should have a potency of at least 1.0 IU/dose, we determined to dilute the proposed reference vaccine by 3 fold and regarded it as the reference vaccine. Finally, we confirmed that there is a good agreement between the results of the potency test by ELISA and the results of the GP potency test. The establishment of the potency test by ELISA has made it possible to monitor the potency in the production process and has contributed to the stable production of the vaccine.     

Classification of abomasal displacement in cows according to histopathology of the liver and clinical chemistry

Histopathological features of livers and blood chemical values in cows with abomasal displacement were investigated. Liver biopsy samples were collected during redressment operations in 92 cows with abomasal displacement, and the samples were stained with haematoxylin and eosin or periodic acid Schiff (PAS). Blood was collected for chemical tests. Livers were histopathologically divided into the following four types: normal histology cases (21%), fatty degeneration cases (36%), cloudy swelling cases (19%) and fatty degeneration cases with cloudy swelling (24%). The number of PAS-positive samples was significantly higher in the normal histology group and significantly lower in the severe fatty degeneration group and severe cloudy swelling group. Cows with fatty degeneration had significantly higher levels of serum 3-hydroxybutyric acid, non-esterified fatty acid and aspartate aminotransferase than did those with cloudy swelling or normal histology. The results indicate that the morbid conditions of cows with abomasal displacement can be classified into four types.     

Prevalence of Giardia intestinalis infection in dogs of breeding kennels in Japan

Giardia intestinalis antigen in fecal samples was examined in 361 dogs of 14 breeding kennels located at various areas in Japan, using a commercial enzyme-linked immunosorbent assay (ELISA) kit. G. intestinalis antigen was detected in 37.4% of the fecal specimens. All of the 14 breeding kennels were positive for G. intestinalis antigen with the range from 6.7 to 59.3%. The prevalence in puppies (54.5%) was significantly (p < 0.01) higher than that in adults (30.9%). There was no difference in prevalence between males and females, and between the puppies from the mother dogs positive and negative for Giardia antigen. In conclusion, G. intestinalis widely invaded the breeding kennels in Japan.     

Circadian variations in salivary chromogranin a concentrations during a 24-hour period in dogs

The purpose of this study was to determine if salivary chromogranin a secretion in dogs exhibits a circadian rhythm. Saliva sampling was performed during three different sessions occurring in three nonconsecutive 24-h periods. Sixteen healthy adult beagle dogs (8 males and 8 females) were moved to a sampling room and housed individually in cages. Saliva samples were obtained every 4 h from 12:00 p.m. to 12:00 p.m. the following day. In the interest of habituation, saliva was obtained hourly from each dog 3 h before the experiment was started. Salivary chromogranin A concentrations were measured using an enzyme-linked immunosorbent assay. No circadian rhythm was detected for salivary chromogranin A secretion, and no differences in salivary chromogranin A concentrations measured every 4 h were demonstrated during the 24-h cycle in dogs.     

Distribution of TNF receptors and TNF receptor-associated intracellular signaling factors on equine tendinocytes in vitro

Although tumor necrosis factor (TNF) alpha is an important key factor in degeneration of equine superficial digital flexor tendon (SDFT), the dynamism of TNF receptors and associated factors on tendinocytes has not been elucidated. To reveal signaling events mediated by TNF-receptors (TNF-Rs) in tendinocytes, we focused on four signaling factors, TNF-R1, TNF-R2, TNF-R-associated factor 2 (TRAF2) and nuclear factor-kappa B (NF-kappaB), and investigated the distribution and production of these factors. Cultured tendinocytes were obtained from SDFTs of thoroughbred horses. The tendinocytes were treated with 10 ng/ml equine TNFalpha medium for 6 hours and then the four factors on tendinocytes were visualized by using an immunohistochemical method, and the amounts of the four factors were determined by Western blot analysis. Although TNF-R1 and TNF-R2 co-localized on the same tendinocyte, in untreated control cells (normal condition), immunoreactivity against TNF -R1 was very weak but TNF-R2 showed a strong reaction. However, TNF-R1 showed the same high level of reaction as TNF-R2 in TNFalpha-treated cells (inflamed condition). Intense TRAF2 and NF-kappaB were detected at inflamed condition, however both factors were also detected at normal condition. The distinct distributions of the four factors under different conditions (normal and inflamed condition) in vitro not only reflect the dynamism of the cytokines but may also provide important clues for a means to prevent from occurrence of tendonitis and progress of tendon degeneration.