Biological activity of recombinant bovine interferon tau using an Autographa californica nuclear polyhedrosis virus expression system

Bovine interferon (bIFN) tau, which plays a key role in maternal-fetal recognition of pregnancy, was expressed by an Autographa californica nuclear polyhedrosis virus expression system. cDNA coding bIFNtau was derived from cultured trophoblast cells. The recombinant (r) bIFNtau had high antiviral activity (1 x 10 (8) IU/mg) and the molecular weight of rbIFNtau was estimated to be 23 kDa by Western blotting analysis. We investigated the biological effect of rbIFNtau on prostaglandin (PG) F(2alpha) synthesis in cultured bovine endometrial epithelial cells in the presence or absence of oxytocin (OT, 100 nM). rbIFNtau suppressed basal and OT-induced PGF(2alpha) production in a dose-dependent manner (1-1,000 ng/ml). These results showed that biologically active rbIFNtau was produced in the baculovirus expression system, and that rbIFNtau had the ability to suppress the synthesis of PGF(2alpha) from bovine endometrial epithelial cells.     

Susceptibility to N-methyl-N-nitrosourea-induced retinal degeneration in different rat strains

To evaluate the potential role of genetic background in the susceptibility to retinal degeneration induced by N-methyl-N-nitrosourea (MNU), female rats of the Sprague-Dawley (SD), Long-Evans (LE) and Copenhagen (CH) strains were administered 50 mg/kg MNU or saline at 7 weeks of age. Retina morphology and morphometric analysis of all rats was performed 7 days after MNU administration. Atrophy of both the peripheral and central outer retina occurred in all rat strains exposed to MNU. Decreased photoreceptor cell ratio and increased retinal damage ratio were observed. The severities of the retinal atrophy were similar among all three rat strains. In conclusion, MNU-induced photoreceptor degeneration developed consistently in all three strains regardless of the absence (SD rats) or presence (LE and CH rats) of melanin in the retina, suggesting that genetic and melanin factors did not affect photoreceptor cell death after MNU.     

Assessment of the measurement of canine and feline serum fibroblast growth factor-23 concentrations by automated chemiluminescence immunoassay

This study compared canine and feline fibroblast growth factor (FGF)-23 concentration measurements between automated chemiluminescence assay (CLEIA) and enzyme-linked immunosorbent assay (ELISA). Seventy serum samples each from dogs and cats were evaluated. FGF-23 measurements by CLEIA significantly correlated with those of ELISA in both dogs and cats. The Bland–Altman test showed that FGF-23 between CLEIA and ELISA had fixed and proportional biases, respectively, in both dogs and cats. Measurements by CLEIA were lower than those of ELISA, especially in higher serum FGF-23 concentrations. This study showed that FGF-23 concentrations in dogs and cats can be evaluated by automated CLEIA. However, FGF-23 cannot be directly compared between CLEIA and ELISA.     

In vitro and in vivo effects of recombinant bovine interferon-tau on bovine leukemia virus

The antiviral effects of recombinant bovine interferon-tau (rboIFN-tau) on bovine leukemia virus (BLV) were examined in vitro and in vivo. In the in vitro experiments, BLV titers decreased in FLK-BLV cells and in peripheral blood mononuclear cells of BLV-infected cattle treated with rboIFN-tau at a concentration higher than 10(2) U/ml. In order to examine the in vivo effects of rboIFN-tau, 10 BLV-infected cattle were subcutaneously injected with rboIFN-tau. In the first experiment, 6 cows were administrated with 10(5) U/kg body weight of rboIFN-tau 3 times per week for 4 weeks, while in the second experiment 4 cows were administrated with 10(6) U/kg body weight of rboIFN-tau 3 times per week for 3 weeks. No adverse effects were observed after the administration of rboIFN-tau. In experiment No. 1, the mean BLV titers in cattle decreased in the post-rboIFN-tau administration period compared to the pre-rboIFN-tau administration period. In experiment No. 2, the mean BLV titers in cattle decreased in the rboIFN-tau administration period. These results suggest that rboIFN-tau decreases BLV titers in vitro and in vivo and that rboIFN-tau possibly reduces the degree of BLV titer in cattle without severe side effects.     

Effect of a single intrauterine administration of recombinant bovine interferon-τ on day 7 of the estrous cycle on the luteal phase length and blood profile in dairy cows

This study tested the effect of recombinant bovine interferon-tau (rboIFN-τ) on the length of estrous cycle, luteal lifespan and side effects of rboIFN-τ in the cow. A normal estrous cycle in six non-lactating cycling Holstein cows was observed (non-treated cycle), and either 2.0 mg of liposomalized rboIFN-τ (treated cycle) or bovine serum albumin (BSA; placebo cycle) was infused in the uterus on day 7 of the estrous cycle (day 0=day of ovulation). Rectal temperature, heart rate and respiratory rate were recorded and blood samples were collected before and after the treatments. The length of the estrous cycle and corpus luteum lifespan in rboIFN-τ treated cycles were not significantly different from those of the non-treated and placebo cycles. In contrast, the rboIFN-τ treatment caused a transient increase in rectal temperature and a decrease in the number of peripheral lymphocytes and neutrophils after the treatment.     

Neuroanatomical distribution of disease-associated prion protein in cases of bovine spongiform encephalopathy detected by fallen stock surveillance in Japan

Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disorder of cattle characterized by accumulation of the disease-associated prion protein (PrP(Sc)) in the central nervous system (CNS). The immunohistochemical patterns and distribution of PrP(Sc) were investigated in the CNS, brains, and spinal cords of 7 naturally occurring BSE cases confirmed by the fallen stock surveillance program in Japan. No animals showed characteristic clinical signs of the disease. Coronal slices of 14 different brain areas in each case were immunohistochemically analyzed using an anti-prion protein antibody. Immunolabeled PrP(Sc) deposition was widely observed throughout each brain and spinal cord. Intense PrP(Sc) deposition was greater in the thalamus, brainstem, and spinal cord of the gray matter than in the neocortices. The topographical distribution pattern and severity of PrP(Sc) accumulation were mapped and plotted as immunohistochemical profiles of the different brain areas along the caudal-rostral axis of the brain. The distribution pattern and severity of the immunolabeled PrP(Sc) in the CNS were almost the same among the 7 cases analyzed, suggesting that the naturally occurring cases in this study were at the preclinical stage of the disease. Immunohistochemical mapping of the PrP(Sc) deposits will be used to clarify the different stages of BSE in cattle.     

Effect of dietary beta1-4 mannobiose in the prevention of Salmonella enteritidis infection in broilers

1. This study investigated the effects of beta1-4 Mannobiose (MNB)-supplemented feeds on the kinetics of Salmonella enterica serovar Enteritidis (SE) in broilers and the ensuing histopathological changes. D-Mannose (MAN) was used for comparison. The diets supplemented with MNB or MAN were fed during the first two weeks after hatching to investigate any protection against SE infection in growing birds and any immunomodulatory functions in the gut. 2. MNB-supplementation reduced SE organ colonisation, caecal carriage and faecal shedding in a time-dependent manner. The high concentrations and persistency of the SE-specific IgA response in those birds given rations supplemented with MNB or MAN were associated with a decline in SE shedding and caecal carriage in the later stages of infection. MNB was more effective against SE infection than MAN. 3. Histological examination of the caecal wall and caecal tonsils at 23 d post-infection indicated a lesser degree of intestinal pathology. An increased number of intra-epithelial mononuclear cells (mature lymphocytes and macrophages) in the lining epithelium of birds fed on the diet supplemented with MNB was accompanied by an increased number of lamina propria cells. 4. The present study indicates that feeding a diet supplemented with MNB during the first two weeks after hatching reduced susceptibility to SE infection. Supplementing the diet with MNB or MAN increased IgA production and improved SE clearance by acting as immunomodulatory agents that prevented intestinal pathology. Feeding a MNB-supplemented diet to broilers could be used as an alternative to antibiotics, because it has no adverse effects on mortality or weight gain.     

Isolation of parapoxvirus from a cow treated with interferon-gamma

A virus was isolated from peripheral blood leukocytes of a cow which was kept in an isolated pen after it was injected with recombinant bovine interferon-γ. The virus was identified as a member of genus Parapoxvirus in the family Poxviridae on the basis of electron microscopic observations and serological tests. Parapoxvirus has seldom been isolated other than from papular lesions, the characteristic sign of parapoxvirus infection. This is the first report of parapoxvirus isolation from the peripheral blood of a cow without any clinical signs. These results show that parapoxviruses are capable of causing persistent infection in cattle without clinical signs and can be activated by stress factors that induce modification of immune reactions. Relationships between the isolated virus and other parapoxviruses isolated previously from cattle in Japan were investigated and discussed.     

Clinicopathological features of canine neuroaxonal dystrophy and cerebellar cortical abiotrophy in Papillon and Papillon-related dogs

Neuroaxonal dystrophy (NAD) was examined in two Papillon dogs and a mix breed dog between Papillon and Chihuahua. In addition, cerebellar cortical abiotrophy (CCA) in a Papillon dog, which had similar clinical and magnetic resonance imaging (MRI) features to those of NAD, was also investigated. The common clinical symptoms of all dogs affected with NAD and CCA, were pelvic limb ataxia and cerebellar ataxia including intention tremor, head tremor, and hypermetria in the early onset. These clinical signs were progressed rapidly, and two dogs with NAD were euthanized by owner's request and the other two died by aspiration pneumonia. MRI examinations and gross observations at necropsy revealed moderate to severe cerebellar atrophy in all cases of NAD and CCA. The most typical histological change of NAD was severe axonal degeneration with marked spheroid-formation in the dorsal horn of the spinal cords, the nuclei gracilis, cuneatus, olivalis and its circumference in the medulla oblongata. The spheroids were characterized as large eosinophilic or granular globes within the enlarged myelin sheaths, sometimes accompanied by moderate accumulation of microglias and/or macrophages. In contrast, such spheroid formation was minimal in the brain of CCA. In the cerebellum, mild to moderate loss of the Purkinje and granular cells were recognized in three dogs with NAD, whereas these changes were more prominent in a dog with CCA. Although the clinical signs and MRI findings relatively resembled between NAD and CCA, the histopathological features considered to be quite differ, suggesting distinct pathogenesis and etiology. Since both NAD and CCA are proposed as the autosomal recessive hereditary disorders, careful considerations might be needed for the breeding of Papillon and Chihuahua dogs.