Genetic selection for resistance to mycoplasmal pneumonia of swine (MPS) in the Landrace line influences the expression of soluble factors in blood after MPS vaccine sensitization

We recently developed a Landrace line that is resistant to mycoplasmal pneumonia of swine (MPS) infection by genetic selection for five generations, and we reported that the immunophenotype of this line is different from that of the non‐selected line in terms of changes in peripheral blood leukocyte population after MPS vaccination. This study followed up previous findings demonstrating changes in soluble factors in blood, namely, hormones, Mycoplasma hyopneumoniae‐specific immunoglobulin G (IgG), and cytokines. These two lines were injected with MPS vaccine on days ?7 and 0 after blood sampling on those days, and blood samples were collected on days ?14, ?7, 0, 2, 7 and 14. We found changes in the levels of many hormones and cytokines in both lines. However, we found that only growth hormone (GH) and interferon (IFN)‐γ levels were statistically different between these two lines. GH concentration was reduced (day 0) and IFN‐γ concentration was increased (day 14) in the MPS‐selected line compared with the non‐selected line, despite unchanged IFN‐γ messenger RNA expression in blood cells. Although detailed mechanisms underlying these phenotypes remain unsolved, these traits would be useful to improve MPS resistance in pig production and provide an insight into MPS infection.     

Staining patterns for actin and villin distinguish M cells in bovine follicle-associated epithelium

M cells play a central role in the initiation of mucosal immune responses. However, a primary source of difficulty for investigations of this is the lack of an available specific marker for bovine M cells. As M cells possess irregular and short microvilli, we investigated the distribution and localization of the microvillar proteins actin and villin by immunohistochemistry of the gut of calves. In ileum of the calf, actin and villin were clearly and continuously immunostained in the brush border of the villous epithelia, however, discontinuous immunostaining with patches of no staining were observed in follicle-associated epithelium (FAE). Electron microscopy revealed that M cells had irregular microvilli and lacked the typical brush border, and it was inferred that these patches of no staining might be the intercellular crevices of M cells. As the microvilli of M cells were very sparse, there were several areas of weak immunostaining in calf jejunal FAE. These results suggest that M cells in calf FAE are detectable by the absence of staining for actin and villin.     

Long-term excretion of Shiga toxin-producing Escherichia coli (STEC) and experimental infection of a sheep with O157

To investigate a long-term shedding of Shiga toxin (Stx)-producing Escherichia coli (STEC) from sheep, a fifteen-month study for STEC isolation from a sheep, which had yielded STEC before, was attempted. The sheep continued to shed STEC and 39 STEC were isolated. The number of STEC in the feces was estimated at 1.7 x 10(3) per gram. In addition, although Stx1-negative O157 and stx2-encoding bacteriophage were experimentally infected to the sheep, Stx-positive O157 or Stx2- producing bacterial cells were not detected. The genetical and biochemical characterization of those 39 STEC strains showed that all STEC strains produced Shiga toxin 1 (Stx1) and were divided into three classes (I to III). From phylogenetic analysis of their amino acid sequences, class-I STEC was classified as group 1 comprising mainly human STEC, and classes II/III were as group 2 comprising sheep STEC. Our results suggest that STEC easily colonized in sheep and that the sheep continued to shed STEC, showing that sheep might be an important reservoir for human STEC infection.     

Iridal coloboma induces dyscoria during miosis in FLS mice

Objective Fatty liver Shionogi (FLS) mice exhibit characteristic retinochoroidal coloboma because of a failure in fusion of the embryonic optic fissure. However, the same pathogenesis should result in iridal coloboma that has not been reported in this strain. The purpose of this study was to describe the physiologic and morphometric changes in iridal tissue involved in ocular coloboma in FLS mice. Procedures The miotic response after light exposure was evaluated in three strains of live mice, and the shape and location of the pupil were judged macroscopically. Subsequently, macroscopic abnormalities in the anterior segment and fundus were observed postmortem in all mice. During miotic and mydriatic responses in the eyes of live male FLS mice with dyscoric and normal pupils, each iris was measured in four radial directions. The enucleated eyes were examined morphometrically and histologically in both sexes of FLS mice. Results Inferior corectopia upon light‐induced miosis was clearly detected in live FLS mice. The deviated pupils were not round but oval‐shaped. Clinical and postmortem examination revealed that all dyscoric eyes had hypoplastic and dysfunctional irides inferiorly in FLS mice. Histopathological examination confirmed that both the dilator and sphincter muscles and iris stroma were quantitatively diminished in the affected inferior iris. Meanwhile, the rate of fundus (retinochoroidal) coloboma in eyes exhibiting dyscoria was remarkably high, although some dyscoric eyes had no fundus coloboma. Conclusions Fatty liver Shionogi mice had iridal coloboma, resulting in inferior corectopia upon light‐induced miosis as an indicator of ocular coloboma.     

Preparation of antibodies directed to the Babesia ovata- or Theileria sergenti-parasitized erythrocytes

To investigate the surface antigens of the bovine red blood cells (RBCs) parasitized by Babesia ovata or Theileria sergenti, attempts were made to produce monoclonal antibodies (mAbs) with BALB/c mice. Comparable numbers of hybridomas producing anti-piroplasm mAbs, as well as anti-bovine RBC mAbs, were obtained from the mice immunized with B. ovata- or T. sergenti-PRBCs. However, mAbs directed to the surface of parasitized RBCs (PRBCs) were obtained only from the mice immunized with B. ovata-PRBCs, but not from those immunized with T. sergenti-PRBCs. When serum samples from the immunized mice and the infected cattle were examined, antibodies recognizing B. ovata-PRBC surface were detected in the sera against B. ovata, but analogous antibodies were undetectable in the sera against T. sergenti, despite that the sera showed substantial antibody titers to T. sergenti piroplasms. The results suggest that significant antigenic modifications occur on the surface of B. ovata-PRBCs, but not on the surface of T. sergenti-PRBCs.     

Epidermal Tissue-Derived T-cell Growth Factor,Colony Stimulating Factor and Nerve Growth Factor in Chickens

The purpose of this study was to determine the mechanism of the local cytokine-mediated immune response in the skin of chickens. The incorporation of 3H-thymidine into spleen T lymphocytes from 9- to 10-week-old chickens was augmented by the addition of epidermal tissue culture supernatant (ESN) from 11-day-old embryos. The colony formation of neonatal chicken bone marrow cells in the methylcellulose medium was also significantly increased by addition of ESN. When axonal outgrowth in matrigel was investigated, the embryonal sympathetic ganglion was found to grow axons outwards towards the epidermal tissue specimens. The above results suggest that chicken epidermal cells (probably keratinocytes) produce T-cell growth factor (corresponding to IL-1), colony-stimulating factor for macrophages (M-CSF) and granulocytes (G-CSF), and nerve growth factor (NGF).     

Mucosal immunoadjuvant activity of the low toxic recombinant Escherichia coli heat-labile enterotoxin produced by Bacillus brevis for the bacterial subunit or component vaccine in pigs and cattle

A gene encoding the mature Escherichia coli heat-labile enterotoxin (LT) lacking the nick site in the A subunit by deleting tripeptides was introduced in a vector pNH301 and expressed extracellularly as mutant molecule of holotoxin at high levels in Bacilus brevis HPD31-S5 of the host bacterium. The mucosal adjuvant activities of the produced mutant LT (mLT) preparation were studied in pigs and cattle. Intranasal immunization of pigs with the recombinant subunit vaccine of Erysipelothrix rhusiopathiae or the component vaccine of Bordetella bronchiseptica mixed with the mLT resulted in a substantial enhancement of both mucosal and serum-specific antibody levels. The immunized pigs were also protected when challenge-exposed intradermally with a highly virulent E. rhusiopathiae strain or challenge-exposed intranasally with a highly virulent strain of B. bronchiseptica. The mLT intranasally administered with recombinant intimin (an outer membrane adhesin) of E. coli O157:H7 also induced an elevation of IgA-specific antibody in the nasal secretion and saliva of calves as well as an elevation of IgG1-specific antibody level against the intimin in the sera and colostrum of cows. The three kinds tested protein antigens were poorly immunogenic when antigen administered intranasally alone. The mLT intranasally administered at a higher effective dose did not induce local adverse reactions or diarrhea in pigs and cattle. The present study demonstrates that the recombinant mLT produced using the B. brevis expression system might represent promising immunoadjuvants for the potential application of intranasal vaccines directed against infectious diseases in pigs and cattle.     

Effects of rumen‐protected methionine on milk production in early lactation dairy cattle fed with a diet containing 14.5% crude protein

We evaluated the influence on milk production of feeding early lactation cows a diet that included 14.5% crude protein (CP) and that did not meet methionine (Met) requirements or that met them by supplying rumen‐protected Met (RPMet). Thirty‐nine multiparous Holstein cows were allocated into two groups. For 15 weeks after calving, each group was fed one of the two total mixed rations, Control (n = 20) or Treatment (n = 19). The Treatment group received added RPMet at 0.034% (8 g/day) of the Control diet on dry matter basis. The adequacies of Met for the Control and Treatment groups were 96% and 106%, respectively, and for other amino acids, >110%. The CP level (14.5%) was 1 percentage point lower than that recommended by the Japanese Feeding Standard (2006). No between‐group differences were found in milk yield (40 kg/day), milk composition, plasma profile, rumen fermentation, nitrogen balance, or cow health. Met intake and the amount of rumen‐undegradable feed Met were higher in the Treatment group (p < 0.05). Microbial Met and total metabolizable Met did not differ between groups. Supplying RPMet in a 14.5% CP diet during early lactation did not dramatically affect milk production, because the amount of total metabolizable Met was unchanged.     

Cellular localization of IL-18 and IL-18 receptor in pig anterior pituitary gland

Pro-inflammatory cytokine interleukin 18 (IL-18) has been proposed to have a role in modulating immuno-endocrine functions. Our previous study showed that IL-18 and IL-18 receptor (IL-18R) colocalized in somatotrophs of the bovine anterior pituitary gland, and the possibility that IL-18 acts on somatotrophs as an autocrine factor. In the present study, we investigated the localization of IL-18 and IL-18R in the pig anterior pituitary gland. RT-PCR analysis showed the expression of IL-18 and IL-18R mRNAin the pig anterior pituitary gland. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs, mammotrophs, thyrotrophs and gonadotrophs. IL-18R was localized in somatotrophs and thyrotrophs. Furthermore, the somatotrophs immunoreactive for IL-18 did not contain IL-18R. Thus, IL-18R and IL-18 were not colocalized in an identical somatotroph. These findings suggest that the localization of IL-18 in pig somatotrophs is different from that in bovine somatotrophs, although IL-18 closely associates with somatotrophs in the anterior pituitary glands in both species.