Genetic diversity of feline morbilliviruses isolated in Japan.

Feline morbillivirus (FmoPV) is an emerging virus in domestic cats and considered to be associated with tubulointerstitial nephritis. Although FmoPV was first described in China in 2012, there has been no report of the isolation of this virus in other countries. In this report, we describe the isolation and characterization of FmoPV from domestic cats in Japan. By using reverse transcription (RT)-PCR, we found that three of 13 urine samples from cats brought to veterinary hospitals were positive for FmoPV. FmoPV strains SS1 to SS3 were isolated from the RT-PCR-positive urine samples. Crandell-Rees feline kidney (CRFK) cells exposed to FmoPV showed cytopathic effects with syncytia formation, and FmoPV N protein was detected by indirect immunofluorescence assays. In addition, pleomorphic virus particles with apparent glycoprotein envelope spikes were observed by electron microscopy. By sequence analysis of FmoPV H and L genes, we found that FmoPVs showed genetic diversity; however, signatures of positive selection were not identified.

Effects of bovine lactoferrin by the intramammary infusion in cows with staphylococcal mastitis during the early non-lactating period.

To evaluate the clinical effects of bovine lactoferrin on staphylococcal mastitis in Holstein cows during the early non-lactating period, 41 mammary quarters were selected randomly from 36 cows on 3 dairy farms. Twelve quarters were infused intramammarily with bovine lactoferrin. Twenty-nine quarters were infused with antibiotic as a control. In the bovine lactoferrin-infused group, 91.7% of mastitic quarters were cured at 7 days after calving, compared with 48.3% in the control group. Furthermore, the changes in mammary secretion induced by the infusion of bovine lactoferrin were investigated. Mean numbers of staphylococci in mammary gland secretions were significantly decreased in both 5 bovine lactoferrin-infused quarters and 5 antibiotic-infused control quarters (p<0.05). Unlike in the control quarters, the mean total cell concentration in the mammary gland secretions increased in bovine lactoferrin-infused quarters. Similar results were obtained in 6 healthy quarters which were infused with bovine lactoferrin. In these quarters, the cell population contained mainly phagocytes such as polymorphonuclear leukocytes and cells positive for CD11b which is known as a complement receptor. The mean concentration of C3 in mammary gland secretions was significantly increased in 5 mastitic quarters infused with bovine lactoferrin (p<0.05), but showed no significant change in 5 mastitic control quarters. These results suggested that bovine lactoferrin treatment for staphylococcal mastitis in the early non-lactating period might increase the rate of cure through the induction of innate immunity in the host.

Anti-inflammatory effects of intramammary infusions of glycyrrhizin in lactating cows with mastitis caused by coagulase-negative staphylococci.

OBJECTIVE: To determine the anti-inflammatory effects of glycyrrhizin (GL) in lactating cows with mastitis attributable to naturally occurring infection with coagulase-negative staphylococci (CNS). ANIMALS: 12 lactating Holstein cows with mastitis attributable to infection with CNS and 2 healthy cows without mastitis. PROCEDURE: Clinical signs, number of bacteria in milk, somatic cell count (SCC) in milk, concentrations of alpha-lactalbumin and lactoferrin in milk, and concentration of histamine in milk were investigated before and after intramammary infusion of GL (6 cows) or antimicrobials (6 cows). Glands of 2 healthy cows were infused with staphylococcal enterotoxin; milk leukocytes were then harvested and incubated with various doses of GL. RESULTS: In cows infected with CNS that had a low bacterial concentration in milk, infusion of GL alone resulted in significant improvements in swelling, firmness of glands, and number of clots in milk, and it decreased the SCC, but not significantly. Percentage of neutrophils decreased significantly (to < 30%) by 2 days after infusion. Use of lactoferrin as a marker of inflammation in mammary glands revealed a decrease in concentrations, whereas use of alpha-lactalbumin as a marker of recovery for mammary glands revealed significant increases in concentrations in the GL-infused group. Accompanying these anti-inflammatory effects, a decrease in the concentration of histamine in milk was observed in the GL-infused group. Glycyrrhizin decreased histamine production by milk leukocytes in a concentration-dependent manner. CONCLUSIONS AND CLINICAL RELEVANCE: Infusion of GL may regulate intramammary inflammation through modulation of inflammatory mediators such as histamine.

Differential gene expression of cytokine and cell surface molecules in T cell subpopulation derived from mammary gland secretion of cows.

PROBLEM: As T cell subpopulations in the mammary gland secretion (MGS) of cows dynamically vary through the lactation cycle, their functional analysis is important to understand the mammary immune responses. METHOD OF STUDY: T cell subpopulations were positively selected from MGS during lactation period and non-lactation period (dry period) by a magnetic cell sorter. The messenger RNA (mRNA) expression of cytokine and cell surface molecules in the subpopulations stimulated with anti-CD3 was investigated using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: CD4+ T cells from MGS significantly expressed mRNA of interferon (IFN)-gamma, interleukin (IL)-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), transforming growth factor (TGF)-beta, tumor necrosis factor (TNF)-alpha, IL-4, CD40 ligand (CD40L), Fas ligand (FasL) and IL-2 receptor (IL-2R) during dry period, and mRNA of IFN-gamma, IL-2 and TGF-beta during lactation period. Their expression during lactation period was always less than that during dry period. CD8+ T cells from MGS substantially expressed mRNA of IFN-gamma, IL-2, GM-CSF, TGF-beta, TNF-alpha, FasL and IL-2R during dry period and mRNA of IFN-gamma, GM-CSF, TGF-beta, TNF-alpha and c-kit during lactation period. The TGF-beta, TNF-alpha, c-kit and IL-2R mRNA expression of T cells in MGS during lactation period mostly depended on gammadelta T cells. Interestingly, c-kit mRNA was exclusively expressed in gammadelta T cells. CONCLUSIONS: The cytokine expression of T cells in MGS of cows depended on the T cell subpopulations. The present findings suggested that the activation of gammadelta T cells via c-kit receptor participated in the suppressed expression of cytokine mRNA in T cells during lactation period.

Inflammatory responses of bovine polymorphonuclear neutrophils induced by staphylococcal enterotoxin C via stimulation of mononuclear cells.

To elucidate the pathological roles of staphylococcal enterotoxin C (SEC) in bovine staphylococcal mastitis, a histopathological analysis of SEC-inoculated mammary glands was performed. SEC-inoculated mammary glands exhibited interstitial inflammation, and the leukocytes that migrated into the gland were predominantly polymorphonuclear neutrophils (PMN). In the gland cistern tissues dissected from SEC-inoculated mammary glands, epithelial cellular degeneration was observed. We also investigated the physiological effects of SEC on PMN in vitro. PMN migration was induced by culture supernatant of SEC-stimulated peripheral blood mononuclear cells (S-PBMC sup) but not by that of nonstimulated PBMC (N-PBMC sup). The concentration of interleukin-8 was significantly (P < 0.05) higher in S-PBMC sup than N-PBMC sup, and a significantly (P < 0.05) higher mRNA expression of growth-regulated oncogenes was detected in SEC-stimulated PBMC than in nonstimulated PBMC. Milk PMN collected from SEC-inoculated mammary glands produced more than 2 times the amount of superoxide at 1 day postinoculation (dpi) than at 0 dpi in the presence of phorbol 12-myristate 13-acetate (PMA). PMN cultured with S-PBMC sup for 24 h also produced significantly (P < 0.05) larger amounts of superoxide than those cultured with N-PBMC sup in the presence of PMA. Moreover, S-PBMC sup induced the long-time survival of PMN. These results indicate that SEC induces the activation of PMN via the stimulation of mononuclear cells.