Methicillin-resistant coagulase-negative staphylococci isolated from healthy horses in Japan

OBJECTIVE: To determine patterns of methicillin-resistant staphylococci isolated from apparently healthy horses. SAMPLE POPULATION: 44 horses from 8 riding clubs in Japan. PROCEDURE: Methicill in-resistant staphylococci were isolated from the skin or nares, using a selective medium containing a beta-(symboric) lactam antibiotic, ceftizoxime. Clonality of isolates was determined by use of pulsed-field gel electrophoresis. Detection of mecA, mecl, and mecR1 genes was accomplished by use of polymerase chain reactions. RESULT: Of the 44 horses, 13 (29.5%) yielded 15 isolates of methicillin-resistant staphylococci. The 15 isolates were identified as 6 species (Staphylococcus epidermidis, S lentus, S saprophyticus, S xylosus, S sciuri, and S haemolyticus). However, methicillin-resistant S aureus was seldom isolated. Each isolate contained the mecA gene and had a high resistance to beta-lactam antibiotics. Some isolates also were resistant to other antibiotics such as erythromycin and kanamycin. CONCLUSIONS AND CLINICAL RELEVANCE: Methicillin-resistant coagulase-negative staphylococci that were highly resistant to various antibiotics were isolated from apparently healthy horses in Japan. These organisms must be considered a potential threat to horses and veterinarians who care for them.     

Identification of canine alpha-lactalbumin

The nucleotide sequence of canine alpha-lactalbumin cDNA from canine mammary tissue was determined by polymerase chain reaction with degenerate primers. A 742 base pairs nucleotide sequence cloned was similar to the size of mRNA in Northern blot analysis. The cDNA encodes 142 amino acid residues containing the conserved sequence motif of alpha-lactalbumin, demonstrating the highest homology with pig (73% identity-82% similarity) among the known amino acid sequences of alpha-lactalbumin. The canine cDNA also showed 71% identity-78% similarity with human, 58-73% with mouse, 60-74% with rat, 67-77% with goat, 66-77% with cattle, and 67-76% with sheep, respectively.     

Isolation of Theileria sergenti piroplasms from infected erythrocytes and development of an enzyme-linked immunosorbent assay for serodiagnosis of T sergenti infections

A method of obtaining a pure suspension of Theileria sergenti piroplasms from infected bovine erythrocytes was developed and the resulting parasites used as antigen in an enzyme-linked immunosorbent assay (ELISA). Piroplasms were freed from infected erythrocytes using the nitrogen cavitation technique and then separated from unbroken erythrocytes by centrifugation at 670 gmax. The parasites in the supernatant were then sedimented by centrifugation at 2700 gmax and the purified fraction examined by electron microscopy. This examination showed that the isolated piroplasms were morphologically intact and that there were few contaminants. SDS-PAGE and spectrophotometric analysis showed that this fraction contained little erythrocyte component. The piroplasms thus obtained were sonicated and treated with Triton X-100 then used for ELISA antigen. The ELISA values had a high correlation with titres obtained using the indirect fluorescent antibody test on sera from cattle infected with T sergenti.     

Enzyme-linked immunosorbent assay using solubilised antigen for detection of antibodies toAnaplasma marginale

An enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against Anaplasma marginale. A marginale bodies were separated from parasitised erythrocytes by a modified nitrogen decompression method, sonicated, then solubilised with Triton X-100 and used as the ELISA antigen. In this ELISA system the required amount of antigen protein was 16.2 ng for each well. In the course of experimental infections, of calves, significant antibody levels were detected by ELISA and the complement fixation test (CFT) at almost the same time. Antibodies against A. marginale were detectable for longer periods using the ELISA than using the CFT. Sera from calves infected with Babesia bigemina, B. bovis, B. ovata, Theileria sergenti and Eperythrozoon wenyoni gave no reaction; however, antisera against A. centrale did react with the A. marginale ELISA antigen.     

Evaluation of plasma erythropoietin levels in normal adult dogs by in vivo bioassay using concentrated plasma.

Measurement of plasma erythropoietin level in normal dogs by in vivo bioassay has been considered to be impossible so far. In the present study, we successfully determined it by using concentrated plasma 60 times which allowed the lower limit to 2.7 mU/ml. This normal plasma erythropoietin level was the first to be determined as an in vivo bioactivity and was 9.14 +/- 7.81 mU/ml in 75 normal adult dogs. This value was sufficiently reliable in terms of accuracy of determination and considered to be meaningful as the low level in vivo bioactivity that hasn't been known to date. Furthermore, erythropoietin levels in normal plasma were within a certain lower range and showed neither difference in plasma erythropoietin level between males and females or among breeds nor correlation between erythropoietin and hemoglobin level.     

Antibody responses of horses to equine influenza viruses during a postepizootic period in Japan.

The antibody responses to equine influenza viruses were investigated during a postepizootic period of the disease. Serum samples were collected from a total of 128 horses on three occasions during the years 1967-77. No significant increase of hemagglutination-inhibition antibody titers to subtypes 1 and 2 of equine influenza virus were detected in any of the sera tested. The maternal hemagglutination-inhibition antibody titers of foals decreased over a four month interval. A marked increase of the titers was recognized in only the equine influenza virus vaccinated horses. These findings suggest that equine influenza virus was not prevalent in the horse populations during the observation period. In such conditions, the dissemination of equine influenza viruses in the horses is discussed in relation to introduction of the disease from abroad. We also examined whether the doctrine of original antigenic sin, an immunological phenomenon recognized in human influenza, was applicable for equine influenza. However, no marked increase of hemagglutination-inhibition antibody titer to the primary infecting subtype in the 44 horses was observed after administration of the heterologous subtype vaccine.     

Melatonin but not the ram-effect reactivates quiescent ovarian activity of mid-anestrous ewe

The present study was conducted to examine how the social cue emanating from rams, the ram-effect, would influence the onset of melatonin-induced reproductive activity in anestrous ewes. Twenty non-lactating ewes were randomly allocated into 4 groups as follows based on a combination of the melatonin treatment (MEL) and the ram-effect (RAM): ewes of Groups A (MEL + RAM) and B (MEL) were subcutaneously implanted with melatonin capsules on April 18 (Day 0), which increased plasma melatonin levels by about 200 pg/ml for at least 5 months, while Groups C (RAM) and D (control) were untreated with melatonin. Rams were introduced to Groups A and C on Day 0, whereas Groups B and D were isolated from rams. Ovarian function of the ewe was assessed on June 9-21 (Days 52-64) by monitoring plasma progesterone (P) profiles. Luteal function (plasma P greater than 1 ng/ml for a week or longer) was evident in all the melatonin-treated ewes but only one in those untreated: 5/5 in Group A, 5/5 in Group B, 1/5 in Group C and 0/5 in Group D. By ultrasonography on Day 105 all the Group A ewes were diagnosed pregnant but none in the Group C despite that both the two groups had been run with rams. These results indicate that chronic melatonin treatment is capable of advancing the reproductive recrudescence in seasonally anestrous ewes, and that progonadal effects of rams are subtle, if any, during the mid-anestrous period.