Pathogenesis of infectious bronchitis virus in vaccinated chickens of two different major histocompatibility B complex genotypes

Infectious bronchitis (IB) disease progression in vaccinated chickens after challenge was evaluated in a single commercial line of layer chickens presenting two different major histocompatibility complex (MHC) B complex genotypes. MHC B genotypes were determined by DNA sequence-based typing of BF2 alleles. In total, 33 B2/B15 and 47 B2/B21 chickens were vaccinated with an Ark-type IB virus (IBV) attenuated vaccine and challenged with Ark-type IBV field isolate AL/4614/98 14 days later. Additional chickens of both genotypes served as unvaccinated/challenged and unvaccinated/nonchallenged controls. Clinical signs, histopathologic analysis, detection of IBV genomes in tears, and IBV-specific immunoglobulin A (IgA) in tears were used to evaluate disease progression and immune response. The incidence of IBV respiratory signs was significantly higher in B2/21 than in B2/B15 MHC genotype birds. However, neither the severity and duration of respiratory signs nor the severity and incidence of histologic lesions differed significantly with MHC genotype. The levels of IBV-specific IgA in tears of vaccinated and challenged chickens did not differ significantly between MHC genotypes. IBV genomes were present in the tears of vaccinated and challenged birds, and the incidence of detectable IBV genomes did not vary significantly with MHC B genotype. From an applied perspective, these results indicate that vaccinated commercial outbred chickens with these MHC genotypes are equally resistant to IBV.     

Allgemeine Bemerkungen zur Durchführung ernährungsbiologischer Untersuchungen

Ohne Zusammenfassung     

Comparison of three commercial rapid agglutination test kits for identification of coagulase positive staphylococci from foods and animals.

Three rapid agglutination assays for the identification of Staphylococcus aureus Monostaph (Bionor A/S, Skien, Norway), Staphyslide-Test (BioMerieux, Lyon, France) and Staph-Rapid-Test (Roche, Basel, Switzerland), were compared. A total of 104 Gram-positive, catalase positive cocci were tested: Nineteen Staphylococcus reference strains comprising 15 spp. (4 strains were coagulase positive), and 7 Micrococcus reference strains comprising 4 spp.; 22 food isolates comprising 13 S. aureus, 8 coagulase positive Staphylococcus spp., and 1 Micrococcus sp.; 56 animal isolates comprising 11 S. aureus, 9 S. hyicus subsp. hyicus, 2 S. intermedius, 15 coagulase positive and 19 coagulase negative Staphylococcus spp. Totally 54 strains were coagulase positive. Considering agglutination of a coagulase positive strain as a correct identification, Monostaph, Staph-Rapid-Test, and Staphyslide-Test correctly identified 52 (96.3%), 47 (87.0%) and 48 (89.0%) of the coagulase positive staphylococci, respectively. Monostaph, Staph-Rapid-Test and Staphyslide-Test showed 1 (2.0%), 4 (8.0%) and 4 (8.0%) false positive reactions respectively. Monostaph, Staph-Rapid-Test and Staphyslide-Test gave 0 (0.0%), 6 (5.8%) and 7 (6.7%) non-interpretable reactions, respectively. Monostaph may be a good alternative to the tube-coagulase test for rapid and reliable identification of coagulase positive staphylococci from both food and veterinary sources. However, false negative reactions may occur with coagulase positive strains of S. hyicus subsp. hyicus and S. intermedius.     

Mycotoxins as a risk factor for the origin of diseases and production decreases in swine facilities--an epidemiologic study]

Feed samples checked for the mycotoxins zearalenone and ochratoxin A from the harvest 1987 were positive at a markedly higher percentage (37.5%) compared to previous years, which is explained by the especially unfavourable harvesting conditions of 1987. In certain herd problems affecting the digestive or respiratory tract, mycotoxins could be detected with a much higher frequency (64.7% and 50.0% respectively). The mean level detected in feed samples by thin layer chromatography ranged within 30.3 ppb for zearalenone and within 58.3 ppb for ochratoxin A. In most cases there was a history of infertility. Considering the clinical situation, which is presented comparatively in herds with positive mycotoxin results, the possible involvement of mycotoxins in the disease, even at very low concentrations, is pointed out. In this context, zearalenone is incriminated of being an indicator of a multitoxic process besides its own direct effects. According to own experiences low levels of zearalenone in the range of 20-50 ppb in the feed have to be considered hazardous. If changing of pig feed in cases of herd problems will be recommended, a level of less than 10 ppb of zearalenone, especially in sow and piglet rations, should not be exceeded. Same may be valid to ochratoxin A.     

Clinical exercise testing in the normal Thoroughbred racehorse

To evaluate normal cardiorespiratory and metabolic responses of Thoroughbred horses to a standardised treadmill exercise test, we examined 28 horses ranging in age from 1 to 4 years. The group consisted of eight yearlings, eight 2-year-olds and twelve 3 and 4-year-olds. All horses except the yearlings were in training, and either racing or ready to race, at the time of examination. None of the horses had histories of performance problems. On the first day the horses received a full physical examination, resting electrocardiogram, upper respiratory tract endoscopy and either one or two acclimatisation runs on the treadmill. The following day they were given an exercise test on a treadmill inclined at 6 degrees (+10% slope). The test consisted of 3 min at 4 m/sec, 90 sec at 6 m/sec and 60 sec intervals at 8, 10, 11, 12 and 13 m/sec. During the last 15 sec of each step, blood samples were collected for plasma lactate determination, expired respiratory gases were obtained using an open flow mask system for measurement of oxygen uptake, and heart rate was measured using telemetry electrocardiogram. From these measurements, various derived values were calculated, which have been used by others as indices of exercise capacity. These values included: V200 (speed at HR of 200 bpm), VHRmax (speed at which horses reached maximum HR), VO2-200 (oxygen uptake at a HR of 200 bpm), VO2max (maximum oxygen uptake), VLA4 (speed at which horses reached a plasma lactate of 4 mmol/l) and HRLA4 (HR at which horses reached a plasma lactate of 4 mmol/l). The yearlings had significantly lower values than the older age groups for most of the derived values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Japanese supercomputer technology

Under the auspices of the Ministry for International Trade and Industry the Japanese have launched a National Superspeed Computer Project intended to produce high-performance computers for scientific computation and a Fifth-Generation Computer Project intended to incorporate and exploit concepts of artificial intelligence. If these projects are successful, which appears likely, advanced economic and military research in the United States may become dependent on access to supercomputers of foreign manufacture.     

Susceptibility of sugarcane, plantation weeds and grain cereals to infection by Sugarcane yellow leaf virus and selection by sugarcane breeding in Hawaii

Hawaiian commercial sugarcane cultivars (Saccharum spp.), noble canes (S. officinarum), robust canes (S. robustum) and wild relatives of sugarcane (S. spontaneum and Erianthus arundinaceus) were tested by tissue blot immunoassay to determine whether they were infected by Sugarcane yellow leaf virus (SCYLV). Two-thirds of the commercial hybrids and noble canes were infected and therefore classified as SCYLV-susceptible, in contrast to the wild cane relatives where less than one third of the varieties were infected. The pedigree list of commercial, registered cultivars showed that 80% of cultivars were SCYLV-susceptible and that also 75–90% of the progeny of resistant (female) parents were susceptible (male parents are mostly unknown because of polycross breeding). In contrast, a cross between a resistant S. robustum and a susceptible S. officinarum cultivar yielded 85% resistant progeny clones, which indicated that SCYLV-resistance is a dominant trait. It is concluded that the breeding program selected against SCYLV-resistance with the result that 80% of the newly bred cultivars were susceptible. Exceptional was the period between 1950 and 1970, in which 50% of the newly-bred clones were resistant. This is the period in which SCYLV had entered Hawaii. Weed grasses and cereal grasses which grew in or next to sugarcane fields were not infected by SCYLV. Thus SCYLV does not spread from infected sugarcane plants to adjacent grasses or cereals under field conditions, although cereal grasses can be infected experimentally.     

Comparative studies of plant and soil analysis for the sulphur status of oilseed rape and winter wheat

Recently S deficiency became one of the most widespread nutrient disorders in North-European agriculture. Therefore precise and reliable methods for the evaluation of the S nutritional status of agricultural crops are required. For the prognosis of the plant available S soil analysis would be a favourite method, however, no relation between plant S concentrations and mobile (extractable sulphate plus extractable organic S) S contents in soils could be stated. The reasons for the impracticability of traditional soil tests seem to be related to interactions between soil water and mobile S in soils, so that site specific models need to be developed for the prognosis of the S status of agricultural crops.     

The sperm quality of 4 boars during the assimilation of mycotoxin-containing feed (ochratoxin A) amd after changing the feed--a case study

In December 1987 and January 1988 in a small station two of four boars showed a marked breakdown in the sperm quality. At the same time the mycotoxin ochratoxin A was identified in the feed at a concentration of about 8 ppb and in the bloodserum of 1 ppb. The relatively low toxin level seemed not to be due to the bad sperm quality, but considering the circumstances and the chronological course it might be an indicator for a higher toxic pressure, which may had happened a few weeks before. As other factors were not visible, most probably the feed must have caused a disturbed sperm production, which could be seen in all four boars. Whether ochratoxin A or other not identified mycotoxins can be hold responsible, could not be clarified. Therefore it is recommended to examine the effects of ochratoxin A on sperm quality of boars in future times.