Biological evaluation of neopeptins isolated from a Streptomyces strain     

Kim YS  Kim HM  Chang C  Hwang IC  Oh H  Ahn JS  Kim KD  Hwang BK  Kim BS 《Pest management science》2007,63(12):1208-1214

BACKGROUND: Microbial secondary metabolites are a rich source of antifungal agents and have merit as alternatives to synthetic fungicides. To develop disease control agents against powdery mildew, the lipopeptide antibiotic neopeptins were identified from the culture broth of a Streptomyces sp., and in vivo control efficacy of the compounds was evaluated on cucumber plants under glasshouse conditions. RESULTS: The Streptomyces sp. KNF2047 antagonistic against powdery mildew development in cucumber plants was isolated from a soil sample. Antifungal compounds were purified from the culture broth and identified as neopeptin A and B. In vitro microtitre assays revealed the inhibitory activities of the compounds in the range 128-512 microg mL(-1) against the mycelial growth of Alternaria mali, Botrytis cinerea, Cladosporium cucumerinum, Colletotrichum lagenarium, Didimella bryoniae and Magnaporthe grisea. Although neither compound showed remarkable in vitro antifungal activity against other plant pathogenic fungi, a mixture of neopeptins (484 mg of neopeptin A and 290 mg of neopeptin B per gram of partially purified powder) showed potent protective and curative activity against cucumber powdery mildew in vivo. The disease control activity of the neopeptins at a concentration of 2.4 mg L(-1) was 92.1%, which was similar to that of the commercial fungicide fenarimol (89.3% at 63 mg L(-1)) and that of the commercial biocontrol agent Actinovate (67.4% at 2 x 10(7) cfu L(-1)). CONCLUSION: Neopeptin mixtures isolated from Streptomyces sp. KNF2047 showed potent disease control activity against powdery mildew development on cucumber plants. .  相似文献   

A regulatory SNP causes a human genetic disease by creating a new transcriptional promoter     

De Gobbi M  Viprakasit V  Hughes JR  Fisher C  Buckle VJ  Ayyub H  Gibbons RJ  Vernimmen D  Yoshinaga Y  de Jong P  Cheng JF  Rubin EM  Wood WG  Bowden D  Higgs DR 《Science (New York, N.Y.)》2006,312(5777):1215-1217

We describe a pathogenetic mechanism underlying a variant form of the inherited blood disorder alpha thalassemia. Association studies of affected individuals from Melanesia localized the disease trait to the telomeric region of human chromosome 16, which includes the alpha-globin gene cluster, but no molecular defects were detected by conventional approaches. After resequencing and using a combination of chromatin immunoprecipitation and expression analysis on a tiled oligonucleotide array, we identified a gain-of-function regulatory single-nucleotide polymorphism (rSNP) in a nongenic region between the alpha-globin genes and their upstream regulatory elements. The rSNP creates a new promoterlike element that interferes with normal activation of all downstream alpha-like globin genes. Thus, our work illustrates a strategy for distinguishing between neutral and functionally important rSNPs, and it also identifies a pathogenetic mechanism that could potentially underlie other genetic diseases.  相似文献   

Oocyst output and transmission rates during successive infections with Eimeria acervulina in experimental broiler flocks     

Velkers FC  Bouma A  Stegeman JA  de Jong MC 《Veterinary parasitology》2012,187(1-2):63-71

The infection dynamics of Eimeria species determine the clinical manifestation of the disease coccidiosis in poultry flocks, and a better understanding of the dynamics may contribute to improvement of control measures. Our aim was to study the course of infection and the transmission of Eimeria acervulina in groups of broilers by quantifying the transmission rate parameter and oocyst output. Three transmission experiments were carried out with groups of 20 male SPF broilers. At 2 days of age, one bird in each trial was orally inoculated with five sporulated E. acervulina oocysts (D0 post-inoculation, pi). One day after inoculation (D1 pi), the inoculated bird was housed with 19 non-inoculated contact birds. Individual faecal droppings were examined daily from D3-D32 pi to quantify the number of oocysts per gram faeces. The inoculated bird started shedding oocysts at D5 pi and contact birds between D10 and D17 pi. Contact birds that became infected due to oocyst excretion by the inoculated bird were characterized as first generation contact birds (C1). Contact birds excreting from D15 pi onwards (C2) became infected after the first C1 birds had started shedding and were considered to belong to a successive generation of the flock infection. Oocyst output was significantly lower for C1 compared to C2 birds, but the transmission rate parameter remained constant for both infection generations. These results suggest that although oocyst load increases, the transmission rate of E. acervulina remains constant between successive generations of infection in a flock.  相似文献   

Standing sedation in captive zebra (Equus grevyi and Equus burchellii)     

Hoyer M  de Jong S  Verstappen F  Wolters M 《Journal of zoo and wildlife medicine》2012,43(1):10-14

Nine Grevy's zebras (Equus grevyi) and three Burchell's zebras (Equus burchellii) were immobilized in a standing position a total of 70 times for minor, nonpainful procedures over a 9-yr period. Standing sedation was successfully obtained with a combination of detomidine and butorphanol on 47 occasions (67.1%). Detomidine i.m. (median 0.10 mg/kg; range: 0.07-0.21) was administered by dart, followed 10 min later by butorphanol i.m. (median 0.13 mg/kg; range 0.04-0.24). The dosages were varied depending on the initial demeanor of the animal. On 23 occasions (32.9%), small amounts of etorphine (median 2.5 microg/kg; range 1.1-12.3 microg/kg) plus acepromazine (median 10 microg/kg; range 4.4-50 microg/kg) (as in Large Animal-Immobilon) had to be administered i.m. to gain sufficient sedation. In these latter cases, the animals were either excited or known for their aggressive character. The zebras were sufficiently immobilized for the length of most procedures (<45 min) without supplementation. At the end of the procedure, the animals were given atipamezole (2 mg per 1 mg detomidine used) and naltrexone (0.1 mg/kg) to reverse the sedative effects, irrespective of whether etorphine was used or not. Standing sedation, using the combination of the alpha-2 agonist detomidine and the partial agonist-antagonist opioid butorphanol (in some cases supplemented with etorphine + acepromazine), proved to be a very efficacious and safe method to be used in zebras under zoo conditions for short-lasting, nonpainful procedures.  相似文献   

Foot and mouth disease virus transmission during the incubation period of the disease in piglets, lambs, calves, and dairy cows     

Orsel K  Bouma A  Dekker A  Stegeman JA  de Jong MC 《Preventive veterinary medicine》2009,88(2):158-163

Transmission of foot and mouth disease (FMD) virus by infected animals may already occur before clinical signs are evident. Quantitative data for FMD transmission rates during this so-called high-risk period are currently lacking and would provide useful information to develop surveillance systems in which the number of new outbreaks is an outcome variable. In order to address this, we used experimental data to quantify transmission in cattle, swine and sheep during the non-clinical phase of the disease. Groups consisted of vaccinated or non-vaccinated animals of one species; half of each group was inoculated with FMDV, the other half was contact-exposed. We estimated the reproduction ratio R(nonclin) using a mathematical SIR model. R(nonclin) was defined as the average number of secondary infections caused by one infectious individual in its non-clinical phase. Animals not showing clinical signs shed lower amounts of virus than clinically affected ones. Therefore, we estimated transmission proportionally to the virus excretion. Low estimates for R(nonclin) in groups with non-vaccinated and vaccinated calves; 0.30 [0.03; 3.43] and 1.03x10(-8) [0; infinity] respectively and 0.21 [0.02; 2.48] for the non-vaccinated and 0.16 [0.009; 2.96] for the vaccinated lambs, were observed. These results indicate that only few secondary infections are to be expected from infected calves and lambs when they are not clinically affected. In groups of non-vaccinated piglets estimates were R(nonclin)=13.20 [4.08; 42.68], and in vaccinated piglets R(nonclin)=1.26 [0.18; 8.96]. The estimate for R(nonclin) for non-vaccinated dairy cows was R(nonclin)=176.65 [80.38; 388.24], whereas R(nonclin) in the vaccinated groups could not be estimated. Our findings suggest that a large number of individuals might have been infected before clinical signs are noticed, especially in non-vaccinated swine and dairy herds. These findings suggest that after clinical recognition of FMD, priority should be given to trace back contacts with swine and dairy farms, as they may already have been infectious in the herd's incubation period.  相似文献   

The reduction of chemical control of leek rust,a simulation study     

P. D. de Jong  R. A. Daamen  R. Rabbinge 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(6):687-693

A model is presented which simulates chemical control against leek rust under a system of supervised control. The spread of disease between fields in one farm and the influx of spores from outside is part of the model. The possible reduction in fungicide sprays against leek rust following various preventive measures is estimated with this model. Results from this preliminary model suggest that supervised control of leek rust will result only in a considerable reduction in the number of fungicide sprays if the leek fields are sufficiently isolated and the planting material is initially disease free. Where isolation between the fields is not feasible, overlap between successive crops should be avoided. Without the use of these preventive measures, there is little prospect for supervised control and the grower will have no option but the heavy use of fungicides.  相似文献   

When can a veterinarian be expected to detect classical swine fever virus among breeding sows in a herd during an outbreak?   总被引：1，自引：0，他引：1  

Engel B  Bouma A  Stegeman A  Buist W  Elbers A  Kogut J  Döpfer D  de Jong MC 《Preventive veterinary medicine》2005,67(2-3):195-212

The herd sensitivity (HSe) and herd specificity (Hsp) of clinical diagnosis of an infection with classical swine fever (CSF) virus during veterinary inspection of breeding sows in a herd was evaluated. Data gathered from visits to herds during the CSF outbreak in 1997-1998 in The Netherlands were used for the analysis. Herds were visited one or more times by the same or by different veterinarians. On the basis of the veterinarians' reports, each visit was coded as 0 (negative clinical diagnosis) or 1 (positive clinical diagnosis). The HSe for clinical diagnosis of CSF was modelled as a function of days elapsed since introduction of the virus. The moment of introduction of the CSF virus in the CSF-positive herds was unknown, so for each herd, a probability distribution for the unknown number of days since introduction was derived from serum samples collected at depopulation. The information from the reports of the veterinarians and from the test results of the serum samples at depopulation was combined in a Bayesian analysis. Data from CSF-negative herds were analysed to estimate HSp of clinical diagnosis of CSF. The HSe of clinical diagnosis was 0.5 at 37 days after virus introduction (95% CI: 31, 45) and reached 0.9 at 47 days after virus introduction (95% CI: 41, 54). The estimated herd specificity was 0.72 (95% CI: 0.64, 0.79). Dependence of HSe and HSp on characteristics of the veterinarians and the herds also was studied. Specialisation of the veterinarian significantly, although not markedly, affected the HSe.  相似文献   

Evaluation of a new antibody-based enzyme-linked immunosorbent assay for the detection of bovine leukemia virus infection in dairy cattle.     

Gustavo E Monti  Klaas Frankena  Bas Engel  Willem Buist  Héctor D Tarabla  Mart C M de Jong 《Journal of veterinary diagnostic investigation》2005,17(5):451-457

The objective of this study was to validate a new blocking enzyme-linked immunosorbent assay (ELISA) (designated M108 for milk and S108 for serum samples) for detecting bovine leukemia virus (BLV) infection in dairy cattle. Milk, serum, and ethylenediaminetetraacetic acid-blood samples were collected from 524 adult Holstein cows originating from 6 dairy herds in Central Argentina. The M108 and S108 were compared with agar gel immunodiffusion (AGID), polymerase chain reaction and a commercial ELISA. Because there is currently no reference test capable of serving as a gold standard, the test sensitivity (SE) and specificity (SP) were evaluated by the use of a latent class model. Statistical inference was performed by classical maximum likelihood and by Bayesian techniques. The maximum-likelihood analysis was performed assuming conditional independence of tests, whereas the Bayesian approach allowed for conditional dependence. No clear conclusion could be drawn about conditional dependence of tests. Results with maximum likelihood (under conditional independence) and posterior Bayes (under conditional dependence) were practically the same. Conservative estimates of SE and SP (with 95% confidence intervals) for M108 were 98.6 (96.7; 99.6) and 96.7 (92.9; 98.8) and for S108 99.5 (98.2; 99.9) and 95.4 (90.9; 98.1), respectively. The ELISA 108 using either milk or serum to detect BLV-infected animals had comparable SE and SP with the official AGID and a commercial ELISA test, which are currently the most widely accepted tests for the serological diagnosis of BLV infection. Therefore, ELISA 108 can be used as an alternative test in monitoring and control programs.  相似文献   

Implications derived from a mathematical model for eradication of pseudorabies virus     

A. Van Nes  M. C. M. De Jong  J. A. A. M. Buijtels  J. H. M. Verheijden 《Preventive veterinary medicine》1998,33(1-4):39-58

Simple mathematical models based on experimental and observational data were applied to evaluate the feasibility of eradicating pseudorabies virus (PRV) regionally by vaccination and to determine which factors can jeopardise eradication. As much as possible, the models were uncomplicated and our conclusions were based on mathematical analysis. For complicated situations, Monte-Carlo simulation was used to support the conclusions. For eradication, it is sufficient that the reproduction ratio R (the number of units infected by one infectious unit) is < 1. However, R can be determined at different scales: at one end the region with the herds as units and at the other end compartments with the pigs as units. Results from modelling within herds showed that contacts between groups within a herd is important whenever R between individuals (R_ind) is 1 in one or more groups. This is the case within finishing herds. In addition, if the R_ind is more than 1 within a herd, the size of the herd determines whether PRV can persist in the herd and determines the duration of persistence. Moreover, when reactivation of PRV in well-vaccinated sows is taken into account, R_ind in sow herds is still less than 1. In sow herds with group-housing systems, it is possible that in those groups R_ind is 1. Results from modelling between herds showed that whether or not R_herd is < 1 in a particular region is determined by two factors: (1) the transmission of infection between nucleus herds and rearing herds through transfer of animals and (2) contacts among finishing herds and among rearing herds. The transmission between herds can be reduced by reduction of the contact rate between herds, reduction of the herd size, and reduction of the transmission within herds.  相似文献   

A meta-analysis quantifying transmission parameters of FMDV strain O Taiwan among non-vaccinated and vaccinated pigs     

Eblé PL  de Koeijer AA  de Jong MC  Engel B  Dekker A 《Preventive veterinary medicine》2008,83(1):98-106

Our aim was to provide additional estimates of main parameters for the transmission of foot-and-mouth disease virus (FMDV) strain O Taiwan (3/97). We used the data of previous experiments in non-vaccinated and vaccinated pigs and combined the data of experiments with the same treatment(s). First, we quantified the reproduction ratio R for the various groups using a final-size method. Our final-size results predicted that vaccination with a four-fold vaccine dose (but not with a single dose) at 1 week before inoculation (-7 dpi) would reduce R compared to the non-vaccinated group. Secondly, we used the daily results of virus excretion to quantify the transmission rate beta (by using generalized linear modelling), and the infectious period T (by using survival analysis). We used the estimates of beta and T to estimate R more precisely as compared to the final-size method and also for the groups for which a finite estimate could not be obtained using a final-size method. Our modelling results predicted that beta for non-vaccinated, for single-dose and four-fold-dose groups would be 6.1 (3.7, 10)day(-1), 2.0 (1.0, 4.0)day(-1) and 0.4 (0.1, 1.4)day(-1), T at 6.5 (5.7, 7.3), 5.3 (4.7, 6.0) and 2.3 (0.9, 5.7) days and R at 40 (21, 74), 11 (4.9, 24) and 1.0 (0.1, 7.8), respectively. These results predicted that both vaccination with a four-fold vaccine dose and with a single dose at -7 dpi would reduce beta, T and R significantly as compared to the non-vaccinated pigs, thereby showing that vaccination will reduce transmission of FMDV significantly already 1 week post vaccination.  相似文献