Ovicidal activity of seven <Emphasis Type="Italic">Pochonia chlamydosporia</Emphasis> fungal isolates on <Emphasis Type="Italic">Ascaris suum</Emphasis> eggs

The ovicidal effect of the nematophagous fungus Pochonia chlamydosporia on eggs of Ascaris suum was tested under laboratory conditions. A. suum eggs were plated on 2% water–agar with seven fungal isolates (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) and control without fungus. After 5, 7, 10, 14, 15 and 21 days of incubation, approximately 100 eggs were removed from the plates and classified according to the following parameters: type 1, biochemical and physiological effect without morphological damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect with morphological alteration of eggshell and embryo showing hyphal penetration and internal egg colonization. The isolates effectively destroyed A. suum eggs and all types of effects were observed during the experiment. There was no variation in ovicidal capacity (type 3 effect) among the isolates (p > 0.05) throughout the experiment. After 21 days, isolate 5 showed the highest percentages of type 3 effect (58.33%). The results indicated that P. chlamydosporia (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) can destroy A. suum eggs and is, therefore, a potential biological control agent of nematodes.     

Effects of cimaterol on rabbit growth and myofibrillar protein degradation and on calcium-dependent proteinase and calpastatin activities in skeletal muscle

The objectives of this study were to examine effects of a beta-adrenergic agonist (cimaterol) on growth and muscle development in rabbits and to examine cimaterol's effects on myofibrillar protein degradation (MPD) and on activities of several proteolytic enzymes including the calcium-dependent proteinases (CDP). Twelve New Zealand White rabbits were assigned to either control diets or to diets containing cimaterol for 35 d, after which they were killed and effects on performance and tissue weight gains were determined. Urine was collected from d 21 through 28 from each rabbit for assessment of N tau-methylhistidine (NMH) excretion. Cimaterol increased rates of gain, efficiency of gain and skeletal muscle weights. Enhancement in muscle weight was associated with an increase in total DNA and with a reduction in NMH. Cimaterol did not affect activities of cathepsin B, cathepsin D or neutral serine proteinase, but it reduced activities of the millimolar and micromolar forms of the CDP by 58 and 57%, respectively, and it reduced activity of the inhibitor of the CDP (calpastatin) by 52%. Cimaterol-dependent myofibrillar protein accretion was likely mediated, at least in part, by a reduction in MPD. The change in MPD was associated with a reduction in muscle CDP activities. Cimaterol-dependent muscle hypertrophy therefore may involve changes in calcium-dependent proteolysis of myofibrillar proteins. The significance of the effects of cimaterol on calpastatin activity is not known.     

Demonstrating freedom from disease using multiple complex data sources 2: case study--classical swine fever in Denmark

A method for quantitative evaluation of surveillance for disease freedom has been presented in the accompanying paper (Martin et al., 2007). This paper presents an application of the methods, using as an example surveillance for classical swine fever (CSF) in Denmark in 2005. A scenario tree model is presented for the abattoir-based serology component of the Danish CSF surveillance system, in which blood samples are collected in an ad hoc abattoir sampling process, from adult pigs originating in breeding herds in Denmark. The model incorporates effects of targeting (differential risk of seropositivity) associated with age and location (county), and disease clustering within herds. A surveillance time period of one month was used in the analysis. Records for the year 2005 were analysed, representing 25,332 samples from 3528 herds; all were negative for CSF-specific antibodies. Design prevalences of 0.1-1% of herds and 5% of animals within an infected herd were used. The estimated mean surveillance system component (SSC) sensitivities (probability that the SSC would give a positive outcome given the animals processed and that the country is infected at the design prevalences) per month were 0.18, 0.63 and 0.86, for among-herd design prevalences of 0.001, 0.005 and 0.01. The probabilities that the population was free from CSF at each of these design prevalences, after a year of accumulated negative surveillance data, were 0.91, 1.00 and 1.00. Targeting adults and herds from South Jutland was estimated to give approximately 1.9, 1.6 and 1.4 times the surveillance sensitivity of a proportionally representative sampling program for these three among-herd design prevalences.     

In vitro effects of bethanechol on specimens of intestinal smooth muscle obtained from the duodenum and jejunum of healthy dairy cows

OBJECTIVE: To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction. SAMPLE POPULATION: Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows. PROCEDURES: Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (A(max)), and area under the curve (AUC) were evaluated. RESULTS: Bethanechol induced a significant, concentration-dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations. Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M(3) antagonists (more commonly for basal tone than for A(max) and AUC). The M(2) receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M(3) receptor antagonists were generally more potent than the M(2) receptor antagonists. In a protection experiment, an M(3) receptor antagonist was less potent than when used in combination with an M(2) receptor antagonist. Receptor antagonists for M(1) and M(4) did not affect contractility variables. CONCLUSIONS AND CLINICAL RELEVANCE: Bethanechol acting on muscarinic receptor sub-types M(2) and M(3) may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows.     

Humoral Response to 2 Inactivated Bluetongue Virus Serotype‐8 Vaccines in South American Camelids

Background: Bluetongue virus serotype 8 (BTV‐8) has caused disease in domestic ruminants in several countries of northern Europe since 2006. In 2008 a mass‐vaccination program was launched in most affected countries using whole virus inactivated vaccines. Objective: To evaluate 2 inactivated vaccines (Bovilis BTV 8; BTVPUR AlSap8) for immunogenicity and safety against BTV‐8 in South American camelids (SAC) in a field trial. Animals: Forty‐two SAC (25 Alpacas, 17 Llamas) aged between 1 and 16 years. Methods: The animals were vaccinated twice at intervals of 21 days. They were observed clinically for adverse local, systemic, or both reactions throughout the trial. Blood samples collected on days 0, 14, 21, 43, and 156 after vaccination were tested for the presence of BTV‐8 virus by real time‐polymerase chain reaction and of specific antibodies by competitive ELISA and a serum neutralization test. Results: All vaccinated animals developed antibodies to BTV‐8 after the 2nd administration of the vaccine. No adverse effects were observed except for moderate local swellings at the injection site, which disappeared within 21 days. Slightly increased body temperatures were only observed in the first 2 days after vaccination. The BTV was not detected in any of the samples analyzed. Conclusions and Clinical Importance: The administration of the 2 inactivated commercial vaccines was safe and induced seroconversion against BTV‐8 in all vaccinated animals. The results of this study suggest that 2 doses injected 3 weeks apart is a suitable vaccination regimen for SAC.     

Failure to observe cross-fertilization between the Echinococcus granulosus G1 and G6 strains after an experimental mixed infection of the definitive host

The classification within Echinococcus granulosus is currently under debate. To assess the reproductive potential between the G1 and G6 strains, an experimental double infection was carried out in a dog. First, two fertile hydatid cysts were collected in Algeria from a cow and a dromedary. They were identified as being G1 and G6 with the markers coxI and nadI. Subsequently, a dog was inoculated with protoscoleces from these two cysts. Sixty days after infection, 85 adult worms were recovered from the intestine of the dog. Then, the two cysts and each of these individual parasites were characterized with the multilocus microsatellite EmsB and compared. For all worms, the scolex and the gravid proglottids, separately analyzed, provided an identical profile: the G1 profile was observed in 70 adults, and the G6 profile in the 15 others. No single worm exhibited a hybrid G1/G6 profile. This result suggests the absence of cross-fertilizing between the two taxa under the given experimental conditions, and so, the presence of a strong cross-reproductive barrier. This observation corroborates with the recent reclassification of G1 and G6 within two distinct species.     

Susceptibility of adult chickens, with and without prior vaccination, to challenge with Marek's disease virus

Marek's disease (MD) outbreaks can occur in previously healthy adult layer or breeder flocks. However, it is not clear whether such outbreaks are caused by recent challenge with highly virulent (vv and vv+) strains of MD virus (MDV; i. e., new infection hypothesis) or by exacerbation of an earlier MDV infection (i. e., old infection hypothesis). To discriminate between these hypotheses, adult White Leghorn chickens of laboratory strains or commercial crosses with or without prior vaccination or MDV exposure were challenged at 18-102 wk of age with highly virulent MDVs, and lesion responses were measured. Horizontal transmission was studied in one trial. Challenge of adult chickens, which were free from prior MDV vaccination or exposure, with highly virulent MDV strains induced transient paralysis or tumors in 60%-100% of 29 groups (mean = 91%), and horizontal spread of virus was detected. The magnitude of the response was similar to that induced by challenge at 3 wk of age. In contrast, comparable challenge of adult chickens, which had been vaccinated or exposed to MDV early in life, induced transient paralysis or tumors in 0%-6% of 12 groups (mean = 0. 5%), although some birds showed limited virologic evidence of infection and transmission of the virus to contacts. The MD responses were influenced by the virulence of the challenge virus strain, and to a lesser extent by virus dose and route of exposure. Strong inflammatory lesions were induced in the brain and nerves of adult specific pathogen-free (SPF) chickens at 9-15 days after infection. The low susceptibility of previously vaccinated and exposed groups to challenge at > or =18 wk of age suggests that late outbreaks of MD in commercial flocks are not likely a result of recent challenge alone and that additional factors could be involved.     

Time course of changes in growth factor mRNA levels in muscle of steroid-implanted and nonimplanted steers

We used a muscle biopsy technique in conjunction with real-time PCR analysis to examine the time course of changes in muscle IGF-I, IGFBP-3, myostatin, and hepatocyte growth factor (HGF) mRNA in the longissimus muscles of Revalor-S-implanted and nonimplanted steers on d 0, 7, 12, and 26 after implantation (nine steers/treatment group). Administration of a Revalor-S implant increased (P < 0.01) ADG and improved (P < 0.05) feed efficiency, 36 and 34%, respectively, compared with steers that received no implant during the 26-d trial. Daily dry matter intake did not differ (P > 0.15) between nonimplanted and implanted steers. Steers receiving the Revalor-S implant had increased (P < 0.001) circulating IGF-I concentrations compared with nonimplanted steers. The longissimus muscles of steers receiving the Revalor-S implant contained increased (P < 0.001) IGF-I mRNA levels compared with longissimus muscles of nonimplanted steers over the 26-d duration of the study. Longissimus muscle IGF-I mRNA levels in implanted steers were increased (P < 0.003) relative to d-0 concentrations on d 7 and 12 (101% and 128%, respectively), and byd 26, longissimus muscle mRNA levels were more than three times (P < 0.0001) those in the longissimus muscles of the same steers on d 0. There was no treatment effect on the level of IGFBP-3, myostatin, or HGF mRNA in the longissimus muscle at any time point; however, levels of IGFBP-3, myostatin, and HGF mRNA increased with time on feed. Based on current and previous studies, we hypothesize that the increased IGF-I level in muscle of implanted steers by d 7 of implantation stimulates satellite cell proliferation and maintains a high number of proliferating satellite cells at a point in the growth curve where satellite cell numbers and activity are normally dropping off. This would prolong the period of rapid muscle growth, resulting in the observed increased rate and efficiency of muscle deposition in implanted steers.