Classical swine fever virus replicon particles lacking the Erns gene: a potential marker vaccine for intradermal application

Classical swine fever virus replicon particles (CSF-VRP) deficient for E(rns) were evaluated as a non-transmissible marker vaccine. A cDNA clone of CSFV strain Alfort/187 was used to obtain a replication-competent mutant genome (replicon) lacking the sequence encoding the 227 amino acids of the glycoprotein E(rns) (A187delE(rns)). For packaging of A187delE(rns) into virus particles, porcine kidney cell lines constitutively expressing E(rns) of CSFV were established. The rescued VRP were infectious in cell culture but did not yield infectious progeny virus. Single intradermal vaccination of two pigs with 10(7) TCID(50) of VRP A187delE(rns) elicited neutralizing antibodies, anti-E2 antibodies, and cellular immune responses determined by an increase of IFN-gamma producing cells. No anti-E(rns) antibodies were detected in the vaccinees confirming that this vaccine represents a negative marker vaccine allowing differentiation between infected and vaccinated animals. The two pigs were protected against lethal challenge with the highly virulent CSFV strain Eystrup. In contrast, oral immunization resulted in only partial protection, and neither CSFV-specific antibodies nor stimulated T-cells were found before challenge. These data represent a good basis for more extended vaccination/challenge trials including larger numbers of animals as well as more thorough analysis of virus shedding using sentinel animals to monitor horizontal spread of the challenge virus.     

The use of impulse oscillometry for separate analysis of inspiratory and expiratory impedance parameters in horses: effects of sedation with xylazine

AIM: To improve the outcome of parameters measured by the impulse oscillometry system (IOS) in horses by separate assessment of inspiratory and expiratory impedance spectra in the frequency range between 1 and 10 Hz. As basis for further studies, the influence of sedation with xylazine on respiratory impedance was also investigated. METHODS: (i) The respiratory impedance of 11 horses was measured using IOS before and 6 min after sedation (xylazine; 0.6 mg/kg b.w.). (ii) The time course of impedance parameters in a period of 24 min after administration of xylazine was evaluated in 12 horses at regular intervals of 3 min. Resistance (R(rs)), reactance (X(rs)), and coherence (Co) were calculated as mean spectra (R(rs),X(rs),Co) of the entire measurement as well as separated into inspiration (Ri(rs),Xi(rs),Coi) and expiration (Re(rs),Xe(rs),Coe) at frequencies of 1, 5, and 10 Hz. RESULTS: (i) R(rs), X(rs) as well as Re(rs) and Xe(rs) revealed no significant influence of sedation. However, separate analysis of inspiration and expiration revealed a significant influence of sedation on all inspiratory impedance parameters. (ii) During the 24 min period after sedation, almost all inspiratory parameters were found significantly dependent on the time course of sedation whereas expiratory parameters Re10, Xe1, and Xe5 were not influenced. These results indicate that confounding factors due to sedation act mainly during inspiration. Muscle relaxation in upper airways due to xylazine is suspected to be the main cause of these phenomena.     

Biological control of horse cyathostomin (Nematoda: Cyathostominae) using the nematophagous fungus Duddingtonia flagrans in tropical southeastern Brazil

The viability of a fungal formulation using the nematode-trapping fungus Duddingtonia flagrans was assessed for the biological control of horse cyathostomin. Two groups (fungus-treated and control without fungus treatment), consisting of eight crossbred mares (3–18 years of age) were fed on Cynodon sp. pasture naturally infected with equine cyathostome larvae. Each animal of the treated group received oral doses of sodium alginate mycelial pellets (1 g/(10 kg live weight week)), during 6 months. Significant reduction (p < 0.01) in the number of eggs per gram of feces and coprocultures was found for animals of the fungus-treated group compared with the control group. There was difference (p < 0.01) of 78.5% reduction in herbage samples collected up to (0–20 cm) between the fungus-treated group and the control group, during the experimental period (May–October). Difference of 82.5% (p < 0.01) was found between the fungus-treated group and the control group in the sampling distance (20–40 cm) from fecal pats. During the last 3 months of the experimental period (August, September and October), fungus-treated mares had significant weight gain (p < 0.01) compared with the control group, an increment of 38 kg. The treatment with sodium alginate pellets containing the nematode-trapping fungus D. flagrans reduced cyathostomin in tropical southeastern Brazil and could be an effective tool for biological control of this parasitic nematode in horses.     

Mineral dust around the Sahara—from source to sink. A review with emphasis on contributions of the German soil science community in the last twenty years

Natural mineral dust has manifold environmental effects reaching from fertilizing aquatic and terrestrial ecosystems to affecting the earth's radiation balance and thus impacting on climate. The Sahara is considered the largest source of natural mineral dust on the globe, so much research attention has been paid to source identification, dust mobilization, transport, and effects in the sink areas. This paper gives a review of the research results concerning these topics emphasizing soil‐science‐related aspects of the last 20 y and the identification of knowledge gaps.     

Canine distemper virus-induced depletion of uninfected lymphocytes is associated with apoptosis

Canine distemper virus (CDV), a negative stranded RNA morbillivirus, causes a multisystemic disease in dogs, which is associated with a severe immune suppression. The aim of the study was to examine the influence of early CDV infection on leukocyte depletion, lymphopenia and virus-induced cell death in dogs infected with a virulent CDV strain. From 10 infected dogs, peripheral blood leukocytes were harvested periodically, phenotyped and analyzed for CDV antigen content and apoptosis using Annexin V-FITC and propidium iodide labeling. CDV infection induced a severe CD3+ T cell and CD21+ B cell depletion in all animals at 3 days post-infection (d.p.i.). For dogs with severe distemper, developing virus persistence in the lymphoid tissue and central nervous system, this lymphopenia lasted until the end of the experiment. Increased levels of lymphocyte apoptosis were found at 3 d.p.i., and monocyte apoptosis at 6 d.p.i. This was more prominent in the group of animals with severe distemper. At 3 d.p.i. no leukocyte infection was detectable indicating that the early lymphocyte depletion and apoptosis was not a direct consequence of virus infection. Taken together, our results demonstrate that CDV-induced lymphopenia is an early event and that the degree of lymphocyte depletion correlates with the severity of disease and virus persistence in the lymphoid tissue and central nervous system.     

Consequences of short term fluctuations of the environmental temperatures in calves--Part 2: Effects on the health status of animals within three weeks after exposure

The aim of the present study was to examine consequences of sudden changes in ambient temperature over a 4-hour period (see part 1 [ELMER & REINHOLD, 2002]) on respiratory health in clinically healthy calves. Therefore, the relationship between short-term changes in ambient temperature and the occurrence of clinical respiratory disease was checked over a period of 3 weeks after exposure in 10 calves exposed to 5 degrees C, in 9 calves exposed to 35 degrees C and in 8 control calves (kept at 18-20 degrees C). Within the period beginning 3 days before exposure and lasting until up to 21 days after exposure, each calf was examined clinically. Rectal temperature and respiratory rate were measured daily. All calves were euthanised on day 21 after exposure. Macroscopically visible pneumonic lesions were evaluated using a semiquantitative system. Tissue samples from tonsils, bronchi, trachea, lung and mediastinal lymph nodes were examined bacteriologically. In contrast to non-exposed control calves, severe respiratory illness was observed in individual calves of both exposed groups (5 degrees C, 35 degrees C). Significant increases in body temperature, respiratory rate and animal losses (2 calves died in the group exposed to 5 degrees C, one calf died in the group exposed to 35 degrees C) were the main clinical findings. At necropsy (3 weeks after exposure), no pneumonic lesions were observed in control calves--despite the fact that this group had the highest microbiological colonisation rates in tonsils and in large airways, i.e. trachea and bronchi, within all groups. However, variable pneumonic lung lesions were seen in remaining calves exposed to cold or warm air (5 degrees C, 35 degrees C). The microbiological examination confirmed that mainly Mycoplasma spp. were identified in the lung tissue of calves exposed to 5 degrees C while Pasteurella multocida and/or Mannheimia haemolytica were the only germs found in the lung tissue of calves exposed to 35 degrees C. The results of parts 1 and 2 of the present study related to health issues of calves should be taken into account for future legislation on animal welfare.