摘要:

SummaryTwo mutant strains of pseudorabies virus (PRV) were selected from the virulent 86/27V virus treated with chemical drugs. The viruses, named 6A1 and 6C2, respectively, appeared to be unable to express thymidine kinase function, as demonstrated by the autoradiography test. They showed a reduced virulence for some susceptible animal species (chickens, mice, rabbits, calves, lambs and piglets) and virus was isolated sporadically. The mutant viruses appeared to be able to protect animals against infection with the virulent strain of PRV.At gross, as well as at histological examination, no lesions in apparatus, system and tissues were detected in pigs inoculated with 6A1 and 6C2 viruses. By contrast, rabbits treated with 6C2 mutant strain presented lymphomononucleated cuffs, microgliosis, and neuronophagia in some areas of the brain. This focal spreading, together with the absence of neuronal necrosis and intranuclear inclusions, suggest an infection induced by a modified strain of PRV.

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00675.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe experiments were carried out on normothermal rabbits and rabbits exposed to cold stress (hypothermia). The animals of the latter group were submerged in ice‐water for 20 s and then placed in a freezer at − 15 °C for 8 min until their body temperature dropped by 3°C. Both the normothermal and hypothermal rabbits were immunized i.p. with 3 ml of 10% sheep red blood cells (SRBC). Levamisole (2 mg/kg), DTC (sodium diethyldithiocarbamate, 20 mg/kg) or mechlorethamine (mustine; 5 μg/kg) were injected i.v. three times at 24‐h intervals. The number of PFC, total (19S + 7S) and 2‐mercapthoethanol resistant (7S) serum haemagglutination titres were determined. It was found that, in normothermal rabbits, all three agents potentiated the number of plaque‐forming cells (PFC); the impact of DTC was the strongest, while the weakest influence was observed for mechlorethamine. Furthermore, DTC increased anti‐SRBC haemagglutinin titre, whereas mechlorethamine did not. Levamisole, on the other hand, reduced total serum haemagglutinin titre. Cold stress reduced humoral response to SRBC, which was reflected in the decreased number of PFC and serum haemagglutination titres (19S + 7S and 7S). Each agent showed a different way of action. Pretreatment with DTC prevented the immunosuppression caused by cold stress, while levamisole and mechlorethamine only reduced the immunosupp

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00676.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryA study was conducted to evaluate the biological activity ofBrucellaallergens extracted with hydrochloride or trichloroacetic acid. Smooth and mucoidBrucella abortuscells and the medium in which brucellae were propagated were used to prepare the allergens. The biological activity of the allergens was estimated in guinea‐pigs sensitized withBrucella abortusstrain 544. The guinea‐pigs were intradermally injected with several allergen dilutions. The dilutions were coded and randomized for site of injection so that none of the dilution was injected twice on the same site. Variance analysis using incomplete Latin square was used for the statistical calculation of the results. The calculated biological activity of the allergens was compared with the biological activity of a ‘standard’ allergen that has proved effective in detecting cattle brucellosis.The skin erythema diameter was best when recorded 32 h after allergen injection. Statistical analysis of the skin erythema diameters showed a great variation in biological activity (12–105%) between the allergens. Only the allergen extracted from the medium in which a mucoidBrucellastrain was propagated was as potent as the standard. The use of the incomplete Latin square for variance analysis resulted in the estimation of the biological activity of nine batches of allergen in only 27 gu

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00677.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummarySignificantly drastic effects of storage on the potency of the alum‐precipitated haemorrhagic septicaemia (APHS) vaccine are reported. The APHS vaccine, studied through challenge infection of vaccinated rabbits (post‐60 days of vaccination), showed 100% potency when stored at 4 °C for 30 days. The potency dropped to 20% when storage period was extended to 60 or more days. At 30 °C, the potency reduced by 40, 40 and 60%, respectively, after 30, 60 and 90 days of storage, while, at 37 °C, the decrease was 60, 60 and 100% after 30, 60 and 90 days of storage, respectively. In view of this, the oil‐adjuvant (OA) HS vaccine was developed by culturingPasteurella multocidaon a medium comprising yeast extract, sucrose, trypticase and sodium bicarbonate, under continuous aeration at 37 °C. This gave a far better bacterial count (maximum count 15 times 108/ml) than the conventional APHS vaccine (maximum count 6 times 108/ml). The OAHS vaccine‐carrying water‐in‐oil emulsion remained stable at room temperature for 1 year. The log protection values of the two batches of the OAHS vaccine, studied in mice, were 5.2 and 5.3, as against 1.9 of t

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00678.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryA microagglutination test andin vitroserum bactericidal assay were used for testing cross‐reactions and cross‐bactericidal activities of 15Campylobacterstrains isolated from ovine abortions. Antisera against certain strains ofC. fetussubsp.fetusandC. jejunishowed higher microagglutination titres and bactericidal activity against homologous and/or heterologous strains. In both tests, cross‐reactions and bactericidal activity were higher among the strains of homologous species than among those of heterologous species. The pregnant guinea‐pig model was used for testing the efficacy of experimental campylobacter vaccines. Monovalent bacterins prepared with eitherC. fetussubsp.fetusorC. jejunidid not produce immunity to cross‐challenge with the opposite species. Guinea‐pigs immunized with the bivalent bacterin were found to be immune to both groups ofCampylobacterwhen subsequently challenged. In vaccinated guinea‐pigs, theirin vivoability to overcome infection is reflected in thein vitrobactericidal capacity of homologous rab

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00679.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThis study was designed to characterize further 88 streptococci of serological group L, isolated from bovines, pigs, poultry and humans. Most group L streptococci from bovines grew as granular sediment with long chains in fluid media and with compact colonies in soft agar. Most group L streptococci from pigs grew with a uniform turbidity in fluid media, short chains, and with diffuse colonies in soft agar. The biochemical characteristics, determined with the Strepzym identification system, revealed no significant differences between the group L streptococci of various origins. A positive opacity factor reaction could mainly be observed with group L streptococci from bovines and humans, but was less pronounced with group L streptococci from pigs and poultry. In addition, 27 group L streptococci reacted with type antigen X or R and 9 cultures with M1 or M6 specific antiserum. The determination of antibiotic resistance patterns revealed that all group L streptococci were resistant to tetracycline and minocycline, part of the cultures were resistant to chloramphenicol, erythromycin and gentamicin, and all cultures were susceptible to penicillin, bacitracin, cefoxitin and nitrofurantoin. All these data allowed an individual characterization of group L streptococci, possibly useful for epidemiological studies.

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00680.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryClostridium perfringenstype C, which produces α‐ and β‐toxin, causes severe haemorrhagic and necrotic enteritis in animals and humans. A polymerase‐chain‐reaction (PCR) assay was developed for the specific detection of the genes encoding α‐, β‐, ε‐ and enterotoxin ofC. perfringensfor rapid typing ofC. perfringensstrains, and especially for the identification of type C strains. Both the α‐ and β‐toxin genes were detected directly in porcineC. perfringenstype C cultures and also in type B and type C collection strains to a sensitivity of 103cells without purification of the DNA. The α‐toxin gene was detected in all types ofC. perfringens.The ε‐toxin gene was found in type B and type D, and the enterotoxin gene in some type A strains. Nine other species ofClostridiumand a variety of intestinal pathogenic bacteria showed no signal for these toxin genes in this PCR assay. The α‐ and β‐toxin genes PCR assay were used to identifyC. perfringensstrains isolated from intestinal contents of 36 necropsied piglets that had suddenly died or died after premonitory signs of diarrhoea. At necropsy, 20 piglets showed necrotizing enteritis (15 acute and 5 chronic cases) and were suspected to have suffered from aC. perfringenstype C infection. All of them hadC. perfringenswhich gave a positive PCR signal for α‐ and β‐toxin genes, and, hence, were identified as type C strains. From the 16 other piglets with lesions other than necrotizing enteritis,C. perfringensstrains with the α‐toxin gene, but no β‐toxin gene, were isolated. The necropsy findings and the anamnesis showed a very good correlation with the PCR identification of toxin genes. It was therefore concluded that the PCR‐based toxin gene examination is a good alternative to the time‐consuming, less specific, and more expensive mouse neut

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00681.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryA polyclonal antibody against the 35 kDa major outer‐membrane protein ofPasteurella multocidacross‐reacted with the 40 kDa major outer‐membrane protein ofActinobacillus pleuropneumoniaeand the 42 kDa major outer‐membrane protein ofHaemophilus parasuis.The N‐terminal amino‐acid sequences of these proteins revealed a strong homology with the putative 35 kDa porin protein ofPasteurella multocida(66.7 and 76.2%, respectively). Significant homologies were also evident between the 40 kDa and the 42 kDa protein (76.2%), and with non‐specific porins of gram‐ne

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00682.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00683.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryIn 33 calves and subadult cattle of the Holstein‐Friesian breed ranging from 1 to 210 days of age, the spectrum of brain lesions induced by intra‐uterine infection with bovine‐virus diarrhoea virus (BVDV) was retrospectively analysed. Of these, 27 animals originated from herds with a long history of BVD. Six calves were derived from dams vaccinated between the 90th and 118th day of gestation with a BVD live vaccine. The most frequent lesion was cerebellar hypoplasia, being present in 25 out of 33 (76%) of the animals. In most of these cases, cerebellar hypoplasia was associated with hydranencephaly, internal hydrocephalus, microencephaly or porencephaly. In cases with hydranencephaly, the fluid‐filled cavities were devoid of ependymal lining. The lumina of the lateral ventricles of these cases were surrounded by glial fibrillary acidic protein (GFAP)‐positive cells and a dense layer of immunoreactive cell processes. In the white matter adjacent to the dilated ventricular lumina, a reactive astrocytosis was present. Porencephalic cysts were surrounded by astrocytes with increased expression of GFAP and vimentin‐positive cells and cell processes. In hydranencephalic brains, staining for neuron‐specific enolase (NSE) revealed a marked reduction of NSE‐positive nerve cells in cortical areas. In all six experimental cases and in several field cases with hydranencephaly or internal hydrocephalus, small groups of heterotopic NSE‐positive neurons were present in the white matter of the cerebral hemispheres. In markedly hypoplastic cerebella, reduction of the cortical cell layers and degenerative changes in, and heterotopia of, Purkinje cells were found. In these cases, NSE‐ and neurofilament‐positive cell processes were either markedly diminished or only remnants of immunoreactive cell processes were present. In five animals without significant gross cerebellar abnormalities, degenerative changes of Purkinje cells were found.Immunohistochemical staining using antibodies against glial and neuron‐specific proteins on these brains, which represent postnatal end‐stage lesions of BVDV‐induced disturbances of the normal brain development, did not provide any insight into the possible pathogenetic mechanisms of these alterations. Application of immunohistochemistry, however, revealed changes, such as reactive astrocytosis and loss of nerve cell processes, which were not obvious on haematoxylin and e

ISSN:0931-1793    

DOI:10.1111/j.1439-0450.1995.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY