首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 22 毫秒
1.
Two-hundred bovine sera from western Zaire were screened for antibodies to 8 viruses: BHV-1, BHV-2, BHV-4, BVD-MD virus, bovine adenovirus A and B, bovine rotavirus and bovine coronavirus. Positive sera were found to all these viruses. For animals whose origin was undoubted, the main features were the high prevalence of infections by rotavirus and BHV-4 and the low prevalence of infections by coronavirus and BVD-MD virus.  相似文献   

2.
The correlation between maternal serum antibodies in beef calves at 2 days old and protection against diarrhea induced by natural bovine rotavirus (BRV) infection was examined. Virus neutralizing (VN) antibody titers against BRV in sera from calves that developed diarrhea by BRV infection within 14 days of age (BRV-diarrheal calves) were significantly lower than those from calves that had no diarrhea. In the BRV-diarrheal calves, a positive correlation was found between the VN antibody titers and age of the onset of diarrhea. There were negative correlations between the VN antibody titers and duration of the diarrhea, VN antibody titers and cumulative diarrhea scores, and the VN antibody titers and duration of virus shedding. These results suggest that the VN antibody titers against BRV in newborn calf serum could be an indicator of protection against BRV-induced diarrhea.  相似文献   

3.
Faeces and, or, paired sera were collected from cows in six dairy herds with classical winter dysentery. Similar samples were collected from cows in three other dairy herds experiencing non-haemorrhagic diarrhoea during the survey period. Coronavirus was the only enteric pathogen identified by immune electron microscopy (IEM) in all six outbreaks, occurring in 26 of 29 (90 per cent) of the affected cows and in one of 11 normal cows from the same herds. Nineteen of 26 affected cows (73 per cent) developed greater than four-fold increases in neutralising antibody titres to the Mebus strain of bovine coronavirus, compared with two of eight normal cows in the same herds. No cows showed greater than four-fold increases in antibody titres to bovine virus diarrhoea virus. None of the cows from the three herds with non-haemorrhagic diarrhoea shed coronavirus in faeces detectable by IEM or developed greater than two-fold rises in coronavirus antibody titres in paired sera. No enteric pathogens were identified in two of the herds. However, two cows in the third herd shed a group B rotavirus detected by IEM. These findings provide additional evidence for a possible role for bovine coronavirus in the aetiology of winter dysentery. Furthermore, this is the first report of a group B rotavirus associated with diarrhoea in adult cattle.  相似文献   

4.
Unsuckled specific pathogen free calves were inoculated at 3-4 weeks of age, either intranasally (IN) or orally (O) with bovine coronavirus or O plus IN (O/IN) or O with bovine rotavirus. Shedding of virus in nasal or fecal samples, and virus-infected nasal epithelial cells were detected using immunofluorescent staining (IF), ELISA or immune electron microscopy (IEM). Isotype-specific antibody titers in sera, nasal and fecal samples were determined by ELISA. Calves inoculated with coronavirus shed virus in feces and virus was detected in nasal epithelial cells. Nasal shedding persisted longer in IN-inoculated calves than in O-inoculated calves and longer than fecal shedding in both IN and O-inoculated calves. Diarrhea occurred in all calves, but there were no signs of respiratory disease. Calves inoculated with rotavirus had similar patterns of diarrhea and fecal shedding, but generally of shorter duration than in coronavirus-inoculated calves. No nasal shedding of rotavirus was detected. Peak IgM antibody responses, in most calves, were detected in fecal and nasal speciments at 7-10 days post-exposure (DPE), preceeding peak IgA responses which occurred at 10-14 DPE. The nasal antibody responses occurred in all virus-inoculated calves even in the absence of nasal shedding of virus in rotavirus-inoculated calves. Calves inoculated with coronavirus had higher titers of IgM and IgA antibodies in fecal and nasal samples than rotavirus-inoculated calves. In most inoculated calves, maximal titers of IgM or IgA antibodies correlated with the cessation of fecal or nasal virus shedding. A similar sequence of appearance of IgM and IgA antibodies occurred in serum, but IgA antibodies persisted for a shorter period than in fecal or nasal samples. Serum IgG1 antibody responses generally preceeded IgG2 responses and were predominant in most calves after 14-21 DPE.  相似文献   

5.
Toxin neutralizing activity of bovine sera and body fluids against Pasteurella haemolytica type A1 cytotoxin was evaluated by 51Cr release assay using bovine peripheral blood mononuclear leukocytes as the target cells. Sera collected from precolostral calves did not exert anticytotoxin activity at 10(-1) or higher dilutions, whereas randomly selected complement fixing antibody-negative sera neutralized on average over 90% of cytotoxin activity at the 10(-1) dilution and less than 50% of the toxin activity at 10(-2) or higher serum dilutions. Nasal secretions and lung washings of some of the cattle tested also contained cytotoxin neutralizing activity. The antibody nature of the cytotoxin neutralizing activity was demonstrated by its neutralization with bovine immunoglobulin G2 purified from pooled seropositive sera. Sera from a group of cattle which were vaccinated with a potassium thiocyanate extract of P. haemolytica, but which subsequently developed fibrinous pneumonia after aerosol challenge with bovine herpesvirus 1 and P. haemolytica, had significantly lower anticytotoxin activity than sera from another group of cattle which did not develop the disease after similar vaccination and challenge. Cattle which survived a natural outbreak of shipping fever had higher anticytotoxin activity than those having fibrinous pneumonia in the aforementioned experimental group, although there was no statistical difference between them and a randomly selected CF seronegative group. It is probable that this cytotoxin neutralizing antibody exerts a beneficial effect in protection of cattle against pneumonic pasteurellosis.  相似文献   

6.
Susceptibility to infection with bovine virus diarrhoea virus (BVDV) was compared for calves with varying amounts of specific antibody in their sera passively acquired from the ingestion of colostrum. Challenge consisted of intranasal exposure to a strain of BVDV isolated from an outbreak of respiratory disease. Resistance to infection, as judged by nasopharyngeal shedding of virus, was directly related to the titre of neutralizing antibodies in sera. Besides protecting against infection of the upper respiratory tract, passive antibody, which was mainly IgG1, also protected against viraemia and, to a lesser extent, leukopenia. In the presence of colostral antibody, neutralizing and IgG1 antibody responses were apparently inhibited, but a specific IgG2 response occurred.  相似文献   

7.
A method for screening of immunoglobulin levels in porcine fetuses is presented. The method is based on rocket electrophoresis. This method is sensitive, but when used for assaying immunoglobulins it is only semiquantitative. It was shown that sera from 11 hysterectomy-derived colostrum-deprived neonatal pigs from a normal gilt contained no IgM or IgA, but small amounts of IgG. Sera from 9 piglets isolated in the same way from a gilt infected with porcine parvovirus contained all 3 antibody classes. IgM was detected by an interspecies reaction using anti human μ-chain immunoglobulin.  相似文献   

8.
A survey of reproductive tracts from nonpregnant cows at an abattoir was conducted. Reproductive tracts from 98 cows were studied microscopically and evaluated with a grading system to determine the severity of pathologic changes. Inflammatory reaction (type and distribution), fibrosis, gland morphology, and appearance were measured, quantified, and scored (1 to 4). Category 1 endometrium (normal) was found in 18 cows, category 2 in 23, category 3 in 34, and category 4 in 23. The category of endometrium was then compared with the retrospective reproductive status, and it was found that reproductive problems had occurred in 6 cows (33.3%) in category 1, in 13 cows (56.5%) in category 2, in 25 cows (73.5%) in category 3, and in 21 cows (91.3%) in category 4. Cervicitis was found in 43 (43.8%) genital tracts; 16 cows (16.3%) had salpingitis. Ovarian lesions were not observed. Serum samples were tested for certain antibodies. Only 1 was seropositive for brucellosis, but 61 of 81 sera had leptospira titers greater than 1:100 and 1:50 (hardjo). The serovar hardjo was the most prevalent. All sera had neutralizing titers against parainfluenza type 3 virus; 74.2% and 56.7% of the sera had neutralizing antibodies against bovine viral diarrhea virus and infectious bovine rhinotracheitis virus, respectively.  相似文献   

9.
A transmissible agent (Breda agent) was isolated from a calf with diarrhea and shown to be infectious by inoculation orally into gnotobiotic and conventionally reared calves. The “Breda” agent had the morphology of a virus and possessed a hemagglutinin. Antigenic studies showed the virus to be antigenically different from bovine coronavirus, parainfluenza 3 virus, bovine rotavirus, bovine parvovirus and bovine pestivirus (BVD). Attempts to culture the virus in cell or organ cultures or in embryonated eggs, were unsuccessful. The virus was either spherical or kidney shaped, with 7–9 nm peplomers on the surface. A few particles possessed coronavirus processes of 17–20 nm, but these were arranged irregularly and were thought to be tissue debris. Three out of eight experimental calves developed severe diarrhea and the lesions in the small and large intestines were similar to those reported for coronavirus. The virus replicated in the jejunal and ileal regions of the small intestine and in the spiral colon, as judged by immunofluorescence. The virus multiplied in all experimental calves and was excreted in the feces; excretion correlating with the onset of diarrhea or a change in the appearance of the feces. There was little or no malabsorption measured by the uptake of D-xylose and the fact that infection of both the crypt and villus epithelial cells was observed, suggests that the pathogenesis may be different from rotavirus and coronavirus. Fourteen of fortyseven calves in the outbreak were infected with the virus, virus was not identified in other farm outbreaks of the disease.  相似文献   

10.
Four newborn calves were experimentally infected with two distinct serotypes of bovine rotavirus (BRV-1 and BRV-2). Initially, three colostrum-deprived calves were inoculated orally with either BRV-1 or BRV-2; all developed severe diarrhea and produced serotype-specific neutralizing antibodies. Fecal virus was first demonstrated by immunofluorescence the day after inoculation. The virus titers reached a maximum of 10(5.2)-10(6.6) fluorescent focus forming units g-1 of feces 2-5 days after inoculation and then decreased. Fecal virus was detected in low titers beyond 28 days after inoculation despite the development of serum neutralizing antibodies. One calf, which had acquired specific active immunity against BRV-1 following oral infection, was further infected orally with BRV-2 4 weeks later. The calf again manifested diarrhea, excreted BRV-2 and showed an increase in serum neutralizing antibody against BRV-2. These results indicated that calves infected with either BRV-1 or BRV-2 do not have cross-protection to infection with heterologous BRV, and that recurrence of the disease can occur. The possible mechanisms of the persistence of BRV in calves and its role in the epidemiology of this infection are discussed.  相似文献   

11.
A fetal response to in utero vaccination with attenuated bovine coronavirus (9 to 49 days before parturition) was determined in 8 calves, 5 vaccinated and 3 controls. Calves were derived by hysterotomy before parturition and were maintained in a closed gnotobiotic environment. The IgA, IgM, and IgG values and coronavirus-neutralizing antibody titers were higher in the sera and intestinal loop fluid from vaccinated calves than in those from control calves. Sections of ileum and ileal lymph nodes from 1-day-old vaccinated calves, when stained with monospecific anti-bovine IgG, IgM, and IgA had numerous positively stained plasma cells. Positive fluorescence was not detected in comparable tissues from controls. When the 8 calves were given virulent coronavirus orally at 6 days of age, vaccinated calves did not become ill, whereas control calves had diarrhea in 19 to 22 hours. All calves were killed at 10 days of age. Control calves had lesions characteristic of coronavirus infection, and intestinal epithelial cells were positive by fluorescent antibody tests. In vaccinated calves, lesions of coronavirus infection were absent, and results of fluorescent antibody tests were negative. Although in utero vaccination with a coronavirus vaccine stimulated immunity in the newborn calf, the frequency of abortions (2 of 14 cows inoculated intra-amniotically) and premature births (4 of 14) precluded practical application.  相似文献   

12.
Serum was obtained at weekly intervals after vaccination of 6 healthy calves with either of 2 commercially available monovalent modified-live bovine viral diarrhea (BVD) virus vaccines. Detectable neutralizing antibodies to each of 10 cytopathic and 10 noncytopathic isolates of BVD virus were produced by 1 or more of the calves by 14 days after vaccination, but no calf produced detectable neutralizing antibodies to all 20 BVD viruses. At that time, precipitating antibodies against viral-induced polypeptides of approximately 115,000; 80,000; 56,000; 48,000; 39,000; and 25,000 daltons were detected in sera from some calves. Also at that time, specificity of the antibodies for polypeptides of certain viruses was detected. At 21 days after vaccination, each calf produced neutralizing antibodies to all 20 BVD viruses. At that time, precipitating antibodies to each of the aforementioned viral induced polypeptides were detected in serum from each calf. Precipitating antibodies to viral induced polypeptides of 61,000 and 37,000 daltons were detected in samples of sera obtained from some calves at 42 days after vaccination.  相似文献   

13.
In order to establish the prevalence of viral infections of the bovine fetus in Argentina, a serological survey for antibodies against viral agents currently affecting cattle in this country was conducted. Antibodies against foot-and-mouth disease virus (FMDV), bovine herpesvirus-1 (BHV-1), bovine leukaemia virus (BLV), bovine rotavirus (BRV), bovine coronavirus (BCV), bovine viral diarrhoea virus (BVDV) and parainfluenza-3 (PI-3) were investigated in a total of 315 fetal serum samples. Conventional techniques were used: indirect immunofluorescence (FMDV, BHV-1, BVDv and BCV), radial immunodiffusion (BLV), ELISA (BRV) and haemagglutination inhibition (PI-3). Antibodies against BHV-1, BVDV and PI-3 were detected in samples from fetuses in the second and third trimester of gestation, with a prevalence of 1·21 per cent (two of 165), 2·03 per cent (four of 197) and 5·08 per cent (nine of 177), respectively. Either antibodies or non-antibody factors able to bind to BRV and Bcv antigens were detected with a prevalence of 2·44 per cent (five of 205) and 4·54 per cent (five of 110), respectively. In addition, 14·68 per cent of non-specific inhibitors of PI-3 mediated haemagglutination were found. No seropositives against FMDV and BLV were detected.  相似文献   

14.
Samples of sera were obtained from 5,725 cows in a semiclosed herd. In each of the preceding 7 years, the herd was vaccinated against bovine viral diarrhea (BVD) with killed virus. Neutralizing antibody tests were done on all samples of sera, using cytopathic virus, BVD-TGAC virus, that was antigenically distinct from the vaccine virus. Most samples of sera had high titers of neutralizing antibodies against BVD-TGAC virus. In 48 samples of sera, neutralizing antibodies were not detected against BVD-TGAC virus, but were detected against the vaccine virus. Neutralizing antibodies against selected noncytopathic BVD viruses were not detected in several samples of serum that had neutralizing antibodies against the vaccine virus and BVD-TGAC virus. Noncytopathic BVD virus was isolated from sera obtained from 3 cows less than 4 years old. Two cows were available for further testing, and persistent infection with BVD virus was confirmed in both cows. The BVD viruses isolated from those cows were not neutralized by several samples of sera. Immunoprecipitation of polypeptides induced by the vaccine virus was done with selected samples of serum. Two patterns of immuno-precipitated viral-induced polypeptides were identified. One pattern was consistent with exposure of cows with live virus. The other pattern was consistent with exposure of cows with only the killed virus vaccine.  相似文献   

15.
Spleen cells from a calf hyperimmunized with bovine enteric coronavirus were fused with nonproducer mouse plasmacytoma cells. Stable hybridoma lines secreting bovine immunoglobulins were obtained. One line secreted monoclonal bovine immunoglobulin G2, which reacted specifically with bovine enteric coronavirus in an enzyme-linked immunosorbent assay, inhibited virus hemagglutination, and precipitated a structural polypeptide with a molecular weight of 26,000 daltons.  相似文献   

16.
Complex trapping blocking (CTB) enzyme-linked immunosorbent assays (ELISAs) and indirect ELISAs for the detection of antibodies to canine parvovirus (CPV), canine coronavirus (CCV) and rotavirus in sera of dogs were established. Double antibody sandwich ELISAs for the detection of CPV-, CCV- and rotavirus antigens in fecal samples were also developed. Both the serological and antigen-detection ELISAs were used to screen samples from dogs in The Netherlands, with or without a history of acute diarrhea. It was shown that the results of the respective serological ELISAs correlated well and that CPV was the major cause of virus-induced acute diarrhea in dogs in The Netherlands.  相似文献   

17.
Enzyme-linked immunosorbent assay (ELISA) was compared with electron microscopy in the examination of faeces from experimental calves and showed 100 per cent agreement in the detection of 19 bovine coronavirus and 15 bovine rotavirus electron microscope positive samples. In a limited field survey of calf diarrhoea 75 selected faeces were examined independently by ELISA and electron microscopy and the agreement between the two tests was 95 per cent for coronavirus and 84 per cent for rotavirus. A further comparison was made with 74 samples submitted for routine diagnosis and this yielded agreements of 82 per cent (coronavirus) and 89 per cent (rotavirus). Factors contributing to discrepant results were examined and the relative advantages and disadvantages of the two tests for routine detection of these enteric viruses are discussed.  相似文献   

18.
The use of direct electron microscopy, enzyme-linked immunosorbent assay, and protein A-gold immunoelectron microscopy for the identification of bovine coronavirus and type A rotavirus were examined. Two hundred and forty-nine samples from diarrheic calves and winter dysenteric cattle from seven geographic areas in Quebec were examined for the presence of viruses by direct electron microscopy of negatively stained preparations. In addition, all the samples were analyzed by enzyme-linked immunosorbent assay, and a random selection of 47 samples were also analyzed by protein A-gold immunoelectron microscopy. Thirty-nine percent of samples examined by direct electron microscopy contained viral particles; bovine coronavirus and type A rotavirus were the most common viruses involved. Overall agreement between any two of the methods used compared favorably with results obtained by others using similar methods. The presence of coronavirus and rotavirus in fecal samples obtained from neonatal calves and the presence of coronavirus in samples from winter dysenteric adult cattle suggested their etiological roles in the respective diseases. Furthermore, results from protein A-gold immunoelectron microscopy of coronavirus-like particles implied that a different coronavirus or some other viruses might be involved in these diseases. Finally, the efficiency of direct electron microscopy, enzyme-linked immunosorbent assay and protein A-gold immunoelectron microscopy as diagnostic tools is discussed.  相似文献   

19.
Sera from several groups of experimental calves were tested for cytotoxin neutralizing capacity. The relationship between this capability and resistance of the animals to an experimental challenge was examined. All undiluted bovine sera tested, other than fetal bovine serum, neutralized cytotoxin. Preadsorption of selected sera with formalin-killed P. haemolytica did not reduce their neutralizing capacity. Crude IgG fractions extracted from bovine sera retained neutralizing capacity as well. Cytotoxin neutralization titers were determined by serial dilution of sera from cattle which were previously unexposed, naturally exposed, or exposed by vaccination to the organism. Both live and killed vaccines were used. Prior exposure to live organisms resulted in the production of antibodies to both cell surface antigens and cytotoxin, whereas exposure to the killed vaccine resulted in the production of antibodies primarily to cell surface antigens. Resistance to experimental challenge with the organism correlated directly with serum cytotoxin neutralizing titers.  相似文献   

20.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号