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1.
Bovine ephemeral fever in Taiwan (2001-2002)   总被引：3，自引：0，他引：3  
Bovine ephemeral fever (BEF), a vector-borne disease of cattle, is caused by the Ephemerovirus of the family Rhabdoviridae. In the past 40 years, Taiwan has had seven BEF epizootics, and we have previously reported the first five. This study summarizes the 2001 and 2002 epizootics; conducted case-control serologic studies on 10 herds involved in the 2001 epizootic; determined whether the recent BEF viruses have varied significantly; and discusses the relationship between epizootic patterns and possible variant BEF viruses. For mature cows that had received at least 2 doses of vaccine before the study, a negative correlation between the prevaccinated (the 3rd dose and after) serum neutralization antibody (SNA) titers and their postvaccinated peak rates was found. When prevaccinated SNA levels were at < or = 32, their postvaccinated SNA levels increased significantly faster (P<0.01) than for those at > or = 32. The glycoprotein gene of isolates from 1999, 2001, and 2002 had a 99.2-99.9% homology, without consistent amino acid variations in the neutralization sites. Phylogenetic analysis of Taiwanese isolates revealed 2 distinct clusters, the 1983-1989 and 1996-2002 isolates. Cross-neutralization tests confirmed the glycoprotein gene sequence analysis results. In conclusion, annual boosters at SNA levels > 32, at more than 2 doses, or at intervals shorter than 6 months are not advisable. The occurrence of frequent small epizootics implies the dominance of BEF virus over host immunity, but not a variant virus.  相似文献   

2.
Bovine ephemeral fever (BEF) virus vaccines, prepared from the brains of suckling mice infected with strain 525 BEF virus, were evaluated in housed cattle and in the field. The virus in lyophilised preparations was stable for 6 months at -50 degrees C. Thirty-four calves, 5 to 18 months old, were used in laboratory vaccination trials. An increase in serum neutralising antibody was detected in 13 of 14 calves initially free of serum antibody, and all 13 failed to develop clinical illness following challenge with virulent BEF virus. Vaccination resulted in no detectable serum antibody increase in 4 calves, 5 months old, with pre-existing antibody of presumed maternal origin. Seven animals, 18 months of age with serum antibody presumed due to previous BEF infection, developed increased antibody titres following vaccination. In 3 animals vaccinated but not challenged, vaccine-induced antibodies decreased to low levels over 5 months. In contrast, the antibody titres following infection with virulent virus in 2 calves were maintained over 5 months. Field trials, involving 236 animals initially free of serum antibody, were conducted on 5 properties near Mackay and 4 properties near Brisbane. Most of 164 animals were vaccinated with a single dose of lyophilised vaccine containing aluminium hydroxide adjuvant. Only 4 animals failed to develop serum antibody and no adverse reactions to vaccination were reported. Natural infection with BEF occurred in 4 herds at Mackay and clinically mild BEF occurred in 3 of 109 vaccinated and 3 of 46 control animals. On the basis of measured serum antibody titres it was assumed that 8 of 53 animals receiving full vaccine volume, 20 of 40 animals receiving half vaccine volume and 18 of 40 control animals became infected with BEF virus. Two dairy herds in Brisbane became naturally infected with virulent BEF virus 7 months after vaccination. Clinical BEF was observed in 8 of 11 control animals and in 3 of 26 animals which received 2 doses of vaccine. Two strains of BEF virus were isolated from unvaccinated animals that developed clinically mild BEF in the field. These strains either failed to infect, or produced subclinical or very mild BEF, when inoculated intravenously into susceptible calves. The anitbody response to natural infection with apparently mild viruses was short-lived, similar to that produced by vaccination.  相似文献   

3.
Lambs which received colostrum from ewes vaccinated with contagious ecthyma (CE) virus and other lambs vaccinated with CE virus were compared for serum anti-CE immunoglobulin (Ig)G levels, delayed-type hypersensitivity (DTH) responses to CE viral antigen, and protective immunity to challenge with CE virus. Ewes vaccinated 3-4 weeks prior to parturition transferred CE antibody to lambs via colostrum. Although these lambs had higher levels of antibody at challenge than lambs vaccinated when 1-4 days old, only the vaccinated lambs were protected against challenge with CE virus at 1 month of age. Furthermore, the presence of colostrum-derived maternal antibody prevented an active antibody response in lambs to vaccination and/or challenge with CE virus, except where pre-inoculation titres were low. In contrast, the DTH response to CE viral antigen and induction of protective immunity by CE vaccination were not impaired by passively-acquired antibody. Actively immunised lambs could be distinguished from those only receiving passively-acquired antibody by the DTH response to heat-killed CE viral antigen.  相似文献   

4.
Safety tests were conducted in 78 pregnant cows vaccinated with a commercial preparation of a temperature-sensitive vaccine strain of bovine viral diarrhea (BVD) virus. After vaccination, seroconversion was detected in 33 (97%) of 34 cattle that did not have antibodies against BVD virus. Overall, 43 (91%) of 47 cows with prevaccination titers less than or equal to 4 seroconverted. During the test period, cows did not become naturally infected with BVD virus, and BVD-associated reactions to the vaccine were not observed in vaccinated cows. Calves born to vaccinated cows did not have clinical signs of fetal BVD. Precolostral blood samples collected from the progeny of cows that were seronegative at vaccination were free of antibody against BVD virus. Bovine viral diarrhea virus was not isolated from the cattle evaluated in the present study.  相似文献   

5.
A CELL CULTURE VACCINE AGAINST BOVINE EPHEMERAL FEVER   总被引：1，自引：0，他引：1  
SUMMARY A vaccine was prepared from cell culture fluids harvested from the twelfth passage of the 919 strain of bovine ephemeral fever (BEF) virus in Vero cell cultures. Cattle were vaccinated subcutaneously with various combinations of strain 919 virus and adjuvants. Neutralising antibodies were assayed at various times after vaccination and some cattle were challenged by intravenous inoculation with the virulent 417WBC strain of BEF virus. Strain 919 virus of the third and twelfth passage levels in Vero cells produced neither fever, clinical illness nor detectable viraemia in 5 calves inoculated intravenously. Nor could viraemia be detected in 5 heifers receiving vaccine subcutaneously. When the vaccine was administered mixed with aluminium hydroxide adjuvant, the production of neutralising antibodies increased with an increase in the volume of vaccine from 2.5 ml to 10 ml and the response to 2 injections was significantly better than the response to a single injection. The neutralising antibody response was decreased when vaccine was diluted in phosphate buffered saline. The neutralising antibody response following 2 subcutaneous vaccinations with strain 919 virus mixed with aluminium hydroxide adjuvant was higher than that following intravenous inoculation with virulent virus. The vaccine-induced antibodies persisted for at least 12 months, and revaccination at this time led to an increase in the titre of neutralising antibody. Antibodies induced by a single subcutaneous administration of strain 919 virus mixed with Freund's complete adjuvant persisted for at least 40 weeks; those induced by vaccine containing Freund's incomplete adjuvant had virtually disappeared within 16 weeks. All these calves responded to vaccination with aluminium hydroxide-containing vaccine with increases in levels of neutralising antibodies. Of 26 vaccinated calves challenged with virulent BEF virus, 24 remained clinically normal. Two developed brief periods of pyrexia on the seventh day after challenge, but no other clinical signs. One of these calves had a viraemia that was demonstrated only by intravenous inoculation of a susceptible calf. The remaining calf had no detectable viraemia. All of 7 unvaccinated calves developed severe clinical BEF within 5 days of challenge. No disease attributable to the 919 virus occurred in 24 vaccinated pregnant heifers or their newborn calves.  相似文献   

6.
Studies were performed to determine if mucosal vaccination with inactivated avian metapneumovirus (aMPV) subtype C protected turkey poults from clinical disease and virus replication following mucosal challenge. Decreases in clinical disease were not observed in vaccinated groups, and the vaccine failed to inhibit virus replication in the tracheas of 96% of vaccinated birds. Histopathologically, enhancement of pulmonary lesions following virus challenge was associated with birds receiving the inactivated aMPV vaccine compared to unvaccinated birds. As determined by an enzyme-linked immunosorbent assay (ELISA), all virus-challenged groups increased serum immunoglobulin (Ig) G and IgA antibody production against the virus following challenge; however, the unvaccinated aMPV-challenged group displayed the highest increases in virus-neutralizing antibody. On the basis of these results it is concluded that intranasal vaccination with inactivated aMPV does not induce protective immunity, reduce virus shedding, or result in decreased histopathologic lesions.  相似文献   

7.
Outbreaks of infectious bovine rhinotracheitis (IBR) have recently been observed in vaccinated feedlot calves in Alberta a few months post-arrival. To investigate the cause of these outbreaks, lung and tracheal tissues were collected from calves that died of IBR during a post-arrival outbreak of disease. Bovine herpesvirus-1 (BHV-1), the causative agent of IBR, was isolated from 6 out of 15 tissues. Of these 6 isolates, 5 failed to react with a monoclonal antibody specific for one of the epitopes on glycoprotein D, one of the most important antigens of BHV-1. The ability of one of these mutant BHV-1 isolates to cause disease in calves vaccinated with a modified-live IBR vaccine was assessed in an experimental challenge study. After one vaccination, the majority of the calves developed humoral and cellular immune responses. Secondary vaccination resulted in a substantially enhanced level of immunity in all animals. Three months after the second vaccination, calves were either challenged with one of the mutant isolates or with a conventional challenge strain of BHV-1. Regardless of the type of virus used for challenge, vaccinated calves experienced significantly (P < 0.05) less weight loss and temperature rises, had lower nasal scores, and shed less virus than non-vaccinated animals. The only statistically significant (P < 0.05) difference between the 2 challenge viruses was the amount of virus shed, which was higher in non-vaccinated calves challenged with the mutant virus than in those challenged with the conventional virus. These data show that calves vaccinated with a modified-live IBR vaccine are protected from challenge with either the mutant or the conventional virus.  相似文献   

8.
某规模养殖场奶牛群发生布氏杆菌病流行和蔓延,能繁母牛出现流产、死胎症状.根据检疫结果对布氏杆菌病阳性牛隔离淘汰处理,对布氏杆菌病阴性牛(假定健康牛)进行免疫接种.奶牛群口服接种S2株活疫苗后15d,即可检出疫苗诱导的布氏杆菌抗体,30d抗体水平达到高峰(36%),45～90d抗体阳性率呈现缓慢下降的趋势.结果表明,S2...  相似文献   

9.
In a closed dairy herd in the province of Utrecht in 1995, nine replacement heifers were erroneously intramuscularly vaccinated with Tracherine, a live virus IBR vaccine. More than 18 months later, serology of the herd revealed that a large part of the herd had developed an antibody response towards BHV1 (62 of 87 animals). To investigate whether Tracherine had recirculated on the farm, four BHV1 antibody positive animals, of which two had been vaccinated with Tracherine, were treated with corticosteroids to reactivate latent BHV1. Two virus isolates were obtained and subsequently analysed by resctriction enzyme analysis. Both isolates were identified as BHV1.1 subtypes. One of the isolates was clearly distinct from Tracherine and was most likely a BHV1 field virus. A BHV1 field virus was most likely introduced into the farm even though the herd was closed, the animals had not been in contact with other cattle, and preventive hygienic measures had been implemented. There was no indication that Tracherine had recirculated.  相似文献   

10.
Two hundred and fifty dairy heifers were vaccinated at three to six months of age with an intranasal infectious bovine rhinotracheitis-parainfluenza-3 vaccine. Eighteen additional heifers were tested prior to vaccination and again three to four weeks after vaccination. Neither cell-mediated nor humoral immunity was significantly raised to parainfluenza-3 virus in either group of cattle.  相似文献   

11.
Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.  相似文献   

12.
Serum antibody analyses for bovine herpesvirus type 1 (BHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), and bovine rotavirus (BRV) were performed on 527 randomly selected cows, before calving, and on 407 three-week-old calves. In cows and calves, BCV and BRV were the most seroprevalent viruses (80% to 100% according to virus and vaccination status). Bovine respiratory syncytial virus was the least seroprevalent in the cows, independent of the vaccination status. In nonvaccinated cows the seroprevalence to BRSV was 36.7%, and 53.5% in cows vaccinated less than two weeks prior to collecting blood, and 67.6% in cows vaccinated two weeks or more prior to blood collection. In their calves, BHV-1 was the least seroprevalent, independent of the vaccination status. The serological status and antibody titers in calves were generally associated with those of the dam. The occurrence of respiratory diseases in the calves was associated with cow and calf serological profiles (BHV-1, BRSV and BCV in the nonvaccinated group, BHV-1, BVDV and BCV in the vaccinated group). The occurrence of diarrhea was not associated with cow and calf serological profiles but was negatively associated with high level calf serum IgG in the nonvaccinated group (odds ratio = 0.73). Bovine coronavirus and BRV were shed by 1.4% and 4.9% of calves in the nonvaccinated group, and by 0% and 9.9% of calves in the vaccinated group, respectively. Bovine rotavirus shedding was associated with fecal diarrheic consistency at the moment of fecal sampling but not with previous occurrence of diarrhea.  相似文献   

13.
Inactivated virus vaccines have been widely used to control bluetongue after introduction of serotype 8 of the bluetongue virus (BTV) in northern Europe in 2006. To evaluate vaccination, quantitative knowledge of its possible side effects is needed. One current adverse reaction with inactivated vaccines is a rise in body temperature, which could reduce cow reproductive performance. The objective of this study was to quantify a possible side effect of vaccination on fertility before the implantation of the embryo of dairy cows under field conditions. The study was performed on herds that were not exposed to BTV. Fertility was assessed by return-to-service following artificial insemination (AI). Biological assumptions for a possible side effect of vaccination were conception failure and embryonic death. Associations between return-to-service rates and vaccine injections were assessed using mixed-logistic regression models and survival analysis. Two models were considered: a 3-week-return-to-service model comparing cows vaccinated between 3 days before and 16 days after AI and unvaccinated cows (assuming an effect on conception failure or early embryonic death), and a 90-day-return-to-service model comparing cows vaccinated between 3 days before and 42 days after AI and unvaccinated cows (assuming an effect on conception failure, early or late embryonic death). Only cows receiving a second vaccine injection between 2 and 7 days after AI had a significantly higher risk of 3-week-return-to-service (RR=1.19 [1.07-1.33]). This corresponds to an increase of return-to-service by 4 percentage points. A side effect of vaccination could be due to early embryonic death. The slight side effect on fertility associated with vaccination was low compared to effects of BTV-8 exposure on fertility.  相似文献   

14.
In order to develop a safe vaccine against bovine ephemeral fever (BEF) which could be used in areas normally free of the disease, studies were carried out on inactivated virus vaccines. Initial experiments were carried out in cattle using virus vaccines that had been inactivated with β-propiolactone or formalin and then made-up in aluminium phosphate gel or Freund's incomplete adjuvant. A minimum inactivated virus dose of 106 PFU was necessary to stimulate a serum neutralizing antibody response in cattle. β-propiolactone inactivated BEF virus vaccines in Freund's incomplete adjuvant gave the best serum neutralizing antibody responses, producing high levels of neutralizing antibody with both high and low passage level virus. However, the magnitude of the antibody response bore little relationship to resistance of vaccinated animals to challenge with virulent BEF virus. A number of animals with high neutralizing antibody titres to BEF virus did not resist challenge. Using 500-fold less live virus at equivalent passage level to the low passage inactivated vaccine, similar or slightly lower antibody levels were attained, but most of the animals resisted challenge. It is suggested that the nature of the immune response and resistance to BEF infection may be complex and that reliance on serum neutralizing antibody as an indicator of resistance may give misleading results.  相似文献   

15.
Protective immunity against avian influenza (AI) can be elicited in chickens in a single-dose regimen by in ovo vaccination with a replication-competent adenovirus (RCA)-free human adenovirus serotype 5 (Ad)-vector encoding the AI virus (AIV) hemagglutinin (HA). We evaluated vaccine potency, antibody persistence, transfer of maternal antibodies (MtAb), and interference between MtAb and active in ovo or mucosal immunization with RCA-free recombinant Ad expressing a codon-optimized AIV H5 HA gene from A/turkey/WI/68 (AdTW68.H5(ck)). Vaccine coverage and intrapotency test repeatability were based on anti-H5 hemagglutination inhibition (HI) antibody levels detected in in ovo vaccinated chickens. Even though egg inoculation of each replicate was performed by individuals with varying expertise and with different vaccine batches, the average vaccine coverage of three replicates was 85%. The intrapotency test repeatability, which considers both positive as well as negative values, varied between 0.69 and 0.71, indicating effective vaccination. Highly pathogenic (HP) AIV challenge of chicken groups vaccinated with increasing vaccine doses showed 90% protection in chickens receiving > or = 10(8) ifu (infectious units)/bird. The protective dose 50% (PD50) was determined to be 10(6.5) ifu. Even vaccinated chickens that did not develop detectable antibody levels were effectively protected against HP AIV challenge. This result is consistent with previous findings ofAd-vector eliciting T lymphocyte responses. Higher vaccine doses significantly reduced viral shedding as determined by AIV RNA concentration in oropharyngeal swabs. Assessment of antibody persistence showed that antibody levels of in ovo immunized chickens continued to increase until 12 wk and started to decline after 18 wk of age. Intramuscular (IM) booster vaccination with the same vaccine at 16 wk of age significantly increased the antibody responses in breeder hens, and these responses were maintained at high levels throughout the experimental period (34 wk of age). AdTW68.H5(ch)-immunized breeder hens effectively transferred MtAb to progeny chickens. The level of MtAb in the progenies was consistent with the levels detected in the breeders, i.e., intramuscularly boosted breeders transferred higher concentrations of antibodies to the offspring. Maternal antibodies declined with time in the progenies and achieved marginal levels by 34 days of age. Chickens with high maternal antibody levels that were vaccinated either in ovo or via mucosal routes (ocular or spray) did not seroconvert. In contrast, chickens without MtAb successfully developed specific antibody levels after either in ovo or mucosal vaccination. These results indicate that high levels of MtAb interfered with active Ad-vectored vaccination.  相似文献   

16.
Aspects of respiratory tract immunity have been investigated in the bovine species. Using Past. hemolytica type I as the antigen for this model the relationship of nasal and serum antibody production to the route of vaccination and type of vaccine was investigated in a series of 15 dairy calves from two to four months of age. Experimental results indicated that an aerosol vaccination with live Past. hemolytica resulted in a significant nasal antibody response while parenterally vaccinated gave calves with equivalent serum titers had no significant nasal antibody response.  相似文献   

17.
The purpose of the study was to evaluate the short- and long-term immunity after intranasal vaccination in pigs with maternally derived antibodies (MDA). In two experiments, 10-week-old pigs with moderate MDA titres against Aujeszky's disease virus (ADV) were vaccinated intranasally with the Bartha strain of ADV to evaluate the protective immunity conferred at 2 weeks, 2 months and 4 months after vaccination. Protection was evaluated on the basis of severity of clinical signs, periods of fever and growth arrest, and duration and amount of virus excreted after challenge with a virulent ADV. During the first 2-3 weeks after vaccination, antibodies to ADV continued to decline as in unvaccinated control pigs. After that, antibody titres stabilized or gradually increased. At 2 weeks, 2 months and 4 months after vaccination, vaccinated pigs were significantly better protected than unvaccinated controls. The vaccinated pigs challenged 2 weeks after vaccination hardly developed any sign of disease. Mild signs of Aujeszky's disease and a growth arrest period of 5 days were observed in vaccinated pigs challenged 2 months after vaccination, whereas vaccinated pigs challenged 4 months after vaccination developed severe signs of disease and a growth arrest period of 13 days. Vaccinated pigs challenged 2 weeks after vaccination did not excrete challenge virus, and pigs challenged 2 or 4 months after vaccination excreted far less virus than unvaccinated controls. The results demonstrate that intranasal ADV vaccination of pigs with moderate MDA titres protected them from 2 weeks to at least 4 months after vaccination. Immunity steadily declined, however, after vaccination.  相似文献   

18.
Cattle attendants on two farms in the Outer Bratislava district showed symptoms of Q-fever. The blood of the cows in these farms was found to contain antibodies to Coxiella burnetti and the causative agent of the disease was detected in milk samples of aborting cows by biological assays on hamsters (Mesocricetus auratus). The naturally invaded dairy cows with antibodies in the blood and heifers without antibodies were vaccinated with different doses of inactivated suspension of C. burnetii in stage I. A different antibody reaction to vaccination was obtained after the application of a four-fold amount of vaccine. It was proved that the animals did not excrete the causative agent of the infection even after administration of lower doses of the vaccine on the 120th day after vaccination.  相似文献   

19.
A controlled calfhood vaccination trial to prevent bovine virus diarrhea was conducted in a 100 head cow-calf operation with a three year history of annual calf losses due to enteric bovine virus diarrhea (persistently infected herd). Approximately 50% of the calves were vaccinated at six, 12 and 24 weeks of age. Paired serum samples and growth data were collected on three occasions for comparison between vaccinates and controls. Three vaccinated calves died of enteric bovine virus diarrhea in the first year of the trial and one nonvaccinated calf died in the second year. Two of the three vaccinated calves had developed bovine virus diarrhea virus neutralization antibody titres of 2048 or greater before developing clinical signs. The control and third vaccinated calf failed to seroconvert before dying of enteric bovine virus diarrhea. Approximately 90% of the vaccinated calves seroconverted compared to approximately 40% of the controls. Paired serum samples collected from 75% of the cows in the spring, summer and fall of each year of the trial, showed persistent high bovine virus diarrhea virus neutralization titres in all samples. Calf vaccination before 12 weeks of age had little effect on seroconversion due to high levels of passive antibody to bovine virus diarrhea. Growth data showed that there was no improvement in weight gain or rate of growth in the vaccinated calves.  相似文献   

20.
L W Jen  B R Cho 《Avian diseases》1980,24(4):896-907
Studies were made to determine whether infectious bursal disease virus (IBDV) infection would affect the response of chickens to turkey herpesvirus (HVT) vaccination in the development and level of HVT viremia and virus-neutralizing (VN) antibodies to HVT. The HVT viremia in the vaccinated chickens was not affected by IBDV, whether IBDV was inoculated simultaneously with HVT vaccination at one day of age or whether it was inoculated 3 weeks postvaccination with HVT. However, VN antibody response to HVT was significantly suppressed (P less than 0.001) when vaccinated chickens were exposed to IBDV either at the time of vaccination or at 3 weeks postvaccination. Such immunosuppression by IBDV of VN antibody response to HVT vaccination may result in a reduced antiviral immunity against Marek's disease virus.  相似文献   

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