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1.
OBJECTIVE: To determine whether passively acquired antibodies prevent development of a protective immune response to live virus in calves. ANIMALS: 18 calves. PROCEDURES: Calves were caught immediately after birth and tested free of bovine viral diarrhea virus (BVDV) and serum antibodies against BVDV. Within 48 hours, 12 calves were fed colostrum that contained antibodies against BVDV and 6 calves received BVDV antibody free milk replacer. Three milk replacer fed and 6 colostrum fed calves were exposed to virulent BVDV2-1373 at 2 to 5 weeks of life when passively acquired serum antibody titers were high. After serum antibody titers against BVDV had decayed to undetectable concentrations (at 7 to 9 months of age), the 3 remaining milk replacer fed calves, 6 colostrum fed calves previously exposed to BVDV2-1373, and 6 colostrum fed calves that had not been exposed to the virus were inoculated with BVDV2-1373. RESULTS: Passively acquired antibodies prevented clinical disease in inoculated colostrum fed calves at 2 to 5 weeks of life. Serum antibody titers did not increase in these calves following virus inoculation, and serum antibody titers decayed at the same rate as in noninoculated colostrum fed calves. Inoculated colostrum fed calves were still protected from clinical disease after serum antibody titers had decayed to nondetectable concentrations. Same age colostrum fed calves that had not been previously exposed to the virus were not protected. CONCLUSIONS AND CLINICAL RELEVANCE: A protective immune response was mounted in calves with passive immunity, but was not reflected by serum antibodies titers. This finding has implications for evaluating vaccine efficacy and immune status.  相似文献   

2.
OBJECTIVE: To determine the effect of maternally derived antibodies on induction of protective immune responses against bovine viral diarrhea virus (BVDV) type II in young calves vaccinated with a modified-live bovine viral diarrhea virus (BVDV) type I vaccine. DESIGN: Blinded controlled challenge study. ANIMALS: 24 neonatal Holstein and Holstein-cross calves that were deprived of maternal colostrum and fed pooled colostrum that contained a high concentration of (n = 6) or no (18) antibodies to BVDV. PROCEDURE: At 10 to 14 days of age, 6 seropositive and 6 seronegative calves were given a combination vaccine containing modified-live BVDV type I. All calves were kept in isolation for 4.5 months. Six calves of the remaining 12 untreated calves were vaccinated with the same combination vaccine at approximately 4 months of age. Three weeks later, all calves were challenged intranasally with a virulent BVDV type II. RESULTS: Seronegative unvaccinated calves and seropositive calves that were vaccinated at 2 weeks of age developed severe disease, and 4 calves in each of these groups required euthanasia. Seronegative calves that were vaccinated at 2 weeks or 4 months of age developed only mild or no clinical signs of disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that a single dose of a modified-live BVDV type-I vaccine given at 10 to 14 days of age can protect susceptible young calves from virulent BVDV type II infection for at least 4 months, but high concentrations of BVDV-specific maternally derived antibodies can block the induction of the response.  相似文献   

3.
OBJECTIVE: To evaluate the efficacy of an adjuvanted modified-live bovine viral diarrhea virus (BVDV) vaccine against challenge with a virulent type 2 BVDV strain in calves with or without maternal antibodies against the virus. DESIGN: Challenge study. ANIMALS: 23 crossbred dairy calves. PROCEDURES: Calves were fed colostrum containing antibodies against BVDV or colostrum without anti-BVDV antibodies within 6 hours of birth and again 8 to 12 hours after the first feeding. Calves were vaccinated with a commercial modified-live virus combination vaccine or a sham vaccine at approximately 5 weeks of age and challenged with virulent type 2 BVDV 3.5 months after vaccination. Clinical signs of BVDV infection, development of viremia, and variation in WBC counts were recorded for 14 days after challenge exposure. RESULTS: Calves that received colostrum free of anti-BVDV antibodies and were vaccinated with the sham vaccine developed severe disease (4 of the 7 calves died or were euthanatized). Calves that received colostrum free of anti-BVDV antibodies and were vaccinated and calves that received colostrum with anti-BVDV antibodies and were vaccinated developed only mild or no clinical signs of disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the modified-live virus vaccine induced a strong protective immune response in young calves, even when plasma concentrations of maternal antibody were high. In addition, all vaccinated calves were protected against viral shedding, whereas control calves vaccinated with the sham vaccine shed virus for an extended period of time.  相似文献   

4.
Colostrum-replacement products are an alternative to provide passive immunity to neonatal calves; however, their ability to provide adequate levels of antibodies recognizing respiratory viruses has not been described. The objective of this study was to compare the serum levels of IgG at 2 d of age and the duration of detection of antibodies to bovine viral diarrhea virus 1 (BVDV-1), bovine viral diarrhea virus 2 (BVDV-2), bovine respiratory syncytial virus (BRSV), bovine herpesvirus 1 (BHV-1), and bovine parainfluenza virus 3 (BPIV-3) in calves fed maternal colostrum (MC) or a colostrum replacement (CR) at birth. Forty newborn male Holstein calves were assigned to the CR or the MC group. Group CR (n = 20) received 2 packets of colostrum replacement (100 g of IgG per 470-g packet), while group MC (n = 20) received 3.8 L of maternal colostrum. Blood samples for detection of IgG and virus antibodies were collected from each calf at birth, at 2 and 7 d, and monthly until the calves became seronegative. Calves in the MC group had greater IgG concentrations at 2 d of age. The apparent efficiency of absorption of IgG was greater in the MC group than in the CR group, although the difference was not significant. Calves in the CR group had greater concentrations of BVDV neutralizing antibodies during the first 4 mo of life. The levels of antibodies to BRSV, BHV-1, and BPIV-3 were similar in the 2 groups. The mean time to seronegativity was similar for each virus in the 2 groups; however, greater variation was observed in the antibody levels and in the duration of detection of immunity in the MC group than in the CR group. Thus, the CR product provided calves with more uniform levels and duration of antibodies to common bovine respiratory viruses.  相似文献   

5.
This study demonstrated that the bovine viral diarrhea virus (BVDV; types 1 and 2) fractions of a multivalent vaccine protected pregnant heifers and their fetuses at 149 to 217 days of gestation against exposure to calves persistently infected with BVDV type 2a. Eighty percent (eight of 10) of the control heifers were viremic at least 1 day following challenge, whereas all (20 of 20) BVDV-vaccinated heifers were virus isolation-negative on all postchallenge assessment days. Ninety percent (nine of 10) of the calves born to control heifers but only 5% (one of 20) of calves born to BVDV-vaccinated heifers seroconverted to BVDV type 2 before ingesting colostrum. One calf born to a control heifer was persistently infected. No calves from BVDV-vaccinated heifers were persistently infected.  相似文献   

6.
OBJECTIVE: To assess the effect of maternal cells or cellular components on neonatal immune responses to intracellular pathogens in calves. ANIMALS: 15 Holstein calves. PROCEDURES: Calves were fed whole colostrum, frozen colostrum, or cell-free colostrum within 4 hours after birth. Leukocytes were obtained from calves before feeding colostrum and 1, 2, 7, 14, 21, and 28 days after ingestion. Proliferative responses against bovine viral diarrhea virus (BVDV) and mycobacterial purified protein derivatives were evaluated. Dams received a vaccine containing inactivated BVDV, but were not vaccinated against mycobacterial antigens. RESULTS: All calves had essentially no IgG in circulation at birth, but comparable and substantial concentrations by day 1. Calves that received whole colostrum had enhanced responses to BVDV antigen 1 and 2 days after ingestion of colostrum. In contrast, calves that received frozen colostrum or cell-free colostrum did not respond to BVDV. No differences were identified among the 3 groups in response to mycobacterial antigens. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that transfer of live maternal cells from colostrum to neonatal calves enhanced responses to antigens against which the dams had previously responded (BVDV), but not to antigens to which the dams were na?ve (mycobacterial purified protein derivatives). Results suggested that cell-mediated immune transfer to neonates can be enhanced by maternal vaccination.  相似文献   

7.
BPIV-3和BVDV双重RT-PCR快速检测方法的建立   总被引：1，自引：0，他引：1  
参照GenBank中登录的牛副流感病毒3型(BPIV-3)和牛病毒性腹泻病毒(BVDV)全基因序列,分别针对BPIV3特异性NP蛋白保守基因和BVDV保守区段E2基因设计2对引物,经优化反应条件建立了快速鉴别BPIV-3和BVDV的双重RT-PCR诊断方法。最佳扩增条件为94℃30s,56.2℃30s,72℃1min,循环30次;72℃延伸5min,16℃10min;BVDV引物浓度为1.0μmol/L,BPIV-3引物浓度为0.5μmol/L。采用该方法检测BPIV-3和BVDV参考病毒株,能同时扩增出预期为425bp和294bp大小的特异性片段,而扩增牛传染性鼻气管炎病毒、牛合胞体病毒、猪瘟病毒以及牛支原体、致病性大肠埃希菌、多杀性巴氏杆菌A型、化脓隐秘杆菌和鼠伤寒沙门菌等均呈阴性反应。对参考病毒株进行梯度稀释检测,结果证明该方法检测BPIV-3的灵敏度可达10-3 TCID50/0.1mL,而BVDV的灵敏度达102 TCID50/0.1mL。  相似文献   

8.
OBJECTIVE: To determine whether strict closure of a dairy herd and eradication of bovine viral diarrhea virus (BVDV) infection would decrease incidence of diarrhea in calves during the first 31 days after birth, whether specific risk factors were associated with incidence of diarrhea in calves, and whether diarrhea was associated with weight gain of the calves. DESIGN: 2-year cohort study. ANIMALS: 448 calves. PROCEDURE: Calves were monitored from birth to 31 days of age. Fecal samples were tested for rotavirus, blood samples were tested for BVDV and antibodies to BVDV, and serum samples were tested for IgG concentration. Risk factors were evaluated by means of survival analysis. RESULTS: Incidence of diarrhea in calves decreased significantly after strict closure of the herd and eradication of BVDV infection. Risk factors for diarrhea in calves interacted in a multifactorial way. Rotavirus infection and low serum IgG concentration increased the risk that calves would develop diarrhea. Calves that developed diarrhea gained significantly less weight than calves that did not develop diarrhea. CLINICAL IMPLICATIONS: To control diarrhea among calves in a dairy herd, emphasis should be on maintaining a strictly closed herd free from BVDV infection. However, other measures, such as measures to prevent rotavirus infection and to ensure that calves receive an appropriate amount of colostrum after birth, should also be taken.  相似文献   

9.
OBJECTIVE: To determine the prevalence of detectable serum IgG concentrations in calves prior to ingestion of colostrum and to assess whether a detectable IgG concentration was related to dam parity, calf birth weight, calf sex, season of calving, or infectious agents that can be transmitted transplacentally. ANIMALS: 170 Holstein dairy calves. PROCEDURES: Serum samples were obtained from calves prior to ingestion of colostrum, and serologic testing for bovine viral diarrhea virus (BVDV) and Neospora caninum was performed. Relative risk, attributable risk, population attributable risk, and population attributable fraction for calves with a detectable serum IgG concentration attributable to positive results for N caninum and BVDV serologic testing were calculated. Logistic regression analysis was used to determine whether dam parity, calf sex, season of calving, and calf weight were associated with precolostral IgG concentration. RESULTS: 90 (52.9%) calves had a detectable total serum IgG concentration (IgG >or= 16 mg/dL). Relative risk, attributable risk, population attributable risk, and population attributable fraction for calves with a detectable serum IgG concentration attributable to positive results for N caninum serologic testing were 1.66, 0.34, 0.014, and 0.03, respectively. Calf sex, calf birth weight, and season of calving were not significant predictors for detection of serum IgG in precolostral samples. CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of IgG concentrations in precolostral serum samples was higher than reported elsewhere. There was no apparent link between serum antibodies against common infectious agents that can be transmitted transplacentally and detection of measurable serum IgG concentrations.  相似文献   

10.
The objective of this study was to demonstrate the efficacy of a modified-live virus (MLV) vaccine in protecting fetuses from infection with type 1 or type 2 Bovine viral diarrhea virus (BVDV) when pregnant heifers were challenged at approximately 170 d of gestation with noncytopathic field isolates. The 83 pregnant heifers had been bred naturally 4 wk after vaccination. Fetuses were collected 60 d after BVDV type 2 challenge, and newborn calves were collected before colostrum intake after BVDV type 1 challenge. Protection was determined by measuring the serum neutralizing (SN) antibody response in the fetus or calf and by virus isolation from thymus, lung, spleen, and kidney tissue samples. There was a measurable SN antibody response to BVDV in all the fetuses and calves of the control heifers, which had received a placebo vaccine. However, only 4 of 22 calves and 7 of the 28 fetuses of the MLV-vaccinated heifers demonstrated SN antibody after BVDV challenge. Type 1 BVDV was isolated from tissue samples of 5 of the 12 calves of control heifers and none of 22 calves of the MLV-vaccinated heifers challenged with type 1 BVDV. Type 2 BVDV was isolated from tissue samples of 17 of the 18 fetuses of the control heifers and 2 of the 28 fetuses of the MLV-vaccinated heifers challenged with type 2 BVDV. The results of this study demonstrate that the MLV vaccine reduces the fetal infection rate by at least 82% for BVDV type 1 and by 75% for BVDV type 2 when heifers are exposed to highly fetotrophic BVDV at 170 d of gestation.  相似文献   

11.
Four calves were infected with noncytopathic (NCP) New York-1 strain of bovine viral diarrhea virus (BVDV). During the observation period of one month the calves remained clinically normal but the virus was repeatedly recovered from their pharyngeal swabbings and blood. Thirty days following infection the four calves were vaccinated, together with two uninfected calves, with a modified-live vaccine containing cytopathic (CP) BVDV, infectious bovine rhinotracheitis virus and parainfluenza-3 virus. No detrimental effects were observed after vaccination. Forty-three days after vaccination the calves were challenged by exposure either with the CP TVM-2 strain or the NCP New York-1 strain of BVDV. The vaccinated calves remained healthy throughout the 60-day observation period.  相似文献   

12.
本研究从疑似牛病毒性腹泻病毒(bovine viral diarrhea virus,BVDV)感染牛的分泌物与排泄物中分离鉴定1株牛病毒性腹泻病毒,并进行E2基因序列分析。结果表明,分离株病毒命名为JN株;Reed-Muench法测定分离株病毒TCID50为10-7.5/0.1 mL;病毒中和试验结果表明,BVDV JN分离株可被BVDV阳性血清特异性中和,而不能被BVDV阴性血清中和;分离株病毒E2基因序列测序结果表明,该分离毒株属于BVDVⅠa亚型。  相似文献   

13.
牛病毒性腹泻病病毒荧光定量PCR检测体系的建立与评价   总被引：2，自引：0，他引：2  
基于实时荧光定量PCR技术建立了一种有效地检测牛病毒性腹泻病病毒(Bovine viral diarrhea virus,BVDV)核酸的方法.对BVDV基因组进行同源比对,选取5'UTR区作为扩增目的区,经软件分析后设计特异扩增引物,扩增片段长度为203 bp.选用SYBR染料作为扩增时信号指示剂,经扩增曲线分析表明,建立的方法可有效地检测BVDV.检测体系可检测到10~2 copies/μL的样品拷贝数.故本研究建立的BVDV实时定量检测体系可用于易感动物,牛源血液生物制品及其他可能感染或污染BVDV样品的检测.  相似文献   

14.
A panel of 40 monoclonal antibodies (MAb) specific for bovine viral diarrhea virus (BVDV) was produced, and each MAb was characterized and grouped according to its viral protein specificity, immunoglobulin subclass, virus-neutralizing activity, and immunoreactivity with a large collection of BVDV isolates. The MAb were found to be specific for 1 of 3 sets of related viral-induced proteins found in cells infected with the Singer strain of BVDV. Group-1 MAb were specific for the 80- and 118-kilodalton (kD) proteins of BVDV. Group-2 MAb recognized 3 proteins with molecular sizes of 54, 56, and 58 kD. Group-3 MAb recognized a 43- and a 65-kD protein. The MAb belonged to either the IgG1, IgG2a, IgG2b, IgG3 subclasses or the IgE class of mouse immunoglobulin. All MAb in group 2 were able to neutralize BVDV and had neutralization titers that ranged from 24 to 1,600,000. The reactivity of the MAb with numerous field isolates of BVDV was highly variable. Both cytopathic and noncytopathic biotypes of BVDV were examined and had the same degree of antigenic variation. The greatest degree of variation was detected with group-2 MAb. The data demonstrate that BVDV isolates have a high degree of antigenic variation that is largely confined to the envelope glycoproteins associated with virus neutralization. The results also suggest that antigenic variability of this virus is important in the development and severity of the disease it causes.  相似文献   

15.
Bovine viral diarrhea virus (BVDV) has been isolated from washed and sonicated, in vitro-produced embryos, but the infectivity of BVDV associated with intact, developing, embryos has not been demonstrated. The objective of this study was to determine if a dose of BVDV infective for co-culture cells was associated with individual, developing embryos, following artificial exposure to the virus and washing. In 5 replicates, zona pellucida-intact, in vitro-produced embryos were assigned to a negative control embryo group, or were incubated in 10(5)-10(6) cell culture infective doses (50%, CCID50) per milliliter of a type I, noncytopathic (strain SD-1) BVDV for 2 h. Unexposed negative control embryos and exposed positive control embryos were washed, sonicated and assayed for BVDV using virus isolation with immunoperoxidase monolayer assay. Immediately or following cryopreservation, remaining virally-exposed, washed embryos were co-cultured individually with BVDV-negative cultures of bovine uterine tubal cells in a medium free of BVDV-neutralizing activity. After two days in culture, uterine tubal cells and embryos (including the zona pellucida) were separated and washed. The culture medium, uterine tubal cells and embryos were then assayed for BVDV. Bovine viral diarrhea virus was not isolated from any negative control embryo group, but was isolated from all positive control embryo groups. Although all uterine tubal cell populations were confirmed to be susceptible to BVDV, virus was never isolated from uterine tubal cells or embryos from post-exposure culture. In conclusion, although BVDV remains associated with washed in vitro-produced embryos, the virus associated with unsonicated embryos was not infective for uterine tubal cells in vitro.  相似文献   

16.
During the past several years, acute infections with bovine viral diarrhea virus (BVDV) have been causally linked to hemorrhagic and acute mucosal disease-like syndromes with high mortality. The majority of BVDVs isolated in such cases have been classified as type II on the basis of genetic and antigenic characteristics. It was our objective to examine clinical disease, lesions and potential sites of viral replication, following experimental BVDV type II infection in young calves. On approximately day 35 after birth, calves that had received BVDV-antibody-negative colostrum were infected by intranasal inoculation of 5 x 10(5) TCID50 of BVDV type II isolate 24,515 in 5 mL of tissue culture fluid (2.5 mL/nostril). Calves were monitored twice daily for signs of clinical disease. Approximately 48-72 h after infection, all calves developed transient pyrexia (39.4-40.5 degrees C) and leukopenia. Beginning on approximately day 7 after infection, all calves developed watery diarrhea, pyrexia (40.5-41.6 degrees C), marked leukopenia (> or = 75% drop from preinoculation values), variable thrombocytopenia, and moderate to severe depression. Calves were euthanized on days 10, 11, or 12 after infection due to severe disease. Gross and histological lesions consisted of multifocal bronchointerstitial pneumonia (involving 10%-25% of affected lungs), bone marrow hypoplasia and necrosis, and minimal erosive lesions in the alimentary tract. Immunohistochemical staining for BVDV revealed widespread viral antigen usually within epithelial cells, smooth muscle cells and mononuclear phagocytes in multiple organs, including lung, Peyer's patches, gastric mucosa, thymus, adrenal gland, spleen, lymph nodes, bone marrow, and skin. This BVDV type II isolate caused rapidly progressive, severe multisystemic disease in seronegative calves that was associated with widespread distribution of viral antigen and few gross or histological inflammatory lesions.  相似文献   

17.
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18.
Bovine viral diarrhea virus (BVDV) persistently infected (PI) calves represent significant sources of infection to susceptible cattle. The objectives of this study were to determine if PI calves transmitted infection to vaccinated and unvaccinated calves, to determine if BVDV vaccine strains could be differentiated from the PI field strains by subtyping molecular techniques, and if there were different rates of recovery from peripheral blood leukocytes (PBL) versus serums for acutely infected calves. Calves PI with BVDV1b were placed in pens with nonvaccinated and vaccinated calves for 35 d. Peripheral blood leukocytes, serums, and nasal swabs were collected for viral isolation and serology. In addition, transmission of Bovine herpes virus 1 (BHV-1), Parainfluenza-3 virus (PI-3V), and Bovine respiratory syncytial virus (BRSV) was monitored during the 35 d observation period. Bovine viral diarrhea virus subtype 1b was transmitted to both vaccinated and nonvaccinated calves, including BVDV1b seronegative and seropositive calves, after exposure to PI calves. There was evidence of transmission by viral isolation from PBL, nasal swabs, or both, and seroconversions to BVDV1b. For the unvaccinated calves, 83.2% seroconverted to BVDV1b. The high level of transmission by PI calves is illustrated by seroconversion rates of nonvaccinated calves in individual pens: 70% to 100% seroconversion to the BVDV1b. Bovine viral diarrhea virus was isolated from 45 out of 202 calves in this study. These included BVDV1b in ranch and order buyer (OB) calves, plus BVDV strains identified as vaccinal strains that were in modified live virus (MLV) vaccines given to half the OB calves 3 d prior to the study. The BVDV1b isolates in exposed calves were detected between collection days 7 and 21 after exposure to PI calves. Bovine viral diarrhea virus was recovered more frequently from PBL than serum in acutely infected calves. Bovine viral diarrhea virus was also isolated from the lungs of 2 of 7 calves that were dying with pulmonary lesions. Two of the calves dying with pneumonic lesions in the study had been BVDV1b viremic prior to death. Bovine viral diarrhea virus 1b was isolated from both calves that received the killed or MLV vaccines. There were cytopathic (CP) strains isolated from MLV vaccinated calves during the same time frame as the BVDV1b isolations. These viruses were typed by polymerase chain reaction (PCR) and genetic sequencing, and most CP were confirmed as vaccinal origin. A BVDV2 NCP strain was found in only 1 OB calf, on multiple collections, and the calf seroconverted to BVDV2. This virus was not identical to the BVDV2 CP 296 vaccine strain. The use of subtyping is required to differentiate vaccinal strains from the field strains. This study detected 2 different vaccine strains, the BVDV1b in PI calves and infected contact calves, and a heterologous BVDV2 subtype brought in as an acutely infected calf. The MLV vaccination, with BVDV1a and BVDV2 components, administered 3 d prior to exposure to PI calves did not protect 100% against BVDV1b viremias or nasal shedding. There were other agents associated with the bovine respiratory disease signs and lesions in this study including Mannheimia haemolytica, Mycoplasma spp., PI-3V, BRSV, and BHV-1.  相似文献   

19.
Reports of bovine viral diarrhea virus (BVDV) infections in alpacas have been increasing in recent years but much is still unknown about the mechanisms of disease in this species. This report characterizes the transmission of BVDV from persistently infected (PI) alpacas to BVDV naïve alpacas, documents shedding patterns, and characterizes the disease effects in both PI and transiently infected alpacas. Two PI alpacas shed BVDV Type 1b virus in most body fluids, and commonly available diagnostic tests verified their status. Bovine viral diarrhea virus Type 1b transient infections produced only mild signs of disease in BVDV naïve alpacas. Viremia was detected in whole blood, but viral shedding during the acute phase was not detected and antibody appeared to be protective upon re-exposure to the virus.  相似文献   

20.
Induction of effective immunity requires the delivery of a protective antigen with appropriate co-stimulatory signals. For bovine viral diarrhoea virus (BVDV) this antigen is the major viral glycoprotein E2. Neutralising antibodies are directed towards the E2 protein and passive transfer of antibodies in serum or colostrum can completely protect against viral infection. DNA vaccination of mice with a construct encoding the E2 glycoprotein induced neutralising antibody levels that were potentially sufficient to prevent virus replication in a challenge system. The co-delivery of interleukin-2 (IL-2) further enhanced the levels of antibody raised. The strong IgG2a component of the antigen-specific antibody suggests a Th1 bias to the immune response induced following vaccination.  相似文献   

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