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1.
Four cytopathic strains (81/32F, 81/36F, 81/40F, 82/80F) of bovine rotavirus were shown to be pathogenic for conventionally reared newborn calves. Calves were infected orally, using 3 calves for each isolate. All became febrile, were depressed and diarrhoeic. Two calves, one of which in the group of those infected with 81/36F isolate, and the other infected with strain 81/40F, were killed when moribund. A 3rd calf from the 81/36F infected group, died. At necropsy localized lesions of the small intestines, which are considered to be typical of rotavirus infection, were found. Virus was consistently isolated from the fecal samples of the inoculated calves up to 13 days post-inoculation. It was speculated that some differences existed in the virulence of the bovine rotaviruses tested. The cross protection tests revealed that 1 strain (81/36F) might be antigenically more complex than the others.  相似文献   

2.
Neonatal calf diarrhea induced by rotavirus   总被引：1，自引：0，他引：1  
This presentation summarizes the results of a comprehensive study on rotaviruses isolated in Italy from calves and rabbits affected by neonatal diarrhea. The results clearly indicated that rotavirus infection is widespread and supported the evidence for an etiologic role of these viruses in neonatal diarrhea. The evidence of differences in virulence among bovine rotaviruses appeared also to be confirmed. Conventionally reared calves were fully susceptible to the experimental infection induced by three rotaviruses originating from heterologous hosts, i.e. monkeys, pigs and rabbits, respectively. When rotavirus strains of bovine, simian, porcine and rabbit origin were compared by cross neutralization tests, it was found the simian and porcine strains were indistinguishable and both appeared to relate antigenically to the bovine strain. On the other hand, a reciprocal antigenic correlation was found between bovine and rabbit isolates. Finally, it was proven that feeding newborn calves with colostrum of their dams, previously vaccinated with an inactivated rotavirus vaccine, could prevent the neonatal diarrhea from occurring.  相似文献   

3.
Inoculation at birth with a live attenuated strain of a bovine rotavirus isolated in the USA (scourvax-reo) induced protection in five gnotobiotic calves seven to 21 days later against a UK isolate of pathogenic bovine rotavirus. However, no protection was induced in three calves challenged three to five days after vaccination. There was a close antigenic relationship demonstrated between the two bovine rotavirus isolates. In contrast only one of three gnotobiotic calves inoculated with foal rotavirus, and one of three with human rotavirus, were protected against bovine rotavirus challenge. Protection in these two calves correlated with high heterologous immunofluorescent antibody titre (320 or greater), although the neutralising antibody titres was less than 20.  相似文献   

4.
This review summarizes the results of a study on rotaviruses isolated from calves affected by neonatal diarrhea.

The results indicated that rotavirus infection is widespread and supported the evidence for an etiologic role of these viruses in neonatal diarrhea. Differences in virulence among bovine rotaviruses appeared also to be confirmed.

Conventionally reared calves were fully susceptible to the experimental infection induced by rotaviruses originating from heterologous hosts, i.e. monkeys, pigs and rabbits.

When rotavirus strains of bovine, simian and rabbit origin were compared by cross neutralization tests, it was found the simian and porcine strains were indistinguishable and both appeared to relate antigenically to the bovine strain.

Finally, it was proven that feeding newborn calves with colostrum and first milk of their dams, previously vaccinated with an inactivated adjuvanted rotavirus vaccine, could prevent the neonatal diarrhea from occurring.  相似文献   


5.
Calves which were continuously fed colostrum from vaccinated cows for the first ten days of life, were fully refractory to experimental infection with strain 81/36 F of bovine rotavirus. By contrast, the response to virus exposure of calves which were treated with normal colostrum was identical to that of the control calves, in that they underwent severe diarrhea and a significant slowing of the growth rate. The antibody titer in the milk of vaccinated cows tends to decline rapidly so that it no longer provides any protective effect. Two alternatives were considered feasible in improving prophylaxis for rotavirus infections: (a) the continuous feeding of calves with 1st day colostrum as part of the ration throughout the period of greatest risk (first week of life), or (b) enhancing the efficacy of the vaccine in pregnant cows to the point where antibody concentration in the milk would remain at a protective level.  相似文献   

6.
Eight strains of rotaviruses isolated from diarrheal animals (4 from calves and 4 from piglets) in China were compared by serotyping with reference animal rotavirus strains (bovine NCDV, porcine OSU and simian SA-11 and human rotavirus Wa strain). Two-way cross neutralization test showed no antigenic difference between all 4 local strains of bovine rotavirus (BRV007, BRV014, HN-7 and BRV6555) and reference NCDV, so they belonged to rotavirus serotype 6 (bovine rotavirus serotype 1 or NCDV-serotype). Meanwhile, the four strains of Chinese porcine rotavirus could be determined into 2 different serotypes. One (Li99) was neutralised to a high titer with the antiserum against reference OSU virus and probably related to OSU (serotype 5 or porcine serotype 1). The other three strains (Lin71, Nan86 and Jiang150) were antigenically obviously different from Li99 and did not react with the antiserum against OSU. They were tentatively considered as porcine rotavirus serotype 2. All the strains of bovine and porcine rotavirus did not cross-neutralise with simian SA-11 and human Wa strain. There was also no antigenic relationship between bovine rotaviruses and porcine rotaviruses.  相似文献   

7.
某肉兔养殖场幼兔发生了一起以水样腹泻为主要特征的疫病,通过对病死兔的临床症状和病理剖检观察、RT-PCR检测、动物回归试验等确诊为该兔场发生了兔轮状病毒的感染,通过采取一系列治疗措施,疫情得到了控制。  相似文献   

8.
Attempts to transmit malignant catarrhal fever (MCF) from 16 bovine cases of the 'sheep-associated' form of the disease are described. On two occasions disease was transmitted to bovine calves but transmission to red deer (Cervus elaphus) was not achieved. In addition, MCF was transmitted from one experimentally affected calf to a rabbit and on another occasion directly to rabbits with material from a field case which failed to transmit to a bovine calf or red deer. Subsequently each of these isolates was readily passaged through rabbits and one was also passaged to Syrian hamsters. Tissue from MCF-affected red deer consistently produced disease on inoculation into rabbits and deer but failed to cause disease in bovine calves. Contact infection between red deer occurred once and roe deer (Capreolus capreolus) were also shown to be susceptible to infection by inoculation. Passage of MCF in rabbits with an isolate from red deer failed to produce evidence of further adaptation even after 125 serial passages. Despite the failure to transmit disease from cattle to deer or from deer to cattle it is considered probable that there is only one sheep-associated agent which causes MCF in both species. The reasons for the anomalies in transmission of this form of the disease are discussed.  相似文献   

9.
Three strains (479 C, 778 TL, 982 LE) of infectious bovine rhinotracheitis (IBR) virus isolated from latently infected calves were compared with the prototype strain of IBR virus (LA strain) in studies which included restriction endonuclease analysis, experimental infection, and reciprocal cross protection tests in cattle. From the restriction endonuclease analysis it appeared that the 3 "latent" viruses were derived from the same isolate, and that it differed slightly from the LA strain. However, latency does not seem to have affected the pathogenicity or the immunogenicity of the virus. This is demonstrated by the identical clinical and virologic response of calves subjected to experimental infection with the various strains under study, and by the finding that when the LA strain and a "latent" strain (982 LE) were tested in cross protection tests in cattle, they proved to be mutually protective.  相似文献   

10.
黑龙江省某规模化奶牛场部分新生犊牛发生了严重腹泻且犊牛病死率较高。为了确诊,无菌采集病料,通过病毒检测、细菌分离、生化试验、细菌和病毒特异性基因PCR扩增、动物致病性试验及药敏试验等方法进行了病毒抗原和微生物检测。结果显示,病毒检测中牛轮状病毒（BRV）呈阳性,PCR扩增得到400 bp的特异性片段;从病料中分离到1株含K99和F41兼性菌毛抗原的高致病性产肠毒素大肠杆菌（ETEC）,该分离菌株对恩诺沙星、头孢唑啉、氯霉素敏感,对其他抗生素有一定的耐药性。流行情况调查结合病原学检查确诊该牛场新生犊牛严重腹泻是由BRV和大肠杆菌混合感染造成的,根据诊断结果进行了针对性地防制,取得了良好的防控效果。  相似文献   

11.
Cross-reactive antibody in immunity to colisepticemia in calves   总被引：1，自引：0，他引：1  
Cattle were immunized with a uridine diphosphate galactose epimerase deficient mutant of Escherichia coli to prepare antiserum cross-reactive with different serotypes of E. coli. Hypogammaglobulinemic calves were given bovine anti-J5 serum before oral challenge with virulent E. coli derived from a septicemic calf. Passively immunized calves had delayed and decreased bacteremia compared with calves given saline before challenge. Calves given antiserum also lived longer than control calves. A second experiment using ampicillin and antibody to treat colisepticemia also showed increased survival in anti-serum-treated calves. Decreased bacteremia was probably not due to the killing of the challenge strain by antibody and complement, as the strain was serum-resistant. However, anti-J5 serum did increase phagocytosis of the challenge strain of E. coli (JL9) by bovine neutrophils. Thus, partial protection by antiserum was probably due to increased clearance of bacteria as well as neutralization of endotoxin.  相似文献   

12.
A total of 568 normal feces from calves on a beef farm in Fukui Prefecture, Japan, in 2011–2012 were examined by RT-semi-nested PCR for rotavirus A (RVA) VP4 genes. Through partial sequencing and BLAST analyses of 84 VP4-positive specimens, we identified an avian-like RVA strain, N2342, which shares highest nucleotide identity (80.0%) with known avian-like bovine strain 993/83, in one specimen. Phylogenetic analysis also revealed a close genetic relationship between N2342 and avian RVAs, suggesting bird-to-cattle transmission. We observed frequent contact of wild birds with calves in the farm, suggesting that these birds were the source of the virus.  相似文献   

13.
Newborn calves in a dairy farms suffered from severe diarrhea disease with high mortality in Heilongjiang province.In order to make a definite diagnosis,the pathological samples were collected aseptically and the viral antigens and microorganism were detected by virus detection,bacteria separation,biochemical test,PCR for the specific gene of virus and bacteria,animal pathogenicity test and antimicrobial susceptibility test. The results showed that the virus detection of bovine rotavirus was positive and specific gene fragment of bovine rotavirus was amplified. One E. coli strain with K99 and F41 adhesin antigens which belonged to highly pathogenic enterotoxigenic E. coli was isolated. This strain was sensitive to enrofloxacin,cefamedin and chloramphenicol,however,it showed resistance for other antibiotics. A polyinfection of bovine rotavirus and E. coli were eventually confirmed through epidemic investigation and pathological diagnosis. It had significant preventive effect by taking effective measures according to the diagnosis results.  相似文献   

14.
A strain of bovine herpesvirus-4 (BHV-4) isolated from bovine cases of mammary pustular dermatitis was used for experimental infection of rabbits. The strain is serologically indistinguishable from the group prototype Movar 33/63 and from the American isolate DN599. Groups of rabbits were inoculated by various routes. Intravaginal and conjunctival inoculations resulted in vulvovaginitis and conjunctivitis, respectively, and in shedding of virus. The rabbits seroconverted for the virus, with high titers of antibodies (indirect fluorescent antibody test) that persisted throughout the experiment. Treatment with dexamethasone, beyond the acute infection, did not produce recrudescence of disease or shedding of the virus. Rabbits were killed at various times, from 3 to 6 months post-infection, and the virus was recovered from explant cultures of spleen and by cocultivation of spleen cells with bovine lung cells. These results demonstrate the usefulness of the rabbit as a model for studying the pathogenesis of BHV-4 infection in cattle.  相似文献   

15.
2022年3月,河南省某规模化奶牛养殖场发生一起新生犊牛腹泻病例,在流行病学调查、临床症状观察、病理剖检的基础上,采集6头腹泻犊牛的新鲜粪便进行了寄生虫卵检查、小球隐孢子虫、牛轮状病毒、冠状病毒、大肠杆菌K99抗体检测,血液样品进行了牛病毒性腹泻病毒抗原检测,组织样品进行了细菌分离。结果表明牛轮状病毒抗原6头阳性,阳性率100%;冠状病毒抗原4头阳性、2头阴性,阳性率66.7%;其他病原均为阴性。根据临床症状、病理变化和实验室检测结果,确诊该病例为牛冠状病毒和轮状病毒混合感染引起的犊牛腹泻。根据诊断结果,采取了改善饲养管理、补液、收敛、止泻等综合性防治措施,疫情得到了有效的控制,为临床防治犊牛腹泻提供了参考。  相似文献   

16.
An assay to detect anti-rotavirus antibody-producing cells was developed in rabbits. Sections of alcohol-fixed, paraffin-embedded tissues were used to make an immunofluorescent "sandwich" consisting of specific antibody-producing cells, a concentrated suspension of bovine rotavirus, and rhodamine-conjugated anti-rotavirus serum. Rhodamine-stained, anti-rotavirus antibody-producing cells could be simultaneously stained by a fluorescein-conjugated antiserum reactive to rabbit immunoglobulin.  相似文献   

17.
牛轮状病毒(Bovine rotavirus,BRV)是导致新生犊牛腹泻的主要病原之一,给养牛业造成一定的损失。本文从BRV感染机制、流行情况、预防措施、种间传播及人畜共患病的影响几方面加以综述,为BRV感染犊牛的研究提供有效的依据。  相似文献   

18.
The intestinal and systemic antibody response of calves vaccinated and/or challenged with rotavirus was studied employing isotype-specific ELISAs for the detection of IgG1, IgG2, IgM and IgA antibodies to rotavirus. Monoclonal antibodies to bovine immunoglobulin isotypes of proven specificity were used as conjugated or catching antibody. Five days after oral inoculation (dpi) of a 5-day-old gnotobiotic calf with rotavirus, IgM rotavirus antibodies were excreted in faeces, followed 5 days later by IgA rotavirus antibodies. The increase in IgM rotavirus antibody titre coincided with the inability to detect further rotavirus excretion. Faeces IgM and IgA rotavirus antibody titres fell to low levels within 3 weeks post infection. IgG1 and IgG2 rotavirus antibodies were not detected in faecal samples. In serum, antibodies to rotavirus of all four isotypes were detected, starting with IgM at 5 dpi. Two SPF-calves, which were fed colostrum free of rotavirus antibodies, were vaccinated with a modified live rotavirus vaccine and challenged with virulent rotavirus 6 days later. Upon vaccination, the calves showed an antibody response similar to the response of the infected gnotobiotic calf. Intestinal IgM rotavirus antibodies were excreted before or on the day of challenge and appeared to be associated with protection against challenge infection with virulent virus and rotavirus-induced diarrhoea. In 3 control calves, which were challenged only, the antibody patterns also resembled that of the gnotobiotic calf and again the appearance of IgM rotavirus antibodies coincided with the end of the rotavirus detection period. Two other groups of 3 SPF-calves were treated similarly, but the calves were fed colostrum with rotavirus antibodies during the first 48 h of life. These calves excreted passively acquired IgG1 and IgG2 rotavirus antibodies in their faeces from 2 to 6 days after birth. After vaccination, no IgM or IgA antibody activity in serum or faeces was detectable. Upon challenge, all calves developed diarrhoea and excreted rotavirus. Seven to 10 days after challenge low levels of IgM rotavirus antibody were detected for a short period. These data indicate that the intestinal antibody response of young calves to an enteric viral infection is associated with the excretion of IgM antibodies, immediately followed by IgA antibodies. This response is absent or diminished in calves with passively acquired specific antibodies which may explain the failure to induce a protective intestinal immune response by oral vaccination with modified live rotavirus of calves fed colostrum containing rotavirus antibodies.  相似文献   

19.
Twelve isolates of bovine rotavirus, originating from eight dairy herds in Quebec known to have frequent epizootics of diarrhea in young calves in the last five years, were successfully propagated in cell cultures. The 12 isolates produced clear-cut plaques in BSC-1 cells and, except for one isolate, agglutinated human group "O" erythrocytes to an higher titer than bovine erythrocytes. Antisera to each isolate were produced in rabbits and used to study their antigenic relationships. All the isolates shared the group-specific immunofluorescent antigen and were antigenically related as demonstrated by the seroneutralization and hemagglutination-inhibition tests. However, the relationships to the Nebraska rotavirus was quite weak in cases of two Quebec isolates. When the genomes of the various isolates were compared by polyacrylamide gel electrophoresis, at least three different reproducible fractionation patterns could be identified.  相似文献   

20.
为了明确新疆石河子某规模化奶牛场犊牛腹泻病死率较高的原因。本研究对腹泻犊牛的粪样及病死犊牛肠道内容物进行病原检测,并对分离菌株进行毒力基因检测、耐药基因检测、动物致病性试验及药敏试验。最终明确病因主要由牛冠状病毒(BCoV)和牛轮状病毒(BRV)和大肠杆菌混合感染引起。药敏试验表明,分离到的大肠杆菌对28种抗生素产生了严重的耐药,仅对多粘菌素和呋喃妥因敏感,并且发现该菌同时携带2种毒力基因和10种耐药基因。本研究分离的一株大肠杆菌携带有丰富的耐药基因,具有多重耐药性,为该奶牛场上临床治疗加大了难度。而本试验结果为该养殖场提供科学的临床药物指导,为该牛场治疗此次犊牛腹泻提供了依据,同时为新疆犊牛腹泻混合感染的防控提供了病例参考和技术资料。  相似文献   

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