Neonatal calf diarrhea induced by rotavirus

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.     

Serotyping and antigenic comparison of some animal rotaviruses isolated in China.

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.     

Identification of a bovine enteric syncytial virus as a nongroup A rotavirus

An atypical or nongroup A rotavirus was identified in feces obtained from gnotobiotic calves in which fecal preparations originally derived during an epizootic of neonatal calf diarrhea had been serially passaged. The epizootic was previously reported to be caused by a noncharacterized viral agent that induced the formation of epithelial syncytia on small intestinal villi of experimentally infected calves. This bovine, nongroup A rotavirus was found to be antigenically related to a described atypical rotavirus of rats by immunofluorescence and by enzyme immunoassay. Complementary DNA derived from the atypical rat rotavirus cross hybridized with RNA obtained from the bovine virus, but not with RNA extracted from group A rotaviruses. Complementary DNA derived from SA-11 group A rotavirus cross hybridized with other group A rotavirus RNA, but not with RNA obtained from either the rat or bovine nongroup A isolates. Additionally, another similar, if not identical, bovine atypical rotavirus was identified in a second epizootic of neonatal calf diarrhea that occurred several hundred kilometers and 8 months apart from the original epizootic.     

Primary isolation of cytopathic bovine rotaviruses on fetal rhesus monkey kidney cells

Primary isolation of bovine rotaviruses was successfully performed on rolling cultures of MA104 cells following trypsin treatment of fecal samples and cells. Fifty-one fecal samples were obtained from 22 herds affected with naturally-occurring acute diarrhea in calves during a period of over two years. Rotavirus particles were demonstrated in only 10 fecal samples by electron microscopy. Fourteen cytopathic bovine rotaviruses were isolated from positive samples and could be serially cultivated on MA104 cells. The presence of virus was identified by specific immunofluorescence in infected cells. These data indicated that approximately 30% of the herds affected with acute diarrhea in their calves were associated with rotavirus infection.     

Experimental infection and cross protection tests in calves with cytopathic strains of bovine rotavirus

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.     

Detection of rotavirus in faecal specimens with a monoclonal antibody enzyme-linked immunosorbent assay: Comparison with polyclonal antibody enzyme immuno-assays and a latex agglutination test

Monoclonal antibodies have been produced against the 81/36F strain of rotavirus. One of them, was chosen as diagnostic reagent: it showed high ELISA reactivity with all the bovine, human and porcine rotavirus strains tested and reacted with VP6, structural protein product known to support the common rotavirus antigen.

A sandwich ELISA procedure using the chosen monoclonal as “capture and detecting” antibody was performed to detect rotavirus in faecal samples from experimentally inoculated newborn calves: it always gave a negative response with meconium and a positive response for the stool specimens which rotavirus have been isolated. This assay was compared with Enzygnost and Slidex Rota Kit tests and with a non-commercial sandwich ELISA test using polyclonal antibodies: it showed more sensitivity than the agglutination test and was as sensitive as the other two tests to detect rotavirus in routine diagnostic material. The test evaluated showed no equivocal results.     

牛病毒性腹泻病毒、大肠杆菌和奇异变形杆菌混合感染致犊牛腹泻的研究

为确定甘肃省临夏州某奶牛场犊牛腹泻的病因,并提供合适的治疗方案和防控措施,试验采集该牛场13头腹泻犊牛的粪便和血清,通过胶体金技术、ELISA方法、细菌分离鉴定、Kirby-Bauer法分别进行病毒病原学检测、病毒血清学抗体检测、病原菌鉴定和药物敏感性试验。病毒学检测结果显示,13份粪样中未检测出牛轮状病毒（BRV）、牛冠状病毒（BCV）的抗原,牛病毒性腹泻病毒（BVDV）抗原阳性率为23.08%（3/13）;未检出BRV和BCV的抗体,BVDV血清学抗体阳性率为38.46%（5/13）。病原菌检测结果显示,13份粪便样品中,分离出13株大肠杆菌和7株奇异变形杆菌。药敏试验表明,分离的大肠杆菌和奇异变形杆菌对20种常规药物均产生了不同程度的耐药,且无对两种细菌均有效的药物。此次犊牛腹泻是由BVDV、大肠杆菌、奇异变形杆菌混合感染引起的,且大肠杆菌和奇异变形杆菌的耐药现象严重,本试验结果为该牛场进一步治疗此次的犊牛腹泻病提供了合理有效的依据。     

Routine isolation and cultivation of bovine rotaviruses in cell culture

Using the bovine embryonic kidney cell line, Aubek, bovine rotaviruses were routinely isolated from fecal samples of calves with diarrhea. Of 125 fecal samples positive for rotavirus by immune electron microscopy and the enzyme-linked immunosorbent assay, 61 isolates were recovered and cultivated continuously.     

An experimental study of Bungowannah virus infection in weaner aged pigs

Animal-to-human interspecies transmission is one of the evolutionary mechanisms driving rotavirus strain diversity in humans. Although quite a few studies emanating from Africa revealed evidence of bovine-to-human rotavirus interspecies transmission, whole genome data of African bovine rotavirus strains are not yet available. To gain insight into the complete genome constellation of African bovine rotaviruses, the full genomes of three bovine rotavirus strains were extracted from stool samples collected from calves, amplified using a sequence-independent procedure, followed by 454(?) pyrosequencing. Strains RVA/Cow-wt/ZAF/1603/2007/G6P[5] and RVA/Cow-wt/ZAF/1605/2007/G6P[5] were both genotyped as G6-P[5]-I2-R2-C2-M2-A3-N2-T6-E2-H3 and were probably two variants of the same rotavirus due to their close nucleotide sequence similarity. The genotype constellation of strain RVA/Cow-wt/ZAF/1604/2007/G8P[1] was G8-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3. The genetic relationships and phylogenetic analyses suggested that these three bovine rotavirus strains may have emerged through multiple reassortment events between bovine, giraffe and antelope rotaviruses. Due to the close relatedness of genome segments 1 (encoding VP1), 7 (NSP2), 9 (VP7) and 10 (NSP4) of strain RVA/Cow-wt/ZAF/1604/2007/G8P[1] to those of the corresponding segments of human rotaviruses, RVA strain 1604 may represent bovine strains that were transmitted to humans and possibly reassorted with human rotaviruses previously. The complete nucleotide sequences of the bovine rotavirus strains reported in this study represent the first whole genome data of bovine rotaviruses from Africa.     

一例冠状病毒、轮状病毒混合感染引起犊牛腹泻的诊治

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。     

Certain enteropathogens in calves of Finnish dairy herds with recurrent outbreaks of diarrhea

The occurrence and distribution of certain enteropathogenic organisms and the manifestation of diarrhea, especially in relation to colostral management, were studied in neonatal calves of eight southern Finnish dairy herds with recurrent outbreaks of enteric disturbances. The fecal samples were obtained from the calves and were provided by the farmers. Potentially pathogenic agents were demonstrated in 52 of the 68 calves studied. Cryptosporidium was found in 36 of them while rotavirus was found in 29 and Escherichia coli in 15 of them, either singly or in combination. Salmonella, coronavirus or parvovirus were not detected in any of the calves. Twenty-six of the 36 calves contracted their Cryptosporidium infection and 18 of the 29 calves their rotavirus infection within the first week of life.

Eighteen of the 52 infected calves developed diarrhea of microbial origin within 20 days of age; the most frequent finding was mixed infection with Cryptosporidium and rotavirus. In addition there were six diarrheic calves where no infection could be demonstrated. Only 10 of the 68 calves had neither infections nor diarrhea. There was a highly significant difference between the mean times of the first colostral feeding of the uninfected non-diarrheic and diarrheic calves and a significant difference between the mean times of the first colostral feeding of the subclinically infected and diarrheic calves. The importance of sucking of colostrum at the first feeding was observed. The smallest amount protecting the calves from infections was 0.75 1 given within 1 h of delivery.     

A study of cytopathic rotavirus strains isolated from calves with acute enteritis

Nine cytopathic bovine rotavirus strains were isolated in MA-104 cell cultures from fecal specimens of dairy calves suffering from diarrhea. Isolation of the virus was accomplished from three outbreaks which occurred on dairy farms located in Central and Southern Italy. Fecal suspensions were treated with a high concentration (1000 micrograms/ml) of trypsin, and inoculated into MA-104 cell cultures grown out in Eagle's minimum essential medium (MEM) containing 5 micrograms/ml of the enzyme. Cytopathic effects (CPE), characterized by intracytoplasmic inclusion bodies of different sizes and shapes, were observed on the 1st passage with five of the strains and on the 2nd (2 strains) or the 3rd (2 strains) passage for the others. The presence of trypsin and the use of MA-104 cells appeared to be essential for the occurrence of CPE, inasmuch as no CPE was detected when trypsin was omitted in the MA-104 cell system. Replication failed to occur when primary bovine embryo kidney cell cultures with or without trypsin were used. Electron microscopy revealed the presence of particles with a typical rotavirus morphology. In MA-104 cells, the titre of virus reached its maximum 48 hr after inoculation. Small, clear-cut plaques were produced by the isolates in MA-104 cells under the overlay of MEM containing carboxymethyl cellulose, trypsin and DEAE-dextran. The nine rotavirus strains were antigenically related, whereas the relationship to either the Nebraska or the Compton rotaviruses was quite weak.     

Enteric infections in veal calves: a longitudinal study on four veal calf units

Forty-five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.     

Mechanism of protection from primary bovine viral diarrhea virus infection. I. The effects of dexamethasone.

A series of investigations was designed to study the role of cellular immunity and passive antibody in protecting neonatal calves from primary bovine viral diarrhea virus infection. Administration of corticosteroids (dexamethasone) in doses capable of suppressing cellular immunity markedly potentiated systemic bovine viral diarrhea virus infection in calves which lacked bovine viral diarrhea passive neutralizing antibody. Immunosuppressed calves did not form neutralizing antibody to bovine viral diarrhea virus and developed a fatal viremia. Calves with high levels of passive bovine viral diarrhea neutralizing antibodies were protected from the effect of corticosteroids. The results suggest an essential role for humoral passive antibody, but not for cellular immunity, in protection from primary systemic bovine viral diarrhea virus infection in calves.     

牛轮状病毒研究进展

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。     

Enzyme-linked immunosorbent assay, using monoclonal antibody, to detect enterotoxic Escherichia coli K99 antigen in feces of dairy calves

A modified, double-antibody, enzyme-linked immunosorbent assay (ELISA) was developed to detect the K99 pilus antigen of enterotoxic Escherichia coli (ETEC) in feces of calves. Extremely high positive to negative ratios (greater than 200) were obtained by using monoclonal antisera as the primary antibody. Strong positive reactions were obtained with strains of E coli known to produce the K99 antigen; however, non-enteropathogenic E coli (strains not producing the K99 antigen), Salmonella, Proteus, Klebsiella, Pseudomonas, Staphylococcus, Streptococcus, and rotavirus produced negative results. Seventy-five fecal samples, 8 from healthy calves and 67 from calves with neonatal calf diarrhea were examined with the K99 ELISA for the presence of ETEC. Rotavirus test and fecal culture results were available on feces from calves with diarrhea and were used with the K99 ELISA results to determine the specific cause of the disease. Enterotoxic E coli was the predominant agent detected in the feces of 29 diarrheal calves less than 5 days of age. Mixed infections of rotavirus and ETEC were also common in these calves, but rotavirus infections alone were not detected. In 38 calves greater than or equal to 5 days, rotavirus was detected without ETEC. Of these calves, only 2 produced positive tests with the K99 ELISA. Salmonella sp and Proteus sp were detected from 5 of 67 calves with diarrhea.     

Correlation between maternal serum antibodies and protection against bovine rotavirus diarrhea in calves

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.     

Enteric infections in veal calves: A longitudinal study on four veal calf units

Summary

Forty‐five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.     

Longitudinal study of bovine rotavirus group A in newborn calves from vaccinated and unvaccinated dairy herds

Reports of rotavirus excretion in calves usually result from cross-sectional studies, and in face of the conflicting results regarding protection of calves born to vaccinated dams against diarrhea, the aim of the present study was to evaluate rotavirus excretion in dairy calves born to vaccinated or unvaccinated dams, to identify the genotypes of bovine rotavirus group A (RVA) strains isolated from these animals as well as to investigate characteristics of the disease in naturally occurring circumstances throughout the first month of life. Five hundred fifty-two fecal samples were taken from 56 calves, 28 from each farm and, in the vaccinated herd, 11/281 samples (3.91%) taken from six different calves tested positive for RVA while in the unvaccinated herd, 3/271 samples (1.11%) taken from 3 different calves tested positive. The genotyping of the VP7 genes showed 91.2% nucleotide sequence identity to G6 genotype (NCDV strain), and for the VP4 gene, strains from the vaccinated herd were 96.6% related to B223 strain, while strains from the unvaccinated herd were 88% related to P[5] genotype (UK strain). Genotypes found in this study were G6P[11] in the vaccinated herd and G6P[5] in the unvaccinated herd. All calves infected with rotavirus presented an episode of diarrhea in the first month of life, and the discrepancy between the genotypes found in the commercial vaccine (G6P[1] and G10P[11]) and the rotavirus strains circulating in both vaccinated and unvaccinated herds show the importance of keeping constant surveillance in order to avoid potential causes of vaccination failure.     

Epizootiology of bovine rotavirus infection.

Published information on rotaviruses as pathogens, the source of virus infection and the method of transmission of infection under normal conditions are reviewed. The antigenic differences between rotavirus isolates from children, calves, pigs, foals and mice are discussed. Bovine rotaviruses isolated in the USA and the UK were shown to be closely related antigenically and the US vaccine strain protected calves from challenge with the UK rotavirus. Nineteen normally reared calves, with 20 or more ZnSO4 units of serum delta globulin, were susceptible to rotavirus inoculation at two days of age. They developed diarrhoea, showed body weight loss but recovered. Three calves with less than 10 ZnSO4 units of serum delta globulin developed diarrhoea and died. In a serological survey of 654 adult cows and calves from three herds, between 2 per cent and 37 per cent of individuals in a group had low rotavirus antibody titres and were probably susceptible to rotavirus infection. These were found in all age groups of animals studied, whether or not the group had suffered a recent rotavirus epizootic. It was not possible to predict whether an epizootic would develop on the basis of a serological survey.