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1.
Despite the impact of bovine group A rotaviruses (GARVs) as economically important and zoonotic pathogens, there is a scarcity of data on cross-species pathogenicity and extra-intestinal spread of bovine reassortant GARVs. During the course of characterizing the genotypes of all 11 genomic segments of bovine GARVs isolated from diarrheic calves in South Korea, a unique G6P[7] reassortant GARV strain (KJ9-1) was isolated. The strain harbors five bovine-like gene segments (VP7: G6; VP6: I2; VP1: R2; VP3: M2; NSP2: N2, and NSP4: E2), five porcine-like gene segments (VP4: P[7]; NSP1: A1; NSP3: T1, and NSP5: H1), and one human-like gene segment (VP2: C2). To investigate if this reassortant strain possessed cross-species pathogenicity in calves and piglets, and could induce viremia and extra-intestinal spread in calves, colostrum-deprived calves and piglets were experimentally inoculated with the KJ9-1 strain. The KJ9-1 strain caused severe diarrhea in experimentally infected calves with extensive intestinal villous atrophy, but replicated without causing clinical symptoms in experimentally infected piglets. By SYBR Green real-time RT-PCR, viral RNA was detected in sera of the calves at post-inoculation day (PID) 1, reaching a peak at PID3, and then rapidly decreasing from PID4. In addition, viral RNA was detected in the mesenteric lymph node, lungs, liver, choroid plexus, and cerebrospinal fluid. An immunofluorescence assay confirmed viral replication in the extra-intestinal organs and tissues of virus-inoculated calves. The data indicates that the homologous/heterologous origin of the NSP4 gene segment (E2 genotype), may play a key role in the ability to cause diarrhea in calves and piglets.  相似文献   

2.
Direct interspecies transmissions of group A rotaviruses (RVA) have been reported under natural conditions. However, the pathogenicity of RVA has never been directly compared in homologous and heterologous hosts. The bovine RVA/Cow-tc/KOR/K5/2004/G5P[7] strain, which was shown to possess a typical porcine-like genotype constellation similar to that of the G5P[7] prototype RVA/Pig-tc/USA/OSU/1977/G5P9[7] strain, was examined for its pathogenicity and compared with the porcine G5P[7] RVA/Pig-tc/KOR/K71/2006/G5P[7] strain possessing the same genotype constellation. The bovine K5 strain induced diarrhea and histopathological changes in the small intestine of piglets and calves, whereas the porcine K71 strain caused diarrhea and histopathological changes in the small intestine of piglets, but not in calves. Furthermore, the bovine K5 strain showed extra-intestinal tropisms in both piglets and calves, whereas the porcine K71 strain had extra-intestinal tropisms in piglets, but not in calves. Therefore, we performed comparative genomic analysis of the K71 and K5 RVA strains to determine whether specific mutations could be associated with these distinct clinical and pathological phenotypes. Full-length sequencing analyses for the 11 genomic segments for K71 and K5 revealed that these strains were genetically nearly identical to each other. Two nucleotide mutations were found in the 5′ untranslated region (UTR) of NSP5 and the 3′ UTR of NSP3, and eight amino acid mutations in VP1-VP4 and NSP2. Some of these mutations may be critical molecular determinants for RVA virulence and/or pathogenicity.  相似文献   

3.
Group A rotaviruses (GARVs) cause severe acute gastroenteritis in children and young animals. Although zoonotic infections with bovine-like G6 and G8 GARVs have been reported in many countries, there is little evidence for reassortment between bovine GARVs and GARVs from heterologous species. The finding of bovine GARVs with the G6 and G8 genotypes in combination with the typical porcine P[7] prompted us to characterize all 11 genes of 30 bovine GARVs isolated from clinically infected calves. By the comparison of the full-length ORF of VP7 and NSP1-5, and the partial VP1-4 and VP6 nucleotide sequences between the 30 Korean and other known strains, three different genome constellations were found. Twenty seven strains showed the G8-P[7]-I5-R1-C1-M2-A1-N1-T1-E1-H1 genotypes, a single strain possessed the G6-P[7]-I2-R2-C1-M2-A1-N2-T1-E2-H1 genotype constellation and 2 strains the G6-P[7]-I2-R2-C2-M2-A3-N2-T6-E2-H3 genotype constellation. The complete genome of a single reference strains for each of these three genotype constellations (KJ25, KJ9-1 and KJ19-2) was determined and analyzed. A detailed phylogenetic analysis revealed a complicated picture, with several reassortments among bovine-like, porcine-like and human-like GARV strains, resulting in several different reassortant strains successfully infecting cattle.  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.
There exists experimental evidence that necrotoxigenic Escherichia coli (NTEC) strains producing the cytotoxic necrotising factor 1 cause intestinal and extra-intestinal disease in piglets. On the other hand, no experimental model has been developed with NTEC strains producing the cytotoxic necrotising factor 2. In all, 14 colostrum-restricted calves were orally challenged with two strains isolated from the faeces of a diarrheic calf (B20a) or from the heart blood of a septicaemic calf (1404). All calves had diarrhoea which lasted until euthanasia in eight of them. In those calves, diarrhoea was correlated with the faecal excretion of the challenge strains. At necropsy, vascular congestion of the intestinal mucosa, hypertrophy of the mesenteric lymph nodes (MLN) and some congestion of the lungs were observed. Bacteriology confirmed the colonisation of the intestine by the challenge strains which were also recovered from the heart blood, the lungs and/or the liver. Histological sections confirmed enterocolitis, lymphadenitis and limited bronchopneumonia. In the intestinal tissue sections, bacteria testing positive in an in situ DNA hybridisation assay with a CNF2 probe were observed. Those results were confirmed by immunohistochemistry with a polyclonal anti-O78 and a monoclonal anti-F17b antisera. Three of the five control calves receiving either saline or a CNF(-), F17a strain (25KH09) had no clinical signs or lesions. The other two presented a profuse liquid diarrhoea but those calves were positive for the presence of K99(+) E. coli. In this model, both NTEC2 strains were thus, able to colonise the intestine, to cause long-lasting diarrhoea and to invade the blood stream with localisation in various internal organs in colostrum-restricted conventional newborn calves.  相似文献   

6.
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.  相似文献   

7.
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   

8.
为研究不同毒力的PRRSV对仔猪肺脏和外周免疫器官损伤的差异,本实验分别采用PRRSV变异株(HuN4株)和PRRSV经典株(CH-1a株)感染35日龄健康的断奶仔猪,并在感染后0 d、3 d、7 d、10 d和14 d各迫杀3头,检测肺、颌下淋巴结、肠系淋巴结、腹股沟淋巴结、扁桃体和脾脏的病毒载量及病理变化情况,同时检测血清中抗PRRSV的抗体水平。结果表明:感染后3 d肺脏及各免疫器官可检测到病毒,HuN4感染组病毒载量比CH-1a感染组病毒载量高1 000倍;HuN4感染组病毒载量峰值出现在感染后10 d,而CH-1a感染组维持着较低水平的病毒载量。组织病理学检测显示HuN4感染组淋巴结内淋巴细胞显著减少,呈空泡状;CH-1a感染组淋巴结内淋巴细胞轻度减少,呈星隙状。本实验表明HuN4株比CH-1a株对肺和外周免疫器官造成更严重的损伤。  相似文献   

9.
Eight clinically healthy calves were inoculated intranasally, four with either noncytopathic or four with cytopathic bovine viral diarrhea virus, and were necropsied 5 or 12 days post-inoculation. The most frequent gross lesion associated with noncytopathic or cytopathic viral infection was proximal colonic mural edema. Consistent microscopic findings were acute to subacute tracheitis, mild enterocolitis with edema, petechial hemorrhages of mesenteric lymph nodes with mild follicular lymphocytic depletion, and paracortical lymphocytic hyperplasia. At necropsy, cytopathic virus was recovered from 4/4 calves and noncytopathic virus was isolated from 2/4 calves. Neutralizing antibodies to noncytopathic bovine viral diarrhea virus were detected in the two calves from which noncytopathic virus was not recovered. Immunohistochemical analysis of lymphoid tissues demonstrated a small, randomly distributed population of mononuclear cells that contained bovine viral diarrhea viral antigen in 7/8 calves.  相似文献   

10.
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.  相似文献   

11.
A study of the basis of virulence variation of bovine rotaviruses.   总被引：3，自引：0，他引：3  
Rotaviruses are enteric pathogens of cattle but sub-clinical infections are common. Virulence variation has been identified with bovine rotaviruses and some rotaviruses replicated without clinical signs in non-immune calves. The rotavirus genome is composed of eleven segments of double-stranded RNA and the fourth largest segment codes for a non-glycosylated surface protein, VP4, which has been linked with virulence. In the present study the biological basis of rotavirus virulence variation was studied in vivo and compared with the known properties of the fourth gene. Calves were inoculated orally with a virulent rotavirus or a rotavirus of low virulence which multiplied but failed to cause diarrhoea. They were taken for necropsy at intervals of 2 days after inoculation. Clinical signs, virus in faeces and the percentage of infected small intestinal epithelium were determined. Damage to the small intestine was assessed by measurement of villus heights and crypt-cell production rates. Virulence was associated with a greater level of colonization of the small intestinal epithelium, greater enterocyte damage and preferential infection of the upper small intestine. The fourth gene determines the ability of rotaviruses to spread in vitro and the finding that virulence was associated with greater colonization in vivo raises the possibility that this gene may have an important role in rotavirus virulence.  相似文献   

12.
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   

13.
Identification of a bovine enteric syncytial virus as a nongroup A rotavirus   总被引：10，自引：0，他引：10  
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.  相似文献   

14.
Rotaviruses are important enteric pathogens of humans and animals. Group A rotaviruses (GARVs) account for up to 1 million children deaths each year, chiefly in developing countries and human vaccines are now available in many countries. Rotavirus-associated enteritis is a major problem in livestock animals, notably in young calves and piglets. Early in the epidemiological GARV studies in humans, either sporadic cases or epidemics by atypical, animal-like GARV strains were described. Complete genome sequencing of human and animal GARV strains has revealed a striking genetic heterogeneity in the 11 double stranded RNA segments across different rotavirus strains and has provided evidence for frequent intersections between the evolution of human and animal rotaviruses, as a result of multiple, repeated events of interspecies transmission and subsequent adaptation.  相似文献   

15.
A bovine viral diarrhea virus (BVDV-C) was isolated from swine tissue culture cells used to attenuate the transmissible gastroenteritis virus (TGEV) after 68 passes. Piglets given a pure culture of BVDV-C developed clinical signs similar to those of a mild TGEV infection and recovered by 10 days postexposure. Villous blunting and fusion was observed in the small intestine, and a lymphocyte depletion was observed in Peyer's patches in the ileum. Piglets given a combination of BVDV-C and attenuated TGEV developed clinical signs similar to those of a virulent TGEV infection and were euthanized. The combined infection induced a generalized lymphocyte depletion throughout the lymphatic system and villous atrophy in the intestinal tract. Piglets exposed to a another type I strain of BVDV (NY-1) either alone or in combination with the attenuated TGEV had mild clinical signs similar to those of a TGEV infection. Moderate villous atrophy in the ileum and a lymphocyte depletion in the mesenteric lymph node were observed in these piglets postmortem. The data indicate a potential problem for diagnostic laboratories in relation to a diagnosis of virulent TGEV infections and in the field for young piglets exposed to a BVDV-contaminated TGEV vaccine.  相似文献   

16.
给8头生后3d的哺乳仔猪经口感染猪流行性腹泻病毒(PEDV)“吉”毒株,于感染后18、30、45和96h各扑杀2头,以透射电镜和扫描电镜观察了小肠粘膜上皮细胞及肠系膜淋巴结的超微结构。结果表明,小肠上皮细胞的病变因感染时间不同而有明显差异。上皮细胞的脱落和残留上皮细胞超微结构的破坏,以感染后30h最严重,病毒在这些上皮细胞内的增殖最显著。感染后45h,见有大量新生上皮细胞修补损伤的肠绒毛。感染后96h,小肠绒毛短缩、粗大乃至发生融合。实验仔猪肠系膜淋巴结内巨噬细胞和淋巴细胞的超微结构均遭到破坏,在巨噬细胞内见有PED冠状病毒粒子。  相似文献   

17.
Routine isolation and cultivation of bovine rotaviruses in cell culture   总被引：3，自引：0，他引：3  
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.  相似文献   

18.
Salmonella dublin strain SL5631, which is auxotrophic for p-amino-benzoic acid and 2,3-dihydroxybenzoate because of a deleted aroA gene, was given orally in a dose of 10(10) live bacteria to 6 calves 5-7 weeks old. The calves tolerated the strain well, had a transient mucoid diarrhea and sacrificed animals showed a moderate acute inflammation in the ileum on day 2. The salmonella strain was seen lining the mucosal epithelium using immunohistopathology. Already in calves sacrificed on day 6 the damage was less pronounced and signs of regeneration were obvious. The healing process was more accentuated in calves sacrificed on day 14. The results demonstrated the attenuating effect of the deleted aroA gene. Groups of 5-7 weeks old calves (n = 25) orally immunized with 10(8), 10(9) and 10(10) S. dublin SL5631 at weekly intervals were challenged 2, 6 or 15 weeks after the immunization. All calves were protected against oral challenge with 10(10) bacteria of the virulent S. dublin strain, which equals 1,000 LD50 doses. At autopsy, calves were sacrificed 3 weeks after challenge, all calves had normal intestinal findings with only slightly enlarged mesenteric lymph nodes. The protective effect is surmised to involve cell-mediated as well as humoral defense mechanisms.  相似文献   

19.
A total of 763 fecal or intestinal samples from diarrheic calves and piglets were examined for viral content by immunofluorescence, electron microscopy or cell culture. Routine fluorescent antibody and cultural tests detected rotavirus (n=126), coronavirus (n=80) and bovine viral diarrhea virus (n=13). Electron microscopy detected rotaviruses (n=24) and coronaviruses (n=17) not identified by standard fluorescent antibody tests. Other viruses detected by electron microscopy included Breda virus-like particles (n=49), astroviruses (n=1), caliciviruses (n=1), rhabdoviruses (n=1), parvoviruses (n=2), enteroviruses (n=3), togavirus-like particles (n=2), and “chained” particles (n=5). Mixtures of several of the viruses were detected in a number of fecal samples.

The survey emphasized the value of electron microscopy as a broad-spectrum diagnostic tool.

  相似文献   

20.
A noncytopathogenic field strain of bovine viral diarrhea virus (BVDV) was isolated from an Iowa farm brood sow and from her hysterectomy-derived, colostrum-deprived (HDCD) piglets. This field isolant was fully virulent for a neonatal calf. The NADL strain of BVDV was passaged through a series of HDCD piglets with no resultant loss of virulence for neonatal calves. Most of the BVD viral isolants recovered from pigs had been changed from a cytopathogenic biotype to a noncytopathogenic biotype. Circumstantial evidence points to swine as “carrier” hosts of BVDV.  相似文献   

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