Identification and characterization of a plaque forming avian rotavirus isolated from a wild bird in Japan.

From fresh faeces of a wild bird (Melanitta fusca), a virus that showed granular cytopathic effects (CPE) on chicken kidney cell (CKC) cultures was isolated. By indirect immunofluorescence analyses (IFA), this isolate reacted with an antiserum against a bovine rotavirus. The isolate produced clear plaques on CKC by conventional techniques, without trypsin. Three virus plaques were selected by plaque size (small, medium, and large) and cloned by three successive plaque cloning. In the SDS-PAGE analyses, dsRNA bands showed a typical profile of avian rotavirus and quite different from that of avian reovirus. With dsRNA patterns, IFA results, CPE, and a morphological property, the clones were identified as avian rotaviruses of group A rotavirus. The clones killed chicken embryos, when they were inoculated to yolk sac.     

A sensitive plaque assay for bovine rotavirus in cultures of the bovine cell line GBK

The Lincoln strain of bovine rotavirus was found to replicate with cytopathic effects in cultures of GBK cells, a stable cell line derived from bovine kidney, when the cultures were maintained in the presence of trypsin. The virus was readily passaged and the infected cells were shown to contain specific viral antigen by indirect immunofluorescent staining. The virus formed plaques in GBK cell monolayers, when trypsin was incorporated in the agar overlay medium. The plaque count increased about twofold when diethylaminoethyl dextran was further included in the overlay medium. Plaque assay in GBK cells was more sensitive than that in MA-104 cells previously reported by Matsuno et al. The specificity of plaques was confirmed by specific inhibition with antiserum against the Lincoln strain.     

Development and comparison of serologic methods for diagnosing chicken anemia virus infection.

This paper describes the development of an indirect immunoperoxidase assay (IIP) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to chicken anemia virus (VAC). The IIP assay developed used CAV-infected MDCC-MSB1 cells for detecting antibody to CAV, whereas the ELISA utilized gradient-purified immunoadsorbed CAV as the target antigen. The IIP and ELISA were compared with the standard indirect immunofluorescent antibody (IFA) assay, which is more conventionally used to screen chicken serum for antibodies against CAV. Comparative test results of 185 field samples of chicken serum by these three methods were in agreement 84% of the time. Both IFA and IIP assays yielded fewer positive tests than did the ELISA. IFA and IIP assays were in agreement 93% of the time, as compared with 91% agreement of IIP and ELISA results, or 84% agreement for comparative IFA and ELISA results.     

The isolation, propagation and characterization of tissue-cultured equine rotaviruses

From 105 field cases of diarrhea in neonatal or young foals, rotavirus was detected by electron microscopy (EM) and/or by enzyme-linked immunosorbent assay (ELISA) in the feces of 65 foals on 16 different premises. ELISA was performed with Rotazyme test kits developed by Abbot and Company for the detection of rotaviruses. Twenty-four field isolates from the feces of diarrheic foals with equine rotavirus infection as ascertained by EM were placed in MA-104 cell cultures after pretreatment of the viral suspension with 10 micrograms ml-1 of trypsin and incorporation of 0.5 micrograms ml-1 or 1 microgram ml-1 of trypsin in Earle's minimal essential medium (MEM), 2% lactalbumen hydrolysate, and antibiotics. The isolates that replicated in cell culture produced varying degrees of cytopathic effect. After the 24 isolates had been transferred 5 or 7 times in cell culture, viral particles were observed in 17 by EM, and 22 had positive ELISA tests as determined by visual color chart and spectrophotometric readings. Concentrated tissue-cultured viral antigen of 9 isolates fixed complement using Nebraska calf diarrhea rotavirus calf antiserum while four isolates gave negative results. The same 13 tissue-cultured viral suspensions failed to fix complement using reovirus antiserum. The 9th passages of two isolates (EID1 and EID2) yielded titers of 10(4.45) ml-1 TCID50 and of 10(4.95) ml-1 TCID50, respectively, as measured by cytopathic effect. After 13 tissue-cultured passages, 2 other isolates, EID3 and EID4, each had titers of 10(6.2) ml-1 TCID50 and of 10(5.95) ml-1 TCID, respectively. Cytoplasmic or intranuclear inclusions were not seen in any cells of the MA-104 infected cell cultures. Small, but distinct, plaques in MA-104 cell cultures were produced by the EID1 isolate. Polyacrylamide gel electrophoresis tests of EID1 and EID2 isolates at the 9th cell passage and EID3 and EID4 isolates at the 13th cell passage each showed that the RNA genome had 11 segments with a migrating pattern that was identical for each isolate and characteristic of rotaviruses. These 4 equine tissue-cultured isolates when tested by ELISA, utilizing a monoclonal antibody serum pool that cross-reacted with many rotavirus isolates, each gave positive values comparable to rotavirus antigen controls.     

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.     

An ELISA for porcine reproductive and respiratory syndrome: production of antigen of high quality.

A reliable method was developed to produce a viral antigen preparation from porcine reproductive and respiratory syndrome virus (PRRSV) infected MARC-145 cells by solubilizing the virus with Triton X-100. This method eliminated problems previously encountered with high background reactions associated with PRRSV antigen or cell control antigen. With this new antigen, an indirect enzyme-linked immunosorbent assay (ELISA) was adapted to detect swine serum anti-body against PRRSV. In the ELISA, non-specific reactions associated with test serum samples have been eliminated by utilizing an effective blocking serum diluent. The ELISA is more sensitive than an indirect immunofluorescent assay (IFA), particularly with late-infection sera, while maintaining a high diagnostic specificity. In a comparison of IFA and ELISA using sera collected from 250 pigs of various ages from 5 herds that had PRRS histories, IFA revealed 178 positive samples and 72 negative samples. All of the IFA-positive sera were proven to be ELISA reactors. However, nearly one-half (34/72) of the IFA-negative samples were also ELISA reactors. The diagnostic specificity and sensitivity of the ELISA were 100% and 96.6% with 257 serum samples collected from known healthy PRRS-negative swine herds and 57 sera collected from infected swine at 6 to 56 days after infection, respectively. The ELISA is technically superior to IFA, time-efficient and cost-effective, and suitable for testing of a large number of samples over a short period of time.     

A群猪轮状病毒VP7蛋白单克隆抗体的制备及鉴定

To prepare the monoclonal antibodies against VP7 protein of group A porcine rotavirus (PoRV) serotype G11,VP7 gene of PoRV serotype G11 was cloned into the vector pGEX-6P-1. The recombinant plasmid was transformed into E.coli competent cells DH5α and induced by IPTG. Hybridomas were produced by fusing SP2/0 cells with spleen cells from mouse immunized with GST-VP7 recombinant protein. One hybridomas secreting MAb against VP7 protein was identified by indirect ELISA. Western blotting analysis showed that the MAb could recognize the recombinant VP7 protein and authentic VP7 protein of PoRV，and the specific immunoflurescence was detected in PoRV infected MA104 cells by indirect immunoflurescence assay.The result of MTT method showed that the MAb had the neutralizing activity. The subtype of the MAb was IgG2b. The results showed that VP7 protein was successfully expressed in E.coli， one MAb was preparated and identified，and it could be used for further study of prevention，diagnosis and treatment of porcine rotavirus disease.     

Attachment and infection to MA104 cells of avian rotaviruses require the presence of sialic acid on the cell surface

To determine the characters of receptors on target cells for avian rotaviruses, the receptors on MA104 cells for the pigeon rotavirus PO-13, the turkey rotaviruses Ty-1 and Ty-3, and the chicken rotavirus Ch-1 were analyzed. Pretreatment of MA104 cells with neuraminidase greatly reduced the infection by all of the four avian rotavirus strains. Binding of the cell-attachment protein, purified VP8 expressed in bacteria, of strain PO-13 to MA104 cells was also inhibited by pretreatment of cells with neuraminidase. These findings suggest that avian rotaviruses primarily utilize sialic acid-containing molecules as receptors on MA 104 cells.     

Monoclonal internal image anti-idiotype antibodies of Theileria sergenti merozoite surface antigen

Monoclonal anti-idiotype antibodies against monoclonal antibody (23C11) to intraerythrocytic merozoites of Theileria sergenti were prepared and examined by indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). Three anti-idiotype antibodies containing antibodies against interspecies cross-reactive idiotopes and/or an internal image of Theileria sergenti merozoite were found. The presence of antibody against Theileria sergenti was shown by ELISA in these anti-idiotype antibodies induced anti-anti-idiotype antibodies.     

Isolation and serial propagation of turkey rotaviruses in a fetal rhesus monkey kidney (MA104) cell line

Turkey rotaviruses from the intestinal contents of poults were isolated and serially propagated in MA104 cell monolayers by a simple procedure. The initial virus isolation was done by low-speed centrifugation of the inoculum onto the monolayers, and subsequent passages were accomplished in roller-tube monolayers using trypsin-treated virus suspensions. Each of the turkey rotavirus isolates possessed the morphologic, antigenic, and genomic attributes characteristic of turkey group A rotaviruses. Attempts to isolate and serially propagate turkey rotavirus-like viruses in MA104 cell monolayers by this procedure were unsuccessful. Turkey reoviruses also did not serially propagate in MA104 cell monolayers by this procedure.     

Isolation of a rotavirus from a newborn dog with diarrhea

A rotavirus was isolated from a newborn dog that died after having clinical signs of diarrhea. Virus particles with rotaviral morphologic features were observed by transmission electron microscopy in the intestinal homogenate collected at necropsy. Cytopathic effects were observed, and rotaviral antigens were detected by indirect immunofluorescence in MA-104 monolayer cultures (a fetal rhesus macaque kidney cell) inoculated with intestinal homogenate. This rotavirus isolate, designated LSU 79C-36, may be a specific canine rotavirus or a rotavirus from another species.     

Relationship of the enzyme-linked immunosorbent assay to indirect immunofluorescent antibody test for the detection of so-called chicken anemia agent antibodies in serum from broiler breeders.

Serum samples collected from breeder chickens ranging in age from 1 day to 55 weeks were tested for CAA antibodies by enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent antibody (IFA) test. The relationship of ELISA to IFA test was determined. The sensitivity of the ELISA relative to the IFA test was 82.64%, and the specificity of the ELISA relative to the IFA test was 56.25%. Agreement between the ELISA and the IFA test was highly significant (Kappa = 0.74, Z = 5.78). We concluded that the ELISA is as good as the IFA test for detecting CAA antibody in sera from chickens.     

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.     

Isolation and serial propagation of porcine epidemic diarrhea virus in cell cultures and partial characterization of the isolate.

Porcine epidemic diarrhea virus (PEDV) was isolated in Vero cell cultures from the small intestine of a piglet experimentally infected with porcine coronavirus 83P-5, that had been isolated during outbreaks of porcine acute diarrhea and passaged in piglets. The isolation of the PEDV was successful only in Vero cells maintained in the maintenance medium (MM) containing trypsin. Infected Vero cell cultures exhibited CPE characterized by cell-fusion and syncytial formation, as well as cytoplasmic fluorescence when examined by the indirect immunofluorescent test using rabbit anti-83P-5 virus serum. The isolate was adapted to serial propagation in Vero cell cultures by adding trypsin to MM. Vero cell-adapted PEDV was successfully propagated in the MA104, CPK and ESK cell lines in the presence of trypsin in MM. Vero cell-adapted PEDV had morphologic and physicochemical characteristics similar to those of other members of the coronaviridae. The isolate differed serologically from porcine transmissible gastroenteritis (TGE) and porcine hemagglutinating encephalomyelitis viruses, and no antigenic relationship between the isolate and TGE virus could be detected by the indirect immunofluorescent test. Attempts to isolate PEDV in 6 types of primary fetal pig cell cultures and 6 of 10 established cell lines resulted in the failure, probably because these cells were damaged by the action of trypsin.     

A Bayesian evaluation of four immunological assays for the diagnosis of clinical cryptosporidiosis in calves

A Bayesian approach was used to evaluate four immunological assays for the clinical diagnosis of cryptosporidiosis in calves: an immunofluorescence assay (IFA), two ELISA tests and an immunochromatographic (dipstick) assay. Faecal samples from 287 calves aged less than 6 weeks with clinical signs of gastrointestinal disease were examined for the presence of Cryptosporidium spp. The high prevalence (63%) of Cryptosporidium spp. indicated the relevance of this agent in the aetiology of diarrhoea in calves. All diagnostic assays were found to be relatively specific (IFA: 94.8%; Tetra ELISA: 95.9%; Techlab ELISA: 92.7%; dipstick assay: 91.5%) and sensitive (IFA: 97.4%; Tetra ELISA: 93.6%; Techlab ELISA: 95.4%; dipstick: 87.8%). Despite a lower sensitivity, the dipstick assay provided a practical alternative to laboratory diagnosis of clinical cryptosporidiosis in calves.     

Comparison of enzyme-linked immunosorbent assay, indirect fluorescent antibody test, and direct agglutination test for detecting Toxoplasma gondii antibodies in naturally aborted ovine fetuses

Results obtained in an enzyme-linked immunosorbent assay (ELISA), an indirect fluorescent antibody test (IFA), and a modified direct agglutination test (MAT) for Toxoplasma gondii antibodies from examination of fetal fluids from 377 aborted ovine fetuses were compared. Sixty-seven samples were positive by MAT (titers 1:16 to greater than 1:65,536), 58 were positive by ELISA, and 62 were positive by immunoglobulin G-IFA. The MAT was preferred because it required less time, labor, and special equipment. It was simple to run, could be done on serum from any species without modification, and it was more effective than the IFA for detecting toxoplasma antibodies in severely autolyzed fetuses. No advantage was found in determining immunoglobulin M antibodies in ovine fetal sera.     

猪轮状病毒的分离与鉴定

将疑似感染猪轮状病毒的内蒙古某猪场的腹泻仔猪粪便样品在MA104细胞上分离培养,得到一株能产生明显细胞病变的毒株(命名为PRV L1株).经纯净性检测,该毒株无菌生长、无支原体污染及外源病毒污染.特异性检测结果显示该PRV L1株能被猪轮状病毒单特异性血清中和,并可被猪轮状病毒单克隆抗体识别,其VP7基因序列与G5型猪轮状病毒VP7基因序列同源性为99％.动物回归试验结果表明,该毒株口服攻击3日龄仔猪,可引起典型的猪轮状病毒病发病症状,并能在发病仔猪小肠内容物中检测到猪轮状病毒.     

Comparisons among two serological tests and microscopic examination for the detection of Theileria annulata in cattle in northern Sudan

We tested the agreement between microscopic examination (ME), a surface protein-detecting enzyme-linked immunosorbent assay (TaSP ELISA) and an indirect fluorescent assay (IFA) for detection of Theileria annulata in 2661 naturally infected cattle from northern Sudan (samples collected between June 2001 and July 2002). In the ME, we detected piroplasms in 364/2661 cattle (14%), and the kappas between the ME and the serological tests were poor (TaSP ELISA 10%; IFA 8%). The TaSP ELISA detected 885/2661 cattle as positive, and the Rogan-and-Gladen corrected true prevalence of this sample was estimated to be 30%. The relative sensitivity and specificity of the IFA (compared to the previously validated TaSP ELISA) were 70.7% and 81.8%, respectively.     

猪A群轮状病毒BJ株的分离与鉴定

轮状病毒是引起幼龄动物和儿童病毒性腹泻的主要病原,轮状病毒的分离鉴定为该病的流行病学调查和分子生物学特性研究奠定了基础。本研究采集北京某猪场腹泻发病仔猪肠内容物,将其接种MA104细胞,分离得到一株能产生明显细胞病变的病毒。对分离毒株进行胶体金、实时荧光定量RT-PCR和免疫荧光等方法鉴定,并对分离毒株的VP4、VP6和VP7基因进行测序及序列分析。结果表明,分离毒株为猪A群轮状病毒。按照A群轮状病毒的最新分类方法,确定该分离株VP4、VP6和VP7基因的基因型分别为P[13]型、I5型和G11型。因此,将该分离株命名为Rotavirus A pig/China/BJ/2015/G11P[13]。     

Isolation and Identification of Porcine Group A Rotavirus BJ Strain

Rotavirus infections are a major cause of viral diarrheas in young animals and children. Isolation and identification of rotavirus make a contribution to epidemiological survey and molecular biology study.A strain of porcine rotavirus was isolated in MA104 cell cultures from the intestinal contents of piglets with diarrhea in Beijing.The virus was identified to be porcine rotavirus by immunochromatography strip test, Real-time RT-PCR, immunofluorescence test and sequencing analysis.According to the sequence analysis, the virus was classified as group A porcine rotavirus, the genotype of VP4, VP6 and VP7 genes belonged to P[13], I5 and G11, respectively.The virus was designated Rotavirus A pig/China/BJ/2015/G11P[13].