Antigenic variation of porcine transmissible gastroenteritis virus detected by monoclonal antibodies

Mouse myeloma cells (SP2/O) were fused with spleen cells from BALB/c mice immunized with detergent-solubilized antigen of purified virus, and 21 monoclonal (MC) antibodies reactive in enzyme-linked immunosorbent assay with the TO-163 strain of porcine transmissible gastroenteritis (TGE) virus were obtained. Of these MC antibodies, 14, 6 and 1 were IgG1, IgG2a and IgM, respectively. All of the MC antibodies contained light chains of the kappa type. Of these MC antibodies, 8 were found to have neutralization (NT) activity against the TO-163 strain. Comparison of 7 strains of TGE virus by NT tests using our panel of MC antibodies confirmed their close antigenic relationships, but also revealed the occurrence of distinct antigenic differences. These results suggest that there may be at least 6 different epitopes involved in NT reaction on the virion of the TO-163 strain. This notion was confirmed by the competitive binding assay.     

Inhibition of virus attachment to CPK cells by monoclonal antibody to transmissible gastroenteritis virus.

Five MAbs, which recognized E2 glycoprotein of TGE virus TO-163 and showed neutralizing activity, were examined to see if they inhibit virus attachment to the susceptible cells (CPK cells). Only one (160/4) MAb blocked the virus attachment to the cells, indicating that the inhibition of virus attachment is one of important mechanisms of neutralizing by antibody.     

Multiplication of low and high cell culture passaged strains of transmissible gastroenteritis virus in organs of newborn piglets

Distribution and persistence of four different strains of transmissible gastroenteritis (TGE) virus in newborn piglets were compared.The piglets inoculated with high-passaged TO-163 strain did not show any clinical signs of TGE on any days postinoculation (DPI), but the piglets inoculated with one of the other three strains, SH-14, SH-164 or TO-16, had soft feces or diarrhea. In the latter cases, the virus was isolated mainly from respiratory organs, lymph nodes, and digestive tract on any DPI, but was rarely detected in the digestive tract of piglets inoculated with the TO-163 strain. The frequency of virus recovery from the tissues was the highest till 4 DPI in all of the piglets inoculated with one of the four virus strains, and it was markedly reduced thereafter in the piglets inoculated with high-passaged strains.The TO-163 strain was subjected to serial passage in newborn piglets for seven passages. There was no evidence of regained pathogenicity with advance in passage, and detection of virus was restricted to lymph nodes and lung of these piglets.In gnotobiotic piglets inoculated with the TO-163 strain, frequent virus recovery and high titers of virus from the tissues were obtained on up to the 4th DPI. The viruses in high titer were found in the digestive tract of some of the piglets; however, none of them showed any clinical signs of TGE.     

The multiplication of transmissible gastroenteritis viruses in several cell lines originated from porcine kidney and effects of trypsin on the growth of the viruses

Plaque formation, replication and related cytopathic function of 9 strains of transmissible gastroenteritis (TGE) virus were examined in primary cells and cell lines such as CPK, IB-RS-2, ESK, and PK-15 originated from porcine kidney and the effects of trypsin on the replication of TGE virus were examined in CPK cells. All strains produced a cytopathic effect and grew well in CPK cells as well as in primary porcine kidney cells. The effect of trypsin on the plaque formation was different from strains. The number of plaques produced by strains TO-163, Ukiha and Niigata increased from 2.6 to 3.52 times when trypsin was present in the medium during incubation at 37 degrees C for 1 hr after adsorption of the virus at 4 degrees C for 2 hr. The plaque sizes of TO-163, h-5, Ukiha and Niigata became larger from 1.4 to 1.7 times, when trypsin was present in the agar MEM overlay.     

Development and Characterization of Monoclonal Antibodies against the Snakehead Rhabdovirus

Abstract

Monoclonal antibodies (MAbs) directed against the snakehead rhabdovirus (SHRV) were produced. These MAbs were characterized by immunofluorescence and neutralization tests, and by their ability to immunoprecipitate viral proteins. Of 15 MAbs developed, 9 were isotyped as IgG1 and 6 were IgG2a. Eight of the MAbs recognized the viral glycoprotein in an immuneprecipitation assay. Three of these, designated E1-9A, P10C, and O10F, had neutralizing activity. By immunofluorescence, 12 MAbs showed good binding activity in SHRV-infected epithelioma papulosum cyprini cells. In an indirect fluorescence assay, the MAbs gave varied staining patterns depending upon the viral structural proteins recognized.     

猪脑心肌炎病毒VP2蛋白单克隆抗体的制备及其识别表位分析

为获得针对猪源EMCV结构蛋白VP2的特异性单克隆抗体,本试验以EMCV结构蛋白VP2为对象,将EMCVBJC3株VP2基因定向插入穿梭质粒中,构建重组腺病毒AdV—VP2,免疫BALB／c小鼠制备单克隆抗体,利用Pepscan技术对单抗识别的抗原位点进行分析。结果显示,间接ELISA及间接免疫荧光法筛选获得了2个阳性细胞克隆株,命名为C11和G8。经检测杂交瘤细胞培养上清抗体效价为1：1600,腹水效价分别为1：2．56×106和1：1.28×106,中和试验鉴定均无中和活性。Western—blot鉴定表明获得的2株单抗均能识别原核表达的重组VP2蛋白。亚类鉴定结果显示2株单抗均为IgG2b亚类,轻链均为κ型。Pepscan分析结果显示,这2株单抗可分别识别EMCVVP2蛋白上的2个B细胞线性表位。本研究获得的蛋白十分接近于其天然构象,很大程度上保证了病毒表面抗原位点的结构和功能。     

Identification of B-cell epitopes in the NSP1 protein of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) was divided into North American and European genotypes. NSP1 was an important non-structural protein of PRRSV, which was auto-cleaved from the replicase polyprotein into NSP1α and NSP1β subunits and played an important role in the immune suppression. In this study, six monoclonal antibodies (MAbs) against the recombinant PRRSV NSP1, expressed in Escherichia coli system, were screened out and identified. Western blot and IFA results indicated that 4 out of 6 MAbs recognized the recombinant NSP1α and 2 MAbs recognized NSP1β. Epitope mapping results indicated that MAb 4H2 recognized the linear epitopes E(54)EPLRW(59) in NSP1α, MAbs (2G5, 3E11 and 4D4) recognized the epitopes H(157)VLTNLP(163) in NSP1α, and MAbs 3C7 and 1H7 reacted with the epitopes 185aa to 232aa in NSP1β. Protein sequence alignment of NSP1 indicated E(54)EPLRW(59) was conserved in all North American PRRSV strains, whereas European type strains has variable amino acids in this region. The epitope H(157)VLTNLP(163) was relatively conserved among all PRRSV strains, except for a L162→S162 change in European type strains. The epitope 185-232aa was variable among North American PRRSV strains. These results may facilitate future investigations into the function of NSP1 of PRRSV and diagnostic methods for PRRSV infection.     

Production of monoclonal antibodies specific to major outer membrane protein of Edwardsiella tarda

Edwardsiella tarda is an important cause for hemorrhagic septicemia in fish and gastro and extra-intestinal infections in humans. Monoclonal antibodies (MAbs) were produced against outer membrane proteins (OMPs) of E. tarda ET-7, isolated from diseased snakehead (Ophiocephalus punctatus). Two stable hybridoma clones, designated as 3F10 and 2C3 MAbs were found to be potentially specific for E. tarda by indirect enzyme linked immunosorbent assay (ELISA). These MAbs recognized major immunogenic OMP band at 44kDa in Western blotting. Both MAbs belonged to the IgG1 isotype and recognized different epitopes of OMP as seen by competitive ELISA. These MAbs strongly reacted with all 17 isolates of E. tarda used in our study by indirect ELISA and Western blotting. Interestingly, no reaction was observed with the reference strain of E. tarda (MTCC 2400). The sensitivity of 3F10 MAb to detect whole cells of E. tarda was up to a level of 1x10(4)CFU/ml in indirect ELISA. No cross-reactivity of MAbs were seen with Escherichia coli, Salmonella arizonae, Pseudomonas fluorescens, Aeromonas hydrophila, Vibrio cholerae, Flavobacterium ferrugineum and Mycobacterium tuberculosis. These MAbs could be used for specific detection of E. tarda infection in fish by immunoassays.     

鲤春病毒血症病毒单克隆抗体的制备及其特性鉴定

为获得针对鲤春病毒血症病毒(SVCV)特异性的单克隆抗体(MAb),以纯化的SVCV为抗原,免疫BALB/c小鼠.将免疫鼠的脾细胞与SP2/0骨髓瘤细胞融合,采用间接ELISA法筛选获得4个能稳定分泌抗SVCV MAb的杂交瘤细胞株;4个杂交瘤细胞制备腹水的MAb效价为1:160 000～1:640 000.亚型鉴定结果表明,这些MAb分属2个亚型(1F1、3E1,IgG2a;3F5、4F9,IgGl),轻链均为K链.Western blot分析显示,MAb1F1、3F5、4F9能特异性地识别SVCV的N蛋白(47 ku),3E1能特异性地识别SVCV的G蛋白(69 ku).采用相加ELISA法对抗原表位分析结果显示,1F1、3F5、4F9可能识别相同的表位,3E1则识别不同的表位.间接免疫荧光试验结果显示4株MAb均能对染毒病灶产生特异性的荧光染色.这些MAb的制备为SVCV免疫学检测方法的建立奠定了基础.     

Production and preliminary characterization of monoclonal antibodies to chicken anemia agent

Mice were immunized with partially purified preparations of the Cux-1 isolate of chicken anemia agent (CAA), and their splenocytes were fused with NSO myeloma cells. Three patterns of staining of CAA-infected cells were recognized when the resulting hybridomas were screened by indirect immunofluorescence (IIF). Hybridomas representative of each staining pattern were cloned, and the monoclonal antibodies (MAbs) were characterized. Type 1 staining was indistinguishable from that produced by polyclonal chicken antisera to CAA. Type 2 staining was confined to large nuclear inclusions. Type 3 staining was predominantly nuclear and granular, and differed from type 1 in being more intense and occurring in a higher proportion of nuclei. Three MAbs producing type 1 staining were predominantly Cux-1-specific by IIF; they also reacted to lower titers with the Gifu-1 isolate but not at all with three other CAA isolates. These MAbs had very slight neutralizing activity against Cux-1. Another MAb giving type 1 staining reacted with all CAA isolates tested to high titers in IIF and neutralization tests. MAbs with type 2 and type 3 staining reacted by IIF with all CAA isolates tested but possessed no neutralizing activity. The availability of MABs to CAA should facilitate development of diagnostic tests for the virus.     

Production and characterization of monoclonal antibodies against an avian group A rotavirus.

Fifteen monoclonal antibodies (MAbs) against an avian group A rotavirus were cloned and characterized. Eight of the 15 MAbs had neutralizing activity (N-MAbs). Five of the N-MAbs (1G1, 5B8, 4E2, 3G1, 2E3) were VP4-specific by radioimmunoprecipitation assay (RIPA), and two N-MAbs (2D11, 6E8) were possibly VP7-specific (faint bands by RIPA). One N-MAb (4H12) of undefined protein specificity cross-reacted with serotype 3 simian rotaviruses. The other seven N-MAbs did not cross-react with any of the eight distinct serotypes of human and mammalian rotaviruses tested. Of the seven non-neutralizing MAbs, three were VP6-specific (3H10, 4B12, 5F6), two were VP8-specific (6C9, 1D1), one was VP4-specific (4E9), and one was of undefined protein specificity (1B11). Four non-neutralizing MAbs recognized only avian group A rotavirus in cell-culture immunofluorescence tests (6C9, 1D1, 4E9 and 5F6), whereas two MAbs (3H10 and 4B12) cross-reacted with all human and animal rotaviruses tested. The MAb 1B11 did not recognize any human rotavirus serotypes but cross-reacted with all nonhuman animal rotavirus serotypes. The MAbs produced in this study should be useful for the detection and further characterization of avian group A rotaviruses.     

Detection of transmissible gastroenteritis virus in feces from pigs by reversed passive hemagglutination

A reversed passive hemagglutination (RPHA) method was developed for the detection of transmissible gastroenteritis (TGE) virus in the fecal specimens from pigs. Ovine erythrocytes fixed with glutaraldehyde and treated with tannic acid were coated with anti-TGE virus swine antibodies, which were purified by affinity chromatographic technique linked with purified TGE virus. The RPHA test was done by the Microtiter method. Erythrocytes coated with purified specific antibodies were agglutinated by TGE virus, but not by porcine rotavirus or porcine enterovirus. The reaction was specifically inhibited by antiserum against TGE virus, confirming the specificity of the reaction. A litter of seven 3-day-old pigs was orally inoculated with TGE virus, and fecal specimens were obtained once a day and serum was obtained every 4th day. With the RPHA test, TGE virus was detected in the diarrheal feces; all of the inoculated pigs developed virus-neutralization antibody for the TGE virus. The RPHA test detected TGE virus in feces from pigs with naturally occurring diarrhea. The RPHA test detected TGE virus in 5 of 6 fecal specimens (80%), whereas the positive rate was only 50% (3/6) for the immunofluorescent staining of primary cultures of porcine kidney cells inoculated with the specimens. The advantages of the RPHA method are simplicity, high sensitivity, and rapid to do.     

鸭1型甲肝病毒亚型VP1蛋白单克隆抗体的研制及鉴定

为制备抗鸭1型甲肝病毒亚型（DHAV-1a）结构蛋白VP1的单克隆抗体（MAbs）,本研究以pGEX-VP1重组蛋白免疫BALB/c小鼠,同时以纯化浓缩的全病毒作为包被抗原,建立了筛选抗VP1蛋白阳性杂交瘤细胞株的间接ELISA方法,经融合、筛选制备杂交瘤细胞及鉴定MAbs的稳定性、特异性、腹水效价和中和活性等生物学活性,获得了2株持续且稳定分泌抗体的杂交瘤细胞（1A2和5G3）。MAbs腹水ELISA效价分别为1：3.2×10⁴和1：2.0×10⁶。亚类鉴定均为IgG1/κ型。Western blotting结果显示,2株MAbs均能与DHAV-1a VP1蛋白和DHAV-1a全病毒发生特异性反应。特异性试验结果显示2株MAbs能与鸭1型甲肝病毒（DHAV-1）和DHAV-1a发生交叉反应。中和试验结果显示5G3株具有中和活性。结果表明2株MAbs的ELISA效价高、特异性强、稳定性好,均能与DHAV-1和DHAV-1a全病毒发生特异性反应,其中一株具有中和活性。     

Characterization and use of monoclonal antibodies to identify Haemophilus paragallinarum serovars

Two serovar-specific monoclonal antibodies (MAbs) to Haemophilus paragallinarum serovars A/1 and C/2 strains, respectively, were developed and characterized by hemagglutination-inhibition (HI) and dot-blotting tests using representative H. paragallinarum serovars A/1, B, and C/2 strains. In both the HI and dot-blotting tests, one MAb (E5C12D10), raised against strain 221, serovar A/1, reacted only with serovar A/1 strains, while the other MAb (F2E6), raised against strain S1 of serovar C/2, reacted with only serovar C/2 strains examined. In both tests, the two MAbs did not react with two serovar B strains. These results indicated that the two MAbs recognize serovar-specific hemagglutinating (HA) antigens of H. paragallinarum serovars A/1 and C/2 strains, respectively, and that a dot-blotting test using these MAbs is a practical alternative to the HI test for serotyping H. paragallinarum. Strains 0222 and Spross of serovar B, which did not react with these two MAbs, were found to possess serovar-specific HA antigen in cross-HI tests.     

Development and Identification of Monoclonal Antibodies against VP1 Protein of DHAV-1a

To prepare the monoclonal antibodies (MAbs) against DHAV-1a, hybridomas were produced by fusing SP2/0 cells with spleen cells from mouse immunized with DHAV-1a pGEX-VP1 recombinant protein. Two hybridomas stablely secreting MAbs against VP1 protein were identified by indirect ELISA detection with DHAV-1a as coating antigen. The ascetic fluids of MAbs were 1:3.2×10⁴ and 1:2.0×10⁶, respectively. The MAbs were IgG1 with κ chain. Western blotting analysis showed that the MAbs could recognize the recombinant VP1 protein and DHAV-1a. The neutralization tests showed that one MAb (5G3) had better neutralization activity. Therefore, the results showed that the ELISA titers and specialities of two MAbs were very good, with excellent stability. In addition, they all had cross interaction with DHAV-1 and DHAV-1a, one of which had good neutralization activity.     

Evaluation of two monoclonal antibodies for serotyping Haemophilus paragallinarum

Two monoclonal antibodies (MAbs) were evaluated for their ability to serotype 108 isolates of Haemophilus paragallinarum. One MAb (E5C12D10) was raised against a Page serovar A strain and the other (F2E6) against a Page serovar C strain. In both dot blot and hemagglutination-inhibition tests, MAb E5C12D10 recognized the type strains of Page serovar A and Kume serovars A-1, A-2, A-3, and A-4. MAb F2E6 recognized the type strains of Page serovar C and Kume serovars C-1, C-2, and C-3. Neither antibody recognized the type strains of Page serovar B or Kume serovars B-1 and C-4. When evaluated with 97 field isolates in a dot blot test, the MAbs serotyped 81 isolates, which was better than agglutinin typing by the Page scheme (69 isolates serotyped). The field isolates that did not react with the MAbs were either Page serovar B/Kume serovar B-1 (three isolates), Page serovar C/Kume serovar C-4 (12 isolates), or nontypable by either the Page or Kume scheme (one isolate).     

尼帕病毒G和F蛋白单克隆抗体的制备与鉴定

为制备抗尼帕病毒(NiV)G和F蛋白的单克隆抗体(MAb),本研究以表达NiV G和F蛋白的真核重组表达质粒pCAGG-NiVG和pCAGG-NiVF分别免疫BALB/c小鼠,采用常规技术制备杂交瘤细胞;以表达G和F蛋白的重组牛痘病毒(rWR-NiVG、rWR-NiVF)分别感染BHK细胞,通过间接免疫荧光(IFA)筛...     

犬副流感病毒单克隆抗体的研制及其特性鉴定

为研制犬副流感特异性诊断试剂,我们以犬副流感病毒(CPIV)免疫8周龄BALB/c小鼠,采用淋巴细胞杂交瘤技术获得4株稳定分泌针对CPIV的单克隆抗体(MAb)细胞株,分别命名为4F386、584C9、4G7F4和4C9D8.4株MAb腹水针对CPIV的间接ELISA抗体效价达1:10~5～1:10~6,与犬瘟热病毒(CDV)和犬细小病毒(CPV)均不发生交叉反应.MAb 4F386和4C9D8为IgG,5B4C9和4G7F4为IgM.Western blot检测表明,4F386与CPIV的F蛋白发生特异性反应,4G7F4与CPW的HN蛋白发生特异性反应,而584C9和4C9D8不与变性的CPIV蛋白发生反应.4株MAb均具有中和病毒活性,间接免疫荧光检测均呈为阳性.本研究为进一步研制CPIV特异性诊断和治疗制剂创造了条件.     

Identification of porcine transmissible gastroenteritis virus in house flies (Musca domestica Linneaus)

Transmissible gastroenteritis (TGE) virus was detected in house flies (Musca domestica Linneaus) by staining with specific fluorescent antibody. The flies were collected within a swine confinement facility in which TGE was enzootic. Laboratory-reared flies were infected experimentally with TGE virus and the virus was recovered from the insects for 72 hours after infection. The TGE virus was identified both by the fluorescent antibody technique and by isolation in cell culture. The nature of plaque formation in cell monolayers inoculated with the virus passaged through flies changed from a large plaque (4 mm or greater in diameter) to a small plaque (1 mm in diameter) over the period. Large plaques were observed early after infection and were attributed to TGE virus mechanically carried by the flies. Small plaques occurred 8 to 12 hours after infection and were considered to be produced by virus replicated in the dipterous cell.     

Development and characterization of monoclonal antibodies against FMD virus type Asia-1 and determination of antigenic variations in the field strains

Twelve mouse monoclonal antibodies (MAbs) were developed against an Indian vaccine strain of foot and mouth disease virus (FMDV) type Asia-1 WBN 117/85. The MAbs were tested for their ability to bind to whole virus particle, trypsin-treated 146S (TT-146S) virus particle, sub-viral (12S and disrupted virus) antigens by ELISA and to neutralize virus infectivity in cell culture. Extensive characterization of MAbs revealed the existence of three different groups based on the binding of non-overlapping epitopes. Eight type Asia-1 specific MAbs (RF7, RF8, RD10, RE11, RC11, RC10/O, RB11 and RC10/M), which formed group 1 (G1), were found to bind a neutralizing, trypsin-sensitive (TS) and conformational epitope. Two MAbs (WB8 and WC3) in group 2 (G2) were found to bind a non-neutralizing, trypsin-resistant, conformational and 12S-specific epitope, which was intertypically conserved in all the four serotypes of FMDV (O, A, C and Asia-1) prevalent in India. Two MAbs (KG10 and KF10), which formed group 3 (G3), were found to be against a non-neutralizing, TS and conformational epitope, common to types Asia-1 and A. Members of G1 were IgG2a isotype, while those of G2 and G3 were IgG1 and IgG2b isotypes, respectively. Antigenic analysis of 31 FMDV type Asia-1 field isolates and two vaccine strains, using a panel of type Asia-1-specific MAbs, revealed antigenic similarity of the virus isolates tested and non-existence of neutralization escape mutants. The developed MAbs have practical utility, especially in the manufacture of FMD vaccine, diagnosis and FMDV characterization.