Virus-neutralizing and passively protective monoclonal antibodies to infectious bursal disease virus of chickens.

Murine monoclonal antibodies (MAbs) were produced to assist in the identification and characterization of the virus-neutralizing epitopes of infectious bursal disease virus (IBDV). Only MAbs that reacted in Western blotting with viral protein 2 (VP2) or immunoprecipitated VP2 neutralized the infectivity of the virus in cell culture and passively protected young chickens from infection. Three of the neutralizing MAbs did not react with denatured viral proteins. Additivity enzyme-linked immunosorbent assays indicated that the six virus-neutralizing MAbs recognized two spatially independent epitopes. The ability of two of the virus-neutralizing MAbs to neutralize a variant of IBDV that had escaped neutralization by all the other MAbs confirmed the existence of two distinct neutralizing epitopes. The results support the hypothesis that there are at least two non-overlapping epitopes recognized by the virus-neutralizing MAbs reported in this study, although these may still be within one conformational site on VP2 of IBDV.     

Antigenic relationships of foot-and-mouth disease virus serotype Asia-1 isolates demonstrated by monoclonal antibodies.

A panel (26) of monoclonal antibodies (MAbs) was elicited against three distinct isolates of foot-and-mouth disease virus (FMDV) serotype Asia-1. Each MAb was characterized according to the location of its epitope: Class I, restricted to the intact virion (140S); Class II, restricted to 140S and the virion protein subunit (12Sps); Class III, available on 140S, 12Sps and virus protein 1; Class IV, restricted to 12Sps. In addition, the MAbs were further categorized by isotype, neutralization of viral infectivity, capacity to bind in radioimmunoassay and precipitation in the Ouchterlony reaction. Neutralization of FMDV infectivity by a MAb of the IgA isotype is reported for the first time. A minimum of seven distinct neutralization epitopes were described on FMDV Asia-1. Some of the neutralizing MAbs bound FMDVs in addition to those that they neutralized. The MAbs defined epitopes common to FMDV serotypes Asia-1, A, O1 and C but neutralizing capacity was restricted to serotype Asia-1. Class IV MAbs defined epitopes highly conserved throughout the FMDV serotypes. Identification of FMDV neutralization epitopes makes possible the direct selection of optimal FMDV strains for vaccine fabrication. In addition, these data are crucial to the design of future synthetic vaccines.     

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.     

基因Ⅶ型新城疫病毒HN蛋白单克隆抗体的制备及特性研究

为制备基因Ⅶ型新城疫病毒(NDV)血凝素-神经氨酸酶蛋白(HN)的单克隆抗体(MAb),本研究利用JS/17病毒株的HN重组蛋白和活病毒分别免疫BALB/c小鼠,取其脾细胞与骨髓瘤细胞(SP2/0)融合,并通过ELISA、间接免疫荧光和western blot方法筛选,制备了3株特异性识别HN蛋白的单克隆抗体(MAb)。其中,MAb1D4和4D9具有病毒中和活性(VN)及血凝抑制作用(HI),可以识别多种基因型的Ⅱ类NDV,但与Ⅰ类NDV病毒株无反应。MAb 2G8识别线性表位131DYIGGIGKE139,该表位在各病毒株中高度保守。获得的3株MAb可以用于NDV的鉴定及HN蛋白的功能研究。     

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.     

Production and characterization of monoclonal antibodies that react to the nucleocapsid protein of avian metapneumovirus subtype C

Monoclonal antibodies (MAbs) were prepared against avian metapneumovirus (aMPV) subtype C (aMPV/ Minnesota/turkey/1a/97). Six MAbs were selected based on enzyme-linked immunosorbent assay activities and characterized by isotyping, neutralization test, western blot analysis, and immunohistochemistry assay. The results showed that three MAbs (3E, 9D, and 12C) belonged to the IgG1 subclass, whereas the other three (5D, 8E, and 16E) were of the IgG2a subclass. None of the six MAbs neutralized aMPV infectivity at a detectable level, but all reacted with both denatured and nondenatured forms of the nucleocapsid (N) protein of aMPV, suggesting that these MAbs may recognize structurally independent epitopes of the N protein. These MAbs provide new tools and methods for investigating aMPV infection and pathogenesis, as well as diagnosis of aMPV disease.     

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.     

Analysis of properties of monoclonal antibodies to transmissible gastroenteritis virus using TO-163 strain

Nineteen monoclonal antibodies (MAbs), reactive in enzyme-linked immunosorbent assay (ELISA), with porcine transmissible gastroenteritis (TGE) virus TO-163 were obtained. Of these MAbs, 5 showed neutralizing (NT) activity (x 3,200 to 25,600) against TO-163. One of the MAbs which had NT activity showed hemagglutination inhibition activity (x 5,120) too. 14 hybridomas of polypeptide specificity against TO-163 strain were developed from which 11, 2, and 1 were specific for protein E2, N, and E1, respectively. Immunofluorescence staining patterns in TGE virus-infected cells reacted with MAbs were divided into three groups (types I, II and III). The fluorescence staining of E2 specific MAbs having NT activity were limited to the perinuclear area. All MAbs having NT activity showed the same fluorescence staining pattern.     

H9N2亚型禽流感病毒中和单克隆抗体的制备与应用

为建立H9N2亚型禽流感病毒（Avian influenza virus,AIV）免疫层析快速检测技术,本研究以差速离心法纯化H9N2亚型AIV免疫BALB/c小鼠,将免疫小鼠脾细胞与骨髓瘤细胞SP2/0进行细胞融合和HAT选择性培养;以H9N2亚型AIV感染MDCK细胞建立异源免疫过氧化物酶单层细胞试验（IPMA）的单克隆抗体检测方法,通过对杂交瘤细胞的IPMA筛选和连续克隆化筛选鉴定抗H9N2亚型AIV中和性单克隆抗体;以胶体金标记HA单克隆抗体,配对HA单克隆抗体和羊抗小鼠IgG为检测线和质控线,制备H9N2亚型AIV快速检测试纸条,测定其特异性和敏感性。结果显示,获得了11株稳定分泌抗H9N2亚型AIV单克隆抗体的杂交瘤细胞,其单克隆抗体腹水IPMA效价在1.28×10^-4至2.56×10^-5之间。单克隆抗体3A2、5H6、6B8、7E10和9G12血凝抑制试验（HI）显示血凝抑制活性,其（HI）效价在6log2~9log2之间。单克隆抗体3A2、6B8和9G12在病毒中和试验中对H9N2亚型AIV有显著病毒中和活性,中和效价分别1∶6 400、1∶25 600和1∶25 600。Western blotting结果提示,该中和单克隆抗体识别HA蛋白线性抗原表位。利用配对单克隆抗体3A2和9G12研制的H9N2亚型AIV检测试纸条检测H9N2亚型AIV尿囊液的效价为9log2,灵敏度与经典血凝试验（HA）相当,与其他亚型AIV （H1、H3、H5、H7）,以及新城疫病毒和鸡传染性法氏囊病病毒等相关病毒均无交叉反应。本研究制备了具有病毒中和活性的抗H9N2亚型AIV单克隆抗体,并初步研制了H9N2亚型AIV检测试纸条,为H9N2亚型AIV新型疫苗研制和快速检测奠定良好的研究基础。     

Monoclonal antibody analysis of porcine reproductive and respiratory syndrome virus epitopes associated with antibody-dependent enhancement and neutralization of virus infection

Enhanced infection and replication of porcine reproductive and respiratory syndrome (PRRS) virus in the presence of specific antibody has been demonstrated in vitro and in vivo, a phenomenon known as antibody-dependent enhancement (ADE). ADE is considered to be a significant obstacle to developing effective vaccines for many viruses for which ADE has been reported, since virus-specific antibodies of maternal origin or those conferred by vaccination can facilitate the entry of the virus into target cells, sometimes resulting in increased severity of the disease. In this study, the role of specific PRRS viral epitopes in ADE and/or virus neutralization (VN) was assessed in vitro using 14 monoclonal antibodies (mAbs) to 4 PRRS viral proteins: nucleocapsid (N), matrix (M), glycoprotein (GP) 5, and GP3. Each mAb recognized a distinct epitope on one of these proteins. One-way ADE and VN assays were performed in vitro using homologous PRRS virus isolates in the presence or absence of each mAb. ADE activity was determined by detecting a significant increase of progeny virus yield in porcine alveolar macrophage cultures in the presence of individual mAbs. Neutralizing activity was determined by detecting a significant reduction or complete blocking of virus replication in MARC-145 cells in the presence of individual mAbs. mAbs could be categorized into 3 groups: enhancing, neutralizing and neither. Viral epitopes which are capable of inducing neutralizing antibodies appeared to reside on the M, GP3 and GP5 proteins, while epitopes that may induce ADE-mediating antibody were associated with the N and GP5 proteins. Identification of the viral proteins and antigens and epitopes responsible for ADE- and VN-mediating antibodies may provide the basis for developing efficacious second-generation vaccines for the control of PRRS virus; yet, further epitope mapping remains to be done.     

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.     

Monoclonal antibodies to the GP5 of porcine reproductive and respiratory syndrome virus are more effective in virus neutralization than monoclonal antibodies to the GP4

The arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) contains six structural proteins the roles of which are not completely understood. In a preceding study, immunization with the dutch isolate I10 of PRRSV had led to the development of MAbs against four structural proteins [Wieczorek-Krohmer, M., 1994. Herstellung und Charakterisierung von monoklonalen Antik?rpern gegen das Virus des Porzinen Reproduktiven und Respiratorischen Syndroms (PRRSV). Inaugural-Dissertation, Ludwig-Maximilians-Universit?t, München] here finally identified by reaction with individual plasmid-expressed PRRSV proteins as products of ORFs 3 (GP3), 4 (GP4), 5 (GP5) and 7 (N). Surprisingly, the MAbs against GP5 revealed the presence of two antigenically distinct virus populations in the isolate I10, the population PRRSV-'PPV', isolated from plaques and the PRRSV-'EPV', gained by end point dilution. MAbs against GP3, GP4 and N reacted with both I10 populations as well as with natural PRRSV isolates. However, the anti-GP5 MAbs exclusively recognized PRRSV-'PPV'. In this study immunization of mice with both separated I10 populations confirmed that solely PRRSV-'PPV' possesses the property to induce an immune response ultimately leading to the establishment of MAbs against GP5. Whereas the 15 anti-GP5 MAbs (derived from four independent fusions) reacted exclusively with PRRSV-'PPV' of the isolate I10, anti-GP4 MAbs detected their target antigen on various isolates of European origin and were able to neutralize them. As indicated by competition assays and selection of neutralization-resistant virus mutants, all GP5 MAbs are directed against a single antigenic site on the ORF 5 protein. Both groups of neutralizing antibodies bound to the surface of purified virions demonstrating that the recognized epitopes represent surface structures of the virion envelope. However, anti-GP5 MAbs mediated the binding of more gold granules than anti-GP4 MAbs. Comparison of the neutralizing effect of anti-GP4 and anti-GP5 MAbs revealed the anti-GP5 MAbs as the more efficient antibodies. For the complete neutralization of about 100 ID50 of PRRSV-'PPV' anti-GP5 culture supernatant was effective up to a dilution of 1:1280 whereas the most effective anti-GP4 antibodies exhibited a comparable effect only up to 1:64. These results indicate that PRRSV GP5 in principle is a major target for neutralizing antibodies, as is found for other arteriviruses, but that in nature 'ORF 5 escape mutants' may develop as easily as in vitro.     

Study on the porcinophilic foot-and-mouth disease virus I. production and characterization of monoclonal antibodies against VP1

Monoclonal antibodies (MAbs) reported here were produced against the porcinophilic foot-and-mouth disease virus (FMDV) that caused the devastating swine disease on 1997 in Taiwan. A panel (25) of MAbs were found to react with VP1 of O/Taiwan/97 (O/97) by ELISA with various potencies. The biological identities of these VP1 reacting MAbs, such as neutralization activity, isotype and capability to distinguish between two serotype O FMDVs, O/97 and O/Taiwan/KM1/99 (O/99), were further analyzed. Eleven out of the total eighteen O/97 neutralizing MAbs were able to neutralize heterologous O/99. Eight O/97 neutralizing and five non-neutralizing MAbs could differentiate two serotype O FMDVs by immunofluorescence assay (IFA) implied that these thirteen MAbs recognized O/97 specific epitope(s). Furthermore, reactivities of the VP1 reacting MAbs with a 29 amino acids synthetic peptide (P29) representing the betaG-betaH loop of VP1 were analyzed by ELISA and fourteen were found positive. MAb clone Q10E-3 reacting strongest with VP1 and P29, neutralizing both but not differentiating two serotype O viruses suggested that the antibody binding site might involve the RGD motif and its C terminal conserved region on betaG-betaH loop. MAbs with diverse characters presented in this study were the first raised against porcinophilic FMDV. The complete set of MAbs may be used for further studies of vaccine, diagnostic methods, prophylaxis, etiological and immunological researches on FMDV.     

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。     

Sensitivity and specificity of an enzyme-linked immunosorbent assay for the detection of bovine viral diarrhea virus antibody in cattle.

A reliable bovine viral diarrhea (BVD) viral antigen was prepared from BVD virus grown on Madin Darby bovine kidney (MDBK) cells by solubilizing the virus with detergent MEGA-10 (decanoyl-N-methylglucamide) followed by removal of hydrophobic proteins with Triton X-100 treatment. By these treatments, problems of high background associated with BVD viral antigen in the enzyme-linked immunosorbent assay (ELISA) were eliminated. With this new antigen, an ELISA was adapted to detect bovine serum antibody against BVD virus. The diagnostic specificity of the assay in 403 bovine sera collected from a BVD virus-free herd was 100%; in 296 bovine sera with serum neutralizing antibody titers of greater than or equal to 1:2, 289 sera were ELISA positive (relative sensitivity of 97.6%), two sera gave false negative reactions (0.7%) and five sera gave suspicious reactions (1.7%). These interpretations were based on positive/negative (P/N) ratio readings, i.e. a P/N ratio of less than 1.50, 1.50-1.99 and greater than or equal to 2.00 were interpreted as negative, suspicious and positive reactions, respectively. The ELISA results gave excellent agreement with serum neutralization in detecting both seropositive and seronegative animals (Kappa = 0.994). The ELISA assay was considered to be technically superior to the serum neutralization test for the routine detection of BVD viral antibody in bovine sera.     

Specific antibody responses and generation of antigenic variants in chickens immunized against a virulent avian influenza virus.

To examine the specificity of the antibody response to the influenza hemagglutinin and the generation of antigenic variants, chickens were immunized against the highly virulent H5 virus A/Ty/Ont/7732/66 (H5N9) and then challenged with a lethal dose of the virus. The antibody responses of these chickens to the hemagglutinin (HA) were examined with an enzyme-linked immunosorbent assay (ELISA) in which their sera were titrated for the ability to block the binding of monoclonal antibodies (MAbs) to five distinct neutralizing epitopes on the viral HA. Based on the ELISA results, a majority (5/6) of the chickens produced antibodies to three of the five neutralizing epitopes on the viral HA. After challenge, two of six immunized chickens shed virus and died; antigenic comparisons of isolates from these two chickens indicated the presence of an antigenic variant; i.e., there was a change in one neutralizing epitope on the HA of virus shed by one chicken. None of the chickens had produced antibodies to this particular epitope on the viral HA. Inoculation of chickens with this variant resulted in 100% mortality, demonstrating that a change in this particular epitope did not alter the virulence of the virus. These studies indicate that chickens immunized against highly virulent influenza viruses may excrete virulent variants following challenge with live virus.     

Competitive enzyme-linked immunosorbent assay for the detection of the antibodies specific to akabane virus.

A competitive enzyme-linked immunosorbent assay (C-ELISA) using neutralizing monoclonal antibodies (MAbs) against Akabane virus (AKAV) was developed to detect antibodies to AKAV in cattle sera. The performance of the test using 7 different competitor MAbs was evaluated in sequential serum samples and sera from cattle infected with various bovine arboviruses. The dynamics of the antibody response expressed by percentage of inhibition (PI) in C-ELISA coincided with those of neutralizing antibody titers in sequential serum samples from 2 cattle experimentally infected with AKAV. The value of PI in C-ELISA for convalescent sera from cattle infected with arboviruses correlated with the neutralizing antibody titer to AKAV but was unaffected by the antibodies to other arboviruses. In the validation experiment of C-ELISA using 286 bovine sera previously examined for the AKAV antibody by serum neutralization (SN) test, the relative specificity of C-ELISA was more than 98%, whereas the relative sensitivities of individual MAbs ranged from 49% to 82.2%. Overall agreement between C-ELISA and the SN test varied from 72% to 90% depending on the MAb. These results suggest that the C-ELISA is acceptable as a rapid and specific method for detecting antibodies to AKAV and is a potential alternative to the SN test.     

Experimental rabies in skunks: Immune response and salivary gland infection

Groups of striped skunks (Mephitis mephitis) were inoculated intramuscularly with graded doses of street rabies virus. At various intervals after inoculation, saliva and sera were tested for rabies virus and neutralizing antibodies, respectively. Skunks that developed rabies were killed in terminal stages of the disease and the following examinations were made: titers of virus and antibody in submandibular salivary glands and brain, extent of immunofluorescence in submandibular salivary glands, and histologic examination of various tissues.

Skunks that received inocula containing 4 × 10⁴ to 4 × 10⁵ mouse intracerebral lethal dose₅₀ (MICLD₅₀) had detectable serum neutralizing antibodies by 7–12 days postinoculation; however, most of the skunks that received lower doses (40 to 4 × 10³ MICLD₅₀) did not have detectable serum neutralizing antibodies until clinical signs began. In the salivary glands, slight and extensive immunofluorescence corresponded to high and low titers of tissue neutralizing antibody. Also low viral titers were associated with high tissue neutralizing antibody titers. There was a close correlation between viral titers in right and left submandibular salivary glands.

The results suggest that the immune response can impede the process of infection of the salivary glands resulting in lack of antigen or low amounts of antigen in this tissue. This could occur through interference with centrifugal neural transport of virus and/or neutralization of virus during transfer from neural elements to epithelial cells. Lack of infectious virus or low viral titers in salivary glands containing antigen and high levels of tissue neutralizing antibodies can be caused partly by postmortem virus neutralization (during viral titration).     

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.     

Expression of the mouse Fc receptor B2 in bovine cells rescues the infectivity of conditionally neutralized bovine viral diarrhea virus

We examined the infectivity of bovine viral diarrhea virus (BVDV) particles opsonized with monoclonal antibodies on bovine cells expressing the murine Fcgamma receptor B2 (FcgammaRB2). Incubation of BVDV with each of five monoclonal antibodies (Mabs) to the envelope glycoprotein E2 led to efficient virus-neutralization, as evidenced by the failure to infect standard bovine testicle cells. In contrast, inoculation of four of these Mab-virus complexes onto transfectant bovine testicle cells expressing FcgammaRB2 resulted in a significant rescue of virus infectivity. Mab-virus complexes were 13.1, 7.37, 5.56 and 4.49 times more infectious for FcgammaR-expressing cells than for cells lacking FcgammaR. Because Mab-opsonized BVDV virion complexes uninfectious for standard cells may initiate productive infection in cells expressing the FcgammaR, the virion-Mab interaction should be described as a conditional neutralization. Interestingly, the infectivity of BVDV complexed with a specific virus neutralizing Mab (10f9) could not be rescued in FcgammaRB2-expressing cells. We postulate that attachment of antibody-virus complexes to FcR may only result in productive infection if the binding of antibody to virions does not interfere with post-attachment entry functions. Conditionally neutralized virions may play a role in the pathogenesis of any of the multiple diseases resulting from BVDV infections in cattle.