Evaluation of the antigenic variation within type-A foot and mouth disease virus isolates from Asia

The serological interrelationships among 17 type A FMD virus strains from eight Asian countries were studied by the two-dimensional microneutralization test. Complex direct and indirect relationships were observed. Overall, however, the virus strains studied could be classified as belonging to the A22 group on the basis of r value differentiation at P less than 0.01.     

Antigenic variants of herpes simplex virus selected with glycoprotein-specific monoclonal antibodies.

Monoclonal antibodies specific for herpes simplex virus type 1 (HSV-1) glycoproteins were used to demonstrate that HSV undergoes mutagen-induced and spontaneous antigenic variation. Hybridomas were produced by polyethylene glycol-mediated fusion of P3-X63-Ag8.653 myeloma cells with spleen cells from BALB/c mice infected with HSV-1 (strain KOS). Hybrid clones were screened for production of HSV-specific neutralizing antibody. The glycoprotein specificities of the antibodies were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates of radiolabeled infected-cell extracts. Seven hybridomas producing antibodies specific for gC, one for gB, and one for gD were characterized. All antibodies neutralized HSV-1 but not HSV-2. Two antibodies, one specific for gB and one specific for gC, were used to select viral variants resistant to neutralization by monoclonal antibody plus complement. Selections were made from untreated and bromodeoxyuridine- and nitrosoguanidine-mutagenized stocks of a plaque-purified isolate of strain KOS. After neutralization with monoclonal antibody plus complement, surviving virus was plaque purified by plating at limiting dilution and tested for resistance to neutralization with the selecting antibody. The frequency of neutralization-resistant antigenic variants selected with monoclonal antibody ranged from 4 X 10(-4) in nonmutagenized stocks to 1 X 10(-2) in mutagenized stocks. Four gC and four gB antigenic variants were isolated. Two variants resistant to neutralization by gC-specific antibodies failed to express gC, accounting for their resistant phenotype. The two other gC antigenic variants and the four gB variants expressed antigenically altered glycoproteins and were designated monoclonal-antibody-resistant, mar, mutants. The two mar C mutants were tested for resistance to neutralization with a panel of seven gC-specific monoclonal antibodies. The resulting patterns of resistance provided evidence for at least two antigenic sites on glycoprotein gC.     

用免疫荧光单克隆抗体对脊髓灰质炎病毒抗原表位的分析

用间接免疫荧光与中和试验筛选出来的抗脊髓灰质炎2型与3型不同毒株的12个单克隆抗体,其中3个仅有免疫荧光活性,9个具有中和与免疫荧光活性。用免疫荧光活性的单克隆抗体进行试验,发现它们在识别特异性抗原表位方面与中和性单克隆抗体相似,显示出株特异的、几个毒株共同特异的或型特异的抗原表位。根据表位分布关系及特征,可以用来鉴别型内毒株的特征、毒株的抗原分析、抗原变异的研究以及疫苗相关病例的鉴别。所得结果与中和性单克抗隆抗体及T1-寡核苷酸指纹图谱分析一致。而免疫荧光单克隆抗体识别抗原表位的活性范围比中和性单克隆抗体更广。另外还发现某些兼有荧光与中和两活性的同一个单克隆抗体,用不同方法(IF与NT)进行试验时,与相同毒株出现不同表位反应,这点是值得引起注意需待进一步证实的重要问题。     

Antigenic site II of the rabies virus glycoprotein: structure and role in viral virulence.

Twelve monoclonal antibodies neutralizing the CVS strain of rabies virus were used to characterize antigenic site II of the viral glycoprotein. Nineteen antigenic mutants resistant to neutralization by some of these antibodies were selected; some continued to normally or partially bind the antibody, whereas others did not. Mutations conferring resistance to neutralization by site II-specific monoclonal antibodies were localized into two clusters, the first between amino acids 34 and 42 (seven groups of mutants) and the second at amino acids 198 and 200 (three groups of mutants). Two intermediate mutations were identified at positions 147 and 184. Four mutations resulted in reduced pathogenicity after intramuscular inoculation of the virus in adult mice. One of the mutants, M23, was 300 times and the others were 10 to 30 times less pathogenic than CVS. In three cases the attenuated phenotype was related to an important modification of antigenic site II, whereas the other known antigenic sites were unchanged.     

Further studies of specificity of antibodies contained in antiserum against poliovirus.

Antigenic components of Mahoney strain (poliovirus type 1) involved in virus neutralization reaction were analyzed with mutant Mahoney strains resistant to inhibitors in equine serum (inhibitor-resistant mutants) by means of the kinetic neutralization test. It was shown that absorption of anti-Mahoney serum with five inhibitor-resistant mutants yielded sera with different antibodies, of which three had distinct specificities and two specificities possibly partly related to one of those three sera. Further, it was found that step wise selection of Mahoney variants resistant to one, two, three and four different inhibitors resulted in gradual deviation of its antigenic composition from that of the original strain. From these results, the possible presence of three or more distinct antigenic determinant sites on the surface of Mahoney strain was indicated.     

Further Studies of Specificity of Antibodies Contained in Antiserum against Poliovirus

Antigenic components of Mahoney strain (poliovirus type 1) involved in virus neutralization reaction were analyzed with mutant Mahoney strains resistant to inhibitors in equine serum (inhibitor-resistant mutants) by means of the kinetic neutralization test. It was shown that absorption of anti-Mahoney serum with five inhibitor-resistant mutants yielded sera with different antibodies, of which three had distinct specificities and two specificities possibly partly related to one of those three sera. Further, it was found that stepwise selection of Mahoney variants resistant to one, two, three and four different inhibitors resulted in gradual deviation of its antigenic composition from that of the original strain. From these results, the possible presence of three or more distinct antigenic determinant sites on the surface of Mahoney strain was indicated.     

The effect of antiserum quality on strain specificity assessment of foot and mouth disease virus by the neutralization reaction

The factors affecting the virus strain specificity of antibody to foot an mouth disease virus prepared by a variety of protocols in several species were evaluated by neutralization tests. The time at which the serum was taken, the antigen dose given, whether or not revaccination had occurred and the animal species in which the sera were prepared, did not appear to affect the strain specificity of serum prepared to inactivated antigens when measured in neutralization tests, probably because of the restricted nature of the antigenic site involved. However, variation was observed with convalescent animal sera or sera from animals which had received trypsin cleaved virus were used. For these reasons banks of reference antisera are prepared as pooled sera using one or two inoculations of inactivated antigen.     

Passive immune protection by herpes simplex virus-specific monoclonal antibodies and monoclonal antibody-resistant mutants altered in pathogenicity.

Virus-neutralizing monoclonal antibodies specific for 13 different genetically defined epitopes of glycoproteins gC, gB, and gD of herpes simplex virus type 1, strain KOS-321, were compared for their ability to provide passive immunity to DBA-2 mice challenged intracranially. Protection was highly specific, since individual monoclonal antibodies failed to protect against infection with monoclonal antibody-resistant (mar) mutants altered in the single epitope recognized by the injected antibody. The dose-response kinetics of passive immunity paralleled the in vitro neutralization titers for each antibody. No correlation was observed between immune protection and antibody isotype or complement-dependent in vitro neutralization titers. This suggests that virus neutralization was not the protective mechanism. In general, antibodies reactive with epitopes of gC were protective at the lowest antibody doses, antibodies specific for gB were less efficient in providing immunity, and antibodies against gD were the least effective. mar mutants with single epitope changes in gC and multiple epitope changes in gB showed highly reduced pathogenicity, requiring up to 5 X 10(6) PFU to kill 50% of infected animals. These findings indicated that antigenic variation affects virus growth and spread in the central nervous system. Thus, mutations which affect antigenic structure also can alter virus pathogenicity. The alteration of these epitopes does not, however, appreciably reduce the development of resistance to infection. Infection of mice with these mutants or inoculation of mice with UV-inactivated, mutant-infected cells before challenge rendered the animals resistant to infection with wild-type herpes simplex virus type 1.     

利用单克隆抗体对乙型脑炎病毒不同毒株抗原分析的研究

实验发现,应用动物免疫血清(多克隆抗体,PcAb)进行抗原分析时,我国分离到的乙型脑炎病毒SA14、P3、A2和高株的抗原性无明显差别,与从日本分离到的中山株有些差别,但仍被PcAb所中和;而用单克隆抗体(McAb)进行分析,情况就明显不同:SA14和P3株抗原性相似,高株和中山株不能被51-8McAb所中和,A2株则介于两者之间。A2和高顺生株的寡核苷酸指纹图谱分析表明,高株比A2株多两个斑点,但大多数斑点是一样的,证实了上述结果。实验还发现不同毒株的保护效果不同,A2株的免疫效果明显优于高株。     

Monoclonal antibodies against different epitopes of a 40 Kd capsid protein of infectious bursal disease viruses.

Nine monoclonal antibodies (Mab) against a 40 Kd capsid protein of infectious bursal disease virus (IBDV) strain P3009 were isolated. They were characterized by enzyme-linked immunosorbent assay, indirect fluorescent antibody staining and virus neutralization. They were divided into two groups concerning virus neutralization. Group I Mabs were able to neutralize virus infectivity; however, group II Mabs were not. Competitive binding assays using these Mabs demonstrated the existence of two distinct antigenic regions (A and B) on the 40 Kd protein. Region A was recognized by group I Mabs and region B was by group II Mabs. The binding reaction with group I Mabs was affected by denaturing of the viral proteins, indicating that the antigenic region involving neutralization was conformation-dependent. The results of enzyme-linked immunosorbent assays and virus neutralization tests suggested that group I Mabs might react with one epitope within region A and group II Mabs with 2 or 3 epitopes within region B.     

Antigenic and functional organization of human parainfluenza virus type 3 fusion glycoprotein.

Twenty-six monoclonal antibodies (MAbs) (14 neutralizing and 12 nonneutralizing) were used to examine the antigenic structure, biological properties, and natural variation of the fusion (F) glycoprotein of human type 3 parainfluenza virus (PIV3). Analysis of laboratory-selected antigenic variants and of PIV3 clinical isolates indicated that the panel of MAbs recognizes at least 20 epitopes, 14 of which participate in neutralization. Competitive binding assays indicated that the 14 neutralization epitopes are organized into three nonoverlapping antigenic sites (A, B, and C) and one bridge site (AB) and that the 6 nonneutralization epitopes form four sites (D, E, F, and G). Most of the neutralizing MAbs were involved in nonreciprocal competitive binding reactions, suggesting that they induce conformational changes in other neutralization epitopes. Fusion-inhibition and complemented-enhanced neutralization assays indicated that antigenic sites AB, B, and C may correspond to functional domains of the F molecule. Our results indicated that antibody binding alone is not sufficient for virus neutralization and that many anti-F MAbs neutralize by mechanisms not involving fusion-inhibition. The degree of antigenic variation in the F epitopes of clinical strains was examined by binding and neutralization tests. It appears that PIV3 frequently develops mutations that produce F epitopes which efficiently bind antibodies, but are completely resistant to neutralization by these antibodies.     

口蹄疫病毒非结构蛋白3AB双抗体夹心ELISA方法的建立

抗原纯净度是口蹄疫(Foot-and-mouthdisease,FMD)灭活疫苗质量检验的一项重要内容,一般采用疫苗2–3次免疫动物后,检测非结构蛋白(Non-structuralprotein,NSP)抗体是否阳转,判断疫苗抗原的纯净度。文中旨在建立定量检测FMD灭活疫苗抗原中NSP3AB含量的ELISA方法,为疫苗质量控制提供参考方法。利用口蹄疫病毒(Foot-and-mouthdiseasevirus,FMDV)NSP3A单克隆抗体和辣根过氧化物酶(Horseradish peroxidase,HRP)标记的3B单克隆抗体,建立定量检测NSP3AB含量的双抗体夹心ELISA检测方法。采用原核表达并纯化的3AB蛋白作为标准品,标准品系列稀释,绘制标准曲线,以标准品与未加抗原的阴性对照吸光值(OD)的比值大于2.0的标准品最低浓度为最低检测限。标准品浓度介于4.7–600.0 ng/mL之间时,测得的OD值与浓度呈线性相关,回归曲线呈直线,相关系数R2=0.99,确定最低检测限为4.7ng/mL。检测12份未纯化灭活抗原中3AB蛋白含量介于9.3–200.0ng/mL之间;而纯化后的...     

非缺陷性网状内皮组织增生病毒的血清学区别

26株来自各种禽的网状内皮组织增生病毒(REV),用多克隆的抗REV鸡血清做交叉中和试验,用REV、T株,Coo1株所制备的单克隆抗体做免疫荧光试验,比较这些毒株之间的抗原关系,从交叉中和试验结果看,它们之间的抗原关系十分接近,可以认为同属于单一血清型;但也确实存在微小差异,因此又可以将它们分为三个血清亚型,这一结果巳被单克隆抗体检验所证实。     

Neutralization epitopes of the F glycoprotein of respiratory syncytial virus: effect of mutation upon fusion function.

Eighteen neutralizing monoclonal antibodies (MAbs) specific for the fusion glycoprotein of the A2 strain of respiratory syncytial virus (RSV) were used to construct a detailed topological and operational map of epitopes involved in neutralization and fusion. Competitive binding assays identified three nonoverlapping antigenic sites (A, B, and C) and one bridge site (AB). Thirteen MAb-resistant mutants (MARMs) were selected, and the neutralization patterns of the MAbs with either MARMs or RSV clinical strains identified a minimum of 16 epitopes. MARMs selected with antibodies to six of the site A and AB epitopes displayed a small-plaque phenotype, which is consistent with an alteration in a biologically active region of the F molecule. Analysis of MARMs also indicated that these neutralization epitopes occupy topographically distinct but conformationally interdependent regions with unique biological and immunological properties. Antigenic variation in F epitopes was examined by using 23 clinical isolates (18 subgroup A and 5 subgroup B) in cross-neutralization assays with the 18 anti-F MAbs. This analysis identified constant, variable, and hypervariable regions on the molecule and indicated that antigenic variation in the neutralization epitopes of the RSV F glycoprotein is the result of a noncumulative genetic heterogeneity. Of the 16 eptiopes, 8 were conserved on all or all but 1 of 23 subgroup A or subgroup B clinical isolates.     

一株广谱中和抗原性出血热病毒株的发现

一株分离自杭州市褐家鼠的出血热病毒Gou_3株的免疫血清对10株I型病毒的中和滴度除二株为160外均为320,而对4株Ⅱ型病毒的滴度为320—640,说明Gou_3株免疫血清对两型毒株中和效价大多数无差异或只差2倍,是一株中和抗原广谱的毒株。用I型和Ⅱ型毒株免疫血清对Gou_3株进行型别检定结果表明Gou_3株是Ⅱ型病毒。     

Studies on the antigenic structure of Japanese encephalitis virus using monoclonal antibodies

The antigenic relationships among 11 strains of Japanese encephalitis (JE) virus were analyzed by using monoclonal antibodies (NARMA) against the Nakayama-RFVL strain in hemagglutination-inhibition (HI) and neutralization (Nt) tests. Of the 14 JE virus-specific HI antibodies, all except NARMA 5 showed Nt reactivity with the homologous strain. The HI and Nt titers of these antibodies were not parallel. The 14 antibodies included the following characteristic antibodies: NARMA 3 is a species-specific antibody with HI and Nt reactivities against JE virus, NARMA 13 is a species-specific HI antibody, NARMA 6 is a Nakayama strain-specific antibody with HI and Nt reactivities, and NARMA 5 is a Nakayama strain-specific HI antibody. The 11 strains of JE virus were divided into four major antigenic groups. However, slight antigenic differences were found among some strains of the same group. Furthermore, competitive binding assays were performed to determine the distribution of antigenic determinants by enzyme-linked immunosorbent assay. The results suggest the existence of at least five HI sites on the JE virus virion, and indicate that the JE species-specific HI site and the flavivirus genus-specific HI site are topologically distinct.     

Biological properties and viral surface antigens of Burkitt lymphoma- and mononucleosis- derived strains of Epstein-Barr virus released from transformed marmoset cells.

Three strains of Epstein-Barr virus (EBV), two from Burkitt lymphoma (BL) and one from infectious mononucleosis (IM) were used to transform separate cultures of the same batch of primary marmoset leukocytes, and the viruses released from the transformants were compared. The three viruses shared properties of the transforming biotype of EBV, namely, stimulation of DNA synthesis and immortalization of cord blood leukocytes, and failure to induce "early antigen" in lymphoblast lines. All viruses produced more virus in transformed marmoset cells than in transformed human cells, as measured by the number of EBV genomes detected by complementary RNA/DNA hybridization, by virus capsid antigen expression, or by released virions and biologically active virus. Reference human sera and sera from primary EBV infections were used to compare the three virus strains in a virus neutralization test based on inhibition of stimulation of DNA synthesis. Specimens taken late in convalescence from patients with mononucleosis and sera from marmosets experimentally infected with virus from a patient with mononucleosis neutralized the homologous virus, as well as the two virus strains isolated from patients with BL. This finding indicates that viral antigens that elicit neutralizing antibodies are shared among the strains. However, in certain sera the neutralizing-antibody titer against one strain was consistently higher than against another strain. Furthermore, sera taken early after onset of IM contained low levels of neutralizing antibody against IM-derived virus, but failed to neutralize BL-derived virus. These latter findings suggest the existence of heterogeneity among surface antigens of EBVs. The results emphasize the biological and antigenic similarity of EBV isolates from BL and IM and do not suggest major subtype variations. It remains to be determined whether antigenic diversity such as described or virus genome variation detectable by other means is epidemiologically significant.     

Characterization of an echovirus type 30 variant isolated from patients with aseptic meningitis

An outbreak of echovirus type 30 infection associated with aseptic meningitis occurred among newborn babies in a hospital neonatal room at Fukui City in 1983. The isolated virus was identified as an antigenic variant of echovirus type 30 by cross-neutralization tests with antisera against the prototype Bastianni strain and the present isolate. Western blot analysis demonstrated that the antigenic determinants responsible for virus neutralization, some of which were type specific and others strain specific, were present on the capsid protein VP1. The current strain was more thermoresistant than the prototype, suggesting some alterations in virus structural proteins.     

Characterization of primary isolate-like variants of simian-human immunodeficiency virus

Several different strains of simian-human immunodeficiency virus (SHIV) that contain the envelope glycoproteins of either T-cell-line-adapted (TCLA) strains or primary isolates of human immunodeficiency virus type 1 (HIV-1) are now available. One of the advantages of these chimeric viruses is their application to studies of HIV-1-specific neutralizing antibodies in preclinical AIDS vaccine studies in nonhuman primates. In this regard, an important consideration is the spectrum of antigenic properties exhibited by the different envelope glycoproteins used for SHIV construction. The antigenic properties of six SHIV variants were characterized here in neutralization assays with recombinant soluble CD4 (rsCD4), monoclonal antibodies, and serum samples from SHIV-infected macaques and HIV-1-infected individuals. Neutralization of SHIV variants HXBc2, KU2, 89.6, and 89.6P by autologous and heterologous sera from SHIV-infected macaques was restricted to an extent that these viruses may be considered heterologous to one another in their major neutralization determinants. Little or no variation was seen in the neutralization determinants on SHIV variants 89.6P, 89.6PD, and SHIV-KB9. Neutralization of SHIV HXBc2 by sera from HXBc2-infected macaques could be blocked with autologous V3-loop peptide; this was less true in the case of SHIV 89.6 and sera from SHIV 89.6-infected macaques. The poorly immunogenic but highly conserved epitope for monoclonal antibody IgG1b12 was a target for neutralization on SHIV variants HXBc2, KU2, and 89.6 but not on 89.6P and KB9. The 2G12 epitope was a target for neutralization on all five SHIV variants. SHIV variants KU2, 89.6, 89.6P, 89.6PD, and KB9 exhibited antigenic properties characteristic of primary isolates by being relatively insensitive to neutralization in peripheral blood mononuclear cells with serum samples from HIV-1-infected individuals and 12-fold to 38-fold less sensitive to inhibition with recombinant soluble CD4 than TCLA strains of HIV-1. The utility of nonhuman primate models in AIDS vaccine development is strengthened by the availability of SHIV variants that are heterologous in their neutralization determinants and exhibit antigenic properties shared with primary isolates.     

Genetic analysis of a cytomegalovirus-like agent isolated from human brain.

An unusual cytomegalovirus (CMV, strain Colburn) isolated from brain biopsy of a boy with clinical encephalopathy was studied for genetic relatedness to human and simian CMV. Cross-examination of the purified viral DNA by DNA-DNA reassociation kinetics analyses showed more than 90% homology between Colburn virus and simian CMV (strain GR2757) and a lack of detectable homology between Colburn virus and human CMV (strains AD-169 and TW-87). Restriction endonuclease analysis of Colburn DNA showed some similarity of the DNA fragment pattern with that of simian CMV DNA, although the DNA fragment patterns were not identical, and showed no similarity to that of human CMV DNA. The molecular size and density of viral DNA were close to those of simian CMV DNA. The antigenic study, as performed by complement fixation and neutralization tests, showed strong cross-reactivity of Colburn virus to simian GR2757 virus. One-way cross-reaction of Colburn virus to several human CMV isolates (AD-169, Davis, and Town) was detected by complement fixation; this one-way cross-reaction was not obvious in a plaque neutralization test. It was concluded that Colburn is a simian CMV-related virus.