IgM antibodies to Epstein-Barr virus-associated membrane antigen in sera of infectious mononucleosis patients

By the indirect immunofluorescence technique, IgM antibodies to the cell surface of an Epstein-Barr virus (EBV) producer cell line, P3HR-1, were detected in sera from infectious mononucleosis (IM) patients but not in sera from patients with Burkitt lymphoma or nasopharyngeal carcinoma nor in sera from healthy adult donors having antibodies to EBV-specific viral capsid antigen (VCA). Titers of the IgM antibodies were higher in the earlier stages of IM, a pattern similar to that for IgM antibodies to VCA. The IgM antibodies to the cell surface were identified as being those against the EBV-specific membrane antigen (MA) by the following criteria: (1) The antibodies were reactive to MA-positive cell preparations but to MA-negative cell preparations. (2) Titers of the IgM antibodies were not significantly affected after absorption of sera with sheep red blood cells which could completely eliminate heterophil antibodies in the same sera. Detection of the IgM antibodies to MA may have a particular diagnostic value for providing evidence of a recent EBV infection.     

Identification of multiple Epstein-Barr virus-induced nuclear antigens with sera from patients with rheumatoid arthritis.

By means of the protein immunoblot technique, the Epstein-Barr virus (EBV) nuclear antigen (EBNA) could be identified in a variety of EBV-transformed cell lines with anti-EBNA-positive sera from normal donors. The molecular weight of EBNA expressed in each of the cell lines varied between 70,000 and 75,000 and was dependent upon the strain of infecting virus. In contrast, 15 of 21 sera from patients with rheumatoid arthritis identified antigens in addition to EBNA. The most prominent of these antigens had molecular weights of 110,000 to 115,000 and 92,000. All of the EBV genome-positive cell lines except for QIMR-GOR and cell lines containing the P3HR-1 virus expressed these antigens. The antigens were not present in the EBV genome-negative Ramos and BJAB cell lines, nor were they identified with EBV seronegative sera, indicating that they were EBV related. There was no direct correlation between the presence of antibodies in sera to EBNA, viral capsid antigen or early antigen, and reaction with the 92,000-molecular-weight antigen in immunoblots, indicating that this antigen was distinct from previously described EBV-related antigens.     

Epstein-Barr virus serology

Because of the ubiquitous nature of EBV, most people are infected with this virus by the time they are adults. People acquire the virus at an early age, earlier in developing countries and in socioeconomically deprived areas of the United States, where about 80% of 5-year-old children are seropositive. In economically privileged areas, only about 40–50% of children are seropositive by age 5. Infections during childhood are usually asymptomatic. In contrast, 50% of adolescents who become infected with EBV develop the fatigue, fever, pharyngitis, and atypical lymphocytosis characteristic of acute infectious mononucleosis (IM). Heterophil antibodies, which are the basis for screening tests for IM, usually appear in the serum of these patients. However, approximately 10% of patients (more commonly children) with EBV induced IM do not develop heterophil antibodies. For this reason, tests for specific antibody-mediated immune responses to EBV may be necessary for diagnosis.     

Production of migration inhibitory factor (MIF) by human leukocytes following exposure to Epstein-Barr virus.

The ability of Epstein-Barr virus (EBV) to induce a cell-mediated immune response (CMI) in cultures of human leukocytes was investigated. Partially purified EBV, obtained from culture fluids of AV-1 cells, was inactivated by uv-irradiation. Inactivated virus was mixed with peripheral leukocytes from Hodgkin's disease (HD), infectious mononucleosis (IM) and malignant lymphoma patients as well as from normal individuals in an in vitro culture system. Production of migration inhibitory factor (MIF), as measured by guinea pig macrophage migration inhibition (MMI), was utilized as an indicator of CMI response. Significant differences in MIF response were observed subsequent to exposure of the cells to EBV. Leukocytes from patients in each of the disease categories tested exhibited greater MIF production than did those from the normal controls. There were significant differences in MIF production by leukocytes from the malignant and non-malignant disease categories. Serum from each subject was examined for immunoglobulin specific for EBV capsid antigen (anti-VCA). Although the majority of individuals within the disease categories tested had elevated anti-EBV serum titers, no correlation could be made between elevated anti-VCA titer and levels of MIF production.     

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.     

Viral attributes and host factors in carcinogenesis: herpesviruses.

This paper describes two different experiments of nature: 1) the persistence of unusual virus strains of Epstein-Barr virus (EBV) (which proved oncogenic in vitro) and cytomegalovirus (CMV) in lymphoid cells following congenital or early acquired infection; 2) the occurence of multiple cases of Burkitt's lymphoma and nasopharyngeal carcinoma in one family. All the members of this family were EBV viral capsid antigen (VCA) and nuclear antigen (EBNA) antibody positive. The two patients with nasopharyngeal carcinoma had high titers of EBV-VCA, EA, and EBNA antibodies. The only member of this family having EBV early antigen (EA antibodies in addition to the patients with tumors was the mother. Borderline IgA deficiency was documented in 3 members of this family. These findings illustrate the importance of host factors (intracellular resistance to transformation and secondarily, immunological surveillance) in the outcome of the host-virus challenge whether cancer or infectious disease is the outcome. Extensive studies of these cases may provide the best insight into the mysteries of viral oncogenesis.     

Membranes of EBV-carrying virus nonproducer cells inhibit leukocyte migration of EBV-seropositive but not seronegative donors

We have previously shown that the leukocytes of healthy EBV-seropositive (but not seronegative) donors respond with migration inhibition (LMI) when confronted with extracts of EBV-carrying (but not EBV negative) cells. In the present study, we have examined whether this EBV-specific LMI response is capable of detecting a membrane antigen on the surface of EBV-carrying virus nonproducer cells. Crude membranes from EBV-genome carrying and EBV-negative cell lines were used as antigen. Contamination with the EBV-determined nuclear antigen (EBNA) was ruled out. Membranes from EBV-genome carrying nonproducer cells inhibited the migration of leukocytes from healthy seropositive donors, whereas membranes from EBV-negative lines had no such effect. Seronegative donors did not show any LMI. The clear difference between the EBV-negative Ramos line and its EBV-converted sublines was particularly conclusive in showing that the membrane component is determined or induced by the viral genome.     

Studies on the presence of antibodies to EB virus and other herpesviruses in normal children and in infectious mononucleosis.

Children free from infectious disease have been examined by indirect immunofluorescence for the presence of antibodies to the intracellular capsid antigen of Epstein-Barr virus (EBV). In the first year of life 46%, between 2 and 6 years of age 66%, and between 7 and 14 years 91%, of the children proved positive. The corresponding percentages for the presence of antibodies to cytomegalovirus (CMV) and herpes simplex virus were about 50%, irrespective of the children's age. Serum samples from 69 patients suffering from infectious mononucleosis (IM) were tested for anti-EBV antibodies. Of the 29 Paul-Bunnell-positive patients 22 had antibodies, 11 of them in high titres (greater than 1 : 80). Of the 40 Paul-Bunnell-negative cases only 21 had antibodies, 8 in high titres. Of the Paul-Bunnell-negative cases, 73% were found to have anti-CMV antibodies, 32% in high titre. The respective percentages for the Paul-Bunnell-positive cases were 42% and 10%.     

Demonstration of EBNA (Epstein-Barr virus nuclear antigen) antibodies of different immunoglobulin classes.

Anit-EBNA IgM, a previously unknown antibody, was detected by the antihuman globulin anticomplement immunofluorescence (ACIF) method in serum samples from acute infectious mononucleosis (IM) of Epstein-Barr virus (EBV) origin. The antibody disappears from the serum in some weeks during convalescence. It was absent in anti-EBV=positive sera of healthy donors and in serum samples taken from patients with IM caused by cytomegalo-virus. The antibody appears simultaneously with anti-EBV IgmM and, reaching a lower titre than the latter, its titre curve runs parallel with the anti-EBV IgM curve. Since in acute EBV infections, anti-EBNA IgM always appeared, its presence may serve as an additional evidence of the acuteness of EBV infection. In EBV-seropositive healthy subjects, the bulk of antibodies belongs to the IgG class, non-complement-fixing IgA antibodies occur only sporadically.     

Detection of antibody-dependent complement-mediated inactivation of both autologous and heterologous virus in primary human immunodeficiency virus type 1 infection

Specific CD8 T-cell responses to human immunodeficiency virus type 1 (HIV-1) are induced in primary infection and make an important contribution to the control of early viral replication. The importance of neutralizing antibodies in containing primary viremia is questioned because they usually arise much later. Nevertheless antienvelope antibodies develop simultaneously with, or even before, peak viremia. We determined whether such antibodies might control viremia by complement-mediated inactivation (CMI). In each of seven patients studied, antibodies capable of CMI appeared at or shortly after the peak in viremia, concomitantly with detection of virus-specific T-cell responses. The CMI was effective on both autologous and heterologous HIV-1 isolates. Activation of the classical pathway and direct viral lysis were at least partly responsible. Since immunoglobulin G (IgG)-antibodies triggered the CMI, specific memory B cells could also be induced by vaccination. Thus, consideration should be given to vaccination strategies that induce IgG antibodies capable of CMI.     

Clinical and immunological effect of intravesical interleukin-2 on superficial bladder cancer

TheBamHI Z EBV replication activator (ZEBRA) protein is involved in the switch from latency to productive cycle of Epstein-Barr virus. A recombinant ZEBRA protein was synthesized and assessed in enzymelinked immunosorbent assay (ELISA) for serum IgG response in nasopharyngeal carcinoma (NPC) patients. In 100 NPC serum samples that were positive for IgA to the EBV viral capsid antigen (VCA), 75% had IgG anti-ZEBRA antibodies. In contrast, only 3/83 (3.6%) serum samples from healthy donors and 2/50 (4%) from other cancers were positive for IgG to ZEBRA. Interestingly, in a selected group of 100 NPC sera negative for IgA to VCA, 25% contained IgG anti-ZEBRA antibodies. This suggests that the ELISA for IgG anti-ZEBRA may also identify earlier cases of NPC not detected by the conventional immunofluorescence test for IgA to VCA.     

Epstein-Barr virus antibodies in patients with ataxia-telangiectasia and other immunodeficiency diseases

An unusual antibody response to the Epstein—Barr virus (EBV) has been noted in patients with ataxia—telangiectasia. Of a group of 16 such patients 8 were found to have antibodies in their serum to the EBV viral capsid antigen (VCA), and 4 of them also had antibodies to the EBV early antigen (EA); antibodies to the nuclear antigen (EBNA), however, were absent in 3 of the 8. The antibody pattern persisted for more than 2 years in the patients available for follow-up study. In comparison, of 24 patients with various other immunodeficiency syndromes 9 were found to have EBV-VCA antibodies in their serum, but none of the 9 had EA antibodies and 3 lacked EBNA antibodies. Two other groups of subjects, all of whom had EBV-VCA and EBNA antibodies in their serum late after an EBV infection, were also studied; 82 had infectious mononucleosis and 55 were healthy and had no such history. EA antibodies were detected in 45 of the first group during the acute phase of the illness but persisted in only 6 of the 68 who were followed up for more than 2 years, and they were detected in only 7 of the second group.All eight lymphoblastoid cell lines established from the peripheral blood of the four patients with ataxia—telangiectasia who are still available for follow-up study express EBV-VCA, whereas most similar cell lines established from normal individuals express only EBNA. In two of these patients cell-mediated immunity, as assessed from lymphocyte transformation induced by mitogens, was markedly decreased but autologous cell-mediated immune regression of EBV-induced transformation of B (bone-marrow-derived)-lymphocytes was normal. The percentage of T (thymus-derived)-helper cells was greatly decreased in two of the three patients in whom it was measured, and the percentage of T-suppressor cells was greatly increased in one of them, but the percentage of total T-lymphocytes was within normal limits in all three.The possible significance of these findings — in particular, the persistence of EA antibodies and the diminished restriction of expression of EA — in the late development of tumours after an EBV infection in patients with ataxia-telangiectasia deserves careful attention. Finally, the apparent correlation between immunoglobulin deficiency and poor or absent EBNA antibody response warrants further study.     

Assessment of the status of cell-mediated immunity in cytomegalovirus-infected renal allograft recipients.

Renal allograft recipients are unusually susceptible to cytomegalovirus (CMV) infections. Since humoral immunity to CMV is uncompromised in these patients, it was felt desirable to assess the competence of cell mediated immunity (CMI). Several parameters were used. On skin testing with candida, SK-SD, mumps, and PPD-5 antigens, 80.0% of patients and 5.0% of controls were unreactive. T-lymphocyte ratios (SRBC rosette test) were 18.7% in transplant patients, vs. 40.3% in controls. These differences are statistically significant. Lymphocyte stimulation assay ([³H] thymidine uptake) was developed to study CMI to CMV. Lymphocytes from all the normal seropositive subjects (10) had increased [³H]thymidine uptake on exposure to CMV antigens. There was no antigen specific stimulation of lymphocytes from the seronegative controls (five). Six of nine (67.7%) CMV infected renal allograft recipients, studied six or more months post-transplantation, had no evidence of CMI to CMV by this assay.     

Epidemiologic studies assessing the role of the Epstein-Barr virus in Hodgkin's disease.

The hypothesis that an infection plays a role in the etiology of Hodgkin''s disease (HD) is suggested by both its clinical and histologic features. Its bimodal age-incidence pattern also suggests an infectious process among younger persons. In economically advantaged populations, the first peak occurs among young adults, while in disadvantaged populations, it occurs among children at a much lower frequency. It appears that the age distribution of HD shadows that of susceptibility to common childhood infections, such as the Epstein-Barr virus (EBV); furthermore, that risk of HD is increased among those susceptible to a relatively late infection, in parallel with infectious mononucleosis (IM), and it has been found that people who have had IM have about three times the expected rate of HD. Serologically, there is a consistent association between EBV and HD. As a group, patients have an altered antibody pattern against EBV which suggests chronic reactivation, both following and preceding diagnosis. This altered pattern is common to all age groups. Severity of infection may alter host control among younger people, while diminished cellular immunity with aging may allow similar reactivation among older persons. Whether the EBV plays a direct role or simply reflects the action of a more primary factor is unknown.     

Absence of cell-mediated immunity to rubella virus 5 years after rubella vaccination.

The long-term effectiveness of rubella vaccination in childhood is particularly important because the ultimate goal of immunization is the prevention of infection during pregnancy. Of 25 healthy children tested 4 to 5 years after rubella vaccination, 19 showed no evidence of cell-mediated immunity (CM) to rubella virus despite the presence of hemagglutination-inhibition or complement-fixation antibodies or both. Twenty-two of 25 seropositive, naturally infected young adults showed evidence of CMI. These results indicate that fetuses of women who have been vaccinated against rubella may not be protected against damage by wild rubella infection during the pregnancy, when CMI is physiologically depressed.     

Sequential detection of different antigens induced by Epstein-Barr virus and herpes simplex virus in the same Western blot by using dual antibody probes

A dual antibody probing technique that permitted a color-coded identification of polypeptides representing different classes of Epstein-Barr virus (EBV) antigens as well as differentiation of the polypeptides induced by different herpesviruses in the same Western blot was developed. When the nitrocellulose sheet was probed first with monoclonal antibody against EBV early antigen diffuse component (EA-D) and then stained with 4-chloro-1-naphthol, four polypeptides specific for EA-D were identified by purple bands. Subsequently, the same nitrocellulose sheet was reprobed with human serum containing antibodies against EBV early antigen, viral capsid antigen, and nuclear antigen and stained with 3,3'-diaminobenzidine. Several brown bands corresponding to early, viral capsid, and nuclear antigen polypeptides were detected. The dual antibody probing technique was used in an analysis to differentiate polypeptides resulting from either EBV or herpes simplex virus infection, either in cells infected by individual virus or in a cell line dually infected by both viruses. On the basis of different colored bands in different lanes of the same gel, 20 polypeptides with molecular weights ranging from 31,000 to 165,000 were identified as herpes simplex virus-specific proteins. These results suggested that the dual antibody probing technique may be applicable in clinical diagnosis for detecting antigens and antibodies derived from different pathogens.     

Mechanisms of infection with Epstein-Barr virus. I. Viral DNA replication and formation of noninfectious virus particles in superinfected Raji cells.

Human lymphoblastoid Raji cells, which do not produce virus, supported replication of Epstein-Barr virus (EBV) upon superinfection. Early antigen, viral capsid antigen, and virions were produced in Raji cells superinfected with EBV. Viral DNA replicated under complete inhibition of host cell DNA synthesis to the extent that a few micrograms of EBV DNA were recovered from 107 superinfected Raji cells, corresponding to 5,000 viral genomes/cell. Homology of the synthesized viral DNA to parental EBV DNA was more than 90%. Virions produced by the Raji cells contained a 55S DNA but failed to induce early antigen, viral capsid antigen, and viral DNA synthesis after a second superinfection of Raji cells.     

Immunoblotting reactivity of human sera from various sources against purified epstein-barr virus

The immunoblotting technique was used to analyse polypeptides of purified Epstein-Barr virus reacting with antibodies present in sera from clinically healthy individuals, from patients with infectious mononucleosis (IM) or AIDS, and from renal transplant recipients with molecular sizes in the range of 40–290 kDa were detected.The 47- and 160-kDa nucleocapsid polypeptides, as well as the 72-, 74-, 140-, 220- and 290-kDa membrane polypeptides were the major viral proteins detected in the sera. Sera from clinically healthy individuals contained antibodies directed against all EBV membrane and nucleocapsid antigens. Sera from renal transplant recipients, from patients with IM and from patients with AIDS failed to react with certain nucleocapsid and membrane antigens; in particular, sera from AIDS patients and renal transplant recipients did not react with the 220-kDa polypeptide, one of the major membrane antigens, while sera from subjects with IM and from healthy individuals did.A high proportion of sera from patients with IM (38% vs 5% of clinically healthy individuals and 0–5% of the AIDS patients and renal transplant recipients) reacted with a 42-kDa polypeptide, suggesting its possible role in acute EBV infection.     

Epstein-Barr病毒特异性T细胞对重组痘苗病毒表达LMP和EBNA2的靶细胞的识别

本文用EB病毒转化自体淋巴细胞所建立的类淋巴母细胞系(LCL),以及用EB病毒潜伏感染膜蛋白(LMP)基因和核蛋白-2(EBNA2)基因与痘苗病毒重组的重组病毒(Vac-LMP和Vac-EBNA2)感染的自身纤维母细胞,同时作为刺激细胞和靶细胞,以~(51)Cr释放法检测5例血清中EB病毒VCA—IgA抗体阳性者及1例阴性健康者外周血单个核细胞(PBMC)的特异性T细胞杀伤效应。结果表明,用自身LCL激活的EB病毒特异性T细胞杀伤效应高峰出现在第14～28天;参与杀伤性细胞免疫反应的T细胞亚群主要是T3、T8阳性的细胞毒性T细胞,其对靶细胞的识别及杀伤受HLA-I的限制。用重组牛痘病毒感染的纤维母细胞作靶细胞或刺激细胞,有1例供者可接受LMP,另1例可接受EBNA2的刺激,并对相应的靶细胞产生特异性T细胞杀伤反应,表明EB病毒-LMP和EBNA2可能既是EB病毒特异性T细胞的刺激抗原,又是其识别的靶抗原。     

Viral antibodies in infectious mononucleosis

Abstract Patients with Epstein-Barr virus (EBV) infectious mononucleosis (IM) usually develop heterophilic antibodies and some autoantibodies. Antibodies to rubella, measles, adeno-, entero-, herpes simplex, cytomegalo- and varicella-zoster viruses were titrated in sera from IM patients and matched healthy controls using the complement fixation test (CFT) and the haemagglutination inhibition test. Except for herpes simplex virus and cytomegalovirus, the IM sera had significantly higher arithmetical and geometrical mean antibody titres and showed in most cases higher antibody prevalences in the CFT. The titre rise was most pronounced for rubella and measles antibodies, between 2- and 3-fold. There were no cases of very high titres occasionally seen in IM. The IM sera had higher total IgG serum levels than the controls, 17.27 g/1 and 11.8 g/1, respectively ( P < 0.001). The present data show that in addition to previously reported high levels of some autoantibodies and of heterophilic antibodies, there is a more general increase in IgG antibodies to commonly occurring viruses. This increase is most likely due to the polyclonal activation of B-lymphocytes following the binding of EBV to the complement receptor CR2 (CD21). When due consideration is given to the possible occasional occurrence of a false positive rubella IgM test, the raised antibody-titres will most likely not interfere with routine diagnostics.