Glycosylation pathways of two major Epstein-Barr virus membrane antigens.

Monoclonal antibodies to the Epstein-Barr virus (EBV) membrane antigens (MA) were used to delineate the sequence of events occurring during MA maturation. Immunoprecipitation experiments performed with B95-8 virus infected 1605L cells, pulse labeled in the presence of tunicamycin or 2-deoxyglucose, suggest that the nonglycosylated forms of the mature 236,000 (236K) and 86K MA have molecular weights of 149K and 69K, respectively. Monensin treatment results in the accumulation of a 189K antigen which is converted to the mature 236K MA after a 2 hr chase in the absence of monensin. Experiments with monensin also suggest that an 84K intermediate is involved in the formation of the mature 86K MA. The mature 236K MA is resistant to endoglycosidase H while the 189K intermediate and the mature 86K MA are partially sensitive to this enzyme. The mature 236K and 86K MA and the 189K intermediate are resistant to endoglycosidase D.

Surface markers of primate B and T lymphoid cell lines identified by antibodies to human and simian lymphocyte antigens.

Simian B and T lymphoid cell lines were shown to maintain surface markers found on mature lymphocytes in vivo. The T lymphoid cell lines expressed Ia-like antigens on their surfaces, further suggesting that they represent mature, activated T cells. These Ia antigens show a structural similarity to Ia on human cells although some diversity exists. The Ia antigen expressed on T lymphoid cell lines was shown to be very similar to those on B lymphoid cell lines. Owl monkey and marmoset T lymphoid cell lines were also shown to express a VH immunoglobulin-related determinant, a marker which is thought to be associated with T cell antigen receptor. Owl monkey and marmoset T cell lines express a surface antigen which identifies the sheep erythrocyte receptor on human T cells and some of these lines express an antigen found on human helper T cells. It is noteworthy that substantial conservation of surface components has occurred within primate evolution such that monoclonal antibodies to human Ia, OKT-11a and Leu 3a markers can be used to type lymphocytes of lower primates.

Production and characterization of monoclonal antibodies against the Epstein-Barr virus membrane antigen.

Five murine hybridoma lines that produce monoclonal antibodies against Epstein-Barr virus membrane antigen (MA) were established. Immunoprecipitation experiments demonstrated that three of the antibodies precipitated both the 236,000 (236K) MA and the 212K MA. The other two antibodies precipitated the 86K MA. Antibodies against the 236K-212K MA and the 86K MA mediated complement-dependent cytolysis of Epstein-Barr-virus-infected cells. The antibodies against the 86K MA neutralized both the B95-8 and P3HR-1 viruses.

Reactivity of monoclonal antibodies against human leucocyte antigens with lymphocytes of non-human primate origin.

The phylogenetic distribution of antigens present on human lymphocytes was investigated by incubating human or simian cells with murine anti-human monoclonal antibodies and then determining the level of reactivity with a radiolabelled anti-murine IgG reagent. The monoclonal antibodies used were specific for a T-cell antigen, lymphoid and lymphoid:myeloid antigens, Ia antigens, and beta 2 microglobulin. The cells examined included B- and T-lymphoblastoid cell lines and fresh peripheral blood lymphocytes separated by sheep erythrocyte rosetting into T-cell and non T-cell fractions. Results of these studies showed that the antibodies gave complete cross-reactivity with gorilla and chimpanzee cells while B-cell lines of orangutan origin had lost lymphoid and beta 2 microglobulin markers. Gibbon cells and cells of Old World and New World monkeys reacted strongly only with monoclonal antibodies against Ia antigenic determinants. These Ia antigens were found on the non T-cell fraction of fresh peripheral lymphocytes, on B-cell lines and on some virus induced T-cell tumour lines. Immunoprecipitation analysis using the anti-Ia antibodies showed a degree of molecular diversity on owl monkey and marmoset cells compared to the Ia antigens associated with human cells.

Identification of an Epstein-Barr virus nuclear antigen by fluoroimmunoelectrophoresis and radioimmunoelectrophoresis.

A 65,000-dalton (65K) antigen found in Raji cells by fluoroimmunoelectrophoresis and radioimmunoelectrophoresis has been identified as an Epstein-Barr virus nuclear antigen (EBNA). This identification is based on the following evidence. The 65K antigen is detected in Raji cells but not in three Epstein-Barr virus (-) human B cell lines. It is not detected with EBNA (-) sera. The 65K antigen is found predominantly in the nucleus and co-elutes with EBNA during partial purification by DNA-Sepharose and Blue Dextran-Sepharose chromatography. Finally, the partially purified 65K antigen is an effective absorbant of EBNA antibody as measured in an anticomplement immunofluorescence assay. Antigens with molecular weights of 72, 70, and 73K have been detected in B95-8, P3HR-1, and Namalwa cells, respectively. These antigens are the likely homologues of the 65K Raji EBNA. In addition, an Epstein-Barr virus-associated, 81K DNA-binding antigen has been detected in both B95-8 and Raji cells.

Comparisons of nuclear antigens of Epstein-Barr virus (EBV) and EBV-like simian viruses.

Nuclear antigens (NA) of EBV (EBNA), Herpesvirus gorilla, H. papio, H. pongo and H. pan were tested with sera of human, gorilla, chimpanzee, orangutan, gibbon and baboon origins. Both conventional anticomplement immunofluorescence (ACIF) and acid-fixed nuclear binding of antigen followed by ACIF (AFNB) procedures were used. Comparisons of antibody titres by ACIF and AFNB suggested that human sera detected the same antigenic determinants on EBNA by the two procedures but gorilla sera measured different determinants on H. gorilla NA. Asymmetric cross-reactions were found with gorilla, chimpanzee and baboon sera but individual human and orangutan sera were found which had extensive cross-reactivities. Absorption experiments with these broadly reactive sera with H. gorilla NA and comparisons of antibody titres of human sera with EBNA, H. gorilla and H. papio NA suggested the presence of an EBV-specific determinant as well as a broadly reactive determinant on EBNA.

Correlation between Epstein-Barr virus membrane antigen and three large cell surface glycoproteins.

A correlation between Epstein-Barr virus membrane antigen (MA) and three surface glycoproteins has been established on the basis of radio-immunoprecipitation and immunoabsorption experiments. For radio-immunoprecipitation, Epstein-Barr virus-infected cells were radiolabeled either with neuraminidase-galactose oxidase tritiated borohydride, a procedure highly specific for surface glycoproteins, or with a general tritiated amino acid mixture. Intact cells were incubated with MA(-) or MA(+) human sera, washed free of unbound immunoglobulins, and then lysed with Nonidet P-40. The antigen-antibody complexes were bound to protein A-Sepharose and after elution with sodium dodecyl sulfate were analyzed by acrylamide gel electrophoresis in sodium dodecyl sulfate. MA(+) sera specifically precipitated three glycoproteins with molecular weights of 236,000, 212,000, and 141,000 from B95-8 cells induced with 12-O-tetradecanoylphorbal-13-acetate (TPA) and from Raji cells superinfected with P3HR-1 virus. These glycoproteins were not detected on Epstein-Barr virus-negative Ramos cells treated with TPA or on B95-8 cells treated simultaneously with TPA and phosphonoacetic acid. Soybean lectin-Sepharose bound all three glycoproteins, and lectin-Sepharose-bound glycoproteins from TPA-induced P95-8 cells absorbed MA-specific antibody from MA(+) human sera. The data strongly suggest that either all three glycoproteins have MA determinants or they are part of a complex in which one or more of the components constitute the reactive antigen.

Establishment of a lymphoblastoid cell line and isolation of an Epstein-Barr-related virus of gorilla origin.

A B-lymphoid cell line was established from a normal gorilla. The cells contained Epstein-Barr virus-related antigens, and herpesvirus particles were demonstrated by electron microscopy. DNA-DNA reassociation kinétics revealed 30 to 40% hybridization to Epstein-Barr virus with 50 genomes per cell. Examination of the viral nuclear antigen with gorilla sera showed this to be a unique isolate termed Herpesvirus gorilla. H. gorilla transformed gibbon B-lymphocytes in vitro.

Antibody responses to Herpesvirus papio antigens in baboons with lymphoma.

An Epstein-Barr virus-related herpesvirus, termed Herpesvirus papio (HVP), was isolated from baboons (Papio hamadryas) at the Institute of Experimental Pathology and Therapy, Sukhumi, USSR, where there is a continuing outbreak of lymphoma. In the present study sera from diseased baboons and from age- and sex-matched control animals were examined for antibodies to HVP antigens. Results showed that animals with lymphoid disease had antibodies to HVP virus capsid, early, soluble, and nuclear antigens at higher frequencies and at higher titers than did control animals. Antibody titers were not age- or sex-related. No concordancy was detected for antibodies to soluble and nuclear antigens. The sera were also examined for antibodies to two other widely distributed viruses of hamadryas baboons, cytomegalovirus and foamy virus. The results of these studies did not indicate a disease-related role for either of these viruses.

Biochemical identification of primate lymphoid cell-surface glycoproteins.

We have employed the galactose oxidase-tritiated sodium borohydride labelling method to examine the surface glycoproteins of cotton-topped marmoset and other primate cell lines either established from tumors or transformed in vitro by different lymphotropic herpesviruses. The labelled surface glycoproteins were separated on acrylamide gels in the presence of sodium dodecyl sulfate (SDS) and analyzed by fluorography. Our results indicate that (1) lymphocytes of the same class from different primate species are similar but can be distinguished; (2) T and B lymphocytes of the same species can be differentiated; (3) cotton-topped marmoset lymphocytes of the same class show marked similarities regardless of tumor or in vitro origin or virus used for transformation; (4) three cell lines established from different EBV-induced tumors of the same marmoset show essentially the same labelling pattern, supporting the hypothesis that they originated from a single clone.

Immunodiagnostic potential of a virus-coded, tumor-associated antigen (AG-4) in cervical cancer.

The central theme of this communication is the recognition of an immunodiagnostic potential in a herpes virus antigen, the molecular interrelationship of which with cervical tumor cells is described. In addition to the productive infection caused by herpes simplex virus type 2 (HSV-2) we are confronted by latency and, as suggested by recent studies, by cancer. These different types of virus-host cell interactions are discussed at the host, as well as at the cellular level. A defined level of molecular interaction between host and viral gene products must exist if the virus is to co-exist with the host, as is the case in latency and carcinogenesis. The molecular interpretations posit the presence, in the squamous cervical tumor cells, of a product of the expression of the viral genome that has immunodiagnostic potential. The antigen designated AG-4 fulfills these predictions and appears to have immunodiagnostic potential. AG-4 is present in cervical tumor biopsies, but not in normal cervical tissue. It is a structural component of the HSV-2 virion that, in tissue cultures infected with HSV-2, is synthesized preferentially under conditions that prevent the normal replication of the virus. In view of its structural nature it is most probably virus-coded. AG-4 antibody identified in complement fixation assays with antigen prepared in tissue culture, disappears following successful tumor removal and reappears during cancer recurrence. This antibody also potentially identifies those patients with cervical atypia that are at high risk of neoplastic progression. The clinical benefits of the assay are evident.

Herpesvirus type 2-related antigens and their relevance to humoral and cell-mediated immunity in patients with cervical cancer.

The central theme of this communication is the interaction of herpes simplex virus type 2 with its host. In addition to the productive infection, we are confronted by latency and, as suggested by recent studies, by cancer. The possible mechanisms of latency and the role it may play as a precursor of carcinogenesis are discussed. If virus is to coexist with its host, a defined level of molecular interaction between host and viral gene products must exist. The association of AG-4 with active tumor growth and its identification as a minor virion protein, also exposed on the surface of the infected cell, open new vistas in the understanding of the role virus-host cell interactions may play in tumor growth. The modulation of the host immune response by the results of this interaction may play a significant role in cancer control. In these terms, the observation that antibody to AG-4 is a macroglobulin and that, therefore, immunity to AG-4 may be T-cell independent, should be given further consideration.

Analysis for antigenic similarities among the 30S ribosomal proteins of Escherichia coli.

Antiserum was made against a single 30S protein, 30S-7. The amount of complement fixed by total 30S protein in the presence of this antiserum indicated that protein 30S-7 was the major antigen in the mixture of proteins. Each of the 30S ribosomal proteins was tested for cross-reactivity with anti-30S-7. This was done by determining if any of the other 30S proteins inhibited complement fixation by 30S-7. None of the other 30S proteins was found to inhibit complement fixation by 30S-7, indicating that 30S-7 is antigenically distinct from the other proteins.

Unique protein moieties for 30S and 50S ribosomes of Escherichia coli.

Each major component of the proteins of 30S ribosomes from Escherichia coli was compared with the proteins of 50S ribosomes. The comparisons were done by using polyacrylamide gel electrophoresis in urea with differentially labeled proteins. The data show that no major protein is common to both ribosomes.