Viral Envelope Antigens Research Articles

Heterophil human antibodies recognize oncovirus envelope antigens: Epidemiological parameters and immunological specificity of the reaction

Human sera were previously shown to possess antibodies capable of recognizing purified retrovirus envelope glycoproteins in standard radioimmunoprecipitation assays (RIAs). In a logical extension of the earlier studies, epidemiological characteristics and the exact specificity of the human antiviral antibodies was analyzed. The antiviral antibodies are not detectable in cord sera but show an age-dependent peak in early childhood and subsequently persist lifelong. Based on epidemiological and additional data obtained by serurn absorptions to cell surfaces, competition RIAs with animal sera and experiments employing deglycosylated virus envelope antigens, we conclude that the majority (if not all) of normal human sera contain naturally occurring, heterophil antibodies that react with the carbohydrate moieties of retrovirus envelope antigens. Similar conclusions have independently been reached by M. Barbacid, D. Bolognesi, and S. A. Aaronson (1980, Proc. Nat. Acad. Sci. USA 77, 1617–1621) and by H. W. Snyder and E. Fleissner (1980, Proc. Nat. Acad. Sci. USA 77, 1622–1626).

Antigenic modulation of mammary tumour virus envelope antigen or GR thymic lymphoma cells in relation to expressions of H-2, TL cell-surface antigens and THY1.

The MLr antigen, a mammary tumour virus-induced antigen on the surface of GR thymic lymphoma cells (GRSL) can be modulated from the cell surface upon incubation with specific antiserum for 1-2 h at 37 degrees C, followed by washing the cells. In contrast, a number of other cell-surface antigens on these GRSL cells cannot be modulated under similar conditions. These antigens include histocompatibility antigens of the H-2 complex (H-2.8 of the K-end and H-2dx(D) of the H-2dx haplotype) and two thymic markers, TL1.2 and Thy1.2. Antigenic modulation of MLr as tested by trypan-blue exclusion and by chromium51 release does not lead to a measurable change in the expression of H-2K, H-2D, TL and Thy1.2 antigens. These results could be confirmed by absorption analysis. The latter analysis showed that the number of antigenic sites per cell are about the same for MLr and the two H-2 antigens, while TL antigens are scarcer and Thy1.2 antigens are more abundant. The procedure of antigenic modulation showed that the MLr antigen resides on MTVgp52, the major protein of the envelope. There was no evidence of internal proteins, such as MTVp27, on the surface of GRSL cells.

Localization of a gene for expression of mouse mammary tumor virus antigens in the GR/Mtv-2- mouse strain.

The GR/Mtv-2- mouse strain is congenic to the GR strain but lacks the Mtv-2 gene for high amounts of mouse mammary tumor virus (MMTV) virion particles in the milk and early mammary tumors. With a sensitive competition radioimmunoassay for individual viral proteins of MMTV, substantial amounts of the gag proteins p27 and p10 could still be detected in extracts of the mammary glands of GR/Mtv-2- mice, but essentially no viral envelope antigens. The genetic transmission of the MMTV gag expression in the GR/Mtv-2- strain was investigated. In a cross with the virus-negative BALB/c strain, the MMTV p27 expression behaved as a dominant feature. Double backcross analysis proved that the p27 expression was governed by a single gene located on chromosome 11, cloe to the Es-3 locus. The gene was thereby not allelic to any of the previously described MMTV induction genes, Mtv-1 and Mtv-2, and is therefore called Mtv-3. It is concluded that the total MMTV expression in the GR strain is under control of two separate loci, Mtv-2 on chromosome 18, inducing high levels of complete virus particles and also early mammary tumors; and Mtv-3 on chromosome 11, coding for partial MMTV expression.

The effect of inoculum concentration on the development of the nuclear polyhedrosis virus of Autographa californica in TN-368 cells

A multiplicity of infection (m.o.i.) of 25 or 50 mean tissue culture-infective doses (TCID 50) of Autographa californica NPV per cell of a TN-368 cell line initially infected >90% of attached cells whereas an m.o.i. of 1 or 5 TCID 50/cell initially infected <50% of the cells. An immunoperoxidase technique first detected nucleocapsid antigens at 6–12 hr postinfection (PI) and polyhedral protein antigen 12–18 hr PI, which was followed 4–6 hr later by polyhedra formation. At a m.o.i. of 50, the extracellular virus titer (nonoccluded progeny virus) increased between 6 and 12 hr PI while at m.o.i. of 25, 5, and 1, the titer increased at 12–18 hr PI. Antisera to nucleocapsids and polyhedral protein were specific and also failed to react with viral envelope antigens.

Naturally Occurring Leukemia Viruses in &lt;italic&gt;H-2&lt;/italic&gt; Congenic C57BL Mice. II. Antibody Response to Viral Envelope Antigens&lt;xref ref-type="fn" rid="FN2"&gt;2&lt;/xref&gt;&lt;xref ref-type="fn" rid="FN3"&gt;3&lt;/xref&gt;

In C57BL mice milk-borne infection with B-tropic murine leukemia virus (V+ denoting positive for milk-transmitted B-tropic virus and V- denoting negative for milk-transmitted B-tropic virus) was accompanied by an antibody response against viral envelope antigens (VEA). Milk transmission of virus led to higher virus titers and lymphoma incidence in B10.A (H-2a) mice than in B10 (H-2b) mice, and the latter strain produced higher titers of anti-VEA antibodies than did the former. H-2 control of the antivirus-antibody response was confirmed in the (B10.A V+ X B10 V+)F2 cross. B10 V+ mice produced both IgM and IgG antibodies, whereas in the sera of B10.A V+ mice only IgM antibodies were demonstrable. The production of IgG and high-titer IgM antibodies to VEA was dominant in (B10.A V+ X B10 V+)F1 animals. The failure of B10.A V+ mice to produce IgG antibodies against VEA was not due to an intrinsic defect of helper T-cell function because these mice produced IgG antivirus antibodies after sc immunization with killed viral vaccine. Furthermore, in B10.A mice without milk-transmitted virus (B10.A V- subline), expression of genetically transmitted virus upon aging was associated with the production of IgG antibodies to VEA. The combined data were compatible with the existence of an H-2-linked dominant immune-response gene regulating the antibody response to milk-transmitted murine leukemia virus.

Inductive requirements for the generation of virus-specific T lymphocytes. II. Poxvirus and H-2 antigens associate without cellular or virus-directed protein synthesis, and remain immunogenic in cell membrane fragments.

The nature of the interaction between vaccinia virus (VAC) and fibroblastic cells that renders the latter capable of being recognized by virus-specific, H-2 identical murine T lymphocytes has been studied. L cells exposed for 10 min to VAC rendered noninfectious by exposure to ultraviolet light became susceptible targets for cytotoxic T lymphocytes (CTL) without the synthesis of new viral proteins. Susceptibility was retained even if cellular protein synthesis was irreversibly inhibited with pactamycin before virus exposure. Immobilization of cell-surface membranes by glutaraldehyde fixation before (but not after) exposure to virus severely impaired the formation of the "virus + self" complex that in vitro stimulated secondary CTL responses by H-2 identical virus-primed memory cells even though virus attachment to fixed cells were unaffected. This stimulatory complex, once formed, was maintained in membrane fragments prepared from cells previously exposed to VAC. These findings indicate that VAC-specific CTL or their immediate precursors can recognize only those viral envelope antigens that become membrane integrated and that this event requires neither host cell-specific nor virus-specific protein synthesis.

Expression of viral RNA in friend virus-induced erythroleukemia cells

The regulation of expression of the Friend virus complex (FV) was studied in clones of H-2 congenic erythroleukemia cell lines. Molecular probes specific for each of the two FV components were generated and hybridized to RNA extracted from clones differing with respect to virus production or viral envelope antigen expression. Sequences representing the defective component of FV continued to be transcribed in cells regardless of virus production. The presence of helper virus-specific sequences, however, was shown to be directly related to virus expression. Molecular hybridization with cytoplasmic and nuclear RNA extracted from the H-2 congenic clones representing various stages of viral expression demonstrated a direct correlation between the level of transcription of FMuLV-specific sequences and the degree of virus expression. These data suggest that regulation of FV expression is primarily related to the cessation of helper virus transcription in the cell lines studied. In this paper we provide further evidence that the defective viral components is responsible for the rapid malignancy associated with Friend disease.

Host antigens on avian oncoviruses: evidence for virus envelope antigens related to specific chicken erythrocyte membrane antigens.

Avian sarcoma viruses (ASV) of subgroups A to D, produced by chick embryo fibroblasts (CEF), are inactivated to a high degree by rabbit antisera to the membrane antigens of adult chicken and chick embryo erythrocytes, notably by antisera to an antigen of embryo erythrocytes, which is lost by adult erythrocytes and to another antigen specific to the latter erythrocytes. Contrary to virus inactivation by anti-CEF serum reported earlier, virus inactivation by the antisera to these two age-specific antigens does not require complement and is not paralleled by virolysis but by aggregation of virions. The two antigens related, or identical, to the age-specific erythrocyte membrane antigens thus shown to be present on the virus envelope do not pre-exist, or pre-exist only in a low amount, on the CEF membrane, since the virus-inactivating capacity of their antisera is not removed by absorption with CEF. Their appearance on the virus does not depend on cell transformation but only on infection, since both antigens are found on a ts ASV mutant produced at restrictive temperature by untransformed CEF and the virus-inactivating capacity of their antisera is removed by absorption with CEF infected with Rous-associated virus (RAV-1). These findings suggest that infection of CEF by avian oncoviruses may elicit the appearance, or enhance the expression at the cell surface of antigens characteristic of another cell type which may contribute to the formation of specific virus budding sites.

Immunochemical characterization of tumor-associated surface antigens on a Moloney leukemia virus-lymphoma, MBL-2.

Tumor-associated surface antigens (TASA) on a Moloney leukemia virus (M-MuLV)-induced lymphoma, MBL-2, in C57BL/6 mice (B6) were characterized. The surface proteins of MBL-2 cells were selectively radioiodinated and then extracted by Nonidet P40. The solubilized materials were then reacted with a variety of antisera: monospecific antisera to murine leukemia viral proteins (anti-gp69/71, anti-p30, anti-p15, anti-p12 and anti-p10), sera from B6 which regressed murine sarcoma tumors induced by murine sarcoma virus (anti-MSV) and a rabbit anti-MBL-2 antiserum. The resulting radioimmune precipitates were analyzed and compared in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The following results were obtained. (1) Among all anti-viral protein antisera tested only anti-gp69/71 was active and detected a protein doublet of gp69/71 and its degradation fragments of 42,000 and 35,000 daltons. (2) Radioimmune precipitates prepared with anti-MSV showed a SDS-PAGE pattern similar to that seen with anti-gp69/71. This result indicated that the surface antigen detected by the anti-MSV serum on MBL-2 tumor cell was probably a viral envelope antigen. (3) The rabbit anti-MBL-2 serum detected on the cell membrane an antigen of approximately 95,000 daltons which was tumor-associated and did not appear to be related to virion components. The anti-MBL-2-serum still reacted with the 95,000 dalton antigen after absorption with disrupted M-MuLV virus and with gp69/71 and p30 purified from the virus.

Cellular and Humoral Immune Reactivity to Tumor-Associated Antigens in Chickens Infected with Rous Sarcoma Virus

Abstract With a leukocyte blastogenesis assay and 3 M KCl extracts of chicken cells infected or infected and transformed by various avian tumor viruses (ATV), the time course of development of cellular reactivity in RSV tumor-bearing chickens to antigens expressed on these cell types was examined. Leukocyte reactivity to mitogens in RSV-injected birds was also investigated. Similarly, humoral responses to ATV-antigens and virus-induced antigens were assessed over time, by measuring the development of antiviral neutralizing antibody, as well as antibody to cell surface antigens on various cell types, by means of an isotopic antiglobulin test (IAT). There were no differences in phytohemmaglutinin responsiveness between the leukocytes of RSV-injected birds and control birds, but responses to pokeweed mitogen were sometimes elevated in RSV-injected animals. Cellular immunity to 3 M KCl extracts, principally to those extracts containing structural components of the virus envelope, developed between 3 and 5 weeks post-injection, during tumor growth and regression, and then declined, although the immune response could be restimulated by virus rechallenge. For the most part, responses to nonvirion tumor-specific surface antigen (TSSA) was weak except after RSV rechallenge. Humoral reactivity as measured by IAT also seemed to correlate well with the presence of virus envelope antigens (VEA) on infected indicator cells and appeared before antiviral neutralizing antibody. The data indicated that, at least during the primary response, major immune reactivity in RSV-injected birds appeared to be directed against VEA and that TSSA appeared to be most immunogenic when VEA was also present.

Elevated titer of antibodies to simian sarcoma virus envelope antigen (gp70) and normal response to influenza virus in untreated danish Hodgkin's patients

Untreated Danish Hodgkin's disease (HD) patients and paired age- and sex-matched controls were tested for serum antibodies to Epstein-Barr virus (EBV), six strains of influenza virus and Simian sarcoma virus/Simian sarcoma-associated virus [SSV(SSAV)] antigens. HD sera showed significantly elevated titers against EBV and both increased incidence and mean titer of antibodies to the envelope glycoprotein of SSV(SSAV), whereas testing against the influenza viruses revealed no differences between HD and controls. A focus reduction assay demonstrated a low incidence in HD and controls of sera with neutralizing effects against SSV(SSAV) and the "baboon" C-type virus component of the human HL-23 virus complex, which seemed coupled to HL-A type W19.

Human antibodies reactive with purified envelope antigens of primate type C tumor viruses.

Human sera from healthy individuals have been shown to react with viral antigens in preparations of detergent-disrupted C type viruses from monkeys. In this report, it is demonstrated that (populations of) these human antibodies react with highly purified envelope glycoproteins of the simian sarcoma virus-simian sarcoma-associated virus complex and the Friend leukemia virus complex. Several immunological parameters influencing human antibody binding to C type tumor virus antigens have been characterized. These parameters indicate that human antibodies tend to bind to what is probably a subset of the antigenic determinants on the virus envelope antigens and that different human sera recognize the same antigenic determinants on the virus envelope antigens tested. The possible origin of these antibodies is discussed.

Production of antibodies against feline leukemia and sarcoma viruses and the feline oncovirus-associated cell membrane antigen in strain 2 guinea pigs

Cloned cell lines of guinea pig tumor induced by the Snyder-Theilen strain of feline sarcoma virus with feline leukemia virus subgroup C as helper, ST-FeSV (FeLV-C), have been established. The cell line releases high titers of ST-FeSV (FeLV-C) (10 3−10 4 FFU/0.2 ml) and 1 log excess of FeLV-C. In vivo studies of one of the cell lines, GPTC C1 1, showed that as little as 100 cells could induce tumors in weanling guinea pigs. The tumors progressively grew and eventually killed the animals within 23 days. Sera from guinea pigs carrying tumors contain antibodies to FeLV group-specific antigen, FeLV-C virus envelope antigen, and feline oncovirus-associated cell membrane antigen (FOCMA). The three groups of antibodies seem to be distinct as demonstrated in the absorption tests with appropriate antigens.

Scanning electron microscopic appearance of viral-antigen-coated polystyrene balls

•A radioimmunoassay (RIA) was recently developed for the detection of antiviral IgG and IgM class-specific antibodies using antigen-coated polystyrene balls as the RIA solid-phase. In this communication the attachment and distribution of herpes simplex virus (HSV) capsid and envelope antigens and rubella viruses on the surface of the balls was examined by scanning electron microscopy (SEM).•In SEM the surface of the untreated ‘clear frosted’ polystyrene balls appeared very uneven with innumerable pits and grooves. The viral particles were haphazardly distributed both in the grooves and on the exposed surface of the balls. The strength of adsorption of the viral antigens onto the balls seemed to be remarkably resistant to outside mechanical forces. HSV antigens frequently appeared in clusters, whereas rubella viruses were mostly found as single particles.

Rheumatoid factor in sera of dermatitis herpetiformis patients

Serum specimens from 44 patients with dermatitis herpetiformis (DH) and 42 control patients were analyzed with solid-phase radioimmunoassay (RIA) developed to detect IgG and IgM class antibodies against herpes simplex virus (HSV) envelope antigen. They were also tested with different tests to detect rheumatoid factor (RF) as well as serum antibodies to gastric parietal cells, glomerular basement membrane, smooth muscle, mitochondria and nuclei. Total serum IgG, IgM and IgA quantification was performed concurrently. IgM class antibodies reacting in HSV envelope antigen RIA were found in 47.8% of the DH patients, but in none of the controls. The age distribution of the IgM positive patients was in accordance with the appearance of RF, representing elderly persons. The presence of RF in serum specimens was confirmed by removing the IgM reactivity with heat aggregated human gamma globulin adsorption and in 13 patients with positive serological tests for RF. No correlation was found with the appearance of RF and duration or severity of the disease or with the detection of RF and serum total IgM concentration. In DH patients antibodies to gastric parietal cells were found in 6 and to smooth muscle in 1 of 32 specimens tested.

Immunization of mice with syngeneic Moloney lymphoma cells induces separate antibodies against virion envelope glycoprotein and virus-induced cell surface antigens.

Immunization of mice with heavily irradiated syngeneic Moloney lymphoma cells evokes antibodies against the major viral envelope antigen, gp71, and the Moloney virus-induced cell surface antigen (MCSA). A9HT cells, an L-cell subline, react with the antibodies against the viral envelope antigen only; this reaction can be completely inhibited by virus or purified gp71. Reactivity to Moloney lymphoma cells (YAC) was only partially inhibited (maximum 30%) or not at all. This can be attributed to the reaction of the YAC cells with antibodies directed against MCSA, a nonvirion cell surface component according to both biological and biochemical evidence. Antibody-induced capping of gp71 or p15(E) did not change the membrane distribution of MCSA or H-2, indicating that these antigens represent distinct entities on the cell surface. MCSA showed only minimal capping and thereby differed in behavior from both H-2 and virion antigens. gp71 could be capped by the mouse antiserum as revealed by subsequent staining with monospecific anti-gp71 antiserum. Under ordinary test conditions this reactivity is overshadowed by the reaction against MCSA. The lack of MCSA capping reflects a difference in anchorage of this antigen.

Active and Passive Immunization of Cats With Inactivated Feline Oncornaviruses 2

The humoral Immune responses of young (<1 mo) and older (>6 mo) cats to killed and live feline leukemia virus (FeLV), feline sarcoma virus (FeSV), and the feline oncornavirus associated cell membrane antigen (FOCMA) were evaluated. in addition, the biologic responses to oncogenic feline oncornavlrus challenge were analyzed in cats actively immunized with inactivated Gardner-Arnstein FeSV (GA-FeSV) or passively immunized with either the Rickard FeLV (R-FeLV) or GA-FeSV. Kittens were immunized during the first month of life with UV- or formalin-inactivated GA-FeSV and challenged at 5–6 weeks of age with a known oncogenic dose of GA-FeSV. Passive immunization was evaluated in kittens that suckled mothers immunized during pregnancy with purified GA-FeSV or R-FeLV. Kittens during the first month of life were capable of producing humoral antibody against FOCMA and keyhole-limpet hemocyanin. Apparently linear disease responses to live R-FeLV from susceptibility (viremia with no FOCMA antibody) to resistance (no viremia and high FOCMA antibody level) were observed in cats from birth to 4 months of age. Newborn kittens failed to develop FOCMA and virus-neutralizing (VN) antibody (<1:2) following challenge, whereas adult cats responded with significant levels of FOCMA and VN antibody 2 months after infection. Thirty-three young kittens immunized with UV- or formalin-inactivated GA-FeSV failed to develop significant levels of VN antibody (≤2) in contrast to 7 immunized adult female cats that responded with significant levels (mean titer, 1:14). No evidence of protection from oncogenic challenge was observed in actively immunized kittens. Moreover, the results suggested that vaccinated kittens were more susceptible to oncogenic virus challenge than were nonvaccinated cats. Actively immunized cats had a shorter survival time, greater primary tumor size, faster rate of tumor growth, and a greater extent of tumor metastases. in addition, significantly fewer immunized cats responded to FOCMA and viral envelope antigens than did nonimmunized cats. With the use of the same criteria, definitive evidence of protection from oncogenic virus challenge was observed in kittens that had been nursed by dams vaccinated during pregnancy.

Differentiation of type D virus from transplantable human cells (Il'in-Bykovskii virus) and Mason-Pfizer monkey virus on the basis of virus envelope antigens

To differentiate between Il'in-Bykovskii virus (IBV) and Mason-Pfizer monkey virus (MPMV) the method of neutralization of the viruses by antisera against virus envelope antigens was used. The viruses were cultured on the same human embryonic cells. The results of virus neutralization were determined by the presence or absence of gs antigen in the affected cells. Antiserum against IBV envelope antigens neutralized IBV but not MPMV. Antiserum against MPMV did not neutralize IBV. It is concluded that IBV and MPMV differ in their virus envelope antigens and must be regarded as different viruses.

Tumor Growth and Antibodies after RSV-Challenge in Normal Chickens and in Chickens Congenitally Infected with Avian Leukosis Virus

Normal chickens and chickens congenitally infected with an avian leukosis virus (ALV) of antigenic subgroup A were challenged with strains of Rous sarcoma virus (RSV) of two different antigenic subgroups (B and C) and tumor induction and growth as well as humoral antibody to viral envelope antigen (VEA) and tumor-specific surface antigen (TSSA) were measured. There was no effect of congenital ALV infection on RSV tumor incidence or latent period but the growth rate and size of the tumors were much higher in congenitally infected birds as compared to controls. Whereas most tumors in the RSV-challenged normal birds regressed, tumors in ALV-infected birds grew progressively. There were no striking differences in the number of birds in either group in the incidence of anti-TSSA or anti-VEA antibodies nor did the presence of either type of antibody reflect the tumor status of the host.

Early presence of ribonucleoprotein antigen on surface of influenza virus-infected cells.

HOST defence against influenza A virus in experimental animals seems to be mediated mainly by antibody1,2. The mechanism by which antibody protects the host, however, is unknown. Antibody may either neutralise viral particles or recognise viral antigens at the surface of infected cells and then act at an early stage of infection, before viral replication is completed. The latter mechanism is theoretically more efficient, but might cause immunopathological destruction of the infected cells with harmful consequences. Viral envelope antigens (haemagglutinin and neuraminidase) have been shown to be present at the surface of influenza virus-infected cells, by haemadsorption3, electron microscopy4 and immunofluorescence5. Two main type-specific internal antigens have been described in influenza A virus—the matrix protein (MP) antigen6 and the ribonucleoprotein (NP) antigen7, a non-glycosylated polypeptide with a molecular weight of 58,000 (ref. 8). Immunofluorescence studies on fixed cells have shown that NP antigen is first demonstrable in the cell nucleus and then appears as granular masses within the cytoplasm, which become prominent at the, cell borders later in infection, suggesting a close association with the cell membrane9. We report here that NP antigen can be detected by immunofluorescence as early as 2 h after the infection on the surface of unfixed mouse cells infected with influenza A virus.