7S Antibody Research Articles

Use of Baculovirus-Expressed Glycoprotein H in an Enzyme-Linked Immunosorbent Assay Developed To Assess Exposure to Chelonid Fibropapillomatosis-Associated Herpesvirus and Its Relationship to the Prevalence of Fibropapillomatosis in Sea Turtles

Chelonid fibropapillomatosis-associated herpesvirus (CFPHV) is an alphaherpesvirus believed to cause marine turtle fibropapillomatosis (FP). A serodiagnostic assay was developed for monitoring sea turtle populations for CFPHV exposure. CFPHV glycoprotein H (gH) expressed in recombinant baculovirus was used in an enzyme-linked immunosorbent assay (ELISA) to detect virus-specific 7S turtle antibodies. Using captive-reared green turtles (Chelonia mydas) with no history of virus exposure as "known negatives" and others with experimentally induced FP as "known positives," the assay had 100% specificity but low sensitivity, as seroconversion was detected in only half of the turtles bearing experimentally induced tumors. Antibodies were detected only in samples collected after cutaneous fibropapillomas appeared, consistent with observations that tumors are significant sites of virion production and antigen expression and the possibility that prolonged/repeated virus shedding may be required for adequate stimulation of 7S antibody responses to gH. Natural routes of infection, however, may produce higher seroconversion rates. High gH antibody seroprevalences ( approximately 80%) were found among wild green turtles in three Florida localities with different FP prevalences, including one site with no history of FP. In addition, all eight loggerhead turtles (Caretta caretta) tested were seropositive despite FP being uncommon in this species. The possibility that CFPHV infection may be common relative to disease suggests roles for environmental and host factors as modulators of disease expression. Alternatively, the possibility of other antigenically similar herpesviruses present in wild populations cannot be excluded, although antibody cross-reactivity with the lung/eye/trachea disease-associated herpesvirus was ruled out in this study.

Serum immunoglobulin M antibody to hepatitis D as a surrogate marker of hepatitis D in interferon-treated patients and in patients who underwent liver transplantation.

The kinetics of the immunoglobulin (Ig) M type antibody to the hepatitis D virus (IgM anti-HD) were investigated in hepatitis B surface antigen (HBsAg) carriers with chronic hepatitis D treated with interferon (IFN) and in patients with terminal hepatitis delta virus (HDV) cirrhosis who underwent liver transplantation. The IgM antibody disappeared in each of 8 patients who responded to IFN therapy with the persistent normalization of aminotransferases and with the clearance of serum HBsAg and HDV-RNA. The IgM reactivity did not decline in the 45 treated patients who did not respond to the cytokine or who experienced a relapse after responding while on therapy. The antibody rapidly disappeared from serum post-transplantation in each of 10 examined patients with HDV who underwent transplantation. In 5 patients who underwent transplantation and who became reinfected with HDV, the antibody remained undetectable during the early reinfection phase, as marked by HDV replication and by the absence of liver damage; however, it rapidly raised to pre-transplantation levels with the recurrence of hepatitis D (HD) in the liver graft. Monomeric 7S IgM anti-HD predominated over pentameric 19S antibody in each of the two patients examined for IgM anti-HD molecular species. The IgM antibody to HDV raises in response to HDV-induced damage and represents a valid surrogate marker of liver damage which is immunopathologically related to HDV infection. Besides providing diagnostic information, it provides the best predictor of impending resolution of chronic HDV disease, whether spontaneous or IFN-induced.

Efecto de la reinfección sobre la evolución de ratas infectadas con Trypanosoma cruzi

The present study was undertaken in order to demonstrate that reinfection could modify parasitemia, serum antibodies, electrocardiographic patterns and/or myocardial lesions already observed in a rat model. Experimental groups IG: rats infected at weaning with 1 x 10(6) T. cruzi; RG: same as IG plus reinoculations each 30 days until completion on day 150; IG1: 51 day old infected rats; C: controls. A high parasitemia was detected in IG and RG until day 20 showing a tendency to become negative on day 30. No parasites were observed in RG after the first reinoculation which could not be attributed to the old age of the host since there was no parasitemia in IG1. Xenodiagnosis were negative in all three groups. Serum antibodies were not significantly modified in RG in comparison with IG, except for 7S antibodies, since RG showed higher titres in some days under study. No distinct patterns of basal ECG were observed in infected rats. The ajmaline test reduced the heart rate (HR) showing no treatment dependence. The PR, QaT and QRS were significantly lengthened in all groups regarding the basal one (p less than 0.05), except for the QaT in C. Besides, the PR and QaT alterations were greater in the infected rats (p less than 0.05). There was also present a wide variety of electric axis orientations, regarding the basal value, accompanied by morphological changes more evident in the RG. The incidence of cardiac lesions histologically detected in the infected group was significantly higher than in C (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Monomeric (7S) immunoglobulin M antibodies to hepatitis delta virus in hepatitis type D

The pattern of the immunoglobulin M antibody to the hepatitis delta virus distinguishes acute from chronic hepatitis D. Expression of the immunoglobulin M antibody to the hepatitis delta virus is relatively weak and short-lived in self-limited hepatitis but strong and persistent in chronic forms. To study the nature of the immunoglobulin M antibody to the hepatitis delta virus in acute hepatitis D and in chronic hepatitis D, antibody-positive sera were submitted to rate zonal centrifugation to separate monomeric 7S from pentameric 19S immunoglobulin M antibodies. Sera were from 6 patients with acute self-limited hepatitis, 4 patients with chronic hepatitis D, and 6 patients with hepatitis D progressing to chronicity. The immunoglobulin M reactivity was measured by a specific immunoassay based on capture of μ-chains by anti-μ linked on a solid phase. Only 19S antibody was found in acute hepatitis D. In contrast, all patients with chronic hepatitis D circulated 7S antibody in addition to the 19S antibody. In patients with progressive hepatitis D, both the 7S and 19S antibody variants were present at the onset of the disease. The difference in the antibody response between acute hepatitis D and chronic hepatitis D is not only temporal and quantitative but also qualitative. The expression of 7S antibody seems to be an immunologic event specific for chronic hepatitis D.

Identification of a trypanocidal factor against Trypanosoma equiperdum in normal human serum.

Normal human serum (HS) contains trypanolytic activity and agglutinins to Trypanosoma equiperdum, while such activities are not found in sera from a range of animals susceptible to infection. HS given to T. equiperdum-infected mice caused a rapid decrease in the number of circulating trypanosomes and protection from lethal infection. Trypanolytic activity of human serum was found to be associated, after DEAE chromatography and Sephadex G-200 gel filtration, with the fraction containing 19S antibodies. Immunofluorescence assays confirmed a binding of human IgM and C1q complement component onto the surface of T. equiperdum. Anti-T. equiperdum activity of HS was specifically directed to T. equiperdum surface components and not to some mouse serum components adsorbed on parasites during the growth in the host, because HS adsorbed in vivo in CD-1 mice retained full protective and agglutinating properties. Trypanocidal activity appears in human serum about the 7th month after birth and persists until late in life. On the contrary, human purified high-density lipoprotein had no significant in vitro or in vivo trypanocidal activity. In conclusion, strong natural anti-T. equiperdum activity in human serum was mainly mediated by natural antibodies of the IgM class. The presence of natural IgM active against T. equiperdum in HS could represent one of the natural mechanisms of resistance of refractory hosts against trypanosome infections. This phenomenon provides further evidence that host specificity of trypanosomes may be partly conditioned by the presence of natural antibodies.

Low and high molecular weight cytomegalovirus-specific immunoglobulin M antibody in renal transplant patients with cytomegalovirus infections.

Sera from 27 renal transplant patients with primary and recurrent CMV infections and which were known to contain CMV-specific IgM antibodies were investigated by indirect immunofluorescence for the presence of virus-specific high molecular weight IgM (19S IgM) and low molecular weight IgM (7S IgM). After sucrose gradient fractionation of the sera, 19S IgM was found in all 27 patients, whereas 7S IgM was present in 11 out of 19 (56%) patients with primary CMV infection and in 1 out of 8 (12%) patients with recurrent CMV infection. The presence of 7S IgM was unrelated to the titre of the virus-specific IgM in whole serum. The presence of IgM rheumatoid factor was monitored by a sensitive fluorescence assay using measles virus antigen/antibody complexes. The absorption of the serum fractions with heat-aggregated gamma globulin failed to remove the specific IgM staining indicating that it was not due to IgM rheumatoid factor. On the other hand adsorption with protein A/sepharose removed the specific IgM staining from the 7S IgM fractions but not from the 19S IgM fractions. This suggests that specific 19S and 7S IgM antibodies may belong to different subclasses of IgM.

Single-serum diagnosis of rubella by combined use of the hemagglutination inhibition and passive hemagglutination tests.

We explored the feasibility of using the passive hemagglutination (PHA) test in combination with the hemagglutination inhibition (HI) test for the single-serum diagnosis of rubella. We found by sedimentation analysis of the serum that early 7S antibody produced within 1 month after the onset of the rash had high HI but much lower PHA titers, whereas the PHA titers of antibody produced later were slightly higher than the HI titers. (19S antibody in the early serum had some PHA activity.) This disparity between the HI and PHA activities of the early 7S antibody could be used for the routine diagnosis of rubella. A comparison of the HI titers of the test serum with the PHA titers of mercaptoethanol-treated serum constitutes a simple method for determining whether the serum sample was taken shortly or remotely after the infection.

Ultrastructural morphology and domain structure of a unique collagenous component of basement membranes.

A disulfide cross-linked collagenous fragment (7 S) has been isolated by pepsin solubilization from several tissues rich in basement membranes including bovine lung, human placenta, and the murine EHS tumor. Examination of this material by the rotary shadowing technique indicates that these fragments are similar to but not identical with the 7S collagen described recently [Risteli, J., Bächinger, H.P., Engel, J., Furthmayr, H., & Timpl, R. (1980) Eur. J. Biochem. 108, 239-250]. The central rodlike portion of the particles was found to be similar in length; however, the peripheral four arms of 7S particles from bovine and murine sources are 10 nm longer in comparison to those from human sources. In addition, about 5-7% of all the particles contain a fifth arm. Specific antibodies to bovine 7 S cross-react with murine 7 S but only to a rather limited extent with human 7 S. These antibodies react with antigenic sites located at the ends of the peripheral arms of the fragment as visualized directly with rotary shadowing techniques. The data are consistent with a structural difference in type IV collagens from bovine, human, and mouse which leads to pepsin cleavage at different sites in a particular noncollagenous region adjacent to 7 S. However, since bovine 7S antibodies cross-react with human and murine tissues by immunofluorescence despite the lack of complete serological cross-reactivity, it is suggested that type IV collagens from all three species have some degree of homology in this region.

Detection in vivo 6 hours after immunization of a mediator with possible antisuppressor activity.

Immunization of mice with foreign proteins or particulate antigen induces the formation of immunoglobulin (Ig)-antigen complexes which are strongly cytophilic for T cells and have been shown recently to markedly enhance the 7 S antibody response. In this report we demonstrate that pretreatment of the animals with cyclophosphamide or anti-I-J antiserum eliminates the difference in the antibody response between the mice injected with the complexes and the controls, in other words, the enhancement. Six hours after allogeneic stimulation the serum of mice contains also a cytophilic (for T cells) Ig which most likely represents, as in the case of the foreign antigens, complexes of Ig with alloantigens. The allogeneically induced 6-h serum (6HS) contains a factor which enhances the cytotoxic T lymphocyte(s) (CTL) response in vivo. As with the 7S antibody response, pretreatment of mice with cyclophosphamide, in doses known to eliminate suppressor cell expression, "masks" the CTL enhancement of the allogeneically induced 6HS. The same result was also observed with the anti-I-J antiserum. In conclusion, the 6-h complexes in cyclophosphamide- and anti-I-J-treated mice do not produce a 7 S antibody or CTL response above that produced by the control group (no complexes). Using heat-treated allogeneic tumor cells, known to induce suppressor cells in vivo, we have shown that for a low dose of tumor cells, the allogeneically induced 6HS did not block the induction of suppressor cells, but completely blocked their function. These results suggest that the enhancement of both humoral and cell-mediated immunity by the 6HS (complexes) is likely to be due to interference with normal suppressor cell function, that is, an antisuppressor mechanism.

Immunoglobulin response to pertussis

In order to study on Immunoglobulin Response in pertussis were used 40 blood samples from 20 children infected with pertussis.Serological methods used for this study were Bacterial agglutination test and Sucrose density gradient centrifugation.The results obtained are summerized as followed:1. In patients, the appearance of 19S antibody was detected in 100% of the cases at the first week, and the 19S antibody persisted for long-term.2. The appearance of 7S antibody was detected later than 19S antibody, and was detected in 100% of the cases at the seventh to eighth weeks. Whereas, in reinfection, it was detected at the first week.3. The appearance of the IgA polymer followed 19S antibody, it was detected in theabout 30% of the cases at the second to sixth weeks.4. In regard to the sedimentation pattern and agglutinin titer, it was found that the agglutinin titer rose in the sequence of negative, 19S, 19S+IgA polymer, 19S>7S, 19S=7S+IgA polymer, 19S<7S.

Treponema-specific and antilipoidal 19S(IgM) antibodies in penicillin-treated and untreated rabbits after infection with Treponema pallidum.

The titres of treponema-specific and antilipoidal 19S(IgG) antibodies were determined in rabbits infected intratesticularly with Treponema pallidum. One group of rabbits was treated with penicillin the other served as control. Using different serological tests it was shown that 19S(IgM) antibodies were still detectable eight months after infection at about the same titres in both groups. In contrast, 19S(IgM) antibody titres in patients with syphilis became undetectable within three to six months after penicillin treatment. It is suggested therefore that the rabbit is not a reliable model for studying the effect of penicillin in human T pallidum infections.

Post-translational processing of 7S and 11S components of soybean storage proteins

The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The α and α' subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a 'signal peptide' as evidenced by the presence of 2α and 2α' peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S α and α' products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S α and α' glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development.

Regulation of primary antibody response in mice by two types of suppressor cells resistant to anti-thy-1 serum treatment.

The anti-SRBC antibody response of normal young adult mice (about 3 months old) was specifically suppressed, when the spleen cells derived from the syngeneic donor mice that had been previously primed with a high dose of SRBC were adoptively transferred at the time of antigenic challenge. The suppression was antigen-specific and was mediated by a fraction of the immune spleen cells which appeared to belong to either B cells or their progeny antibody-forming cells. The differences were observed in the properties of the suppressor cells in terms of the period after the priming and the radiosensitivity; i.e., immune spleen cells taken from the mice which had been immunized with SRBC 5 days earlier were able to suppress only 19S PFC, whereas those taken from the mice which had been immunized 14 days earlier were able to suppress both the 19S and 7S PFC responses, and the former cells were susceptible to 400 R X-rays, but not the latter. These two types of suppressor cells appeared to play an important role in the regulation of the sequential change of 19S and 7S antibodies during the primary immune response.

A requirement for native (undenatured) IgG for detection of species specificity of the IgG-Fc receptor on lymphocytes

The species specificity of the Fc receptor involved in binding of preformed antibody-antigen complexes was examined using complexes of deaggregated 7S antibodies and albumin antigens. Complexes prepared with mouse antibodies bound to 3–4 times as many cells as complexes prepared with rabbit, guinea pig, or goat antibodies. Using lymphocytes from each species, it was shown that homologous complexes consistently labeled a higher frequency of cells than heterologous complexes. The binding of heterologous complexes seemed to be generally restricted to monocytic populations which were also capable of binding monomeric 7S immunoglobulins. It is concluded that the lymphocytic Fc receptor for antigen-complexed 7S immunoglobulin displays strict species specificity. Heat aggregation of the heterologoud immunoglobulins eliminated the species restriction on their binding to the lymphocytic Fc receptor. It is therefore suggested that artificially aggregated immunoglobulins may not be reliable probes for the specificity of the Fc receptors.

Human antibody to influenza C virus: its age-related distribution and distinction from receptor analogs.

Sera from persons of four age groups (1 to 2 years, 2 to 5 years, 20 to 30 years, and 65 to 85 years) were analyzed for hemagglutination inhibition (HI) activity for influenza C virus. Significant HI activity was found in 66% of the 237 sera tested, and titers ranged from 8 to 512. In the yoiung adult group, 96% had antibody and the highest mean titer (74.7) of any age group. Positive sera were far less common in young children (36 to 47%), and relatively low titers (18.3) were common among adults over 65. The high percentage of sera with antibody to influenza C virus suggests that infections with this virus occur at a rate greater than previously recognized. The high percentage of young adults with elevated levels of HI antibody suggested either that an immune response to influenza C infections is common or that the observed HI activity might be attributable, in part at least, to nonspecific inhibitors in the sera. We showed both directly and indirectly that most if not all the inhibitory activity in the human sera we examined was due to specific antibody, mostly immunoglobulin G. This conclusion is based on the finding that the single serum protein fraction with HI activity was found to have a molecular weight equivalent to that of 7S antibody (150,000) and that the HI activity was removed by absorption to staphyloccal protein A. Moreover, immunoglobulin from only HI-positive sera bound specifically to cells infected with influenza C virus, as shown by inhibition of hemadsorption and immunofluorescence. These findings were supported by similar results obtained with chicken antisera to C virus.

IgG+ platelets in the marmoset: their induction, maintenance, and survival

Immunization of marmosets with platelets from another species of marmoset leads to antibody formation to the donor platelets, deposition of IgG on the host's platelets, and thrombocytopenia. This disease closely resembles posttransfusion purpura of man, which may develop after one or two transfusions of whole blood. The mode of immunization in the marmoset was found to be important: intravenous (i.v.) inoculations were without effect, while intramuscular (i.m.) immunizations led to the disease. Intramuscular inoculations were characterized by formation of 7S antibodies, as measured by indirect immunofluorescent (IF) and complement-dependent platelet cytotoxicity (PC) tests; in contrast, i.v. immunizations, while leading to 7S antibodies by the IF test, yielded only 19S antibodies reactive in the PC assay. The titers were also consistently higher with i.m. immunizations. Antibody was not limited to the donor platelets, but auto- or host-type reactivity was also present; this antibody was in very low titer and could be found only when the animal was thrombocytopenic. A primary finding was the ability to maintain increased deposition of IgG on the host's platelets in the absence of thrombocytopenia by biweekly or monthly inoculations of the donor platelet antigen. The amount of IgG found on platelets of normal and immunized marmosets was comparable to that reported for normal humans and patients with clinical immune thrombocytopenia. Finally, platelet survival studies in animals with lgG+ platelets and normal platelet counts indicated a rapid turnover, suggesting operation of a compensatory mechanism to maintain platelet levels.

Phylogeny of immunoglobulin structure and function—VIII: Intermolecular heterogeneity of shark 19S IgM antibodies to pneumococcal polysaccharide

Significant IgM antibody responses to the pneumococcal capsular polysaccharide were demonstrated in nurse sharks immunized with pneumococcal vaccines. The antibodies isolated from immune sera by affinity chromatography were exclusively of the 19S variety; no 7S antibodies were isolated from any of six animals studied for periods up to twelve months. Equilibrium dialysis studies of the isolated antibodies demonstrated several important points: (1) the IgM antibodies contained ten combining sites per 19S molecule, (2) in all cases, the isolated antibodies showed marked heterogeneity of combining sites, (3) the antibodies were all of low average affinity, and (4) there was no increase in the average affinity of the antibodies isolated from any single animal for periods of up to twelve months after the start of immunization. In order to determine if a single IgM molecule contains ten equivalent combining sites, the antibodies isolated from several animals were fractionated by liquid isoelectric focusing. Equilibrium dialysis experiments using focused fractions showed the presence of ten functionally identical combining sites per IgM molecule. As a proof of the structural homogeneity of focused fractions, antibodies were separated into H and L chains, § recombined and tested for the regeneration of the original combining site by equilibrium dialysis. The results indicated that recombinants of focused antibody fractions contained binding sites identical to those of the intact antibody, whereas heterogeneous (unfocused) recombinants and isolated H and L chains failed to show any binding activity. The conclusion from this study is that the heterogeneity of ligand binding exhibited by nurse shark 19S antibodies to the capsular polysaccharide of the Type III pneumococcus can be attributed to intermolecular heterogeneity.

Characterization of Lymphoma-Derived Cell Lines: Comparison of Cell Lines Positive and Negative for Epstein-Barr Virus Nuclear Antigen. II. Surface Markers

Fifteen of 16 lymphoma-derived cell lines and the Faji and P3HR1 cell lines were characterized with regard to certain surface markers, particularly immunoglobulins, complement receptors, Epstein-Barr virus (EBV) receptors, and Fc receptors. Ten lines positive for EBV nuclear antigen (EB-pos) were stained weakly or not at all by antihuman immunoglobulin fluorescein isothiocyanate conjugates, whereas EBV nuclear antigen negative (EB-neg) cell lines stained brightly. EB-pos lines frequently manifested Fc receptors, particularly for 7S antibody, whereas EB-neg lines did not. Receptors for the C3b component of complement and for EBV, which correlated significantly with each other, were expressed to a much lesser extent by EB-neg lines than by EB-pos lines. These findings are pertinent to an understanding of the infrequent association of this virus with American undifferentiated lymphomas of the Burkitt's and non-Burkitt's types.

Binding dynamics in biological systems. Interaction of MOPC‐315 with 19F labelled nitrophenyl haptens

AbstractWe have studied the dynamics of binding of 19F labelled haptens by mouse plasmacytoma antibody MOPC‐315, a protein which shows specificity for nitrophenyl haptens. The off‐rates for the dissociation of hapten from MOPC‐315 proteins (7S, Fab′ and Fv) were determined by the application of several methods including a technique which, in certain cases, allows the direct determination of the rate of exchange of nuclei between magnetically non‐equivalent sites without requiring prior knowledge of intrinsic line widths. Used in conjunction with independently determined data on line widths, chemical shifts, and binding affinities, these studies show that the rates for hapten association to, or dissociation from, the intact 7S antibody, the Fab′ fragment, and the Fv fragment of MOPC‐315 are essentially the same. They also indicate the presence, probably in the Fv region, of a low affinity (K∼ 103 M−1) site(s) for hapten binding. The mobility of the hapten combining site decreases as the size of the protein increases. These rate data, which were determined at relatively high protein concentrations (up to 40 mg ml−1), agree with on‐rates determined at much lower protein concentrations (≤1 mg ml−1); we therefore conclude that protein aggregation, if it does occur, does not significantly affect binding in these systems.

Immunochemical approaches to DNA structure investigation—I: Immunochemical identification of the product of cytosine modification with bisulphite and o-methylhydroxylamine mixture

Highly specific antibodies to modified nucleotides are obtained by immunization animals with DNA modified O-methylhydroxylamine and bisulphite. Analysis by Sephadex G-200 column chromatography showed that immunized with modified DNA animals produced 19S and 7S antibody. The significance of the HSO − 3 group for specific antigenic determinant formation is demonstrated. Possibilities of combined use of immunochemical and chemical methods for studying the molecule acid structure are discussed.