Identification of measles virus-specific hemolysis-inihibiting antibodies separate from hemagglutination-inhibiting antibodies.

The occurrence of antibodies giving hemolysis inhibition (HLI) but not hemagglutination inhibition (HI) was examined in human convalescent and rabbit hyperimmune sera. HI antibodies, which through their interaction with hemagglutinin components display HLI activity, were removed by absorption with Tween 80-ether (TE)-treated measles virus material. This absorption did not change the titer of non-HI HLI antibodies. After removal of HI antibodies from 16 late measles convalescent sera and three batches of gamma globulin. HLI antibody titers showed a two- to eightfold reduction. The titers of neutralizing antibodies were reduced from 1/4 to 1/20 of the original titers. There was a good correlation between the titers of neutralizing and HLI antibodies both in sera from which HI antibodies had been removed by absorption and in sera spontaneously showing markedly higher HLI than HI antibody titers. HLI antibodies with these characteristics could be identified in HI tests when whole virus instead of TE-treated material was used an antigen and anti-antiserum was added to the tests. In contrast to the situation in human sera, antibodies remaining after removal of HI antibodies from rabbit hyperimmune sera against purified virus particles were detectable in neutralization and HLI tests only in the presence of anti-antiserum. However, virus particles from which the major fraction of all envelope projections had been removed by treatment with 0.004% trypsin induced the production of non-HI HLI antibodies active also in the absence of anti-antiserum. TE and formalin treatment destroyed the hemolytic activity of virus preparations and also their capacity to induce a production of non-HI HLI antibodies.     

Sensitive hemagglutination inhibition test for mumps antibody.

Incorporation of heterologous immunoglobulin against human immunoglobulin G into the mumps HI tests provided a highly sensitive and specific way of measuring mumps antibody in human sera. The sensitivity of this enhanced mumps HI test compared favorably with that of an anti-immunoglobulin-enhanced virus plaque neutralization test, but the HI test required considerably less time and effort to perform.     

Identification of Different Measles Virus-Specific Antibodies in the Serum and Cerebrospinal Fluid from Patients with Subacute Sclerosing Panencephalitis and Multiple Sclerosis

Matched serum and cerebrospinal fluid (CSF) samples from eight cases of subacute sclerosing panencephalitis (SSPE) and 15 cases of multiple sclerosis (MS) were characterized in neutralization, hemolysis-inhibition (HLI), hemagglutination-inhibition (HI) with Tween 80—ether-treated antigen, complement-fixation (CF), and immunodiffusion tests. CF tests were carried out with crude virus material, purified nucleocapsids, and small particle hemagglutinin as antigens. A certain diversity in the relative content of antibodies against different virus products in various sera was found. There was a high degree of correlation between titers of neutralizing and HLI antibodies, but a less strict correlation between titers of HLI and HI antibodies. Serum samples from two cases of MS and one case of SSPE contained high titers of HLI and neutralizing antibodies in the presence of only low titers of HI antibodies demonstrable with Tween 80—ether-treated antigen. The major fraction of antibodies detected in CF and immunodiffusion tests reacted with nucleocapsids. There was a tendency of nucleocapsid CF antibody titers, as compared to neutralization and HLI antibody titers, to be higher in samples from patients with SSPE than from cases of MS. No significant differences were found between antibody titers recorded in neutralization, HLI, and HI tests carried out with two different measles virus strains, Edmonston and a strain (LEC) derived from a case of SSPE. Comparison of antibodies against measles virus products and, as a reference, against a group-specific vertex capsomer antigen of adenovirus in matched serum and CSF samples revealed a production of measles virus-specific antibodies within the central nervous system of all cases of SSPE and 8 out of 15 cases of MS.     

Appearance and Persistence of Antibodies Against Different Virus Components After Regular Measles Infections

Different measles virus-specific antibody activities in acute, early (11 to 40 days after rash) and late (4 to 20 years postinfection) convalescent sera and gamma globulin were determined. Early immunoglobulin G antibodies gave a poor neutralization, which was increased 10- to 60-fold by addition of anti-gamma globulin.There was a high degree of correlation between titers of hemolysis-inhibiting (HLI) and hemagglutinating-inhibiting (HI) antibodies. However, in one out of fifteen late convalescent sera an HLI antibody titer of 640 in the presence of titer of only 20 in HI tests with Tween 80-either-treated antigen was found. Similar findings were made with sera from two patients with multiple sclerosis included in a parallel study. A somewhat higher titer of HI antibodies was demonstrable in these three sera when untreated material was used as antigen. These findings are interpreted in the following way. Antibodies against the hemagglutinin can block not only virus-specific agglutination but also lysis of red cells. In contrast, antibodies against the hemolysin, besides blocking the biological activity of this component, carry only a slight HI activity. This HI activity can be detected only by use of antigen preparations containing hemagglutinin-associated hemolysin.Complement-fixation (CF) and immunodiffusion tests (the latter were carried out with antigen preparations treated with 0.25% sodium dodecyl sulfate) demonstrated that, in almost all cases, antibodies against nucleocapsid structures dominated quantitatively among antibodies appearing in connection with and persisting after regular measles infections. Generally, only low titers of antibodies reacting with purified small particle hemagglutinin (HA; 10 to 14S) or additional structural or nonstructural components were identified in CF and immunodiffusion tests.     

Attempts at the detection of antibodies to Newcastle disease virus by haemofusion-inhibition test

Two modifications of a haemofusion-inhibition test (HFI-1 and HFI-2) were applied for the titration of antibodies to Newcastle disease virus (NDV) in chicken sera. Statistical analysis revealed a positive correlation of the HFI-1 antibody titres with those measured by the standard haemagglutination-inhibition (HI), virus neutralization (VN) and haemolysis-inhibition (HLI) tests. The same appeared true when the HFI-2 antibody titres were compared with the HI, VN, and HLI tests. Except for the several sera collected from birds immunized with formalin-inactivated vaccine, the HFI-2 antibody titres of individual serum samples were usually lower than those determined by HFI-1. The interpretation of these differences as well as some advantages and disadvantages of the proposed test are discussed.     

Antibody responses to mumps virus proteins in natural mumps infection and after vaccination with live and inactivated mumps virus vaccines

Paired sera from 20 patients with acute mumps infection, 16 from persons vaccinated with live attenuated mumps virus vaccine, and 12 from persons vaccinated with formalin-inactivated virus vaccine were studied for mumps antibodies by single radial hemolysis (SRH), hemagglutination inhibition (HI), and by enzyme immunoassays (EIA) specific for whole virus, envelope glycoprotein, and nucleocapsid antibodies. Mumps patients had diagnostic rises in serum mumps antibodies in 90–100% of the cases depending on the method of assay. Vaccination resulted in seroconversion in 75–88% (live vaccine) and in 92% (inactivated vaccine) of the cases as detected by SRH or EIAs, whereas HI detected seroconversion only in 38% and 58% of the cases, respectively. Immunoprecipitation analyses revealed that all sera from mumps patients and nearly all postvaccination sera had antibodies against the main structural proteins of mumps virus. By immunoblotting, antibodies against denatured hemagglutinin-neuraminidase (HN) and fusion protein (F) were detected in 15–25 % of mumps patients and persons vaccinated with live vaccine, whereas most postvaccination sera from those vaccinated with inactivated vaccine had HN (92%) and F (83%) protein antibodies, suggesting that antibodies against the denatured form of proteins are formed.     

Comparative measurement of equine influenza virus antibodies in horse sera by single radial hemolysis, neutralization, and hemagglutination inhibition tests.

Single radial hemolysis (SRH), neutralization (NT), and hemagglutination inhibition (HI) tests were carried out on sera from horses immunized against the Prague and Miami strains of equine influenza virus. The HI and NT tests demonstrated good sensitivity; the sensitivity of the SRH test was somewhat lower. The NT titers of individual sera were correlated very closely with the HI titers, although the NT titers were higher. SRH zone diameters of individual sera also showed significant correlation with the NT and NI titers. The SRH test appears to be suitable for large-scale serological surveys and offers the advantages of rapidity and simplicity.     

Serological diagnosis of parainfluenza virus infections: verification of the sensitivity and specificity of the haemagglutination-inhibition (HI), complement-fixation (CF), immunofluorescence (IFA) tests and enzyme immunoassay (ELISA).

Using four serological tests paired sera were examined of 117 patients with acute respiratory diseases, in whom parainfluenza viruses (PIV) infection was demonstrated by virus isolation, and of 41 patients with typical clinical mumps symptoms. Comparative analysis showed the high sensitivity of IFA and ELISA. A significant rise of antibodies in convalescent sera with homologous antigen of PIV was found in nearly 100 percent of cases. Only the sera of youngest children with high titres of persisting maternal antibodies remained without seroconversion. Cross heterologous antibody responses could be found by means of ELISA in 45% and by IFA in 10%, of patients who in the past experienced infection with one or more PIV or mumps virus--apart from homologous antibody reaction. HI and CF test proved to be less sensitive for detection of postinfections antibodies, especially in primoinfections with PIV types 1 and 2.     

The significance of hemolysing-inhibiting antibodies in protection against measles

The occurence of hemagglutinating-inhibiting (HI), hemolysinginhibiting (HLI) and nucleocapsid complement fixing (NC-CF) antibodies in serum samples from individuals immunized with measles virus antigens under various conditions was analyzed. After regular measles infections all three kinds of antibodies were detectable and removal of HI antibodies by absorption with Tween 80 and ether treated virus material only caused an about 2-fold reduction of titers of HLI antibodies. Immunization with further attenuated measles vaccine also induced a production of antibodies detectable in the three different tests. However the response of non-HI HLI antibodies and NC-CF antibodies was relatively less pronounced than after regular measles. Immunization with three or four doses of Tween 80 ether treated inactivated measles vaccine caused a production of HI antibodies and in some cases NC-CF antibodies. Non-HI HLI antibodies were not detectable. The combined immunization with inactivated vaccine followed by further attenuated live vaccine caused the appearance of high titers of HI antibodies but in contrast to the situation of administration of only live vaccine non-HI HLI antibodies were not detectable. The significance of non-HI HLI antibodies in protection against disease also was indicated by observations on the reactions of individuals immunized with inactivated vaccine and subsequently exposed to wild measles virus. The non-HI HLI antibody response was poorer in the vaccinees who contracted a complicated infection as compared to those who had only a subclinical or a mitigated infection. An accentuated non-HI HLI antibody and NC-CF antibody response was seen in patients with subacute sclerosing panencephalitis. It is proposed that the failure of hitherto used inactivated measles vaccines is due to the absence of certain envelope antigens in the preparations which leads to a deficiency as concerns the capacity to induce a production of non-HI HLI antibodies.     

Mumps-specific immunoglobulin M and G antibodies in natural mumps infection as measured by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay for the demonstration of mumps immunoglobulin G (IgG ELISA) and immunoglobulin M antibodies (IgM ELISA) in serum was compared with complement fixation (CF), hemagglutination inhibition (HI), and hemolysis-in-gel (HIG) tests. The antibody levels measured by IgG ELISA had a high positive correlation with the CF and HIG tests, whereas only a moderate correlation was found between IgG ELISA and HI. Similar patterns of antibody response were observed with IgG ELISA, CF, and HIG: the antibody titres increased rapidly after the onset of symptoms and reached the maximal values in about three weeks. The HI antibodies developed more slowly during the first week of disease, after which the titres increased rapidly up to the fourth week. IgM antibodies measured by ELISA developed soon after onset of symptoms; most patients had IgM antibodies from the second day, and the highest titres were reached within the first week. The antibody response in mumps parotitis did not differ from that in mumps meningitis/encephalitis, while relatively higher antibody titres were found in patients with orchitis/epididymitis. The diagnostic efficiencies of the methods were compared with serum specimens from 33 patients who had a serologically verified mumps infection by at least one of the five methods used (rising antibody titres in paired sera or detectable IgM): IgM ELISA detected all 33 cases, IgG ELISA 29, HIG 28, HI 23, and CF 13. In 27 cases, IgM antibodies were already present in the acute phase serum specimens. It was concluded that mumps IgM ELISA is a more rapid and sensitive means for the serological diagnosis of mumps infection than the conventional tests.     

Hemadsorption immunosorbent technique for determination of mumps immunoglobulin M antibody

We used hemadsorption immunosorbent technique (HIT) to detect mumps immunoglobulin M (IgM) antibody. IgM from human sera was adsorbed into anti-human IgM-coated wells in plates, and mumps-specific IgM was detected by adding mumps virus hemagglutinin and guinea pig erythrocytes consecutively. Specific IgM-positive sera showed hemadsorption, whereas negative sera showed hemagglutination. All 81 patients with current mumps infections tested showed mumps-specific IgM antibody, with titers ranging from 160 to 327,680. In most cases IgM antibody was already present on day 1 or 2 after the onset of illness. IgM antibody persisted for 6 to 10 weeks. Of 57 patients with acute respiratory illnesses caused by parainfluenza virus, 5 showed cross-reactions in the hemadsorption immunosorbent technique assay for mumps IgM. The hemadsorption immunosorbent technique assay is specific for the IgM class of antibody and avoids false-positive results due to rheumatoid factor. This test is an efficient and sensitive method for rapid and early diagnosis of mumps infections.     

Hemolysis-in-gel and neutralization tests for determination of antibodies to mumps virus.

A hemolysis-in-gel test for the demonstration of antibodies to mumps virus is described. The results were compared with those of neutralization tests using a modified microtechnique. In the neutralization test viral replication was demonstrated by the hemadsorption of guinea pig erythrocytes, the visibility of which could be further enhanced by the use of o-tolidine. Good correlation was found between the results of the two techniques. The hemolysis-in-gel test was simple to perform, rapid, sensitive, and shown to be a useful test for the demonstration of mumps antibodies.     

Cost and performance analysis of haemagglutination inhibition, passive haemagglutination, radial haemolysis, and enzyme immunoassay for measuring rubella antibody

Cost and performance of non-commercial haemagglutination inhibition (HI) and radial haemolysis (RH) tests, and the commercially available passive haemagglutination (PHA) Rubacell and enzyme immunoassay (EIA) and Rubazyme assays were compared in their ability to detect rubella antibodies in 316 sera. Correlation coefficients were: HI to RH 0.96; HI to EIA 0.86. All 4 tests were in agreement on pre- and post-rubella immunization sera from 10 subjects. Eleven sera collected between 1 and 15 days after natural infection possessed clear HI titres whereas only 4 of them showed positive responses by PHA, RH or EIA. Immunity screening 285 sera identified 7 discordant results (positive in 2 of 4 tests). A detailed cost analysis for testing 100 sera showed a cost per test from +2.10 for HI to +3.71 for EIA. The labour component of the total cost was different for each assay and affected the unit cost of testing a single specimen. Results are discussed in view of antibody responses to specific rubella polypeptides and recommendations for diagnosis or immunity screening are made according to the findings.     

Properties of mouse leukemia viruses. V. Hemagglutination-inhibition and indirect hemagglutination tests

Although the presence of nonspecific inhibitors precluded the use of untreated sera in hemagglutination-inhibition (HI) tests with mouse leukemia virus (MuLV) hemagglutinating antigens, preparations of immunoglobulin G (IgG) lacked nonspecific inhibitory activity and were suitable for use. Hemagglutination (HA) induced by intact, enzyme-treated MuLV and by hemagglutinating MuLV subunits was inhibited by IgG isolated from MuLV antisera. Low titer HI reactions were obtained with IgG from feline leukemia virus (FeLV) antisera. IgG from a broad spectrum of control antisera was noninhibitory. The HI activities of three FMR (Friend-Moloney-Rauscher) antisera against FMR antigens were totally type-specific as revealed by absorption tests. Gross leukemia virus (GLV) antisera also appeared to react type-specifically against GLV antigen. However, the inhibition of FMR antigens by IgG from one nonneutralizing FMR (gs) antiserum, GLV antisera and FeLV antisera, all of which lacked FMR type-specific antibodies, indicated that gs-like reactivity also could be detected by the HI test in at least certain sera.In related studies, an indirect HA reaction employing heterotypic Friend virus antiserum (IgG) revealed a new, possibly monovalent hemagglutinin from degraded GLV. The HA activity of this GLV antigen could be reconstituted by most FMR sera tested, but not by sera directed against GLV, FeLV or other control antigens. The reconstituted hemagglutinin was specifically inhibited by homotypic GLV antiserum (IgG). This indirect HA test not only constitutes direct evidence for the existence of gs antigenic determinants on the surface of the virion but also provides a tool for the detection of such antigens and their corresponding antibodies.     

BK virus: I. Seroepidemiologic studies and serologic response to viral infection

Sera of 656 patients in seven age groups were tested by hemagglutination=inhibition (HI) and complement=fixation (CF) tests for antibodies to BK virus. Both tests revealed that BK virus antibodies are common in the population of southern Germany, and that primary infection is apparently acquired during childhood. The highest rate of positive sera, 71% in the HI test and 56% in the CF test, was found in the 15–30 year old group. The antibody titers correlated in both serologic tests, but HI tests were more sensitive and reliable than CF tests. An indirect immunofluorescence assay for the detection of BK virus-specific IgM antibodies was also developed. Studying umbilical cord blood sera from 846 healthy donors, BK virus IgM antibodies were detected in 77 sera (9.1%).     

Production of antibodies against measles virions by use of the mouse hybridoma technique

Summary Mouse hybridoma cell lines were produced by fusion of P3 × 63 Ag8 myeloma cells with spleen cells from BALB/c mice immunized with purified measles virions. About 60 per cent of single cell colonies in wells were found to produce measles antibodies as determined by a radioimmune assay. Selected measles antibody producing hybridoma cell lines were passaged intraperitoneally in mice and ascites fluids were collected. This material contained 20–200 times higher antibody titers than unconcentrated medium from hybridoma cell lines propagated in tissue culture. The ascites fluid antibody products of 23 hybridoma cell lines were characterized by different measles serological tests. Seventeen lines produced high titers of hemagglutination inhibiting (HI) and hemolysis-inhibition (HLI) antibodies. One hybridoma cell line produced Ig with low HI but high HLI activity and the remaining 5 hybridoma cell line products only carried HLI activity. Unexpectedly it was found in radioimmune precipitation assays that all hybridomas studied, including those showing HLI but no HI antibody activity, gave a selective precipitation of the 79K measles hemagglutinin polypeptide. Radioimmune precipitation assays with sera from immunized animals showed that they contained high titers of antibodies precipitating the 79 K polypeptide but in addition also somewhat lower titers of antibodies precipitating the 60 K nucleoprotein, 40 K fusion and 36 K matrix polypeptides. Homogeneous Ig products carrying measles antibody activity were demonstrated by imprint immunoelectrophoresis of ascites materials.With 2 Figures     

Enzyme-linked immunosorbent assay (ELISA) for mumps virus antibodies

An ELISA for the detection of mumps virus-specific IgG and IgM antibodies was developed. Three different antigen preparations were compared. Equally good results were obtained with virus concentrated by ultracentrifugation and with virus that was further purified by sucrose gradient centrifugation. Crude infected allantoic fluid was unsuitable for use as antigen. The variability and reproducibility of the tests were satisfactory. When the ELISA was compared to conventional serological methods, a good correlation of IgG absorbance values with complement fixation (CF) antibody titers was found (r = 0.574), the ELISA being more sensitive in detecting antibodies in acute-phase sera. For the determination of immunity, ELISA IgG values were compared with results obtained in hemagglutination-inhibition (HI) and hemolysis-in-gel (HIG) tests. Again there was a good correlation with both tests (r_HI = 0.528, r_HIG = 0.667). The ELISA was more sensitive than the HI and HIG test for the detection of low levels of antibodies.     

Increased sensitivity for detecting avian influenza-specific antibodies by a modified hemagglutination inhibition assay using horse erythrocytes

The hemagglutination inhibition (HI) assay is a widely used serological method to measure the levels of protective antibody responses against influenza viruses. However, the traditional HI assay which uses chicken erythrocytes is not sufficiently sensitive for detecting HI antibodies specific to avian influenza viruses. Previously, it was demonstrated that employing an assay using horse erythrocytes was able to increase the sensitivity of HI assay. The current report describes further optimization of this modified HI assay. It was shown that this method was able to increase detection of HI activities in rabbit sera immunized with H5 HA antigens, and proved that this increased sensitivity is useful in dissecting the strain specificity of HI antibody responses. In addition, the modified HI assay using horse erythrocytes increased the sensitivity of detecting HI antibodies specific for three major serotypes of avian influenza viruses, H5, H7 and H9, in people who may have asymptomatic infection with avian influenza viruses. Based on these results, the optimized use of horse erythrocytes should be standard practice for detecting HI activities against avian influenza viruses.     

A mixed hemadsorption assay for detection of cell surface binding anti-tumor antibodies in human sera

A practical mixed hemadsorption assay (MHA) was developed for the detection of cell surface binding anti-tumor antigen antibodies (anti-TA Ab) in the human sera. The assay was compared to enzyme-linked immunosorbent assay (ELISA) and dot ELISA in the detection of the antibodies developed against GA733-2 antigen. SW1116 cell line and recombinant GA733-2E protein were used as targets in the MHA and solid phase immunoassays (SPIA), respectively. Sera were obtained from healthy donors and vaccinated-colon carcinoma patients. The sensitivity level of the MHA was very high for detection of anti-TA Ab in sera.     

Contribution to laboratory diagnosis of mumps and parainfluenza

Specific IgM and IgG antibodies to mumps virus (MV) were detected in sera of mumps-patients by ELISA in agreement with the results obtained by indirect immunofluorescence (IF). Of given sera 37.5% contained IgM reacting in indirect ELISA also with the antigens of parainfluenza virus (PiV) T3. In all patients with respiratory illness over 2 years of age, the significant increase of antibodies to PiV in haemagglutination inhibition (HI) test was in good correlation with serum IgM and IgG antibody levels to PiV T3 determined by ELISA; but, in addition, 30.7% of these sera cross-reacted with MV antigens. The cross-reactions were eliminated by using MV-nucleocapsid antigen in indirect ELISA, or in direct ELISA using the peroxidase-labelled whole virion antigen. In some children under two years of age a discrepancy was observed between the significant increase of serum antibodies in HI and the inability to detect specific IgM antibodies by means of ELISA in their sera. The low-avidity antibodies appearing after primary PiV infection were probably washed off during the ELISA procedure.