Clinical findings and serological evidence of HTLV-III infection in homosexual contacts of patients with AIDS and persistent generalised lymphadenopathy in London

Between 1980 and 1984 28 homosexual men who had had ano-genital intercourse with patients with either acquired immunodeficiency syndrome (AIDS) or persistent generalised lymphadenopathy (PGL) were followed up. The pattern of the sexual links indicated that within this group there were two clusters, one consisting of 7 men and the other of 13.17 of the 28 contacts became ill with either AIDS or PGL; among those in the clusters, 4 died of AIDS and 11 had PGL, and of the rest 2 had PGL. 16 of the 19 men in the clusters who were tested for HTLV-III antibodies were seropositive, as were 7 of those not in the clusters. 111 men attending a genitourinary medicine clinic who had not had known contact with either AIDS or PGL patients and who were being screened for syphilis served as controls. Of these, 19/86 who were homosexual and 0/25 who were heterosexual were positive for HTLV-III antibodies. None of the 4 who died of AIDS had had contact with each other. The 2 in the first cluster seemed to have been linked by a symptomless HTLV-III-negative man, who was also probably the link between the two clusters, while in the second cluster the chief "carrier" seemed to be a seropositive man in whom PGL developed. These findings are consistent with the hypothesis that HTLV-III is the sexually transmitted causative agent of AIDS and PGL.

Low prevalence in the UK of HTLV-I and HTLV-II infection in subjects with AIDS, with extended lymphadenopathy, and at risk of AIDS

Antibodies reacting selectively with human T-cell leukaemia virus type I (HTLV-I) were detected in approximately 5% patients with extended lymphadenopathy syndrome (ELAS) and in less than 1% of unselected homosexual patients and drug abusers. None of 22 patients with acquired immunodeficiency syndrome (AIDS) had HTLV-I antibodies and neither did 85 haemophiliacs and 940 blood donors. 3 out of 113 drug addicts had high titres of antibodies to human T-cell leukaemia virus type II (HTLV-II). A T-cell line was derived from 1 of the seropositive ELAS patients. This line was found to be infected with, and releasing, HTLV-I. Infection by HTLV-I and HTLV-II retroviruses thus occurs more frequently in ELAS patients and drug addicts than in the UK population as a whole, but the low prevalence of these infections in ELAS and AIDS patients indicates that these two strains of lymphotropic retroviruses have no aetiological role in ELAS and AIDS.

The immunoglobulin M response to rubella vaccine in young adult women

Rubella vaccination histories were taken from 333 young women working in the head office of a retail organization: 29% said they had had vaccine and 47% said they had not. The remainder did not know. Forty-six per cent of those less than or equal to 25 years old (who should have been offered vaccine at school), and 6% of those greater than 25 years old, said they had been vaccinated. When screened for immunity to rubella by radial haemolysis (RH) 3% had a low level of antibody (less than 15 i.u./ml) and 11% had no antibody. After immunization with Cendevax the specific rubella IgM response was measured by an IgM antibody capture radioimmunassay (MACRIA). It was only detectable in the group without RH antibody, and was present in 26/31 of them. The IgM response to Cendevax was strongest in specimens taken 20-39 days after immunization, but in 10 out of 11 cases tested was still present at around 71 days. The specific IgM responses to Cendevax were very similar to those in women given Almevax in an earlier study, when measured in parallel tests. Taking both vaccines together, specific IgM was present in 35 out of 36 vaccinees without pre-existing antibody tested between 40 and 77 days post-immunization. Detection of specific IgM by MACRIA would therefore be an effective means of determining susceptibility retrospectively in rubella vaccinees found to be pregnant.

Monoclonal antibodies to hepatitis Be antigen (HBeAg) derived from hepatitis B core antigen (HBcAg): their use in characterization and detection of HBeAg

A panel of mouse hybridomas secreting monoclonal antibody to serum hepatitis Be antigen (HBeAg) was produced from mice immunized with denatured hepatitis B core antigen (HBcAg). This panel could be divided broadly into two groups. Within each group, the monoclonal antibodies recognized a single antigenic site, designated either e-alpha or e-beta, and generally exhibited a high degree of cross-inhibition. In contrast, between the two groups of antibodies there was little or no cross-inhibition. The antigens of serum HBeAg and denatured HBcAg appeared to be very similar. Both behaved as molecules carrying only a single e-alpha or e-beta site, in spite of native serum HBeAg having an apparent molecular weight of 300 000. It is inferred that e-alpha and e-beta sites may be involved in the polymerization of HBeAg into HBcAg and that during this process mutual masking of antigenic sites may occur.

Immunological characterisation of rubella virion polypeptides

Antibodies specific for rubella virion polypeptide, VPI, secreted by clones of hybridoma cells or produced in rabbits in response to specific antigenic stimulation, located determinants for haemagglutination inhibiting (HI) and neutralising (Nt) antibodies on this envelope component.

Relationship between expression of hepatitis B virus antigens in isolated hepatocytes and autologous lymphocyte cytotoxicity in patients with chronic hepatitis B virus infection

Previous studies demonstrated that peripheral blood lymphocytes are cytotoxic to autologous hepatocytes in patients with chronic hepatitis B virus infection. We examined whether cytotoxicity is specifically directed against hepatocytes expressing HBsAg or HBcAg. Viral antigens were detected by immunofluorescence in isolated hepatocytes before and after exposure to T and non-T lymphocytes from 28 patients with chronic HBV infection in an autologous cytotoxicity assay. There was significant reduction in the percentage of HBcAg-positive hepatocytes after exposure to T lymphocytes and, to a lesser extent, after exposure to non-T cells; hepatocytes expressing HBsAg were not affected. Other studies showed that many hepatocytes containing HBcAg have IgG of anti-HBc specificity bound to their nuclei. In the present study, there was significant association between the presence of HBcAg and nuclear IgG in isolated hepatocytes. The ratio between the percentages of HBcAg-positive and IgG-positive hepatocytes (reflecting the proportion of hepatocytes containing free-core antigen) correlated significantly with reduction in HBcAg-positive liver cells after exposure to T cells, but not to non-T cells. These results suggest that hepatocytes in which viral replication is occurring and which express core determinants are susceptible to cell-mediated cytotoxicity and that T-cell cytolysis may be modulated by anti-HBc which is bound to hepatocytes.

Antibody assays for varicella-zoster virus: comparison of competitive enzyme-linked immunosorbent assay (ELISA), competitive radioimmunoassay (RIA), complement fixation, and indirect immunofluorescence assays

The competitive ELISA test was compared with competitive RIA, complement fixation, and indirect fluorescent antibody test for the detection of antibody to varicella-zoster virus (VZV). ELISA and RIA were the most sensitive tests, being tenfold as sensitive as indirect immunofluorescence and 20 times as sensitive as complement fixation, which was surprisingly inadequate for detecting anti-VZV in sera from regular haemodialysis patients. The ELISA test was found to be the most suitable assay, employing a routine complement fixation test (CFT) grade viral antigen and not requiring radiolabelling and counting facilities, which are unavailable in most virology laboratories.

Serological markers in fulminant hepatitis B

Serological markers for hepatitis B virus infection have been examined in 34 patients with acute hepatitis B, 17 of whom developed fulminant hepatic failure. Hepatitis B surface antigen concentrations were significantly lower and hepatitis Be antigen was less frequently detectable in patients with fulminant hepatic failure compared with those with acute hepatitis (median 0.64 micrograms, range 16-0 and median 32 micrograms and range 100-4 micrograms respectively, p less than 0.001; HBeAg detected in 12% and 88% respectively, p less than 0.001). The IgM component of hepatitis B core antibody was significantly higher in the patients with fulminant hepatic failure with median values of 500 IU/ml compared with those with uncomplicated hepatitis (median 202 IU/ml, p less than 0.05 Wilcoxon's rank test). Three patients who developed a fulminant course had detectable levels of either anti-HBs or anti-HBe. These results are consistent with enhanced antibody responses to all three hepatitis B virus antigens and more rapid clearance of the latter during fulminant hepatic failure.

Rubella-specific IgM reactivity in sera from cases of infectious mononucleosis

Eight sera from 125 cases of infectious mononucleosis (IM) were reactive for rubella-specific IgM in an M-antibody capture radioimmunoassay. The reactivity of individual sera varied depending upon the source of the rubella antigen used in the assay. One serum gave strongly positive results with some rubella haemagglutinating antigens but negative results with others and may have contained an IgM antibody which was capable of distinguishing between strains of rubella virus. If the diagnosis of rubella is based solely on detection in solid-phase immunoassay of rubella-specific IgM, IM should be excluded.

Production of monoclonal antibodies to hepatitis B surface and core antigens, and use in the detection of viral antigens in liver biopsies

Hybridomas secreting monoclonal antibodies to HBsAg and HBcAg were prepared from immunized mice. An antibody capture radioimmunoassay was used to detect and select appropriate hybrids for propagation and cloning. The advantages of this assay were discussed. The resulting monoclonal antibodies were compared with conventional polyclonal antisera for the detection of virus antigens in liver tissue and found to give excellent results.

Screening for anti-rubella IgM ad libitum

There are few applications of virology to clinical medicine that have received more attention than the laboratory diagnosis of rubella. Many laboratories attempt it and most readers of this journal will be familiar with the techniques that have been used. It would therefore be superfluous to review the ‘state of the artm’ had there not recently been an innovation that is likely to alter laboratory practice in this field.

The production of monoclonal antibodies to rubella haemagglutinin and their use in antibody-capture assays for rubella-specific IgM

Mice were immunized by three intraperitoneal and one intravenous injection of rubella haemagglutinin. Splenocytes from these mice were fused with the cells of a syngeneic myeloma cell line, and following culture for various periods of time, single-cell clones were derived by the technique of limiting dilution. A total of 139 clones were derived from 13 parent hybrid cultures. To date, four of these cloned cultures have been propagated as ascitic tumours in mice. The preparation of IgG from ascitic fluid and labelling of this antibody with 125I is described. Results indicate that the use of labelled monoclonal antibodies as indicator reagents in solid-phase IgM antibody capture assays for the detection of rubella-specific IgM results in enhanced performance of these tests.

Are many women immunized against rubella unnecessarily?

Radial haemolysis (RH) was used to test sera for immunity to rubella from 1317 patients attending a general practice. One hundred and forty-one (10.7%) were treated as susceptible and offered an attenuated virus vaccine (RA 27/3). Pre-immunization sera from 43% of these patients were reactive at low levels in RH (less than 15 international units rubella antibody per ml). Pre- (S1) and post- (S2) immunization sera from 66 vaccinees were studied in detail. Antibody was detected by RH, haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA), and the specific IgM response was measured by a solid-phase M-antibody capture radioimmunoassay (MACRIA). The vaccine-induced IgM response was only detected if the S1 serum was non-reactive by all tests for rubella antibody. It was weaker than that seen following wild virus infection. It could be detected reliably for six weeks, and in most cases for nine weeks, after immunization. In contrast, patients with S1 specimens reactive by RH, HI or ELISA never showed an IgM response in the S2 specimen despite "significant' antibody rises often being present. It was considered that an IgM response to RA 27/3 was the best indicator of pre-immunization susceptibility to rubella. The failure of many vaccinees to make an IgM response implied that a significant proportion were already immune. It is suggested that the threshold for a report of immunity to rubella could be lowered from 15 i.u. antibody per ml and so fewer women immunized without vaccine being withheld from those who need it.

Development of an enzyme-linked immunosorbent assay (ELISA) for hepatitis B e antigen and antibody

Horseradish peroxidase has been conjugated with human immunoglobulin containing antibody to hepatitis B e antigen (anti-HBe). This was used in a solid-phase 'sandwich' enzyme-linked immunosorbent assay designed for reading by eye, to test sera for HBeAg and anti-HBe. Optimum conditions for preparing the conjugate and for performing the test are described. Results of testing hepatitis B surface antigen (HBsAg)-positive sera were compared with those obtained using a sensitive solid-phase radioimmunoassay. The enzyme assay provided a simple and sensitive method of testing for HBeAg and anti-HBe, and correlated well with the radioimmunoassay.

IgM-antibody response to the hepatitis B core antigen in acute and chronic hepatitis B

A solid phase M-antibody capture radioimmunoassay (MACRIA) and a serum fractionation method were used to quantitate the IgM response to the hepatitis B core antigen (IgM anti-HBc) in acute and chronic hepatitis B infections. Antibody to the core antigen was predominantly of the IgM class during the acute phase of hepatitis B. Resolving acute infections remained positive by MACRIA, but at decreasing levels, for as long as 6 months. IgM anti-HBc persisted in HBsAg carriers but at levels very much lower than seen in acute infections. There was no correlation of IgM anti-HBc with severity of chronic liver disease in carriers. Measurement of IgM anti-HBc by MACRIA enabled accurate identification of acute hepatitis B on single serum specimens.

Antibody capture radioimmunoassay for anti-rubella IgM

An M-antibody capture radioimmunoassay (MACRIA) for anti-rubella IgM was developed. Under optimum conditions positive serum specimens bound up to 20 times as much radioactivity as negative specimens. Positive reactions were expressed in arbitrary units/ml by comparison with a calibration curve derived from results obtained with dilutions of a standard serum. The specificity of the assay was confirmed by testing IgM and IgG rich fractions of positive sera. One hundred and forty specimens from blood donors, patients whose sera contained rheumatoid factor and patients with acute, non-rubella, virus infections were tested by MACRIA. No significant non-specific reactions were detected. Paired sera from acute rubella (25 patients) and individual sera from suspected rubella (69 patients) were tested for anti-rubella IgM by MACRIA and by haemagglutination inhibition following sucrose-density-gradient fractionation. There was close agreement between the two methods. The capture assay was more sensitive and could be used to detect the weak IgM response in women given RA 27/3 vaccine. After the natural infection, the MACRIA was strongly positive for two months and remained weakly so for a further two months. Repeat testing of sera demonstrated good reproducibility of the assay. MACRIA proved a simple, sensitive and specific test for anti-rubella IgM and compared favourably with currently used techniques.

Detection of antibody to varicella-zoster virus by competitive and IgM-antibody capture immunoassay

A simple, sensitive, and specific competitive solid phase immunoassay for antibody to varicella-zoster virus (anti-VZV) is described. The assay uses reagents that can easily be prepared and is sparing of viral antigen. Using a solid phase coated with sheep IgG from a serum raised against human mu-Fc, the same reagents will accurately detect anti-VZV IgM. The competitive assay divided sera from children from adults into immune and nonimmune groups that closely correlated with a history of previous VZV illness. It was not affected by the presence or absence of antibody to other herpes viruses. The IgM antibody capture assay demonstrated the presence of anti-VZV IgM in sera from patients with both varicella and zoster and gave negative results in patients with infections unrelated to VZV and in healthy blood donors.

Hepatitis B carrier state produced by a blood transfusion

A renal transplant patient was infected by a transfusion of blood from a chronic carrier of hepatitis B and he also became a symptomless carrier. Stored sera enabled detailed retrospective measurement of the rate of decline of passively transferred HBsAg, anti-HBc, and anti-HBe. Active HBsAg production was detected after two months and anti-HBc after six months; neither HBe nor anti-HBe was actively produced although there were many 42 nm HBV particles in the patient's serum.