The detection of antibodies to cytomegalovirus in the sera of renal transplant patients by an IgM antibody capture assay

Treatment of acute bronchiolitis with Chinese herbs

In a randomised single blind trial the Chinese herbs Shuang Huang Lian were evaluated for the treatment of acute bronchiolitis. Children with acute bronchiolitis and serological evidence of recent respiratory syncytial virus infection were studied in a tertiary hospital in Harbin, China. The 96 children were randomised into three treatment groups: herbs, herbs with antibiotics, and antibiotics alone. The herbs were prepared by the medical school pharmacy and administered daily by intravenous infusion for seven days. The main outcomes, assessed blindly, were symptomatic improvement in cough, fever, wheezing, chest signs, and duration of stay in hospital. The mean duration of symptoms from the start of treatment was 6.2 (confidence interval 5.6 to 6.9) days in the two groups treated with herbs compared with 8.6 (confidence interval 7.5 to 9.8) days in the group treated with antibiotics alone. The mean reductions in duration of clinical manifestations for treatment with antibiotics alone compared with herbs were: from 3.1 to 1.5 days for fever, 9.1 to 6.1 days for cough, 6.5 to 4.1 days for wheezing, and 7.2 to 4.9 days for chest crackles. No adverse effect of Shuang Huang Lian herbal treatment was detected. In conclusion, this study confirms Chinese experience with Shuang Huang Lian that it is safe and effective, and warrants further study.

Comparison of three immunoassays for the detection of anti-HHV6

Sera from 96 blood donors were tested for antibody to human herpesvirus 6 by indirect immunofluorescence (IF), circle immunoassay (CIA) and competitive radioimmunoassay (RIA). The correlation between the three assays was good but the CIA and competitive RIA were more sensitive for the detection of HHV6 antibody than indirect IF. The crossreaction of HHV6 antibody with that to the other human herpesviruses was also studied in this blood donor group. No correlation was found between antibody to human herpesvirus 6 by any of the methods described and antibody to any of the other human herpesviruses in these sera.

Antibodies to cytomegalovirus in renal allograft recipients: correlation with isolation of virus

A cohort of 47 renal transplant recipients was studied prospectively for up to one year after transplantation. Cytomegalovirus (CMV) was isolated from 21 of the patients. The first time the virus was isolated seven patients were IgM positive, nine showed a significant rise in IgG titres, and 12 had a four-fold or greater rise in complement fixation titre. There was no significant difference in the time at which virus was first detected following transplantation between patients with primary CMV infection and those with reinfection or recurrent infection. In general, patients with primary infection shed virus consistently over long periods. Those with reinfection or recurrent infection shed virus intermittently or not at all. There were considerable differences between individual patients in the timing and pattern of the immune response. Taken overall, a four-fold rise detected by the complement fixation test correlated best with the onset of CMV shedding in primary infection. There was more variation in the pattern of antibody response in cases of reinfection or recurrent infection, with no single serological test correlating better than the others. It is concluded that serology is of limited value in the detection of active CMV infection after renal transplantation.

Detection by enzyme-linked immunosorbent assay of specific immunoglobulin G isotypes in primary and established cytomegalovirus infections

An enzyme-linked immunosorbent assay using monoclonal antibodies was developed to study the subclass distribution of immunoglobulin G (IgG) to cytomegalovirus (CMV) in individuals from a number of clinical groups. Most CMV-seropositive individuals had IgG1 and IgG3. IgG2 and IgG4 were detected less frequently at very low levels of activity, mostly among mothers at delivery and renal patients. Most seroconversions were accompanied by an important increase of the IgG1 activity, whereas IgG3 appeared at lower levels; neither IgG2 nor IgG4 occurred. This suggests that these isotypes play a secondary role in the response to the CMV infection and that they may be considered markers of past infections. Anti-CMV IgG1 is the most efficiently transmitted through the placenta. Whether infected or not, newborns had the same subclass distribution and activity levels as their mothers. Isotype determination did not offer a decisive explanation of a number of discrepancies observed between CMV IgG enzyme-linked immunosorbent assay and complement fixation test results.

Detection of cytomegalovirus-specific IGM in renal transplant recipients

We have compared two IgM-specific cytomegalovirus (CMV) antibody assays, an immunofluorescence assay (IFA-M) and an enzyme-linked antigen immunoassay (ELA-M), with an assay for CMV total antibody (ELISA) and viral culture for the detection of active CMV infection in renal transplant recipients. Of 75 patients (49 ELISA negative pretransplant, 26 ELISA positive), CMV-specific IgM was detected in 35 (27 ELISA negative pretransplant, 8 ELISA positive) using the IFA-M assay and in 25 (16 ELISA negative pretransplant, 9 ELISA positive) using the ELA-M test. Of the 25 patients identified as positive by ELA-M, 21 had positive viral cultures post-transplant, two seronegative patients had evidence of infection indicated by post-transplant seroconversion, and two patients were seropositive pretransplant but remained viral culture negative throughout the follow-up period. ELA-M and CMV total antibody ELISA detected primary infection in renal transplant recipients equally well, but ELA-M was found to be superior to ELISA and IFA-M for detecting reinfection and reactivation infections.

Cytomegalovirus infections in heart and heart and lung transplant recipients

Of the first 166 heart and 15 heart and lung transplant recipients at Papworth Hospital, Cambridge, who survived for more than one month after transplantation, 162 were investigated for cytomegalovirus (CMV) infection by serological methods. Altogether, 73 (45%) developed CMV infection after transplantation: 30 (18.5%) had acquired primary infection and 43 (26.5%) reactivation or reinfection. Six patients died of primary infection, probably acquired from the donor organ. Recipients negative for CMV antibody who received an organ from an antibody positive donor had the most severe disease. Heart and lung transplant recipients experienced more severe primary CMV infection than those in whom the heart alone was transplanted. The most sensitive and rapid serological method was a mu-capture enzyme linked immunosorbent assay (ELISA) for detecting CMV specific IgM, the amount of which was often of prognostic value and influenced the management of patients.

Kinetics of specific immunoglobulins M, E, A, and G in congenital, primary, and secondary cytomegalovirus infection studied by antibody-capture enzyme-linked immunosorbent assay

Antibody-capture enzyme-linked immunosorbent assay (ELISA) using enzyme-labeled cytomegalovirus (CMV) nuclear antigen is a reliable and easily performed test suitable for routine use. As the serologic response to CMV infection may, however, vary considerably among patients, we have studied the kinetics of CMV-specific immunoglobulin M (IgM), IgE, IgA, and IgG antibodies in 352 sera from 61 patients by using antibody-capture ELISA and complement fixation (CF) tests. In a CMV mononucleosis group (n = 17), most patients had antibodies of all four immunoglobulin classes, but antibody levels decreased rapidly, with half the patients having a borderline-positive or a negative reaction for all classes, except IgG, 2 months after the appearance of symptoms. Twelve patients with a primary CMV infection after renal or bone marrow transplantation also developed all immunoglobulin-class antibodies. In only two patients did CMV IgM and IgE antibodies precede seroconversion of CF antibodies, and in one patient, these antibodies lagged months behind. Most patients had all classes of CMV antibodies, except IgA, for a year or more. Among 10 transplant patients with a secondary CMV infection, 50% had long-lasting IgM antibodies, and very few had IgE or IgA antibodies, but all had IgG antibodies to CMV. In 13 infected infants, the CMV-specific serologic response was also characterized by long-lasting IgM, IgE, and IgG antibodies. Two patients did not develop detectable IgM antibodies, and one of these did not show IgE antibodies either. The IgA response in infants as a whole was lacking; a few, however, were borderline positive. Of the nine acquired immunodeficiency syndrome patients with CMV infection studied during their last year of life, only one had antibodies in all four classes, the rest had only CF antibodies, and all except for one had IgG-class antibodies. All sera studied were also tested against a control antigen produced from noninfected cell nuclei. It was found that some patients developed antibodies to nuclear antigens in parallel with the rise in specific antibodies. The nonspecific antibodies occurred in all four classes, but most often they were of the IgM class. Addition of unlabeled control antigen to the conjugates was not always sufficient to abort this nonspecific reaction.

Complement-mediated cytolytic activity associated with cytomegalovirus complement-fixing IgM antibody

Cytomegalovirus-specific complement-fixing IgM (CMV CF-IgM) antibody was detected in 12/84 (14.3 percent) sera containing CMV-specific IgM. Higher titres were obtained by using a purified antigen preparation containing enveloped virus particles and membrane fragments when compared with a crude extract of infected cells, suggesting that the CF component of CMV IgM reacts predominantly with antigens on the surface of the infected cells. This also accounts for its complement-mediated cytolytic activity. Neither CMV-specific non-complement-fixing IgM nor CMV-specific IgG demonstrates cytolytic activity.

An enzyme labelled nuclear antigen immunoassay for detection of cytomegalovirus IgM antibodies in human serum: specific and non-specific reactions

A mu-capture enzyme linked immunosorbent assay was developed for detection of IgM antibody to cytomegalovirus (CMV). Virus-specific IgM was detected using horseradish peroxidase labelled nuclear CMV antigen (CMV-ELA). False-positive reactions caused by Paul-Bunnell-Davidsohn (PBD) positive sera and antinuclear antibody (ANA) positive sera were identified in a combination assay employing enzyme labelled nuclear control antigen (CO-ELA) in parallel to the CMV-ELA. Four of five PBD positive and 30 of 31 ANA positive sera reactive with the CMV-ELA were identified as false positive reactions in the combined ELA-assay. The reactivity in PBD-positive sera could not be explained by antigenic cross reactivity between CMV and Epstein-Barr virus, and the results further suggested that different cell specified components of the CMV-ELA were responsible for the reactivity of PBD-positive as compared to ANA-positive sera. One of 314 healthy blood donors, 12 of 12 patients with primary CMV infection, and 11 of 15 patients with secondary CMV infection had detectable CMV IgM antibodies. Comparison of different CMV-ELAs revealed that pronounced differences in specificity as well as sensitivity may exist.

Antibody isotype response after human cytomegalovirus infection

The antibody isotype response to human cytomegalovirus (CMV) was studied in paired sera from patients with primary and recurrent CMV infection. The majority of sera was obtained from immunocompromised patients. In the 48 patients with primary CMV infection, CMV-specific IgM (CMV-IgM) and IgG (CMV-IgG) antibodies were found in all patients, and CMV-specific IgA (CMV-IgA) and IgE (CMV-IgE) antibodies in 46 patients. CMV-IgM, -IgA, and -IgE antibodies were found in, respectively, 21, 31 and 4 of the 53 patients with recurrent CMV infection, and in, respectively, 3, 3 and 1 of the healthy controls. The results indicate that CMV-IgE is a better marker of primary CMV infection than CMV-IgM, and confirm that detection of CMV-IgM and -IgA may also be useful for diagnosis of recurrent CMV infection.

Viral hepatitis markers in patients on haemodialysis in a hyperendemic area

Antibody profiles for cytomegalovirus (CMV), hepatitis A virus (HAV), hepatitis B virus (HBV) and the delta-agent were determined on 55 serum samples drawn from 55 Saudi patients on maintenance haemodialysis for periods ranging from 1.5 months to 2 years. The exposure rates for CMV, HAV, and HBV were 100%, 100%, and 72.7%, respectively. There was no intersex difference in positivity for HBV surface antigen (HBsAg), antibody to HBsAg (anti-HBs), antibody to HBV core antigen (anti-HBc); 15.4%, 65.4%, 3.8% in males and 6.9%, 55.2%, and 0% in females, respectively. Among six HBsAg carriers, one and three were positive for e antigen (HBeAg) and antibody to HBeAg (anti-HBe), respectively, with two negative for HBeAg and anti-HBe. The six carriers were also negative for anti-delta antibody. A comparison of the above antibody profile to the profile of voluntary blood donors and those seeking treatment for minor ailments in the local general hospital, obtained earlier using identical test procedures, revealed no difference for CMV and HAV exposure rate. The HBV exposure rate was higher in the haemodialysed patients (P less than 0.001). The epidemiological measures for preventing nosocomial viral hepatitis including immunisation of susceptibles, can be supplemented, among carriers, by interferon and acyclovir therapy for active viral replication. In HBV hyperendemic areas, haemodialysis patients exposed to HBV should be screened periodically for early signs of hepatocellular carcinoma.

Elimination of nonspecific cytomegalovirus immunoglobulin M activities in the enzyme-linked immunosorbent assay by using anti-human immunoglobulin G

Direct enzyme-linked immunosorbent assay methods offer several advantages in assessing past or recent exposure to cytomegalovirus (CMV) infection, but there persist many pitfalls in the use of these methods for determining specific immunoglobulin M (IgM). The efficiency of absorption of sera by IgG-coated latex beads, aggregated human IgG, or Staphylococcus aureus, i.e., for removing nonspecific CMV IgM activities, was evaluated in comparison with the effect of an anti-human IgG hyperimmune serum. Large routine series comprising serum samples from patients of various clinical groups and healthy individuals were examined. The CMV IgM-positive samples were at first treated with latex or aggregated IgG, but these absorptions left too many CMV IgM-positive individuals. S. aureus increased the nonspecific activity of some sera and, in other cases, removed or impaired specific IgM activities. The anti-IgG treatment caused the disappearance of nonspecific CMV IgM activities that had resisted the other treatments, whereas specific activities remained intact. Utilizing this method, only 1.03% of the routine series patients remained CMV IgM positive by the enzyme-linked immunosorbent assay, a figure in good agreement with a mean probability of CMV antibody acquisition of 0.33% for the population living in Belgium. On the other hand, in a series of patients who were investigated for serological response to several viruses, eight individuals displayed multiple IgM activities after anti-IgG treatment. In these cases, most IgM activities were found in patients who had IgG toward the related antigen for a long time before transient IgM was detected. This result implies that to assess a diagnosis of primary infection, it is necessary to examine serial specimens for IgG acquisition accompanying specific IgM.

Detection of Ross River virus immunoglobulin M antibodies by enzyme-linked immunosorbent assay using antibody class capture and comparison with other methods

An enzyme-linked immunosorbent assay based on antibody class capture was developed for the detection of Ross River virus-specific immunoglobulin M antibodies (RRV IgM). The assay was specific, reproducible and precise. When compared with conventional tests for the detection of RRV IgM, such as hemagglutination inhibition following sucrose density gradient centrifugation and indirect enzyme-linked immunosorbent assay, the class capture assay was more sensitive. In 186 sera which were collected from 39 patients with RRV infection over a period of 1-4 yr from onset of initial symptoms, RRV IgM persisted for at least 1-2 yr. Sera were tested both at a single dilution from which the results were expressed as a binding index and in a dilution series in which they were expressed as an antibody titre. Binding index values gave better discrimination between sera collected during acute and later phases of the disease and may be of greater value than antibody titres in the diagnosis of RRV infection.

Determination of specific cytomegalovirus IgM antibodies using infected air dried cells and isolated nuclei by immunoperoxidase assay

A simple immunoperoxidase assay (IPA), adapted for detection of serum IgM antibodies to cytomegalovirus (CMV) is described. The antigen consisted of CMV infected human embryonic fibroblasts or isolated nuclei. The sera were absorbed with aggregated gamma-globulins prior to testing. Rabbit anti-human IgM peroxidase conjugate was used to detect IgM bound to viral antigen. In parallel the enzyme linked immunosorbent assay (ELISA) technique was used to determine IgG and IgM antibodies to CMV, respectively. All patients with acute CMV infections who were tested had CMV-specific IgM antibodies by IPA, both whole cell and nuclei antigen. The maximal IgM titers were higher by ELISA than by IPA but in 3 of the CMV patients IgM was detected earlier by IPA (with both types of antigens) than by ELISA. In 3 of 5 transplant patients with recurrent CMV infection IgM was demonstrated by immunoperoxidase techniques, while by ELISA IgM was demonstrated in only 2 of them. No cross reactivity with other herpes viruses was observed. The described IPA is simple, rapid and has the potential for widespread use in routine laboratories.

Homosexual men in London: lymphadenopathy, immune status, and Epstein-Barr virus infection

By November 7, 1983, 24 cases of AIDS in the United Kingdom had been reported to the Communicable Disease Surveillance Centre. At the same time an increasing number of homosexual men with unexplained lymphadenopathy syndrome (LAS) have been seen in our department. Between December 1982 and July 1983, 14 homosexual men with LAS and 11 healthy homosexual men were studied. Patients with LAS had a high number of lifetime episodes of sexually transmitted diseases, a history of recent sexual activity in the United States (9 of 14), sexual contact with British AIDS patients or other persons with LAS (7 of 14), and hypergammaglobulinemia. Low T-helper/T-suppressor ratios (less than 0.8), due mainly to a decrease in T-helper cells, were found in both groups. Lymph node biopsies showed follicular hyperplasia and hypocellular pattern. All 25 patients studied had antibodies to Epstein-Barr virus capsid antigen (anti-VCA) and 11 had antibodies to early antigen (anti-EA); 13 of 17 were excreting the virus; and two showed no Epstein-Barr-virus-specific regression. Peripheral blood immunoglobulin-producing B-cells from six patients with hypergammaglobulinemia were negative for the Epstein-Barr virus nuclear antigen (EBNA). Five lymph node biopsies showed no EBNA-positive cells. Epstein-Barr virus reactivation is common in the patients with LAS and healthy homosexual men in London, but would not seem to be the cause of the polyclonal B-cell activation or lymphadenopathy.

Detection of immunoglobulin M and G antibodies against cytomegalovirus early and late antigens by enzyme-linked immunosorbent assay

A sensitive and reproducible enzyme-linked immunosorbent assay (ELISA) is described for the detection of immunoglobulin M and antibodies with specifity for human cytomegalovirus (CMV) early (CMV-EA) and late (CMV-LA) antigens. The emphasis is on the production of high-quality CMV antigens, CMV-EA and CMV-LA separately, and conditions for their application in the ELISA. The induction of CMV-EA and -LA in infected cell extracts was studied in detail by using human sera with defined antibody specificity for CMV-EA and CMV-LA. This resulted in the development of a simple whole cell extraction procedure that provided a high yield of CMV antigens with reproducible antigen quality. The antigens were specific for the detection of anti-CMV antibodies. The influence of autoantibodies on the determination of CMV-specific antibodies was investigated. Parallel analysis of 322 human sera by indirect immunofluorescence and ELISA showed a high correlation between both assays (r = 0.9674 for CMV-EA and 0.9362 for CMV-LA). Antibody titers determined by ELISA were equal to (for CMV-EA) or slightly higher (for CMV-LA) that those determined by immunofluorescence but significantly higher (20- to 5,120-fold) than those determined by complement fixation. From 191 sera positive by ELISA (titer greater than or equal to 40) 4 (2.1%) were negative by immunofluorescence (titer less than 40), and from 61 ELISA-positive sera 12 (19.6%) were negative (titer less than 8) when tested by complement fixation. Consequently, ELISA for CMV may prove to be more reliable for the selection of CMV-seronegative blood donors than these other methods. The use of high-quality antigens allows more economic handling of large-scale serum determinations. Possibilities for further automation are discussed.

Detection of IgM antibodies against cytomegalovirus: comparison of two radioimmunoassays, enzyme-linked immunosorbent assay and immunofluorescent antibody test

The sensitivity and specificity of direct antibody radioimmunoassay (RIA), M-antibody capture RIA (MACRIA), enzyme-linked immunosorbent assay (ELISA), and the immunofluorescent antibody (IFA) test for the detection of CMV-specific IgM was compared using 40 sera selected from different groups of patients. RIA, MACRIA, and ELISA gave concordant results with thirty-two sera but discordant results with eight sera, of which three were cord sera from congenitally infected babies, three were from immunocompromised patients with recurrent CMV infections, and two were from patients with lymphadenopathy and Paul-Bunnell-positive mononucleosis, respectively. RIA, MACRIA, and ELISA were of similar sensitivity with sera from adult patients, but ELISA was apparently less sensitive than RIA and MACRIA for the detection of CMV IgM in cord serum. By comparison IFA was significantly less sensitive than the other three tests. Rheumatoid factor is reactive in RIA, ELISA, and IFA but can efficiently be removed by absorption with latex-IgG beads or cross-linked human IgG.