Immunoradiometric assay for cytomegalovirus-specific IgG antibodies: assay development and evaluation in blood transfusion practice

HLA mismatching and cytomegalovirus infection as risk factors for transplant failure in cyclosporin-treated renal allograft recipients

In a study of the effects on renal allograft survival of HLA mismatching, mismatching for cytomegalovirus (CMV) antibody status, and post-transplant CMV infection, 148 cyclosporin-treated renal transplant recipients were given kidneys optimally matched for HLA-A, -B, and -DR antigens but not matched for CMV antibody status. Mismatching for HLA-B and -DR antigens was associated with a greater number of rejection episodes and a lower graft survival, but mismatching for CMV antibody status and posttransplant primary or recurrent CMV infection exerted no effect on graft survival. The role of matching of renal transplant recipients and donors for CMV antibody status in preference to HLA matching (proposed as a means of reducing the mortality associated with primary CMV infection) is discussed.

Detection of false seroconversions in cytomegalovirus seronegative platelet donors by serial complement fixation or IgG-specific radioimmunosorbent tests

A panel of 421 cytomegalovirus (CMV) seronegative-platelet donors was followed using complement-fixation (CFT) and IgG-specific radioimmunosorbent tests (RIST) to detect seroconversion. During 4623 person-months of observation 2452 serum specimens were tested, and the annual rate of seroreactivity detected by RIST was 56%. However, most of the positive RIST results were followed by negative results with later serum samples. CFT seroreactivity was a poor predictor of RIST seroreactivity. The high rate of transient seroreactivity detected by RIST may have reflected the lack of absolute specificity of the test. Alternatively, the results could illustrate the difficulty of determining whether an individual harbours latent CMV infection using antibody tests when some seronegative individuals appear to be latently infected. In the light of our observations recommendations for CMV antibody testing of blood donors are proposed.

Sensitive non-isotopic DNA hybridisation assay or immediate-early antigen detection for rapid identification of human cytomegalovirus in urine

A sensitive non-radioactive DNA hybridisation assay employing digoxigenin-labelled probes was compared with immediate-early antigen detection and conventional virus isolation for the identification of human cytomegalovirus (HCMV) in 249 urine samples. Of 44 specimens yielding HCMV by virus isolation, more were positive by DNA hybridisation (32; 73%) than by immediate-early antigen detection (25; 52%) (P = 0.05). The specificity of the hybridisation assay in 45 apparently falsely positive specimens was supported by detection of HCMV DNA in 40 of these specimens using the polymerase chain reaction. Many urine specimens may thus contain large amounts of non-viable virus or free viral DNA. Evaluation of various protocols for the extraction and denaturation of virus DNA prior to hybridisation showed that proteinase K digestion with phenol/chloroform extraction was the most sensitive and reliable procedure. We conclude that the non-radioactive DNA hybridisation assay described is a potentially valuable routine diagnostic test.

Screening of bone marrow and kidney transplant donors and recipients for cytomegalovirus antibody by commercial latex agglutination or competitive enzyme-linked immunosorbent assays

A commercial competitive enzyme-linked immunosorbent assay and a sensitive in-house radioimmunosorbent test detected cytomegalovirus (CMV) antibody in similar numbers of serum specimens (66 and 67 of 152, respectively) obtained from bone marrow and renal transplant donors and recipients. In contrast a commercial latex agglutination assay for CMV antibody apparently gave false positive results when testing serum specimens obtained from organ donors. The implications for CMV screening of organ transplant donors and recipients are discussed.

An immune dot-blot technique for the diagnosis of ocular adenovirus infection

The development of a monoclonal antibody based radio-immune dot-blot technique (IDBT) for the rapid detection of adenovirus is described. 718 conjunctival swabs from patients with acute keratoconjunctivitis were examined by conventional cell culture isolation techniques and IDBT. IDBT identified adenovirus in 64 of 75 culture positive samples and also in a further 34 culture negative samples [Sensitivity (IDBT versus culture) 85.3%; Specificity 92.2%]. IDBT is considered to be a simple, clinically relevant, technique for the rapid identification of adenovirus infection of the eye.

Diagnosis of cytomegalovirus infection in cyclosporin-treated renal allograft recipients

The relative merits of antibody response and virus shedding as markers of cytomegalovirus (CMV) infection among cyclosporin-treated renal allograft recipients were analysed. CMV-specific antibody was assayed by IgG-specific radioimmunosorbent test (RIST) and by complement fixation test (CFT). CMV shedding was assayed by virus isolation and by the rapid test immediate early nuclear antigen detection (IENAD). RIST and CFT detected seroconversion in similar numbers of patients, but the former test was the more sensitive when CMV antibody was sought in pretransplant sera to differentiate primary from recurrent infection. IENAD detected or excluded CMV shedding for more urine specimens than virus isolation (462/515 [90%] vs. 366/515 [71%]), but the reverse applied to saliva specimens (33/57 [58%] vs. 54/57 [95%]). The high specificity of IENAD allowed positive results by IENAD to be accepted when virus isolation failed to provide a result. IENAD was, however, less sensitive than virus isolation even when specimens yielding CMV by IENAD, but no result by virus isolation, were included in the analysis (27/44 [61%] vs. 38/44 [86%]). Assays of both antibody response and virus shedding were required to maximise the diagnosis of recurrent CMV infections, but the former assay detected all primary CMV infections. The diagnostic implications of these results are discussed.