Detection of cytomegalovirus in bronchial lavage and urine using a monoclonal antibody to an HCMV early nuclear protein

Human cytomegalovirus infection: diagnostic potential of recombinant antigens for cytomegalovirus antibody detection

Recombinant antigen-based enzyme immunoassays (EIAs) for the detection of human cytomegalovirus (HCMV) specific antibody are believed to yield a higher sensitivity and specificity than virus lysate EIAs. The aim of the present study was to evaluate the accuracy of newly established HCMV assays (Copalis CMV Multiplex, Sorin; Cobas Core CMV IgG and IgM EIAs, Roche Diagnostics; Anti-HCMV recombinant IgG, gB-IgG, IgM and IgA, Biotest; and ETI-CYTOK-G PLUS and M reverse PLUS, Sorin) based on recombinant antigens and/or virus lysate for laboratory diagnosis of HCMV infection. For the assessment of sensitivity, follow-up samples from patients suffering from active HCMV infection were tested. Testing a large number of potentially interfering samples challenged the specificity of the assays. There was no statistically significant difference in the performance of HCMV IgG assays. The results were more heterogeneous for the detection of serological markers of active infection (HCMV IgM, HCMV IgA and anti-CM2). The sensitivities of the different assays ranged between 40.5 and 71.4%. A variable number (17.8-1.7%) of false-positive results were obtained among potentially interfering serum samples. Two of the recombinant antigen based assays showed a high degree of interference with EBV VCA-IgM-positive sera. The best performance was achieved with ETI-CYTOK-M reverse PLUS since it combined the highest sensitivity with specificity. Commercially available assays based on recombinant antigens showed, overall, a poorer performance than the virus lysate EIA.

Bronchioloalveolar lavage in the diagnosis of CMV pneumonitis in lung transplant recipients: an immunocytochemical study

Cytomegalovirus (CMV) pneumonitis is a common opportunistic infection in lung transplant recipients. Its diagnosis usually rests on the identification of viral inclusions in lung parenchyma obtained by transbronchial biopsy, or by examination of the cytologic material obtained by bronchioloalveolar lavage (BAL). To determine whether the use of immunocytochemistry (ICC) increases the sensitivity of cytology in the diagnosis of CMV pneumonitis, we retrospectively selected 17 cases in which transbronchial biopsy and BAL were performed simultaneously, and had positive histology with negative cytology. Five negative controls were selected. The 22 slides were decolorized and restained with ICC for CMV. Of the 17 slides, nine (53%) showed cells with positive nuclear staining. All controls were negative. These results were then correlated with the number of infected cells present in the biopsy tissue, and the location of the cells (interstitial vs. intraalveolar). A good correlation was found between positive cytology and intraalveolar location of infected cells, and no correlation was seen between number of infected cells in the biopsy and the positive cytology. In summary, although histologic evaluation of lung parenchyma obtained by transbronchial biopsy is more sensitive for diagnosis of CMV pneumonitis, the sensitivity of the cytologic evaluation of BAL material can be increased by the use of ICC. The likelihood of positive ICC seems to be related to the presence of infected cells in the alveolar space rather than to the number of infected cells.

New PCR assay for rapid and quantitative detection of human cytomegalovirus in cerebrospinal fluid

Rapid Chelex extraction combined with an automated hybridization assay for the detection of PCR-amplified human cytomegalovirus DNA from cerebrospinal fluid was established. Quantitation of DNA was performed with a plasmid being used as an external standard. The detection limit was 10 copies per microliter. Quantitative detection of human cytomegalovirus DNA could be achieved over a range from 10 to 10(4) copies per microliter.

Serological diagnosis of cytomegalovirus infection: comparison of 8 enzyme immunoassays for the detection of HCMV-specific IgM antibody

BACKGROUND

Recently, numerous commercial ELISA kits for the detection of HCMV-specific IgM antibodies have been developed and are available on the international market.

OBJECTIVE

The aim of the present study was to compare eight different ELISAs for the early serological diagnosis of HCMV infection.

STUDY DESIGN

A panel of paired sera obtained from patients suffering from primary or secondary infection and potential cross-reactive serum samples positive for IgM antibodies against other herpesviruses, antinuclear antibody and rheumatoid factor were investigated with 5 indirect ELISAs (1-5) and 3 mu-capture assays (ELISAs 6-8).

RESULTS

The highest sensitivity for IgM detection was achieved by a mu-capture assay (ELISA 8) and a traditional indirect ELISA (4). Their respective sensitivities were 78.0 and 76.0%. Overall, mu-capture immunoassays (ELISAs 6-8) detected HCMV infection earlier than indirect ELISAs (1-5) and showed a higher sensitivity for antibody detection in dilution series of IgM positive serum samples. Whereas ELISAs 1, 2, 5 and 6 showed a specificity of 100%, the alternative assays were affected by a variable number of false positive results obtained by testing potential cross-reactive serum samples. Their specificities ranged from 72.0% (ELISA 8) to 96.0% (ELISA 3).

CONCLUSION

The results of the present study show that recent mu-capture and indirect ELISAs permit a relatively sensitive and reliable diagnosis of HCMV infection. Cross-reactive antigens and interference from antinuclear antibody may limit the specificity of commercial kits.

Low correlation of human cytomegalovirus DNA amplification by polymerase chain reaction with cytomegalovirus disease in organ transplant recipients

Seventy-five organ transplant recipients underwent prolonged virological and serological follow-up for early detection of human cytomegalovirus (HCMV) infection after transplantation. HCMV DNA detection by nested polymerase chain reaction (PCR) and HCMV early structural antigen (pp65) detection were carried out in 576 peripheral blood leucocyte (PBL) samples. Furthermore, 563 blood specimens were investigated by a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of specific immunoglobulins G, M, and A against HCMV structural antigens. In eight of nine symptomatic organ transplant recipients, HCMV DNA was detected in one or more consecutive blood samples. HCMV DNA PCR was also positive in one or more samples from eight patients who never developed HCMV-related symptoms. HCMV pp65 antigen was detected almost exclusively in PBL samples from organ transplant recipients suffering from HCMV disease. However, antigenaemia was not detected in four PCR positive patients presenting clinical signs attributable to HCMV infection. Two of the initially HCMV DNA positive samples were not confirmed by retesting and hybridisation. The results of the present study demonstrate that despite the high specificity of nested PCR, HCMV DNA may be detected in the absence of clinical symptoms attributable to HCMV infection. In asymptomatic reactivation, limited replication of viral DNA may be responsible for positive results of PCR without any clinical relevance. In this context, pp65-antigen detection from PBL seems to have a better prognostic value, but is not always detected when clinical symptoms are present.

Detection of human cytomegalovirus in urine samples by cell culture, early antigen assay and polymerase chain reaction

With the advent of effective therapy rapid, sensitive and reliable assays for diagnosis of human cytomegalovirus (HCMV) infections are required. In a total of 1,928 urine samples, detection of HCMV-immediate early antigen in a spin amplified microplate culture by a monoclonal antibody and immunoperoxidase staining (EA-assay) was compared with virus isolation in cell culture. Sensitivity of the EA assay was 85.5% and specificity was 99.5% compared with virus isolation. Overall agreement of both assays was 97.8%. In addition, in 235/1,928 urine samples amplification of HCMV-DNA was performed by means of polymerase chain reaction (PCR) using primers from the immediate early (IE1) gene region and 141/1,928 using primers from the late region (LA). The sensitivity of PCR compared with virus isolation was 67.8% for IE1 primers and 94.1% for LA primers (statistical significance: p < 0.01, Chi-square-test). Overall agreement between virus isolation and PCR was 88.5% for IE1-PCR and 84.4% for LA-PCR. Discordant results were more often found in adults with acute infection and immunocompromised patients than in infants.

Immunoglobulin A and M patterns to human cytomegalovirus during recurrent infection in patients with AIDS using a modified western blot

Immunoglobulin A and M patterns to human cytomegalovirus (HCMV) were investigated in sera from actively HCMV infected AIDS patients (n = 61) and healthy HCMV seropositive controls (n = 28) by a Western blot method (modi-blotting) and ELISA. The Western blot showed a higher detection rate for both IgA (78.7% vs. 52.5%) and IgM (83.6% vs. 13.1%) than ELISA in the immunocompromised patients suffering from active HCMV infection. Of the healthy seropositive individuals, 35.7% and 21.4% had a weak positive IgA- and IgM-class antibody reactivity respectively with HCMV-specific bands in the immunoblot. Immunoglobulins M and A were not detected by ELISA in the healthy control group. Immunoreactions in this group were restricted to viral polypeptides with M(r) of 68 kDa and 123 kDa. Additional bands were found in the actively infected patients only and were observed more frequently with IgA than IgM (47.5% vs. 29.5%). Results from the present study indicate, that using a sensitive Western blot technique, a higher serologic detection rate of active recurrent infection is achieved in AIDS patients. Nevertheless, immunoglobulin A and M are detected in a certain percentage of HCMV-seropositive healthy individuals not suffering from active HCMV infection. Broader immune reactions of HCMV-IgA as determined by HCMV Western blot assay are associated with an active infection, but were not present in all the actively infected patients.

Detection of neutralizing antibodies against human cytomegalovirus: influence of strain variation

The influence of human cytomegalovirus (HCMV) strain variation on neutralizing antibody titers was investigated in sequential sera obtained from 12 organ transplant recipients (11 renal transplant recipients, 1 liver transplant patient) suffering from primary or secondary HCMV infection. Cross-neutralization assays using either the international HCMV reference strain AD169 or individual clinical isolates from patients showed congruent results. Restriction enzyme analysis of the hypervariable alpha-sequence of the L-S junction of AD169 and HCMV isolates amplified by polymerase chain reaction (PCR) were carried out to confirm the expected strain differences. At least 6 groups of clinical strains were differentiated. The results of this study demonstrated that despite the strain heterogenicity of HCMV, the neutralization assay using AD169 permitted a reliable and quantitative serologic detection of neutralizing antibodies against HCMV.

Improvement of serological diagnosis of human cytomegalovirus infection in renal transplant recipients by testing for specific immunoglobulin E by ELISA

The kinetics of human cytomegalovirus (HCMV)-specific immunoglobulin E (IgE), M (IgM), A (IgA) and G (IgG) were studied in 421 sera obtained from 19 renal allograft recipients by enzyme-linked immunosorbent assay (ELISA). Cytomegalic inclusion disease (CID) occurred in 11 (57.9%) patients. HCMV infection was diagnosed in all (100%) of these patients by testing for specific IgE. In contrast, increased levels of IgM and IgA class antibody against HCMV were detected in only 45.5% and 18.2% patients suffering from primary or recurrent HCMV infection, respectively. Concerning the time interval between the onset of clinical symptoms and the first positive test, no significant differences in the kinetics of HCMV-specific immunoglobulins E, M, A and G were observed. Elevated specific IgE levels persisted for longer time intervals than the other immunoglobulin classes. As shown by the present study, specific IgE proved to be a more reliable serologic marker than IgM and IgA for the serologic detection of HCMV infection in renal allograft recipients.

A microneutralization enzyme immunoassay for antibody to human cytomegalovirus

We have developed a relatively rapid, sensitive and quantitative microneutralization assay for antibody to human cytomegalovirus (HCMV). Cell monolayers in 96-well microtiter plates inoculated with pre-incubated virus-antibody mixtures were fixed after 3 days. Infectious foci were stained with peroxidase-labeled human monoclonal antibody to a 64 kDa immediate early antigen of HCMV, and the plates were read at OD450. The 50% neutralization titer of the antibody was calculated. A study with 20 human sera and a human monoclonal antibody which neutralizes virus showed that this microneutralization enzyme immunoassay is more sensitive than, and as quantitative as, the conventional plaque reduction assay for antibody to HCMV. The neutralizing antibody titers of each sample measured by these two methods showed good correlation (n = 19, r = 0.884). Thus, this new assay is a useful and valid alternative to the conventional method for mass screening of sera and hybridoma fluids, and considerably more rapid.

Improvement of rotavirus isolation in the cell culture by immune peroxidase staining

Peroxidase-labeled monoclonal antibody against rotavirus group-specific antigen (inner capsid) was used for the detection of rotavirus by immunoperoxidase staining (IPS) in trypsin-free MA104 cells within 18 h post-inoculation with clinical specimens. One hundred and twenty-one fecal samples from children with acute gastroenteritis were evaluated by IPS, conventional virus isolation in cell culture and a commercially available group A-antigen ELISA (Rotazyme II, Abbott Laboratories). Fifty-eight (47.9%) stool samples were found positive by IPS. In contrast, rotavirus was isolated from only 4 (3.3%) fecal specimens by conventional cell culture (i.e. demonstration of a cytopathogenic effect). A total of 93 (76.9%) samples were positive by ELISA. IPS permits rapid detection of rotavirus infections and detects shedding of infectious virus. The method should be useful for the investigation of nosocomial spread of rotavirus infection in hospitals, contamination of environmental surfaces and desinfectants.

Comparison of shell viral culture and serology for the diagnosis of human cytomegalovirus infection in neonates and immunocompromised subjects

The present retrospective study compares the laboratory diagnosis of cytomegalic inclusion disease (CID) by the use of "shell vial culture" [i.e., immunoperoxidase staining of human cytomegalovirus (HCMV) early antigen in human fibroblasts 24 h postinoculation] to the results of serology (i.e. immunoglobulins IgG, IgM, and IgA HCMV antibody testing) in 21 infants with congenital or postnatally acquired HCMV infection, 5 patients with lymphoproliferative disorders, 35 human immunodeficiency virus (HIV)-seropositive patients who met the Centers for Disease Control (CDC) criteria for stages IVA and IVB of HIV infection, and 115 patients suffering from the acquired immunodeficiency syndrome, AIDS (stages IVC-IVE according to CDC criteria). HCMV infection was diagnosed by means of the shell vial culture inoculated with patient samples (e.g., urine, bronchoalveolar lavage, induced sputum, etc.) and serology in 163 (92.6%) and 65 (36.9%) patients, respectively. Viral shedding was detected by shell vial culture in 100% of the neonates, 80% of the patients suffering from lymphoproliferative disorders, 100% of the AIDS related complex (ARC) and 89.6% of the AIDS patients. In contrast, serologic testing for HCMV-specific antibodies was positive in only 28.6%, 42.9%, and 34.8% of the neonates, ARC, and AIDS patients, respectively. In lymphoma patients, serologic testing gave identical results (80%) to the shell vial culture technique. With the use of the shell vial procedure, active HCMV infection in immunocompromised subjects and neonates can be recognized more reliably than by serologic testing. Nevertheless, in a low percentage of patients (7.4%), virus isolation by the shell vial culture may fail to detect HCMV infection.

Laboratory diagnosis of congenital human cytomegalovirus infection using polymerase chain reaction and shell vial culture

Congenital HCMV infection was diagnosed at the 22th week of gestation. The infection was suspected because HCMV IgM was detected in a serum sample obtained from the woman's husband. HCMV infection was detected in the amniotic fluid by polymerase chain reaction, shell vial culture (immunoperoxidase assay) and conventional virus isolation. Serologic testing in paired sera of the woman and in umbilical cord blood for specific IgM and IgA remained negative. As serological data (preconceptional HCMV serostatus) were incomplete, a clear differentiation between primary and secondary infection could not be achieved; consequently, risk quantification could not be determined. Viruria was detected in the offspring during the 1st week post partum. No clinical signs of cytomegalic inclusion disease were diagnosed up to six weeks post partum. Our case report indicates that for pregnancy surveillance, serologic testing for HCMV antibody should also be performed in the spouse.