Development and evaluation of serological assays for detection of Hantaanvirus-specific antibodies in human sera using yeast-expressed nucleocapsid protein

Indirect and capture enzyme-linked immunosorbent assays (ELISAs) for detection of Hantaan virus (HTNV)-specific immunoglobulins G (IgG) and M (IgM) in human serum samples were developed on the basis of recombinant yeast-expressed nucleocapsid (N) protein of HTNV. The sensitivities and specificities of the indirect and capture ELISAs were evaluated by comparing the reactivity of sera from patients with hemorrhagic fever with renal syndrome (HFRS) from China with that of a commercial IgG/IgM kit. The sensitivity of the indirect IgG and IgM ELISA tests was both 100% and the specificity of the indirect IgM and IgG ELISA test was 98% and 99%, respectively. The sensitivity and specificity of the capture IgM ELISA was 100% and 97%, respectively. The novel assays were found to detect HTNV-specific antibodies in acute phase sera from suspected HFRS patients in China. The results indicate that these novel ELISAs are suitable for the diagnosis of HTNV and for sero-epidemiological studies.     

Development of an ELISA to detect Sin Nombre virus-specific IgM from deer mice (Peromyscus maniculatus)

Peromyscus maniculatus (deer mouse) is the primary reservoir for Sin Nombre virus (SNV). Although the presence of IgG antibodies is often used as a marker of infection, it provides little information on active infections in a population but usually is an indicator of past infections. The presence of IgM antibodies is a much better marker for determining whether active infections are present in a population. A mu-capture SNV-specific IgM enzyme linked immunosorbent assay (ELISA) was developed. From live-trap and release studies a total of 68 rodent sera were studied for the presence of Sin Nombre virus-specific IgG and IgM antibodies. In these studies, IgM responses were detected in a number of animals. In some cases early SNV infection was determined through the presence of anti-SNV IgM before IgG antibodies could be detected. From the set of animals analyzed, it was concluded that the IgM response against SNV can persist anywhere from 1 to up to over 2 months, with a median of less than 1 month. Most importantly, it was demonstrated that anti-Sin Nombre virus IgM is an important tool for detection of early infections in rodents and should be considered as a key diagnostic tool.     

Improved immunoglobulin M serodiagnosis in Lyme borreliosis by using a mu-capture enzyme-linked immunosorbent assay with biotinylated Borrelia burgdorferi flagella.

A mu-capture enzyme-linked immunosorbent assay (ELISA) for detection of serum immunoglobulin M (IgM) antibodies to Borrelia burgdorferi by using biotinylated purified B. burgdorferi flagella was developed. The diagnostic performance of the mu-capture ELISA was compared with that of a conventional indirect ELISA. Sera from untreated patients with erythema migrans (n = 50), neuroborreliosis (n = 100), and acrodermatitis chronica atrophicans (ACA; n = 48) were investigated. The cutoff of the ELISAs was adjusted to a diagnostic specificity of 98% on the basis of examination of 200 serum specimens from healthy controls. The mu-capture ELISA increased the diagnostic sensitivity in patients with erythema migrans from 32 to 48% (P less than 0.01) and in patients with neuroborreliosis from 37 to 57% (P less than 0.001). Because of an increased signal/noise ratio, the mu-capture ELISA yielded a significantly better quantitative discrimination of individual positive measurements from the cutoff (P less than 0.001). The increased signal/noise ratio was most likely a consequence of the elimination of IgG competition for the test antigen. This may also explain why 12% of patients with ACA showed significantly increased specific IgM levels only by the mu-capture ELISA. Of patients with ACA, 27% had IgM rheumatoid factor. The mu-capture principle with a directly labeled antigen showed no interference with IgM rheumatoid factor, in contrast to the indirect ELISA. The high diagnostic performance and ease of this three-step mu-capture ELISA make it suitable for routine anti-B. burgdorferi IgM serodiagnosis.     

Detection of human immunoglobulins G and M antibodies to Rift Valley fever virus by enzyme-linked immunosorbent assay.

Rift Valley fever virus (RVFV) is an important human and animal pathogen in Africa and has been responsible for infections in travelers. Because of the aerosol infectivity and risk of dissemination of the virus, a need exists for simple, safe, serological tests for diagnosis. An enzyme-linked immunosorbent assay (ELISA) was developed to detect RVFV-specific immunoglobulins (immunoglobulin G [IgG] and IgM). In the test, a betapropiolactone-inactivated, sucrose-acetone-extracted, suckling mouse liver RVFV antigen was captured by mouse RVFV antibodies adsorbed to polystyrene plates. The test sample (human serum) was then added, and the binding of specific antibodies was indicated by alkaline phosphatase-conjugated swine anti-human IgG or IgM. A mu-capture IgM ELISA was also developed by using polystyrene plates coated with goat anti-human IgM incubated successively with serum sample, RVFV antigen, and indicator antibodies. The ELISA for RVFV-specific IgG proved to be more sensitive than hemagglutination inhibition or complement fixation tests and almost as sensitive as the plaque reduction neutralization test in detecting specific antibodies in human sera after vaccination. The two ELISA IgM tests could detect specific IgM antibodies during the first 6 weeks after RVFV vaccination. Three injections of inactivated vaccine were given on days 0, 6 to 8, and 32 to 34. ELISA IgM values for sera obtained on days 6 to 8 were negative or in the lower range of significance, on days 32 to 34 they were strongly positive, and on days 42 to 52 they were waning. Later sera were negative. The plague reduction neutralization test was negative on days 6 to 8 but rose progressively in later samples. These findings suggest that the three doses of RVFV vaccine induce a prolonged primary antibody response. The ELISA IgM could become an important tool for early diagnosis in acute human infection. A number of African sera, some of which were positive for RVFV by plaque reduction neutralization test, were also tested by ELISA IgG. There was good agreement between both tests.     

Performance of immunoglobulin G (IgG) and IgM enzyme-linked immunosorbent assays using a West Nile virus recombinant antigen (preM/E) for detection of West Nile virus- and other flavivirus-specific antibodies

Focus Technologies developed an indirect immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) and a mu-capture IgM ELISA for the detection of West Nile virus (WNV)-specific antibodies based on a WNV preM/E protein recombinant antigen. Normal and disease state serum panels were used to assess the performance characteristics of the two WNV ELISA kits. Totals of 807 and 1,423 sera were used to assess the IgG ELISA and IgM ELISA kits, respectively. The Focus Technologies IgG ELISA had a sensitivity of 97.6% and a specificity of 92.1% (excluding non-WNV flavivirus sera). The comparative method for WNV IgG may lack sensitivity in detecting IgG in early WNV infection, so the specificity of the Focus IgG ELISA may be higher than 92.1%. When sera from patients either infected with or vaccinated against other flaviviruses were tested on the WNV IgG assay, 35% of the sera reacted as positive for WNV IgG. Yellow fever and Japanese encephalitis vaccinees were less reactive in the IgG ELISA than St. Louis and dengue fever patients. The Focus Technologies IgM ELISA had a sensitivity and a specificity of 99.3% (excluding the non-WNV flavivirus sera). The overall cross-reactivity for the IgM ELISA to flavivirus sera was 12%, with 31% of St. Louis encephalitis patients found to be WNV IgM positive and no yellow fever vaccinees found to be WNV IgM positive. In a selected population of 706 sera, 15 false-positive WNV IgM sera were identified. The use of a background subtraction method for the IgM ELISA eliminated all 15 false-positive results, giving a specificity of 100% for the Focus IgM ELISA.     

Development of novel immunoglobulin G (IgG), IgA, and IgM enzyme immunoassays based on recombinant Puumala and Dobrava hantavirus nucleocapsid proteins

Human infections with Asian and European hantaviruses can result in hemorrhagic fever with renal syndromes of differing severities characterized by renal dysfunction and sometimes by pulmonary symptoms. For the serological detection of human infections by hantaviruses relevant for Europe, we developed monoclonal antibody capture immunoglobulin G (IgG) and IgA enzyme-linked immunosorbent assays (ELISAs) based on yeast-expressed nucleocapsid proteins of Puumala and Dobrava hantaviruses. Moreover, for diagnosis of acute infections, mu-capture IgM ELISAs were established with nucleocapsid proteins expressed in Drosophila melanogaster Schneider S2 cells. The cutoff values of the ELISAs were determined by investigation of up to 500 human anti-hantavirus-negative serum samples. The specificities of the Puumala and Dobrava virus-specific IgM, IgA, and IgG ELISAs were found to be 100%. The sensitivities of these ELISAs were determined to be 100% with panels of characterized anti-Puumala or anti-Dobrava virus-positive human serum samples. In most cases, Puumala and Dobrava virus infections could be differentiated by ELISA reactivity alone, i.e., endpoint titration with homologous and heterologous antigens.     

Diagnostic potential of puumala virus nucleocapsid protein expressed in Drosophila melanogaster cells

Puumala virus (PUU) nucleocapsid protein (N) was expressed in insect cells by using the Drosophila Expression System (DES; Invitrogen BV, Groningen, The Netherlands). Stable transfectants were established by hygromycin B selection and showed continuous expression of the recombinant protein (DES-PUU-N) for at least 5 months. The antigenic property of DES-PUU-N was shown to be identical to that of native PUU N when examined with a panel of hantavirus-specific monoclonal antibodies. Enzyme-linked immunosorbent assays (ELISAs) for detection of human immunoglobulin M (IgM) and IgG antibodies were established by using DES-PUU-N as antigen and were compared to assays based on native N. The ELISAs were evaluated for patient diagnosis and seroepidemiological purposes with panels of sera collected from patients with hemorrhagic fever with renal syndrome (HFRS) and from healthy blood donors. Equally high sensitivities and specificities for detection of PUU-specific IgM in acute-phase HFRS patient sera were obtained by the ELISA based on DES-PUU-N and the assay based on the native antigen. For detection of PUU-specific IgG, the ELISA based on monoclonal antibody-captured DES-PUU-N antigen showed optimal sensitivity and specificity.     

Enzyme-linked immunosorbent assay for mumps IgM antibody: comparison of IgM capture and indirect IgM assay

We have established two enzyme-linked immunosorbent assays (ELISAs) for detection of mumps IgM antibody, i.e., indirect IgM ELISA and IgM capture ELISA, for serodiagnosis of recent mumps infection. In the latter method, peroxidase-conjugated monoclonal antibody to mumps virus was employed. Both methods detected mumps antibody of IgM class only in serum fractions separated by centrifugation through a sucrose density gradient. Optical density values given by both ELISAs were correlated for most sera examined. Indirect IgM ELISA, however, gave a false positive reaction for sera containing both rheumatoid factor and mumps IgG antibody, while giving a false negative reaction for sera containing high titers of mumps IgG antibody. This technique was, therefore, less reliable than IgM capture ELISA. IgM antibody detectable by IgM capture ELISA was present in all patients with mumps by the fifth day of illness and persisted for up to 3 mth in most and up to 5 mth in same cases.     

Comparative analysis of antibodies to Francisella tularensis antigens during the acute phase of tularemia and eight years later.

Approximately 8 years after treatment for tularemia, 14 of 22 (63.6%) individuals tested still had a positive microagglutination test for Francisella tularensis antibodies. An enzyme-linked immunosorbent assay for anti-F. tularensis outer membrane antibodies was positive for 55% (immunoglobulin A [IgA]), 95% (IgG), and 27% (IgM) of the late-phase sera, but with antibody levels significantly reduced from those in the acute-phase sera. IgG and IgA antibody levels in the late-phase sera showed significant correlation with levels in the acute-phase sera. The IgG/IgM ratio calculation discriminated between acute-phase and persistent antibodies for most sera, but Western blot (immunoblot) patterns did not. Immunoblotting indicated that the F. tularensis lipopolysaccharide is a major target for antibodies in both groups of sera. Our results substantiate the need for caution in the interpretation of positive serological test results for tularemia, which could result from disease occurring years earlier.     

Differential sensitivities of severe acute respiratory syndrome (SARS) coronavirus spike polypeptide enzyme-linked immunosorbent assay (ELISA) and SARS coronavirus nucleocapsid protein ELISA for serodiagnosis of SARS coronavirus pneumonia

The use of recombinant severe acute respiratory syndrome-coronavirus (SARS-CoV) nucleocapsid protein (N) enzyme-linked immunosorbent assay (ELISA)-based antibody and antigen tests for diagnosis of SARS-CoV infections have been widely reported. However, no recombinant SARS-CoV spike protein (S)-based ELISA is currently available. In this article, we describe the problems and solutions of setting up the recombinant SARS-CoV S-based ELISA for antibody detection. The SARS-CoV S-based immunoglobulin M (IgM) and IgG ELISAs were evaluated and compared with the corresponding N-based ELISA for serodiagnosis of SARS-CoV pneumonia, using sera from 148 healthy blood donors who donated blood 3 years ago as controls and 95 SARS-CoV pneumonia patients in Hong Kong. Results obtained by the recombinant S (rS)-based IgG ELISA using the regenerated S prepared by dialysis with decreasing concentrations of urea or direct addition of different coating buffers, followed by addition of different regeneration buffer, identified 4 M urea and 1 M sarcosine for plate coating and no regeneration buffer as the most optimal conditions for antibody detection. The specificities of the S-based ELISA for IgG and IgM detection were 98.6% and 93.9%, with corresponding sensitivities of 58.9% and 74.7%, respectively. The sensitivity of the rN IgG ELISA (94.7%) is significantly higher than that of the rS IgG ELISA (P < 0.001), whereas the sensitivity of the rS IgM ELISA is significantly higher than that of the rN IgM ELISA (55.2%) (P < 0.01). An ELISA for detection of IgM against S and N could be more sensitive than one that detects IgM against N alone for serodiagnosis of SARS-CoV pneumonia.     

Detection of nephropathia epidemica (Puumala virus)-specific immunoglobulin M by enzyme-linked immunosorbent assay.

Nephropathia epidemica (NE), a less severe form of hemorrhagic fever with renal syndrome, is caused by Puumala virus (PUU). This communication reports the development of a mu-capture enzyme-linked immunosorbent assay (ELISA) for detection of specific immunoglobulin M (IgM) antibodies to PUU virus in human sera. Acute- and early-convalescent-phase sera (collected 1 to 41 days after disease onset) from 29 Swedish patients with clinical NE were tested for PUU virus-specific IgG and IgM antibodies by the indirect immunofluorescence test and ELISA, respectively. Late-convalescent-phase serum was also collected from 18 of these patients 3 to 24 months postinfection and assayed. The IgM ELISA values were strongly positive in sera collected during the first 2 months; at 3 to 9 months, they were negative or in the lower range of significance, and at 24 months all sera were negative. Paired sera from NE patients often fail to show seroconversion or a significant titer rise when tested by indirect immunofluorescence. Since all acute- and early-convalescent-phase sera were positive by IgM ELISA, this test could become an important tool for early diagnosis of acute human NE infections.     

Serodiagnosis of Epstein-Barr Virus Infection by Using Recombinant Viral Capsid Antigen Fragments and Autologous Gene Fusion

Using recombinant 15- to 30-kDa fragments and fusion with glutathione S-transferase (GST), we investigated the seroreactivity of three large structural proteins of Epstein-Barr virus (EBV), p150 (BcLF1, capsid), p143 (BNRF1, tegument), and gp125 (BALF4, membrane) in Western blots. None of 13 fragments tested, however, was qualified for diagnostic application. In contrast, the two small viral capsid antigens (VCA), p18 (BFRF3) and p23 (BLRF2), demonstrated sensitive (100%) EBV-specific immunoglobulin G (IgG) reactivities. While p18 additionally showed maximum sensitivity for IgM detection, the IgM sensitivity of p23 was restricted (44%). An autologous fusion protein, p23-p18, which consists N-terminally of full-length p23, followed by the carboxy half of p18, was constructed. This antigen was subjected to indirect VCA enzyme-linked immunosorbent assays (ELISAs), for IgG and IgM, as well as to a micro-capture (microc) IgM ELISA. All assays were found to be 100% specific when EBV-negative sera were tested. Using sera from previously infected individuals, the p23-p18 fusion revealed an improved IgG sensitivity of 99% compared to sensitivities of 97 and 93% for the single antigens p18 and p23, respectively. The sensitivity and specificity of the indirect IgM ELISA with samples of primary and past infections, respectively, were 100%. The microc principle for IgM overcame completely the interference by rheumatoid factors. Compared to the specificity of the indirect IgM version, the specificity with sera collected from rheumatoid arthritis patients increased from 48 to 100%. In summary, the p23-p18 IgG and microc IgM ELISAs showed excellent performances and are promising new diagnostic tests for the detection of EBV-specific antiviral capsid antibodies.     

抗人μ链单克隆抗体的制备、鉴定及初步应用

目的:制备高效价的鼠源性抗人μ链单克隆抗体(mAb),并建立可用于感染性疾病早期血清学诊断的ELISA捕捉法。方法:以人IgM全分子免疫BALB/c小鼠,按常规方法进行细胞融合,用间接ELISA法筛选及克隆化,建立可稳定分泌抗μ链mAb的杂交瘤细胞株。mAb的特性(效价、Ig亚类、特异性及相对亲和力)采用ELISA及Westernblot法鉴定。以纯化的mAb包被建立ELISA捕捉法,并用于可疑乙脑患者标本中特异性IgM抗体的检测。结果:筛选到1株可稳定分泌抗人μ链mAb的细胞株2E5。mAb腹水的ELISA效价为1×10-6,Ig亚类(型)为IgG1(κ),相对亲和力为1×10-5。Westernblot结果显示mAb2E5仅与IgM的μ链结合,Mr为75000。以辛酸硫酸铵法纯化的mAb2E5包被,建立了ELISA捕捉法,用于30份乙脑患者血清IgM的检测,敏感性及特异性良好。结论:成功地制备1株抗人μ链mAb2E5,建立了可用于感染性疾病早期血清学诊断的ELISA捕捉法。     

Enzyme-linked immunosorbent assay for IgG and IgM antibodies against human parvovirus B19: use of monoclonal antibodies and viral antigen propagated in vitro

Enzyme-linked immunosorbent assay (ELISA) systems for serum IgG and IgM antibodies to human parvovirus B19 were established by utilizing anti-B19 monoclonal antibodies (mAbs) and human plasma B19 antigen. The specificities of IgG and IgM ELISA were confirmed by indirect immunofluorescence staining and Western blot immunoassay with panel sera. The series of serum specimens obtained from two B19-infected patients were examined with ELISA. The IgM antibody titers increased quickly after the onset of the symptoms and returned to a negative range after five months. The IgG antibody titers also increased just after the increasing of IgM titers and the elevated levels continued for more than a year. We also established the same ELISA systems by utilizing in vitro propagated B19 antigen and similar results were obtained.     

Combination of native and recombinant cytomegalovirus antigens in a new ELISA for detection of CMV-specific antibodies

BACKGROUND: Serological detection of cytomegalovirus (CMV)-specific antibodies varies greatly due to antigen composition and the lack of antigen standardization. OBJECTIVES: To develop and evaluate a new ELISA with native and/or recombinant cytomegalovirus antigens for the detection of anti-CMV IgG and IgM antibodies. RESULTS: The diagnostic performance of three anti-CMV ELISAs coated with different CMV antigen preparations, (i) native CMV antigen, (ii) a mixture of recombinant CMV peptides pp150, pp28, gB2 and pp52 and (iii) a combination of native CMV antigens and recombinant CMV IE1 antigen applied in the new Genzyme Virotech CMV ELISA, were compared. All tested sera were derived from patients or healthy blood donors and were predefined with the Dade Behring Enzygnost((R)) CMV ELISA as well as by CMV PCR analysis. Additionally, official well-characterized serum panels were also tested. The new Genzyme Virotech CMV ELISA IgG/IgM test applying a combination of native antigens and recombinant IE1 antigen was evaluated and the performance was compared to the Dade Behring Enzygnost((R)) CMV ELISA. The sensitivities were 98.9% (IgG) and 98.2% (IgM), the specificities were 98.8% (IgG) and 98.9% (IgM) for the Genzyme Virotech CMV ELISA. Furthermore all sera of the BBI mixed titer performance panel as well as the BBI seroconversion panel were identified 100% correctly with the new Genzyme Virotech ELISA. CONCLUSIONS: These data suggest that the new Genzyme Virotech CMV ELISA has higher sensitivity and specificity than ELISAs based on native antigens or recombinant peptides only. Specific combinations of native and recombinant antigens increase the serological detection of CMV infections and may add to further standardization of CMV serology.     

Comparison of Western blot and enzyme-linked immunosorbent assay for diagnosis of Lyme borreliosis

The usefulness of Western blot in the serological diagnosis of Lyme borreliosis was evaluated compared with an ELISA using a whole cell sonicate antigen. Fifty-three of 68 (78 %) patients with neuroborreliosis had positive IgM and/or IgG immunoblots and 40 of 68 (59 %) had positive IgM and/or IgG ELISA titers in serum. Eight of 44 (18 %) controls with meningitis/encephalitis of non-borrelia etiology had positive IgM and/or IgG immunoblots and 4 of 44 (9 %) had positive IgM and/or IgG ELISA titers in serum. Western blot was more sensitive than ELISA, the difference being most pronounced in sera from patients with neurological disease for four weeks or less. Both patients and controls lived in an area endemic for Lyme borreliosis and some ELISA negative but Western blot positive controls were thought to have been previously exposed toBorrelia burgdorferi. However, the specificity for current disease was not improved by Western blot. In conclusion, Western blot does not seem to be the method of choice for screening purposes in a routine laboratory but can be used as a complement to ELISA for serodiagnosis in patients with disease of short duration.     

Recombinant Protein-44-Based Class-Specific Enzyme-Linked Immunosorbent Assays for Serologic Diagnosis of Human Granulocytic Ehrlichiosis

Recombinant protein 44, expressed and purified as a maltose-binding protein fusion peptide of the human granulocytic ehrlichiosis (HGE) agent (Ehrlichia phagocytophila genogroup), was used as antigen in enzyme-linked immunosorbent assays (ELISAs) to detect total antibodies, immunoglobulin (Ig) M antibodies, and IgG antibodies. Of the 67 human sera obtained from 64 HGE patients 3-5 weeks after the onset of illness and confirmed as having total immunoglobulins to whole-cell antigen by indirect fluorescent antibody analyses, 63 were positive in a polyvalent ELISA. Fifty-six and 61 sera had IgM or IgG antibodies, respectively. Fifty sera had both IgM and IgG antibodies. In specificity tests of 110 sera, one serum sample from a patient who had Lyme borreliosis reacted to the protein 44 antigen in the analysis for IgM antibody (specificity, 99%). There were no false-positive results in an ELISA for IgG antibodies. With their high sensitivity and specificity, class-specific ELISAs can be used in conjunction with indirect fluorescent antibody analyses or immunoblotting methods to help diagnose human granulocytic ehrlichiosis.     

Comparison of six commercial enzyme linked immunosorbent assays for detecting IgM antibodies against Toxoplasma gondii.

To evaluate the usefulness of different commercial enzyme linked immunosorbent assays (ELISAs) for the detection of IgM antibodies against Toxoplasma gondii the results of six of these assays for a panel of 81 sera were compared. The following tests were selected: Toxoplasma gondii IgM ELISA (Clark Laboratories), Toxoplasma IgM EIA (Labsystems), Toxo-M EIA (Abbott), Toxonostika M (Organon), Toxo M Enzyme Immunoassay (Hybritech) and Platelia Toxo IgM (Diagnostics Pasteur). An antibody capture ELISA developed at our laboratory was used as the reference test. An IgM immunoblotting assay was also performed. Four (Toxoplasma IgM EIA, Tox-M EIA, Toxonostika M, and Platelia Toxo IgM) of the commercial IgM ELISAs gave a high sensitivity and a high specificity. Toxo-M EIA, Toxonostika M, Toxoplasma IgM EIA and the Toxo M Enzyme Immunoassay were too insensitive, and the Toxoplasma gondii IgM ELISA was both insensitive and unspecific. No remarkable differences were observed between the results of indirect or antibody capture ELISAs, and between the results of ELISAs performed with polyclonal or monoclonal antibodies.     

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.     

Screening of blood donors for human cytomegalovirus (HCMV) IgG antibody with an enzyme immunoassay using recombinant antigens.

BACKGROUND: Screening of blood donors for human cytomegalovirus (HCMV) infection is usually performed by the combined detection of specific IgG and IgM antibody. However, in most of the cases of primary infection HCMV IgG seroconversion is observed concomitantly to IgM production and HCMV IgM antibody detection for blood donor screening is subject to a relatively high frequency of false positive results. OBJECTIVE: In the present study a newly established HCMV IgG ELISA based on recombinant antigens (anti-HCMV recombinant IgG ELISA, Biotest) was evaluated in terms of sensitivity and specificity for blood donor screening. STUDY DESIGN: A total of 442 serum samples including follow-up sera of five patients suffering from primary HCMV infection, selected seropositive and seronegative blood donors and routine specimens were comparatively investigated with three HCMV antibody ELISAs (anti-HCMV recombinant IgG ELISA, Biotest; Enzygnost anti-CMV/IgG + IgM, Dade Behring; and Captia CMV-TA, Centocor). RESULTS: IgG seroconversion was detected with anti-HCMV recombinant IgG ELISA as early as IgM in all five patients suffering from primary infection. The alternative ELISAs were less sensitive, detecting seroconversion one to three bleeds later in 2 (Enzygnost anti-CMV/IgG + IgM) and 4 patients (Captia CMV-TA), respectively. Anti-HCMV recombinant IgG ELISA showed a 99.1% agreement with Enzygnost anti-CMV/IgG + IgM and/or Western blot in the preselected blood donors and routine specimens. Relatively high numbers of false negative (n=20) and positive results (n=7) were obtained with Captia CMV-TA. CONCLUSIONS: Our preliminary data suggest that HCMV antibody screening of blood donors can be performed reliably by detection of specific IgG provided that a highly sensitive assay system is used.