Evaluation of a Cytomegalovirus Glycoprotein B Recombinant Enzyme Immunoassay To Discriminate between a Recent and a Past Infection

Abstract

Fetal damage following cytomegalovirus (CMV) intrauterine infection is mostly linked to primary infection.To differentiate primary infection from nonprimary infection, immunoglobulin M (IgM) tests are not reliable enough, and measurement of the IgG avidity appears to be the method that is the most widely used at present. In the present study the performance of the Vidas (bioMérieux) avidity assay was compared with that of a new enzyme immunoassay based on the use of a recombinant CMV glycoprotein B protein (Biotest).Human cytomegalovirus (CMV) is the most common cause of viral intrauterine infection. Symptomatic infection and fetal damage are mostly due to maternal primary infections. It is therefore important to differentiate primary from recurrent or persistent CMV infection in pregnant females. Serological diagnosis is easy in cases of seroconversion, but the discovery of immunoglobulin M (IgM) antibodies in the first serum sample obtained during pregnancy does not allow the diagnosis of a recent CMV primary infection. CMV-specific IgM antibodies can persist for months after primary infection (7) or reappear during recurrences (13). In some cases, specific IgM may also be due to a heterotypical immune response caused by an intercurrent infection (11,12). No "gold standard" assay and no reference test exist for the detection of primary CMV infection. Different approaches (microneutralization, Western blotting, or avidity assays) were developed to differentiate between recent and past CMV infection (2,4,5,8,9). Avidity assays for distinguishing CMV primary infection (with low-avidity IgG antibody) from CMV secondary infection (with high-avidity IgG antibody) are the most widely used techniques (2,6,10,14). More recently, an enzyme immunoassay (EIA) based on the determination of the IgG antibody response to the CMV glycoprotein B (gB) was developed for disitnguishing CMV primary or past infection (Biotest, Dreieich, Germany). Indeed, the anti-CMV gB response occurs 50 to 100 days after primary infection, so the absence of anti-gB IgG is suggestive of a recent infection.The aim of this study was to compare the performance of the commercially available Vidas IgG avidity assay (bioMérieux, Marcy l'Etoile, France) with an EIA based on the use of a recombinant CMV glycoprotein B (gB) protein (gB-EIA; Biotest). The combination of these two methods based on different approaches appears to be a simple system that can be used to improve serological diagnosis and to avoid unnecessary amniocentesis. MATERIALS AND METHODSCMV-specific IgG and IgM serology. All serum specimens were tested for CMV-specific IgG and IgM by microparticle EIAs (Axsym; Abbott Diagnostics, Wiesbaden-Delkenheim, Germany). For the IgM test, the procedure and the interpretation were as recommended by the manufacturer. The result was negative when the index value was Յ0.399, equivocal when the index value was Ͼ0.400 and Յ0.499, and positive when the index value was Ն0.500. For the IgG test we added a grey area to the manufacturer's recommendations. The ...

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

“…Many recombinant antigens have been produced and characterized for their ability to bind CMV specific antibodies (Vornhagen et al, 1994;Van Zanten et al, 1993;Sipewa et al, 2002). However, the exact composition of the antigenic mixture representative of the entire complex of CMV antigens to be used for detecting CMV antibodies is still a matter of study.…”

Improving diagnosis of primary cytomegalovirus infection in pregnant women using immunoblots

“…Two primary sera with low avidities (19% and 23%) according to conventional serology were classified as recent infection using Recomblot as these samples were IgG gB2 positive. Although gB2 is a late phase antigen, approximately 10% of sera from pregnant women with confirmed primary CMV as determined by seroconversion have antibody reactivity to gB2 [Sipewa et al, 2002]. Recent studies have also demonstrated gB2 can develop in human umbilical vein endothelial cells (HUVECs) as early as 10 days from the onset of infection [Gerna et al, 2008].…”

PCR detection of viral DNA in serum as an ancillary analysis for the diagnosis of acute mononucleosis-like syndrome due to human cytomegalovirus (HCMV) in immunocompetent patients

“…In addition, IgM antibodies, which appear to react specifically with HCMV may in fact be Epstein-Barr virus (EBV)-cross reactive antibodies . Demonstration of either HCMV-low avidity serum IgG (Grangeot-Keros et al, 1997) or the lack of HCMV gB (AD-1 epitope)-specific antibodies in serum specimens Sipewa et al, 2002) has been proposed as a means of differentiating between recent and past infections. Nevertheless, the diagnosis of symptomatic primary HCMV infections by serological methods often remains elusive.…”