Immunoglobulin G - Journal of Clinical Microbiology - American ...

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Marburg, Germany) and the IMx microparticle-based EIA. (MEIA; Abbott Laboratories, Abbott Park, Ill.) for the detec- tion of RV IgG antibodies in 484serum ...
JOURNAL OF CLINICAL MICROBIOLOGY, Apr. 1994, p. 1085-1087 0095-1 137/94/$04.00+0 Copyright © 1994, American Society for Microbiology

Vol. 32, No. 4

Comparison of Novel Synthetic Peptide-Based DETECT-RUBELLA Enzyme Immunoassays with Enzygnost and IMx for Detection of Rubella-Specific Immunoglobulin G LOUISE PEDNEAULT,I2* MAAN ZREIN,3 LOUISE ROBILLARD,- FRANCE LANDRY,2 MARTIAL LACROIX,3 AND JEAN JONCAS' 2 Department of Microbiology and Immunology, Universite de Montreal, Montreal, Quebec H3C 3J7,1 Department of Microbiology and Infectious Diseases, H6pital Sainte-Jiustine, Montreal, QiuMbec H3T ]C5,2 and BioChem ImmunoSystems, Montreal, QuMtbec H3M 3A2, Canada Received 30 July 1993/Returned for modification 28 October 1993/Accepted 12 January 1994

Enzyme immunoassays (ELAs) using synthetic peptides SP-E1 and SP-E1E2 (DETECT-RUBELLA [BioChem]) were compared with two viral lysate-based ELAs (Enzygnost [Behring] and IMx [Abbott]) for the detection of rubella virus-specific immunoglobulin G antibodies. Sensitivities of 94.7, 100, 98.6, and 100% and specificities of 100, 97.4, 100, and 73.7% were found for the SP-E1, SP-E1E2, Enzygnost, and IMx EIAs, respectively.

Because hemagglutination inhibition (HI) and neutralization tests were previously shown to correlate better with the development of protective immunity, they were originally performed to document rubella immunity and HI testing became the "gold standard" against which other rubella serological tests were measured. However, as the HI assay was time consuming and difficult to perform and to standardize, screening for rubella virus (RV)-specific immunoglobulin G (IgG) antibodies is now determined by enzyme immunoassay (EIA) or by passive agglutination in most clinical laboratories (for a review, see reference 3). A caveat to most RV EIAs actually on the market resides in the fact that the antigen used in these tests is the RV propagated in cell culture and thus contaminated to some extent with cellular by-products. Therefore, nonspecific reactions are to be expected, and do occur, when some of these EIAs are used (10). In order to evaluate the performance of two novel RV synthetic peptide (SP)-based EIAs now commercially available (DETECT-RUBELLA IgG SP-El and DETECT-RUBELLA IgG SP-E1E2; BioChem Immunosystems, Montreal, Canada), we compared them with the Enzygnost EIA (Behringwerke, Marburg, Germany) and the IMx microparticle-based EIA (MEIA; Abbott Laboratories, Abbott Park, Ill.) for the detection of RV IgG antibodies in 484 serum samples. Sera were randomly selected from those submitted to our hospital-based laboratory for rubella immunity screening. Specimens were stored at - 20°C and underwent, on average, two freeze-thaw cycles. All assays were performed blindly by a laboratory technician at Sainte-Justine Hospital according to the manufacturer's instructions. The SP-EIA is based on the use of a SP antigen, SP-El (previously referred to as BCH-178 [6, 14]), corresponding to amino acids 213 to 239 of the El RV glycoprotein (Therien strain). This SP was used alone or in combination with another

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Corresponding author. Mailing address:

H6pital

SP, SP-E2, corresponding to amino acids 10 to 36 of the E2 RV glycoprotein. The Enzygnost is a standard EIA which requires the use of two wells per serum sample tested; one well is coated with a viral lysate from RV grown on BHK-21 cells (viral antigen), and the other well is coated with uninfected cell culture lysate (control antigen). On the other hand, to perform the IMx MEIA, the patient's serum is added to microparticles coated with RV propagated in BHK-21 cells, and after incubation, an aliquot of the antigen-antibody complex formed is transferred to a glass fiber matrix. The microparticles will bind irreversibly to this matrix, and a conjugate followed by the appropriate substrate will then be added. A result was considered discrepant if total agreement among all EIAs was not reached. HI was performed blindly in an independent laboratory, according to standard procedures, in an attempt to resolve discordant results. An antibody titer of -1:8 was considered positive, and a titer of