Evaluation of Three Multiplex Flow Immunoassays Compared to an Enzyme Immunoassay for the Detection and Differentiation of IgG Class Antibodies to Herpes Simplex Virus Types 1 and 2

The diagnosis of herpes simplex virus (HSV) infections is routinely made based on clinical findings and supported by laboratory testing using PCR or viral culture. However, in instances of subclinical or unrecognized HSV infection, serologic testing for IgG class antibodies to type-specific HSV glycoprotein G (gG) may be useful. This study evaluated and compared the performances of three multiplex flow immunoassays (AtheNA Multi-Lyte [Zeus Scientific], BioPlex 2200 [Bio-Rad Laboratories], and Plexus HerpeSelect [Focus Diagnostics]) for the simultaneous detection of gG type-specific IgG antibodies to HSV types 1 and 2 (HSV-1 and HSV-2). Serum specimens (n = 505) submitted for routine gG type-specific HSV IgG testing by enzyme immunoassay (EIA) (HerpeSelect; Focus Diagnostics) were also tested by the three multiplex flow immunoassays. Specimens showing discordant results were tested by HSV type-specific Western blotting (WB). For HSV-1 IgG, the AtheNA, BioPlex, and Plexus assays demonstrated agreements of 94.9% (479/505 specimens), 97.8% (494/505 specimens), and 97.4% (492/505 specimens), respectively, with the results of EIA. For HSV-2 IgG, the AtheNA, BioPlex, and Plexus assays showed agreements of 87.9% (444/505 specimens), 97.2% (491/505 specimens), and 96.8% (489/505 specimens), respectively, with EIA results. Timing studies showed that the AtheNA, BioPlex, and Plexus assays could provide complete analysis of 90 serum specimens in 3.1, 1.5, and 2.9 h, respectively, versus 3.1 h by EIA. These findings suggest that the gG type-specific HSV IgG multiplex immunoassays may be beneficial to high-volume clinical laboratories experiencing significant increases in the number of specimens submitted for HSV serologic testing. The evaluated systems provide comparable results to those of EIA, while reducing hands-on time and eliminating the necessity to aliquot specimens prior to testing.Herpes simplex virus type 1 (HSV-1) and HSV-2 are common causes of disease worldwide, with transmission resulting from direct contact with virus-infected secretions. The prevalence of HSV-1 infection increases with age, and >70% of adults worldwide are seropositive for the virus (18). The incidence of antibodies to HSV-2 is dependent on age, sex, and risk factors (e.g., number of sexual partners) and may reach 60 to 95% in certain high-risk groups, such as patients infected with HIV (11, 13, 20). However, a relatively small percentage of patients (10 to 20%) know that they are infected with genital herpes (12, 13, 21), thereby contributing to increased transmission of disease.The diagnosis of HSV-associated disease is routinely made based on clinical findings and supported by laboratory testing using PCR or viral culture (13, 22). However, in instances of subclinical or unrecognized HSV infection, serologic testing for immunoglobulin G (IgG) antibodies to type-specific HSV glycoprotein G (gG) may be useful. Due to significant antigenic cross-reactivity among HSV structural proteins, only gG-based serologic assays have been shown to accurately differentiate between IgG class antibodies to HSV-1 and HSV-2 (2, 4, 9, 15), and FDA-approved, conventional, HSV type-specific enzyme immunoassays (EIA) and Western blot (WB) assays are commercially available. Although EIA and WB have demonstrated excellent sensitivity and specificity (2, 3, 15, 24), they require separate assays to be performed for the detection and differentiation of antibodies to HSV-1 and HSV-2. This may increase the potential for aliquoting errors, as well as the associated technologist and instrument time required for testing.Recently, a number of multiplex flow immunoassays (MFI) have been described for the serologic evaluation of various infectious diseases (6, 8, 16). This approach is similar to traditional EIA but allows for the simultaneous detection and identification of multiple analytes in a single reaction tube. MFI technology uses a liquid suspension array of up to 100 unique microspheres (5- to 6-μm beads), each conjugated to a different capture molecule (e.g., antibody, antigen, or nucleic acid). Each capture analyte is detected and quantitated following the addition of a fluorescently labeled reporter molecule (e.g., phycoerythrin) whose emission is measured by a flow-based detector. Since 2008, three multiplex flow immunoassays (AtheNA Multi-Lyte [Zeus Scientific], BioPlex 2200 [Bio-Rad Laboratories], and Plexus HerpeSelect [Focus Diagnostics]) have received FDA clearance for the detection and differentiation of IgG class antibodies to HSV-1 and HSV-2. These assays are fully automated and designed for high-throughput analysis of the HSV type-specific antibody response.Due to increasing test volumes (∼105% in the past 3 years) and the limitations of conventional methods for HSV antibody testing (e.g., limited throughput and labor-intensive testing), we undertook a study to evaluate and compare the AtheNA, BioPlex, and Plexus multiplex assays for the detection and differentiation of IgG class antibodies to HSV-1 and HSV-2. The objective of this study was to compare the results of MFI and EIA testing, using WB to further evaluate specimens showing discordant results.