2003. consecutive patients and sent in by general practitioners, we also decided Epstein-Barr nuclear antigen IgG and viral capsid antigen IgG in a two-phase approach. Concordance of the EBV serologic status was 96.2% between Liaison and Immulite, 96.4% between Immulite and BioPlex, and 97.8% between BioPlex and Liaison. The three EBV IgM immunoassays that we evaluated have acceptable and comparable performances. Epstein-Barr computer virus (EBV) is the causative agent of infectious mononucleosis, a clinical syndrome characterized by especially fever, pharyngitis, and Cdh15 adenopathy. However, many other pathogens, such as cytomegalovirus (CMV), human herpesvirus 6, = 21), antithyroid-peroxidase antibodies (= 27), rheumatoid factor (= 39), anticardiolipin IgM antibodies (= 5), intrinsic factor antibodies (= 6), chronic lymphocytic leukemia (= 16), and IgM paraproteinemia (= 12). The second group consisted of Robenidine Hydrochloride 117 patients with various acute and chronic infectious diseases: acute hepatitis A (= 15), chronic hepatitis B (hepatitis B surface antigen positive, = 26), chronic hepatitis C (hepatitis C RNA positive, = 11), human immunodeficiency computer virus (HIV RNA positive, = 12), acute toxoplasmosis as shown by an IgG seroconversion (= 9), and acute herpes simplex virus contamination as shown by a herpes simplex IgG seroconversion (= 4). In addition, in this second group 18 sera were included that contained immunoblot-confirmed IgM antibodies against sensu lato and 22 sera from patients with evidence of a contamination (Rapid Plasma Reagin and hemagglutination assay positive). The third group consisted of 30 patients with acute parvovirus B19 infections (= 15) and acute rubella virus infections (= 15). This third group was considered different from the second group because we have previously shown that during the acute phase of these infections, false-positive EBV IgM results can occur on Liaison (2). The fourth group consisted of 20 patients with an acute CMV contamination. In this group the diagnosis of an acute CMV contamination was ascertained by either a CMV IgG seroconversion (= 8) or a significant CMV IgG titer change (i.e., 4, = 12), without concurrent changes in the EBV VCA IgG titers. Moreover, EBNA IgG was positive in these 20 patients, virtually excluding an acute EBV contamination. In these 293 sera, if a positive Robenidine Hydrochloride EBV IgM result was obtained in any of the three methods, Robenidine Hydrochloride an EBV IgM immunoblot was performed as a confirmatory method. In the third part of the study, we prospectively evaluated the serologic EBV status on samples from 500 consecutive patients (335 females and 165 males; mean age, 29 years), which were sent in by general practitioners with a request for EBV IgM determination. On these samples we determined, in addition to the EBV IgM, the EBV IgG antibodies in a two-phase approach: Epstein-Barr nuclear antigen (EBNA) IgG was assessed and, if the sample was found to be unfavorable, viral capsid antigen (VCA) IgG was assessed. The purpose here was to evaluate the effect of possible erroneous EBV IgM results on the final serologic EBV status, keeping in mind that EBNA IgG virtually excludes a recent EBV contamination, and therefore its presence in serum has a major impact on the final serological interpretation. In this patient group, if a different serological interpretation between the three methods due to discrepancies in the EBV IgM results was obtained, EBV IgM immunoblotting was performed as a confirmatory method. During the evaluation of the results from the present study, we suspected possible false-negative EBV VCA IgG results from the BioPlex analysis. Although it was not our primary intention to evaluate the EBV VCA IgG methods, we considered these results important, and we decided to further evaluate this possible problem. We therefore analyzed 56 samples from our serum repository: paired serum samples from 15 patients with an acute EBV contamination, as shown by a VCA IgG seroconversion (= 13) or significant titer rise (i.e., 3, = 2). From eleven patients three or more samples were available. In this fourth and added a part of our study an important selection bias was present since these samples were all selected on results obtained from Liaison. In this fourth part Robenidine Hydrochloride we also further investigated the sera from the first part of the study Robenidine Hydrochloride (the heterophile antibody-positive group) by determining VCA IgG around the three platforms. Methods. EBV VCA IgM, VCA IgG, and EBNA IgG determinations were performed on three.