Guide: A Basic Overview Of Serum Protein Manual Agarose Electrophoresis
June 25th, 2019
Study: Detection Of Benzodiazepines In Oral Fluid By Homogeneous Enzyme Immunoassay
June 20th, 2019
MEDICA 2019 - World Forum for Medicine
Düsseldorf, GermanyBooth No.: 3/D35-2
AACC Annual Scientific Meeting and Clinical Lab Expo
Anaheim Convention Center ~ Anaheim, CABooth No.: 2627
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--- Mathew Anderson, New Jersey
The DRG EBV-VCA IgG ELISA test system is an enzyme-linked immunosorbent assay ELISA) designed for the qualitative detection of IgG class antibodies to Epstein-Barr Virus viral capsid antigen (EBV-VCA) in human serum. The test system is intended to be used for the diagnosis of EBV-associated infectious mononucleosis when used in conjunction with other EBV serologies.
Epstein-Barr Virus (EBV) is a ubiquitous human virus which causes infectious mononucleosis (IM), a self limiting lymphoproliferative disease (1). By adulthood virtually everyone has been infected and has developed immunity to the virus. In underdeveloped countries, seroconversion to the virus takes place in early childhood and is usually asymptomatic (2). In more affluent countries, primary EBV infections are often delayed until adolescence or later, and manifest as IM in about 50% of this age group (3-5).
Following seroconversion, whether symptomatic or not, EBV establishes a chronic, latent infection in B lymphocytes which probably lasts for life (6). EBV replicates in oropharyngeal epithelial cells and is present in the saliva of most patients with IM (7). Also, 10-20% of healthy persons who are EBV antibody positive shed the virus in their oral secretions (6-8). Reactivation of the latent viral carrier state, as evidenced by increased rates of virus shedding, is enhanced by mmunosuppression. pregnancy, malnutrition, or disease (8,9). Chronic EBV infections, whether latent or active, are rarely associated with disease. However, EBV has been implicated at least as a contributing factor in the etiology of nasopharyngeal carcinoma, Burkitt's lymphoma, and lymphomas in immunodeficient patients (4,8).
The Paul-Bunnell-Davidsohn test for heterophile antibody is highly specific for IM (10). However, 10-15% of adults and higher percentages of children and infants with primary EBV infections do not develop heterophile antibodies (11). EBV-specific serotogical tests are needed to differentiate primary EBV infections that are heterophile negative from mononucleosis-like illnesses caused by other agents such as cytomegalovirus, adenovirus, and Toxoplasma gondii (4). Antibody tilers to specific EBV antigens correlate with different stages of JM (4, 10-12). Both IgG and IgG antibodies to the viral capsid antigen (VGA) peak 3 to 4 weeks after primary EBV infection. IgG anti-VCA decline rapidly and is usually undetectable after 12 weeks. IgG anti-VCA liters decline slowly after peaking but last indefinitely. Antibodies to EBV nuclear antigen (EBNA) develop from 1 month to 6 months after infection and, like anti-VCA, persist indefinitely (11,12). Antibodies to EBNA indicate that the infection was not recent (11).
EBV early antigens (EA) consist of two components; diffuse (D), and restricted (R). The terms D and R reflect the different patterns of immunofluorescence staining exhibited by the two components (13,14). Antibodies to EA appear transiently for up to three months during the acute phase of IM in 85% of patients (15,16). The antibody response to EA in IM patients is usually to the D component, whereas silent seroconversion to EBV in children produces antibodies to the R component (5,11). A definitive diagnosis of primary EBV infection can be made with 95% of acute phase sera based on the detection of antibodies to VCA, EBNA, andEA(12).
High levels of anti-VCA together with anti-EBNA and anti-EA-R are associated with reactivation of the latent viral carrier state (16,17). High levels of IgG anti-VCA are found in sera of patients with immunodeficiencies (6,18), recurrent parotitis (19), multiple sclerosis (20), and nasopharyngeal carcinoma (21); as well as immunosuppressed patients (8, 22), pregnant women (23), and persons of advanced age (17).
Screening for the presence of antibodies to VCA and related antigens of EBV can provide important information for the diagnosis of EBV infection. Indirect immunofluorescence has been the serologic method most commonly used to detect antibodies to EBV antigens (11). However, the ELISA procedure, first described by Engvall and Penman (24,25), may be a sensitive and reliable method for detection of antibodies to EBV antigens (26,27). The ELISA procedure allows an objective determination of antibody status to be made on a single dilution of the test specimen and is suitable for screening large numbers of patient samples.