Measles Virus IgG Avidity ELISA
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Zika Virus IgG/IgM/IgA ELISAThe Native Antigen Company (NAC) Zika Virus IgG/IgM/IgA ELISA assay is designed for the detection of Zika-specific antibodies in human serum. It is minimally cross-reactive with antibodies to Dengue virus (a closely-related flavivirus), and so can be used to distinguish human anti-Zika antibodies from other flavivirus and infectious disease antibodies, especially in epidemiological studies. Use of the assay is intended for detection of IgG in convalescent sera, although IgM/IgA are also detected earlier on in the infection cycle. The Zika Virus ELISA has an assay time of only 2 hours, with specificity and sensitivity both in excess of 90%, even in endemic Dengue virus regions. Due to the novel assay format the test may also be used in any species, making it of particular value for researchers studying animal models of Zika infection Zika virus (ZIKV) is a member of the virus family Flaviviridae and the genus Flavivirus, transmitted by Aedes mosquitoes, such as A. aegypti and A. albopictus. Its name comes from the Zika Forest of Uganda, where the virus was first isolated in 1947. Zika virus is related to Dengue, Yellow Fever, Japanese Encephalitis, and West Nile viruses, and many antibodies (e.g. those produced as a response to infection) cross-react between these viruses. This cross-reaction causes severe problems in identifying individuals seropostive for Zika as the much wider spread background of Dengue infections cause many false positives in most standard serological ELISAs. NAC’s Zika virus antibody capture ELISA uses an in-house manufactured Zika virus-specific antigen to virtually exclude cross reactions and is thus suitable for the accurate detection of serum antibodies to Zika virus, indicating exposure. The detection of Zika specific antibodies is relevant for epidemiological studies, particularly in populations with high prevalence of Dengue and Chikungunya virus. THIS ELISA ASSAY IS FOR RESEARCH USE ONLY. IT IS NOT FOR USE IN DIAGNOSTIC PROCEDURES.
MEASLES VIRUS IgG AVIDITY ELISA
Enzyme immunoassay for the indication of Measles virus specific IgG avidity in human serum or plasma (citrate, heparin) to differentiate between acute and past infection.
The presence of IgG antibodies to Measles virus indicates the occurrence of the infection but does not distinguish between recent and past infection. Specific IgM antibodies are first detected approximately in ten days and peak at about four weeks post infection. They may persist for several months after acute infections. Based on the evidence that antibody avidity gradually increases after exposure to an immunogen, avidity of IgG antibodies can be used as a marker for distinguishing recent primary from long-term infections. Avidity describes the binding strength of a specific antibody to its antigen. Low-avidity IgG antibodies indicate a primary infection, whereas the presence of IgG antibodies with high avidity points to persistency or reactivation of infection.
The qualitative immunoenzymatic determination of specific antibodies is based on the ELISA (Enzyme-linked Immunosorbent Assay) technique. Microplates are coated with specific antigens to bind corresponding antibodies of the sample (dual pipetting). After washing the wells to remove all unbound sample material, one well is incubated with avidity reagent and the corresponding well with washing buffer. The avidity reagent removes the low-avidity antibodies from the antigens whereas the high-avidity ones are still bound to the specific antigens. After second washing step to remove the rest of avidity reagent and low-avidity antibodies, a horseradish peroxidase (HRP) labelled conjugate is added. This conjugate binds to the captured antibodies. In a third washing step unbound conjugate is removed. The immune complex formed by the bound conjugate is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is proportional to the amount of specific antibodies in the sample. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorbance at 450/620 nm is read using an ELISA microwell plate reader.
- The evaluation of the diagnostic performance of the Avidity Measles Virus IgG test was performed in comparison to well defined samples. The resulting relative agreement was 100 %.
- Short assay time – <3 hours
- 1 x 48 tests
Measles or morbilli virus belongs to the RNA viruses of the family Paramyxoviridae. The virions are spherical particles of 150-250 nm in diameter consisting of the ribonucleoprotein with helical symmetry and an envelope with spikes containing the strain-specific and hemagglutinating antigens. Morbilli viruses have no neuraminidase activity. Measles is a classic childhood disease. The virus is endemic: at the age of 20 about 90% of the population has had immunological experience with it. Newborns are protected by maternal antibodies for the first 3-4 months of life; the active disease leaves lifelong immunity. The measles virus has a contagiousity index of about 96%, is worldwide distributed, and can be serious. Bacterial superinfection was a serious threat in the pre-antibiotic era, but the prognosis of uncomplicated measles is now good. CNS complications such as encephalomyelitis (0.1%) which may occur after the acute phase of measles infection subsides, however still have a high mortality (10%). Prognosis of recovery in these patients is poor. Between 10-30% of all cases are fatal; 20-50% develop significant damages. Subacute sclerosing panencephalitis (SSPE) is a rare (1:1000) degenerative disease of the CNS which is thought to be a slow virus infection.
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THIS ELISA ASSAY IS FOR RESEARCH USE ONLY. IT IS NOT FOR USE IN DIAGNOSTIC PROCEDURES.