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Western blot test results. The first two strips are a negative and a positive control, respectively. The others are actual tests. Like the ELISA procedure, the western blot is an antibody detection test. However, unlike the ELISA method, the viral proteins are separated first and immobilized.
Other related techniques include dot blot analysis, quantitative dot blot, immunohistochemistry and immunocytochemistry, where antibodies are used to detect proteins in tissues and cells by immunostaining, and enzyme-linked immunosorbent assay (ELISA). The name western blot is a play on the Southern blot, a technique for DNA detection named ...
[28] [29] ELISA can also be used in toxicology as a rapid presumptive screen for certain classes of drugs. Enzyme-linked immunosorbent assay plate. The ELISA was the first screening test widely used for HIV because of its high sensitivity. In an ELISA, a person's serum is diluted 400 times and applied to a plate to which HIV antigens are attached.
An HIV antibody test usually detects the HIV antibodies within two to eight weeks, but can have a valid negative result for a long as 2 to 6 months after initial infection. Viral load tests can also be used to diagnose HIV infection, especially in children under 18 months born to mothers with HIV, where the presence of maternal antibodies ...
Western blotting allows the detection of specific proteins from extracts made from cells or tissues, before or after any purification steps. Proteins are generally separated by size using gel electrophoresis before being transferred to a synthetic membrane via dry, semi-dry, or wet blotting methods. The membrane can then be probed using ...
The false-positive prevalence was 4.8% of Western blot–positive donors and 0.0004% (1 in 251000) of all donors (95% confidence interval, 1 in 173000 to 1 in 379000 donors)." So if you're low risk (a donor) and come out HIV-positive by ELISA + WB, chances of being misdiagnosed is 4.8%.
On top of that, false positive can occur and the disease specificity is lower than other techniques. While each technique has their advantages and disadvantages, ELISA has the least severe disadvantages of potential for false positives (which are less dangerous than false negatives) and expensive. [5]
The second study, conducted by Pascoe, et al., compared saliva antibody testing to serum antibody testing using ELISA followed by confirmatory Western Blot analysis in 591 individuals. [54] The accuracy of saliva anti-HIV antibody testing has been confirmed by many additional studies, leading to approval of this method by the U.S. Food & Drug ...