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The plaque reduction neutralization test is used to quantify the titer of neutralizing antibody for a virus. [1] [2] The serum sample or solution of antibody to be tested is diluted and mixed with a viral suspension. This is incubated to allow the antibody to react with the virus. This is poured over a confluent monolayer of host cells.
Neutralization assays are capable of being performed and measured in different ways, including the use of techniques such as plaque reduction (which compares counts of virus plaques in control wells with those in inoculated cultures), microneutralization (which is performed in microtiter plates filled with small amounts of sera), and ...
Many viruses can be grown in cell culture in the lab. To do this, the virus sample is mixed with cells, a process called adsorption, after which the cells become infected and produce more copies of the virus. [3]
Surrogate virus neutralization test (sVNT) results were reported as mean inhibition rate (%). Up to day 28 (before 2nd vaccination), inhibition rates of all groups were below cut-off value of 30%. At day 35, mean inhibition of groups Nanocovax 25 mcg, 50 mcg, 75 mcg and placebo were 58.5% , 63.8% ,70.2%, and 11.1% , respectively.
A general procedure for HA is as follows, a serial dilution of virus is prepared across the rows in a U or V- bottom shaped 96-well microtiter plate. [5] The most concentrated sample in the first well is often diluted to be 1/5x of the stock, and subsequent wells are typically two-fold dilutions (1/10, 1/20, 1/40, etc.).
Viral inactivation is different from viral removal because, in the former process, the surface chemistry of the virus is altered and in many cases the (now non-infective) viral particles remain in the final product. Rather than simply rendering the virus inactive, some viral inactivation processes actually denature the virus
A 2010 review study by Puren et al. [2] categorizes viral load testing into three types: (1) nucleic acid amplification based tests (NATs or NAATs) commercially available in the United States with Food and Drug Administration (FDA) approval, or on the market in the European Economic Area (EEA) with the CE marking; (2) "Home–brew" or in-house NATs; (3) non-nucleic acid-based test.
A surrogate endpoint of a clinical trial is a laboratory measurement or a physical sign used as a substitute for a clinically meaningful endpoint that measures directly how a patient feels, functions or survives. Changes induced by a therapy on a surrogate endpoint are expected to reflect changes in a clinically meaningful endpoint. [8]