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A viral titer is the lowest concentration of a virus that still infects cells. To determine the titer, several dilutions are prepared, such as 10 −1, 10 −2, 10 −3, ... 10 −8. [1] The titer of a fat is the temperature, in degrees Celsius, at which it solidifies. [4] The higher the titer, the harder the fat.
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.
Reference ranges (reference intervals) for blood tests are sets of values used by a health professional to interpret a set of medical test results from blood samples. Reference ranges for blood tests are studied within the field of clinical chemistry (also known as "clinical biochemistry", "chemical pathology" or "pure blood chemistry"), the ...
Virus quantification is counting or calculating the number of virus particles (virions) in a sample to determine the virus concentration. It is used in both research and development (R&D) in academic and commercial laboratories as well as in production situations where the quantity of virus at various steps is an important variable that must be monitored.
Biological responses to ligand concentrations typically follow a sigmoidal function. The inflection point at which the increase in response with increasing ligand concentration begins to slow is the EC 50, which can be mathematically determined by derivation of the best-fit line.
The titer value of that sample is the inverse of the dilution, i.e., 40. In some cases, the virus is initially so dilute that agglutinated wells are never observed. In that case, the titer of these samples is commonly assigned as 5, indicating the highest possible concentration, but the accuracy of that value is clearly low.
Titers of 1:4 or higher is considered critical for Kell (compared to 1:16 for most other antibodies) and is considered to confer a high risk of fetal anemia. [17] Such high titers may be managed by weekly follow-up by obstetric ultrasound , assessing the peak systolic velocity of the fetal middle cerebral arterial (MCA), amniotic fluid volume ...
The Widal test is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia.