Titer
Encyclopedia
A titer is a way of expressing concentration. Titer testing employs serial dilution
to obtain approximate quantitative information from an analytical procedure that inherently only evaluates as positive or negative. The titer corresponds to the highest dilution factor that still yields a positive reading. For example, positive readings in the first 8 serial twofold dilutions translate into a titer of 1:256
(i.e, 2−8). A specific example is a viral titer, which is the lowest concentration of virus
that still infects cells. To determine the titer, several dilutions are prepared, such as 10−1, 10−2, 10−3,...,10−8.
There are two main kinds of titer testing that one can do. First there is the physical titer; this titer gives one the concentration of virus particles per unit of measurement. The second way to measure viral titers is to perform an infectious titer level. This test tells one the concentration of infectious particles that have the ability to cause infection. A physical titer is much easier and faster to perform but does not always tell one if that level is an infectious amount or not.
Many traditional serological
tests such as hemagglutination
or complement fixation employ this principle. Such tests can typically be read visually, which makes them fast and cost-effective in a "low-tech" environment. The interpretation of serological titers is guided by reference values that are specific for the antigen or antibody in question; a titer of 1:32 may be below the cut-off for one test but above for another.
The titer of a fat is the temperature, in degrees Celsius, at which it solidifies. The higher the titer, the harder the fat. This titer is used in determining whether an animal fat is considered tallow
(titer higher than 40 °C) or a grease
(titer below 40 °C).
A titer (when referring to a library titration) is the number of plaque forming units per milliliter. The reason why the titer is important is because we need to make sure that the library has enough viable phage particles to represent all of the original genome. Also, a certain phage density needs to be plated in order to be able to screen the library successfully.
Serial dilution
A serial dilution is the stepwise dilution of a substance in solution. Usually the dilution factor at each step is constant, resulting in a geometric progression of the concentration in a logarithmic fashion. A ten-fold serial dilution could be 1 M, 0.1 M, 0.01 M, 0.001 M.....
to obtain approximate quantitative information from an analytical procedure that inherently only evaluates as positive or negative. The titer corresponds to the highest dilution factor that still yields a positive reading. For example, positive readings in the first 8 serial twofold dilutions translate into a titer of 1:256
Ratio
In mathematics, a ratio is a relationship between two numbers of the same kind , usually expressed as "a to b" or a:b, sometimes expressed arithmetically as a dimensionless quotient of the two which explicitly indicates how many times the first number contains the second In mathematics, a ratio is...
(i.e, 2−8). A specific example is a viral titer, which is the lowest concentration of virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
that still infects cells. To determine the titer, several dilutions are prepared, such as 10−1, 10−2, 10−3,...,10−8.
There are two main kinds of titer testing that one can do. First there is the physical titer; this titer gives one the concentration of virus particles per unit of measurement. The second way to measure viral titers is to perform an infectious titer level. This test tells one the concentration of infectious particles that have the ability to cause infection. A physical titer is much easier and faster to perform but does not always tell one if that level is an infectious amount or not.
Many traditional serological
Serology
Serology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
tests such as hemagglutination
Hemagglutination
Hemagglutination, or haemagglutination, is a specific form of agglutination that involves red blood cells . It has two common uses in the laboratory: blood typing and the quantification of virus dilutions.-Blood Typing:...
or complement fixation employ this principle. Such tests can typically be read visually, which makes them fast and cost-effective in a "low-tech" environment. The interpretation of serological titers is guided by reference values that are specific for the antigen or antibody in question; a titer of 1:32 may be below the cut-off for one test but above for another.
The titer of a fat is the temperature, in degrees Celsius, at which it solidifies. The higher the titer, the harder the fat. This titer is used in determining whether an animal fat is considered tallow
Tallow
Tallow is a rendered form of beef or mutton fat, processed from suet. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.In industry,...
(titer higher than 40 °C) or a grease
Yellow grease
Yellow grease is derived from used cooking oil from the fast-food industry. It is used to feed livestock, and to make soap, make-up, clothes, rubber, detergents, and bio-diesel fuel....
(titer below 40 °C).
A titer (when referring to a library titration) is the number of plaque forming units per milliliter. The reason why the titer is important is because we need to make sure that the library has enough viable phage particles to represent all of the original genome. Also, a certain phage density needs to be plated in order to be able to screen the library successfully.