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Assaying the Potency of Influenza Vaccines.

Minor PD - Vaccines (Basel) (2015)

Bottom Line: The potency of vaccines must be determined to ensure that the appropriate dose is given.Single radial diffusion has been used for decades and provides a relatively simple way to measure the amount of biologically active materials present in the vaccine.It requires reagents, which are updated on a regular, frequently yearly, basis and alternative methods continue to be sought.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Biological Standards and Control/MHRA, Blanche Lane, Potters Bar, Hertfordshire EN6 3QG, UK. Philip.Minor@nibsc.org.

ABSTRACT
The potency of vaccines must be determined to ensure that the appropriate dose is given. The manufacture and assessment of influenza vaccines are complicated by the continuously changing nature of the pathogen, which makes efficacy estimates difficult but also confounds attempts to produce a well-validated, consistent potency assay. Single radial diffusion has been used for decades and provides a relatively simple way to measure the amount of biologically active materials present in the vaccine. It requires reagents, which are updated on a regular, frequently yearly, basis and alternative methods continue to be sought.

No MeSH data available.


Related in: MedlinePlus

Single Radial Diffusion assay of influenza haemagglutinin. Stained plate showing zones and plot of zone size against dilution of analyte illustrating slope ratio statistical method for measuring potency.
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vaccines-03-00090-f002: Single Radial Diffusion assay of influenza haemagglutinin. Stained plate showing zones and plot of zone size against dilution of analyte illustrating slope ratio statistical method for measuring potency.

Mentions: SRD requires two reagents, an antibody reacting with the strain to be assayed and a reference antigen of known potency, which is homologous to the precise strain used in the vaccine. Wells are introduced into a slab of agarose containing the antibody at a concentration that will give zones of an appropriate size. Serial dilutions of the antigen to be assayed are then placed in the wells and the antigen diffuses until it reaches the zone of equivalence with the antibody dilution, where a precipitin ring forms. The agarose is washed free of excess antibody, dried and stained with Coomassie blue or some other appropriate agent to visualise the rings, whose size is measured. The greater the antigen content the larger the ring area. The reference is run in the same way and the ring sizes compared to measure antigen potency expressed relative to the reference. The potency of the reference is expressed in micrograms of haemagglutinin. The assay could involve choosing the dilutions used for the test and reference so that the ring sizes for both are in the same range and assessing the dose response statistically as a parallel line assay. Practically it is simpler to use the same dilutions for the test and reference and analyse the results by the ratio of the slopes of the dose response curves; the higher the initial content the steeper the slope as the test article is diluted. An example is shown in Figure 2.


Assaying the Potency of Influenza Vaccines.

Minor PD - Vaccines (Basel) (2015)

Single Radial Diffusion assay of influenza haemagglutinin. Stained plate showing zones and plot of zone size against dilution of analyte illustrating slope ratio statistical method for measuring potency.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494238&req=5

vaccines-03-00090-f002: Single Radial Diffusion assay of influenza haemagglutinin. Stained plate showing zones and plot of zone size against dilution of analyte illustrating slope ratio statistical method for measuring potency.
Mentions: SRD requires two reagents, an antibody reacting with the strain to be assayed and a reference antigen of known potency, which is homologous to the precise strain used in the vaccine. Wells are introduced into a slab of agarose containing the antibody at a concentration that will give zones of an appropriate size. Serial dilutions of the antigen to be assayed are then placed in the wells and the antigen diffuses until it reaches the zone of equivalence with the antibody dilution, where a precipitin ring forms. The agarose is washed free of excess antibody, dried and stained with Coomassie blue or some other appropriate agent to visualise the rings, whose size is measured. The greater the antigen content the larger the ring area. The reference is run in the same way and the ring sizes compared to measure antigen potency expressed relative to the reference. The potency of the reference is expressed in micrograms of haemagglutinin. The assay could involve choosing the dilutions used for the test and reference so that the ring sizes for both are in the same range and assessing the dose response statistically as a parallel line assay. Practically it is simpler to use the same dilutions for the test and reference and analyse the results by the ratio of the slopes of the dose response curves; the higher the initial content the steeper the slope as the test article is diluted. An example is shown in Figure 2.

Bottom Line: The potency of vaccines must be determined to ensure that the appropriate dose is given.Single radial diffusion has been used for decades and provides a relatively simple way to measure the amount of biologically active materials present in the vaccine.It requires reagents, which are updated on a regular, frequently yearly, basis and alternative methods continue to be sought.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Biological Standards and Control/MHRA, Blanche Lane, Potters Bar, Hertfordshire EN6 3QG, UK. Philip.Minor@nibsc.org.

ABSTRACT
The potency of vaccines must be determined to ensure that the appropriate dose is given. The manufacture and assessment of influenza vaccines are complicated by the continuously changing nature of the pathogen, which makes efficacy estimates difficult but also confounds attempts to produce a well-validated, consistent potency assay. Single radial diffusion has been used for decades and provides a relatively simple way to measure the amount of biologically active materials present in the vaccine. It requires reagents, which are updated on a regular, frequently yearly, basis and alternative methods continue to be sought.

No MeSH data available.


Related in: MedlinePlus