Hemagglutination assay

Jump to navigation Jump to search

WikiDoc Resources for Hemagglutination assay

Articles

Most recent articles on Hemagglutination assay

Most cited articles on Hemagglutination assay

Review articles on Hemagglutination assay

Articles on Hemagglutination assay in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Hemagglutination assay

Images of Hemagglutination assay

Photos of Hemagglutination assay

Podcasts & MP3s on Hemagglutination assay

Videos on Hemagglutination assay

Evidence Based Medicine

Cochrane Collaboration on Hemagglutination assay

Bandolier on Hemagglutination assay

TRIP on Hemagglutination assay

Clinical Trials

Ongoing Trials on Hemagglutination assay at Clinical Trials.gov

Trial results on Hemagglutination assay

Clinical Trials on Hemagglutination assay at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Hemagglutination assay

NICE Guidance on Hemagglutination assay

NHS PRODIGY Guidance

FDA on Hemagglutination assay

CDC on Hemagglutination assay

Books

Books on Hemagglutination assay

News

Hemagglutination assay in the news

Be alerted to news on Hemagglutination assay

News trends on Hemagglutination assay

Commentary

Blogs on Hemagglutination assay

Definitions

Definitions of Hemagglutination assay

Patient Resources / Community

Patient resources on Hemagglutination assay

Discussion groups on Hemagglutination assay

Patient Handouts on Hemagglutination assay

Directions to Hospitals Treating Hemagglutination assay

Risk calculators and risk factors for Hemagglutination assay

Healthcare Provider Resources

Symptoms of Hemagglutination assay

Causes & Risk Factors for Hemagglutination assay

Diagnostic studies for Hemagglutination assay

Treatment of Hemagglutination assay

Continuing Medical Education (CME)

CME Programs on Hemagglutination assay

International

Hemagglutination assay en Espanol

Hemagglutination assay en Francais

Business

Hemagglutination assay in the Marketplace

Patents on Hemagglutination assay

Experimental / Informatics

List of terms related to Hemagglutination assay

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

The hemagglutination assay (or haemagglutination assay; HA) is a method of quantification for viruses or bacteria by hemagglutination. It is an easy, simple and rapid method which can be applied to large numbers of samples. The hemagglutination assay and its extension, the hemagglutination inhibition assay, were invented in 1941–42 by American virologist George Hirst.[1][2]

The hemagglutination assay of a virus, in contrast to other forms of virus quantification such as a plaque assay or 50% Tissue Culture Infective Dose, does not give any measure of viral infectivity, because no virus replication is required in this assay. The same may not be true when using HA for bacteria.

Mechanism

Some viral families and many bacteria have envelope or surface proteins which are able to agglutinate (stick to) human or animal red blood cells (RBC) and bind to N-acetylneuraminic acid. As each of the agglutinating molecule attaches to multiple RBCs, a lattice-structure will form.

Procedure

The detailed conditions depend on the type of virus or bacteria being assayed since certain pH values and ionic strengths can impact the activity of the proteins of interest in a difficult to predict manner.

Normally, a virus dilution (e.g. 2-fold from 1:4 to 1:4096) will be applied to an RBC dilution (e.g. 0.1% to 0.7% in steps of 0.2%) for approx. 30 min, often at 4 °C, otherwise viruses with neuraminidase activity will detach the virus from the RBCs. Then the lattice forming parts will be counted and the titer calculated.

Virus concentration in virions per millilitre = 107 x HA titer.[3]

The titer of a hemagglutination assay is determined by the last viable "lattice" structure found. This is because it is at the point where, if diluted anymore, the amount of Virus particles will be less than that of the RBCs and thus not be able to agglutinate them together.

For bacteria, depending on species, a bacterial dilution will be applied to an equal part RBC dilution and then incubated for 30 min to an hour at an optimal growth temperature before being observed.[4]

Hemagglutination Inhibition Assay

The hemagglutination inhibition assay is a common variation of the HA assay used to measure flu-specific antibody levels in blood serum. In this variation, serum antibodies to the influenza virus will interfere with the virus attachment to red blood cells. Therefore hemagglutination is inhibited when antibodies are present at a sufficient concentration.[5] The hemagglutination inhibition assay may also be used as a laboratory confirmatory method for dengue virus infection.

Related Chapters

References

  1. George Keble Hirst, 84, is dead; a pioneer in molecular virology. New York Times (26 January 1994) (accessed 22 February 2013)
  2. Hirst GK. (1942) The quantitative determination of influenza virus and antibodies by means of red cell agglutination. Journal of Experimental Medicine 75: 49–64 (pdf)
  3. Donald HB, Isaacs A (1954). "Counts of influenza virus particles". J. Gen. Microbiol. 10 (3): 457–64. PMID 13174769.
  4. X. Chen ; et al. (2007). "The S-Layer Proteins of L. crispatus strain ZJ001 is responsible for competitive exclusion against E. coli O157:h7 and S. typhimurim". Int. J. Food Microbiology. 115 (3): 307–312. doi:10.1016/j.ijfoodmicro.2006.11.007. PMID 17289201.
  5. http://www.virology.ws/2009/05/27/influenza-hemagglutination-inhibition-assay/