Serum Bactericidal Assay
Serum Bactericidal Assay - Related Videos
05:40
A Serum Bactericidal Assay for the Complement-Mediated Bactericidal Activity of Antibodies
0 Views •
2025
This video demonstrates a technique to evaluate the complement-mediated bactericidal activity of antibodies present in serum. This approach combines isolated serum with pathogenic bacteria and exogenous complement proteins. Upon incubation, the bacteria are grown on an agar plate, and the produced colonies are quantified to measure the serum bactericidal titer.
02:55
Determining the Role of Vitronectin in Bacterial Resistance to Bactericidal Activity of Human Serum
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2025
This video demonstrates the role of vitronectin, a human serum glycoprotein, on bacterial resistance. Antibodies in the serum interact with bacterial surface proteins, activating complement proteins and forming the membrane attack complex, causing bacterial cell lysis. Vitronectin binding on bacterial membrane protein prevents the membrane attack complex formation, resulting in bacterial survival.
06:11
A High-throughput Shigella-specific Bactericidal Assay
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Cited by 6 •
2019
Here we present a protocol to measure Shigellacidal activity of antibodies in serum. Serum is mixed with bacteria and exogenous complement, incubated, and the reaction mixture is plated on agar plates. Viable bacteria form colonies which are counted, using an automated colony enumerator, and used to determine the bactericidal titer.
05:59
Determining the Reactivity and Titre of Serum using a Haemagglutination Assay
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Cited by 3 •
2010
Haemagglutination is a form of agglutination where antibodies bind to red blood cells. Red blood cells are both readily available and the results are readily observable using the naked eye. This video demonstrates the steps involved in a haemagglutination assay, interpreting the results and determining the titre.
03:59
The Hemagglutination Inhibition Assay to Detect Serum Antibodies Against a Target Antigen
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2025
The video demonstrates a hemagglutination inhibition assay for detecting serum antibodies against specific antigens. Confirmation of hemagglutination inhibition in the test well and hemagglutination in the control well is achieved through distinct visual patterns. This assay plays a crucial role in assessing immune response, vaccine effectiveness, and studying viral infections in virology and immunology.
FAQs
Antibacterial killing in this assay depends on cooperation between serum antibodies and complement. These components contribute to a functional outcome: complement can participate in antibody-associated damage to bacterial membranes, while antibodies help direct the serum’s antibacterial activity toward the tested organisms. Measuring this combined effect is informative for protection-related research because it evaluates their interaction rather than either component in isolation.
The endpoint is the greatest dilution at which the serum still shows bactericidal activity under the assay conditions. It summarizes how well killing persists after the serum has been progressively diluted, rather than simply reporting whether undiluted serum works. Researchers can use this value to compare functional antibacterial activity among sera or between immune-response groups.
Strain selection determines which serum-bacterium interaction is being measured. Testing the same serum against multiple bacterial strains can show whether bactericidal activity is broadly maintained or varies with the organism. This comparison is useful in infection research because it distinguishes a functional immune response that operates across tested strains from activity that is more limited to particular bacterial targets.
Controlled incubation keeps the serum, complement, and bacteria together under defined conditions while their interaction occurs. This consistency matters because the measured endpoint should reflect the serum’s bactericidal activity rather than uncontrolled changes during incubation. Standardized conditions therefore support meaningful comparisons among serum dilutions, biological samples, or bacterial strains tested in the assay.
Serum is prepared in serial dilutions and incubated with bacteria under controlled conditions. Afterward, samples are cultured so that surviving organisms form colonies that can be counted. The colony total provides a readout of how many bacteria escaped serum-mediated killing. Comparing counts across dilutions helps identify where bactericidal activity is retained and where survival becomes more evident.
Vaccine studies can use the assay to determine whether immunization is associated with serum that retains antibacterial activity across dilutions. This functional readout adds information about what the immune response can do against bacteria, rather than only indicating that an immune response is present. Results can help compare sera and evaluate differences in antibacterial activity after vaccination.
In immunology and infection research, the results can support characterization of immune responses, comparison of serum activity against bacterial strains, and investigation of mechanisms linked to protection or treatment outcomes. Because the assay measures surviving bacteria after serum exposure, it connects immune components such as antibodies and complement with a measurable antibacterial effect that can be compared across experimental conditions.