Serum Bactericidal Activity
Serum Bactericidal Activity - 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.
08:26
Measuring the 50% Haemolytic Complement (CH50) Activity of Serum
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Cited by 92 •
2010
The classical pathway is activated by antibody and culminates in target cell lysis. The CH50 assay provides a measure of the complement activity of a serum sample. This video demonstrates the steps involved in determining the CH50 of a serum sample, the calculations and interpreting of results.
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.
06:08
A Charcoal Agar Resazurin Assay to Evaluate Test Compound Activity Against Mycobacteria
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2025
This video showcases the Charcoal Agar Resazurin Assay (CARA) for evaluating the activity of antimicrobial compounds against Mycobacterium tuberculosis. CARA aids in assessing the efficacy of these compounds by gauging their impact on bacterial growth and distinguishing between bactericidal and bacteriostatic effects.
FAQs
The response depends on cooperation between antigen recognition and complement activity. Antibodies bind bacterial surface antigens, creating a targeted signal that engages complement. Complement can then enhance opsonization, meaning marking bacteria for immune handling, and contribute to membrane attack complex formation. These linked events help explain why serum activity can culminate in bacterial lysis rather than simple growth inhibition.
Complement inactivation helps separate complement-dependent killing from other antimicrobial effects present in serum. Comparing untreated serum with serum in which complement has been inactivated shows whether bacterial survival changes when complement activity is removed. This control clarifies the contribution of complement to the measured result and prevents the assay from treating all serum-mediated inhibition as one mechanism.
Surface antigen recognition determines whether antibodies can engage the bacterium effectively. When antibodies recognize relevant bacterial antigens, they can activate complement and promote downstream effects such as opsonization, membrane attack complex formation, and lysis. Consequently, assay results depend on the relationship between the antibodies in a serum sample and the surface features of the bacterial strain being tested.
A typical assay exposes susceptible bacteria to a serum sample and then measures bacterial survival. The experiment can include paired conditions in which complement remains active or is inactivated. Comparing survival across these conditions indicates the overall bactericidal effect and helps identify how much of that effect depends on complement rather than other serum-associated antimicrobial mechanisms.
Researchers measure it when they need to characterize serum-mediated protection against clinically important bacteria. The assay can support vaccine evaluation, assessment of therapeutic antibodies, and investigation of susceptibility to recurrent infection. Because it measures bacterial survival after serum exposure, it provides an outcome that links immune recognition and complement activity with the ability of serum defenses to control a pathogen.
These measurements show how effectively humoral defenses control susceptible bacteria under defined laboratory conditions. They reflect the combined contribution of antibodies and complement, while complement-inactivated comparisons help distinguish complement-dependent effects from other mechanisms. In immunology, the results can therefore provide context for understanding protective responses, evaluating antibody function, and examining why some individuals may experience recurrent infections.