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Related Concept Videos

Complement System01:27

Complement System

The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...
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Bacterial Phylum Chlamydiae

The phylum Chlamydiae or Chlamydiota is composed of a single order, Chlamydiales. This phylum consists entirely of obligate intracellular parasites that infect eukaryotic hosts. While human pathogens within this group have been studied extensively, the phylum encompasses many species capable of interacting with various eukaryotic organisms. Members of Chlamydiae are typically small cocci, approximately 0.5 μm in diameter, and exhibit a distinctive developmental cycle. As is characteristic of...
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Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
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Antibody Actions

Antibodies, or immunoglobulins, are critical players in the immune system's arsenal against invading pathogens. Produced by B cells and plasma cells, their primary role is to detect and bind to specific antigens, molecules found on the surface of pathogens like bacteria or viruses. Beyond antigen recognition, antibodies perform several vital functions that contribute to immune defense.
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Related Experiment Video

Updated: Jun 6, 2026

Cell-Free Scaled Production and Adjuvant Addition to a Recombinant Major Outer Membrane Protein from Chlamydia muridarum for Vaccine Development
12:53

Cell-Free Scaled Production and Adjuvant Addition to a Recombinant Major Outer Membrane Protein from Chlamydia muridarum for Vaccine Development

Published on: March 16, 2022

Native properdin binds to Chlamydia pneumoniae and promotes complement activation.

Claudio Cortes1, V P Ferreira, Michael K Pangburn

  • 1Department of Biochemistry, Center for Biomedical Research, University of Texas Health Science Center, Tyler, Texas 75708, USA. claudio.cortes@utoledo.edu

Infection and Immunity
|December 8, 2010
PubMed
Summary
This summary is machine-generated.

Properdin binds to Chlamydia pneumoniae, enhancing complement activation and controlling infection. This suggests properdin acts as a pattern recognition molecule in resisting Chlamydia pneumoniae infections.

More Related Videos

Forward Genetic Approaches in Chlamydia trachomatis
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Forward Genetic Approaches in Chlamydia trachomatis

Published on: October 23, 2013

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Last Updated: Jun 6, 2026

Cell-Free Scaled Production and Adjuvant Addition to a Recombinant Major Outer Membrane Protein from Chlamydia muridarum for Vaccine Development
12:53

Cell-Free Scaled Production and Adjuvant Addition to a Recombinant Major Outer Membrane Protein from Chlamydia muridarum for Vaccine Development

Published on: March 16, 2022

Forward Genetic Approaches in Chlamydia trachomatis
09:03

Forward Genetic Approaches in Chlamydia trachomatis

Published on: October 23, 2013

Area of Science:

  • Immunology
  • Microbiology
  • Infectious Diseases

Background:

  • Complement activation is crucial for natural resistance against pathogens.
  • Properdin regulates the alternative complement pathway and binds to microbial surfaces.
  • Chlamydia pneumoniae causes community-acquired pneumonia and is an obligate intracellular bacterium.

Purpose of the Study:

  • To investigate properdin's role in complement activation on Chlamydia pneumoniae surfaces.
  • To determine if properdin influences Chlamydia pneumoniae infection control.

Main Methods:

  • Studied the binding of human properdin (P₂, P₃, P₄ forms) to Chlamydia pneumoniae.
  • Measured complement activation via C3b and C9 deposition on bacteria.
  • Assessed Chlamydia pneumoniae infection control in HEp-2 cells using properdin-depleted serum.

Main Results:

  • Physiological forms of human properdin directly bind to the Chlamydia pneumoniae surface.
  • Properdin binding accelerates complement activation, evidenced by increased C3b and C9 deposition.
  • Properdin-depleted serum failed to control Chlamydia pneumoniae infection, but function was restored upon properdin addition.

Conclusions:

  • Properdin directly interacts with Chlamydia pneumoniae, promoting complement activation.
  • Properdin plays a significant role in host resistance against Chlamydia pneumoniae infections.
  • Properdin functions as a pattern recognition molecule in the context of Chlamydia infection.