Page last updated: 2024-10-24

detection of molecule of bacterial origin

Definition

Target type: biologicalprocess

The series of events in which a stimulus from a molecule of bacterial origin is received and converted into a molecular signal. [GOC:add, GOC:rl]

The detection of molecules of bacterial origin involves a complex interplay of innate and adaptive immune responses. Here's a detailed breakdown of the process:

**1. Recognition of Bacterial Molecules:**

* **Pattern Recognition Receptors (PRRs):** Immune cells possess PRRs that recognize conserved molecular patterns found on bacteria, known as pathogen-associated molecular patterns (PAMPs). These PAMPs include:
* **Lipopolysaccharide (LPS):** Found on the outer membrane of gram-negative bacteria.
* **Peptidoglycan (PGN):** Found in the cell walls of both gram-positive and gram-negative bacteria.
* **Flagellin:** A protein component of bacterial flagella.
* **Lipoproteins:** Found on the surface of bacteria.
* **Toll-like Receptors (TLRs):** TLRs are a key type of PRR that bind to specific PAMPs. For example, TLR4 recognizes LPS, TLR2 recognizes PGN, and TLR5 recognizes flagellin.

**2. Innate Immune Response:**

* **Activation of Immune Cells:** When PRRs bind to PAMPs, they trigger signaling pathways within immune cells, leading to the production of cytokines and chemokines. These molecules help to:
* **Recruit other immune cells:** Neutrophils, macrophages, and dendritic cells are attracted to the site of infection.
* **Initiate inflammation:** Inflammation helps to contain the infection and facilitate tissue repair.
* **Activate adaptive immunity:** Dendritic cells present bacterial antigens to T cells, initiating adaptive immune responses.

**3. Adaptive Immune Response:**

* **Antigen Presentation:** Dendritic cells process and present bacterial antigens to T cells, which are specialized immune cells responsible for recognizing specific pathogens.
* **T Cell Activation:** T cells recognize specific antigens displayed on MHC molecules (major histocompatibility complex) on the surface of dendritic cells. This activation leads to:
* **CD4+ T cell differentiation:** Helper T cells (Th) differentiate into different subsets, such as Th1 and Th17, which secrete cytokines that support the immune response.
* **CD8+ T cell differentiation:** Cytotoxic T cells (CTLs) kill infected cells.
* **B Cell Activation:** Helper T cells also activate B cells, which produce antibodies that specifically bind to bacterial antigens. These antibodies help to:
* **Neutralize bacteria:** Antibodies can bind to bacterial toxins and prevent them from harming cells.
* **Opsonize bacteria:** Antibodies coat bacteria, making them more easily phagocytosed by immune cells.
* **Activate complement:** Complement is a system of proteins that can directly kill bacteria or help to opsonize them.

**4. Immune Memory:**

* **Long-lasting Immunity:** The adaptive immune response generates memory B and T cells that can rapidly respond to future encounters with the same bacterial pathogen, providing long-lasting immunity.

**5. Bacterial Evasion of the Immune System:**

* **Antibiotic Resistance:** Bacteria have developed mechanisms to resist antibiotics, making treatment more difficult.
* **Capsular Polysaccharides:** Some bacteria produce capsules that mask their surface PAMPs from the immune system.
* **Biofilms:** Bacteria can form biofilms, which are communities of bacteria encased in a protective matrix, making them more resistant to immune responses.

**6. Detection Techniques:**

* **Microscopy:** Direct visualization of bacteria using light microscopy or electron microscopy.
* **Culture:** Growing bacteria in laboratory media to identify their characteristics.
* **Molecular Techniques:** Using PCR or other molecular techniques to detect bacterial DNA or RNA.
* **Serological Tests:** Detecting antibodies against specific bacterial antigens in the blood.

**Note:** This is a complex and multifaceted process, and variations exist depending on the specific bacteria and the host's immune system.'
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Proteins (1)

ProteinDefinitionTaxonomy
Toll-like receptor 9A Toll-like receptor 9 that is encoded in the genome of human. []Homo sapiens (human)

Compounds (1)

CompoundDefinitionClassesRoles
hydroxychloroquinehydroxychloroquine : An aminoquinoline that is chloroquine in which one of the N-ethyl groups is hydroxylated at position 2. An antimalarial with properties similar to chloroquine that acts against erythrocytic forms of malarial parasites, it is mainly used as the sulfate salt for the treatment of lupus erythematosus, rheumatoid arthritis, and light-sensitive skin eruptions.

Hydroxychloroquine: A chemotherapeutic agent that acts against erythrocytic forms of malarial parasites. Hydroxychloroquine appears to concentrate in food vacuoles of affected protozoa. It inhibits plasmodial heme polymerase. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p970)
aminoquinoline;
organochlorine compound;
primary alcohol;
secondary amino compound;
tertiary amino compound
anticoronaviral agent;
antimalarial;
antirheumatic drug;
dermatologic drug