Diversity of PRRs and the Types of PAMPs They Detect

Pattern recognition receptors (PRRs) are a diverse group of proteins that play a crucial role in detecting conserved molecular patterns associated with various pathogens. Here are different families of PRRs and the types of infectious diseases they recognize:

1. Toll-Like Receptors (TLRs):
   • Recognition: TLRs recognize a variety of microbial components, including bacterial lipopolysaccharide (LPS), peptidoglycan, flagellin, viral dsRNA, and CpG DNA motifs.
   • Infectious Diseases: Recognize a broad range of pathogens, including bacteria, viruses, fungi, and parasites.
2. NOD-Like Receptors (NLRs):
   • Recognition: NLRs often sense intracellular pathogens or cellular stress and damage, recognizing components like bacterial peptidoglycan and viral RNA.
   • Infectious Diseases: Involved in the detection of intracellular pathogens such as bacteria and viruses.
3. RIG-I-Like Receptors (RLRs):
   • Recognition: RLRs, including RIG-I and MDA5, recognize viral RNA, especially dsRNA.
   • Infectious Diseases: Primarily involved in the detection of RNA viruses.
4. C-Type Lectin Receptors (CLRs):
   • Recognition: CLRs recognize various carbohydrate structures, including β-glucans, mannans, and other fungal cell wall components.
   • Infectious Diseases: Important for the detection of fungal pathogens and some bacterial pathogens.
5. AIM2-Like Receptors (ALRs):
   • Recognition: ALRs, including AIM2, detect cytoplasmic DNA, especially dsDNA.
   • Infectious Diseases: Involved in the detection of intracellular pathogens, including some DNA viruses and certain bacteria.
6. Cyclic GMP-AMP Synthase (cGAS):
   • Recognition: cGAS recognizes cytoplasmic DNA and catalyzes the synthesis of cyclic GMP-AMP (cGAMP), leading to the activation of the STING pathway.
   • Infectious Diseases: Involved in the detection of DNA viruses, bacteria, and parasites.
7. Nucleotide-Binding Oligomerization Domain (NOD):
   • Recognition: NOD proteins, part of the NLR family, recognize bacterial peptidoglycan components.
   • Infectious Diseases: Important for detecting bacterial pathogens.
8. Retinoic Acid-Inducible Gene I (RIG-I) and Melanoma Differentiation-Associated Gene 5 (MDA5):
   • Recognition: RIG-I and MDA5 recognize viral RNA, particularly in the cytoplasm.
   • Infectious Diseases: Primarily involved in the detection of RNA viruses.

These families of PRRs collectively contribute to the immune system’s ability to recognize a wide range of pathogens, including bacteria, viruses, fungi, and parasites. The specificity of each family allows the immune system to distinguish between different types of infectious agents and mount appropriate responses.

Next Topic: Cellular Responses Downstream of PAMP Recognition

Source: ChatGPT response prompted and edited by Joel Graff.

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