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Zorluk: ZorInfectious Disease Mechanisms

An infectious disease specialist is preparing a grand rounds presentation on the diverse strategies that human pathogens use to evade the host immune system and establish productive infections. The presentation highlights several distinct mechanisms, including the subversion of cellular peptide transport, the secretion of immunomodulatory analogs, escaping intracellular degradation, and the constant alteration of surface antigens. Match the following pathogens to their corresponding primary molecular mechanism of immune evasion or intracellular survival.

  • Epstein-Barr virusSynthesis of an interleukin-10 homolog that inhibits Th1 immune responses and prevents macrophage activation.
  • Herpes simplex virus type 1Production of a protein that binds to and inhibits the transporter associated with antigen processing (TAP), preventing MHC class I loading.
  • *Neisseria gonorrhoeae*Extensive antigenic variation achieved through homologous recombination of silent gene cassettes into an active expression locus.
  • *Listeria monocytogenes*Secretion of a sulfhydryl-activated cytolysin that mediates escape from the phagolysosome into the host cell cytoplasm.

Cevap

Epstein-Barr virus produces an IL-10 homolog; Herpes simplex virus type 1 inhibits the TAP complex; Neisseria gonorrhoeae undergoes pilin antigenic variation; and Listeria monocytogenes secretes a cytolysin to escape the phagolysosome.
Each pathogen has evolved unique molecular mechanisms to establish infection and evade host defenses. Epstein-Barr virus mimics host immunosuppressive cytokines, Herpes simplex virus blocks intracellular antigen presentation, Neisseria gonorrhoeae constantly alters its surface antigens via genetic recombination, and Listeria monocytogenes escapes destruction by physically breaking out of the phagolysosome.

Adım Adım Çözüm

1
Analyze the immune evasion mechanism of Epstein-Barr virus (EBV).
EBV synthesizes a viral IL-10 homolog (BCRF1).
This cytokine analog suppresses Th1 cell activation and macrophage function, promoting viral persistence.
2
Analyze the intracellular survival strategy of Herpes simplex virus type 1 (HSV-1).
HSV-1 produces the ICP47 protein which binds to the Transporter Associated with Antigen Processing (TAP).
Inhibiting TAP prevents the loading of viral peptides onto MHC class I molecules, evading CD8+ cytotoxic T-cell recognition.
3
Identify the primary mechanism of evasion for Neisseria gonorrhoeae.
N. gonorrhoeae evades humoral immunity via extensive antigenic variation of its pili.
This is driven by homologous recombination between silent pilS cassettes and the active pilE expression locus.
4
Determine the pathogenesis of Listeria monocytogenes upon phagocytosis.
L. monocytogenes secretes listeriolysin O, a sulfhydryl-activated cytolysin.
This pore-forming toxin lyses the phagolysosome membrane, allowing the bacteria to escape into the host cell cytosol.

Anahtar Kavram

Specific molecular mechanisms of immune evasion and intracellular pathogenesis used by viral and bacterial pathogens.
Tahmini Süre:1m 30s
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