Advanced Course in Immunology On Demand Lecture Recordings-Immune Response to Viruses

Video Transcription

Video Summary

The speaker gave a broad overview of how organisms detect and respond to viral infection. The talk emphasized that viruses are especially challenging because they are obligate intracellular pathogens and often resemble host molecules, so the immune system must carefully distinguish self from non-self without causing excessive damage.<br /><br />The lecture began with barriers to infection, such as skin, mucus, pH, microbiota, and tissue-specific features that block pathogens before they enter cells. Once viruses breach these barriers, cells rely on pattern recognition receptors to detect viral products. The most important viral signals discussed were nucleic acids: double-stranded RNA, 5′ triphosphate RNA, unusual RNA structures, and cytoplasmic DNA. Sensors such as Toll-like receptors, RIG-I/MDA5, PKR, OAS, cGAS, and STING were highlighted as key detectors that trigger antiviral signaling.<br /><br />These pathways activate interferons, especially type I and type III interferons, which induce hundreds of interferon-stimulated genes and create an antiviral state. The speaker noted that different interferon types may be specialized for different tissues, especially barrier tissues like the gut, lung, and placenta.<br /><br />The talk then described innate immune cells, including macrophages, dendritic cells, and NK cells, which help amplify early defense and link innate and adaptive immunity. Finally, it covered adaptive immunity: CD4 T cells coordinate responses, CD8 T cells kill infected cells, and B cells produce neutralizing antibodies. Throughout, the speaker stressed that viruses evolve antagonists to these defenses, driving an ongoing arms race between pathogen and host.

Asset Subtitle

Lecture 19: Sara Cherry, University of Pennsylvania

Immune Response to Viruses

Asset Caption

Sara Cherry, University of Pennsylvania Perelman School of Medicine
Immune Response to Viruses

Keywords

viral infection

innate immunity

pattern recognition receptors

interferons

type I interferon

type III interferon

double-stranded RNA

cGAS-STING pathway

RIG-I MDA5

natural killer cells

CD8 T cells

neutralizing antibodies