Viruses Flashcards
What is the capsid of a virus?
A protein shell that protects the viral genome and aids in host cell attachment.
What is the envelope in some viruses?
A lipid bilayer from the host cell membrane with glycoproteins for host cell entry.
What role do viral nucleic acids play?
Encode viral proteins; can be DNA or RNA.
What are viral spikes, and what is their function?
Glycoproteins that mediate host cell attachment and entry.
Give examples of DNA viruses and their associated diseases.
HSV (cold sores), Hep B (hepatitis), varicella zoster (chickenpox).
Give examples of RNA viruses and their associated diseases.
Influenza (flu), Hep C (hepatitis), HIV (AIDS).
What are the steps of the viral replication cycle?
Adsorption: Virus attaches to host receptors.
Penetration: Entry via endocytosis or fusion.
Uncoating: Releases viral genome into cytoplasm.
Synthesis: Host machinery produces viral proteins/nucleic acids.
Assembly: Formation of new virions.
Release: Virions exit via lysis or budding.
Why are viruses obligate intracellular parasites?
They lack enzymes for nucleic acid synthesis and energy production, relying on host machinery.
What is the infection cycle of rotavirus?
Attachment to intestinal epithelial cells.
Entry via endocytosis.
Uncoating and replication in cytoplasm.
Production of double-layered particles.
Release into the intestinal lumen, disrupting epithelial function and causing diarrhea.
Name drugs used for HBV and their targets.
Tenofovir, entecavir (HBV DNA polymerase inhibitors); interferon-alpha (immune modulation).
Name drugs used for HIV and their targets.
NRTIs: Zidovudine (inhibits reverse transcriptase).
NNRTIs: Efavirenz (inhibits reverse transcriptase).
Protease inhibitors: Lopinavir (blocks viral protein processing).
Fusion inhibitors: Enfuvirtide (blocks viral entry).
What are the symptoms of Ebola virus?
Fever, headache, muscle pain, nausea, vomiting, diarrhea, unexplained bleeding/bruising, multiorgan failure, and shock.
How does acyclovir work in DNA chain termination?
Phosphorylated by viral thymidine kinase to acyclovir triphosphate.
Incorporated into viral DNA by DNA polymerase.
Lacks 3’-OH group, causing premature DNA chain termination.
Why is acyclovir selective for infected cells?
It relies on viral thymidine kinase for activation.
What are the uses of acyclovir?
HSV-1 and 2, VZV (chickenpox/shingles), prophylaxis in immunocompromised patients.
