Introduction to Virology Flashcards
(25 cards)
Name examples of enveloped viruses.
Influenza virus, HIV, SARS-CoV.
What types of nucleic acid can viral genomes be made of?
DNA or RNA, single- or double-stranded, circular or linear, sometimes segmented.
What is the typical viral life cycle?
Attachment → Entry → Uncoating → Replication → Assembly → Release.
How is viral infectivity commonly measured?
Using a plaque assay, which counts areas of infected and lysed cells (e.g., on HeLa cells with Poliovirus).
What are the four major outcomes of viral infection in animal cells?
Lytic infection, persistent (chronic) infection, latent infection, and transformation.
What happens during a lytic infection?
Host cells are destroyed; viruses are released and usually cleared within days, leading to immunity.
What happens in a persistent (chronic) infection?
Virus is slowly released without killing the cell, often not cleared due to weak immune response.
What is a latent infection?
A dormant virus remains in the host for life, reactivating under stress (e.g., HSV cold sores reactivated by UV).
What is transformation in viral infection?
Virus alters host cell growth, potentially causing tumors (e.g., SV40 T antigen).
What are the two main modes of viral transmission?
Direct (contact, fluids, vertical) and indirect (food, water, aerosols).
Give examples of viruses transmitted directly.
Herpes (HSV), HIV, Hepatitis B, Epstein-Barr Virus (EBV).
Give examples of viruses transmitted indirectly.
Norovirus (via oysters), Poliovirus, Influenza, Rhinovirus.
What is the host range determined by?
The virus’s ability to bind specific surface receptors on host cells.
What kinds of organisms can viruses infect?
All living organisms including animals, plants, fish, insects, bacteria, and even fungi.
What is virology the study of?
The interaction between viruses and their host cells.
What is a virus?
A submicroscopic, obligate intracellular parasite that lacks machinery for energy production and protein synthesis, and depends on a host to replicate.
What is the typical size range of viruses?
0.02 to 0.3 micrometers (µm); even the largest virus is smaller than the smallest bacteria.
What are virus particles called when outside the host cell?
Virions.
What are the two major types of viruses based on structure?
Non-enveloped (naked) viruses and enveloped viruses.
What surrounds the genome in a non-enveloped virus?
A protein capsid made of repeating subunits called capsomeres.
Why do non-enveloped viruses have a capsid?
To protect the genome from physical, chemical, and enzymatic damage and to help deliver the genome to host cells.
What are two examples of symmetrical shapes of virus capsids?
Icosahedral (spherical) and helical (rod-like).
Name examples of viruses with icosahedral symmetry.
Herpesvirus, Poliovirus, Rhinovirus.
Name examples of viruses with helical symmetry.
Tobacco Mosaic Virus (TMV), Rabies virus.
