3.1, 3.2 Virology Basics Flashcards
A virus is an infectious __________________ parasite comprising ___________ surrounded by a ___________ and/or an __________ derived from a host __________________.
obligate intracellular; genetic material (DNA or RNA); protein coat; envelope; cell membrane
what protects the viral nucleic acid genome
protein coat
How do viruses replicate
inside host cells
All viruses must make __________, to be translated by ____________
mRNA; host ribosomes
T/F viruses are dependent on the infected cell ribosomes to synthesize viral proteins
T; this is partly why they are obligate intracellular parasites
T/F viruses can use the host cell to provide energy for replication, or they can use their own energy sources
F; they are absolutely dependent on the host to provide energy
Viruses are ABSOLUTELY DEPENDENT on the host for what (2)
1) ribosomes to translate their viral mRNA into viral proteins
2) energy for viral replication
What is the difference between virus and virion
Virus is a broad term to describe the viral particles in any stages, as well as the nucleic acids and proteins; virion refers exclusively to the physical particle in its extra-cellular phase
what are 2 similarities between viruses and bacteria
1) both have either DNA or RNA (bacteria have both)
2) both CAN be obligate intracellular pathogens (all viruses and some bacteria)
T/F you can see viral particles with a light microscope
F; however, you can see cytoplasmic or nuclear aggregates of viral particles/nucleic acids on light microscopy
what are the 4 basic components of viruses
1) viral genome (DNA or RNA)
2) proteins (structural or non-structural)
3) lipids (form the envelope of some viruses)
4) carbohydrates (glycolipids or glycoproteins)
what are 4 ways to CLASSIFY viruses
1) nature and sequence of nucleic acid
2) diameter or shape
3) symmetry of protein shell
4) presence or absence of lipid envelope
what 3 terms can be used to describe the symmetry of a viral protein shell
icosahedral, helical, complex
what is the outermost surface of a non-enveloped virus
the capsid
what is the outermost surface of an enveloped virus? what does it contain?
lipid bilayer envelope; contains viral glycoproteins
are enveloped or non-enveloped viruses more stable outside the host
non-enveloped
T/F non-enveloped (naked) viruses are rapidly inactivated by solvents, detergents, and bile salts
F; enveloped viruses are
are most enteric animal viruses enveloped or non-enveloped
enveloped
what are the consequences of asymptomatic or subclinical viral infections
persistent infection, immunity or recovery
what are the consequences of acute viral infection/disease
death, recovery or persistent infection
what are the consequences of chronic viral infection/disease
recurrent clinical disease or persistent infection
what are the stages of viral replication
1) recognition
2) attachment
3) penetration
4) uncoating
5) mRNA synthesis
6) protein synthesis
7) genome replication
8) assembly
9) lysis and release (naked) OR budding and release (enveloped)
what influences tissue tropism for viral infection
presence of cellular receptors that permit entry of the virus