9.1 VIRO INTRO Flashcards
What is the smallest infectious agent?
Viruses
What is the size range of viruses?
20 nm to 300 nm in diameter
Which virus is the only one visible under a light microscope?
Pox virus
Which virus is the largest of all viruses?
Pox virus
What type of microscope is typically used to view viruses?
Electron microscope
Where are electron microscopes commonly found?
Research-based laboratories
What are viruses made of?
One type of nucleic acid (RNA or DNA) encased in a protein shell
Which nucleic acid does SARS-CoV-2 contain?
RNA
Which nucleic acid do hepatitis B, herpes, pox, papilloma (HPV), and parvovirus contain?
DNA
Why are viruses considered intracellular parasites?
They are inactive outside the host and replicate only in living cells
What is the mode of virus multiplication?
Replication of genome inside a host cell
What are the two main types of viral structures?
Icosahedral (Piattos-like) and Helical (coil-like)
What are the two types of viral envelopes?
Enveloped and Non-enveloped (naked)
What are the two types of viral genomes?
RNA and DNA
Can a virus contain both RNA and DNA?
No
What are the two strategies of viral replication?
Positive sense and Negative sense
What determines the host range of a virus?
Receptor specificity (Lock and Key Theory)
What type of viruses infect bacteria?
Bacteriophages
What is an example of a virus with a specific host range?
HIV (infects immune cells like lymphocytes and macrophages)
Protein shell, or coat, that encloses the nucleic acid genome
Capsid
Clusters of polypeptides that do not necessarily correspond to chemically defined structural units
Capsomeres
Virus particle that is functionally deficient in some aspect of replication
Defective virus
An example of a defective virus that requires hepatitis B virus to replicate
Hepatitis D
The specific component that hepatitis D lacks
Hepatitis B surface antigen (HBsAg)
Lipid-containing membrane that surrounds some virus particles
Envelope
Process by which viruses acquire an envelope from the host cell
Budding
Virus-encoded glycoproteins exposed on the surface of the envelope
Peplomers
The packaged form of the viral genome consisting of protein and nucleic acid
Nucleocapsid
Basic protein building blocks of the viral coat, made of more than one nonidentical protein subunit
Structural units (Protomer)
A single folded viral polypeptide chain
Subunit
A complete virus particle that transfers viral nucleic acid from one cell to another
Virion
Viruses in which the virion is identical to the nucleocapsid
Papillomaviruses, Picornaviruses
Viruses in which the nucleocapsid is separate from the envelope
Herpesviruses, Orthomyxoviruses
Theory stating that viruses originated from host DNA or RNA components that evolved to replicate independently
First theory of viral origin
Theory stating that viruses may be degenerate forms of intracellular parasites
Second theory of viral origin
The structural classification of a virion as either icosahedral or helical
Virion morphology
The classification of a virus based on whether it has RNA or DNA
Virus genome properties
The classification of a virus based on its susceptibility to ether or organic solvents
Physicochemical properties
The type of viruses that are susceptible to destruction by organic solvents like ether and alcohol
Enveloped viruses
The classification of a virus based on the structure and function of its proteins
Virus protein properties
The classification of a virus based on how its genome is organized and replicated
Genome organization and replication
The classification of a virus based on its antigenic makeup
Antigenic properties
The classification of a virus based on its biological behavior, such as host range and transmission
Biologic properties
The hierarchical system that divides viruses into orders, families, subfamilies, genera, and species
Universal system of virus taxonomy
The category in viral taxonomy that groups virus families sharing common characteristics
Order
An example of an order that includes Bornaviridae, Filoviridae, Paramyxoviridae, and Rhabdoviridae
Mononegavirales
The major viral grouping based on virion morphology, genome structure, and replication strategy
Family
The viral classification that subdivides families based on biological, genomic, physicochemical, or serologic differences
Genus
The symmetry and shape of all DNA viruses except pox viruses
Icosahedral
The symmetry and shape of pox viruses
Complex and brick-shaped
The symmetry of most RNA viruses except picornaviruses
Helical
The only RNA virus family that has a double-stranded RNA genome
Reoviridae
The human virus that infects immature erythrocytes and causes ‘slap cheek disease’
Parvovirus B19
The virus family under picornaviruses
Polyomaviridae
The HPV types associated with cervical cancer
HPV 16 and 18
The only viral family that includes a virus causing hepatitis
Hepadnaviridae
