| What is PCR? |
Exponential (2^n) amplification of DNA |
| What are three methods to use in growth and assay of viruses? |
Cytopathic Effect (CPE); Plaque Assay; Molecular techniques (PCR) |
| What is the plaque assay used for? |
To determine viral titres; PFU's (show and tell) |
| T or F: All viruses produce Cytopathic effect (CPE) |
False; most do but not all |
| What definition: The characteristic morphological changes which occur
in the cell due to the infection of a particular virus. |
Cytopathic Effect (CPE) |
| T or F: Growth and assay of viruses requires a high multiplicity of
infection (MOI) |
TRUE |
| The reproductive cycles of ALL viruses exhibit what common feature?
|
One-step growth curve |
| What is the singlemost important thing produced by viruses that gives
them the ability to multiply and determines the fate of the infected cell?
|
The synthesis and function of the VIRAL PROTEINS |
| What type of infection: The infection and subsequent lysis of
susceptible cells by a virus. |
Lytic |
| What type of infection: The abnormal growth of cells resulting from
the continuous expression of one or more viral genes. |
Viral Transformation |
| What type of infection: The virus persists in the cell in a
noninfectious form. |
Latent |
| What type of infection: The infection of a cell which does NOT result
in the multiplication of infectious viral progeny. |
Abortive |
| What type of infection: The infection of a receptive cell with a virus
particle which results in the MULTIPLICATION of infectious viral progeny.
|
Productive |
| Name the 5 types of Infections: |
1. Productive; 2. Abortive; 3. Latent; 4. Viral transformation; 5.
Lytic |
| What determines host range? (2 things) |
1. Cellular Receptors (specificity of attachment); 2. Host
intracellular factors |
| T or F: Sometimes the target cells are at the portal of entry. |
TRUE (ie, influenza, gets into airway and stays there) |
| What are the cells called that are targeted by the virus and result in
clinical disease? |
Target cells (ie CNS and HSV) |
| Cells that become immediately infected are susceptible cells at the
______ ___ __________. |
Portal of Entry |
| What definition? The capacity of a cell or animal to become infected.
|
Susceptibility |
| What definition? The spectrum of cells which can be productively
infected by a given virus. |
Tissue tropism |
| What definition? The kinds of tissue cells and animal species that a
virus can productively infect. |
Host Range |
| Steps to multiply a virus |
cell entry, genome replication, viral particle assembly, Egress
(escape from host cell) |
| No clearly identifiable capsid. But several coats around the nucleic
acid. An example is _______ |
Complex virion, poxviruses |
| Enveloped virus w/ helical symmetry, the _____ is coiled w/in the
________. An example is ______ |
Nucleocapsid, envelope, orthomyxoviruses (influenza) |
| Enveloped virus w/ icosahedral symmetry, the _____ is surrounded by
the ________. An example is ______ |
capsid, envelope, herpes |
| Morphological subunits that can be seen when capsid is broken (hard to
"see" in an intact virus). Surface structures composed of 5-6 protein
molecules |
Capsomeres |
| Symmetry observed w/ spherically shaped viruses. Involves the packing
together of many identical subunits. (soccer ball) |
Icosahedral symmetry (or cubic symmetry) |
| Can helical particles form w/o the genome? |
No |
| Helical symmetry examples (5) |
influenza, measles, mumps, rabies, poxviruses (also tobacco mosaic
virus - non animal) |
| The capsid of a virus composed of many copies of a single kind of
protein subunit arranged in a close-packed helix |
Helical symmetry |
| The simplest viral symmetry (proteins bind to nucleic acid not a
capsule) |
Helical symmetry |
| The symmetry observed w/ cylindrical viruses (like a slinky) |
Helical symmetry |
| The structure of the capsid &/or envelope (spikes) has important
implications for (3 things) |
adsorption, hemagglutination (used for ID), recognition of viruses by
neutralizing antibodies |
| Virion structural protein which locates on the cytoplasmic side of the
transmem glycoprotein spike. It attracts the completed nucleocapsid for
mem fusion. |
matrix protein |
| Protein or glycoprotein structure(s) which emanates from the surface
of the virus particle |
Spikes |
| The lipid bilayer & associated glycoproteins that surround many
types of virus particles |
Envelope |
| The capsid & nucleocapsid are composed of ___ or at most ___
different kinds of proteins in a crystalline array. Why? |
1, a few. Small genome - rest of genome for intracellular activity |
| The complete protein-nucleic acid complex that is the packaged from of
the genome in a virus particle |
Nucleocapsid |
| The protein shell directly surrounding the viral nucleic acid. |
Capsid |
| The association of core proteins & the genome is required to
_______ the viral genome during viral ______ & virion _______ |
condense, assembly, formation |
| The _____ is the association between nucleic acid & basic proteins
either coded by the virus or histones from the host cell |
core |
| Retroviruses have a ______ genome |
diploid (2 identical copies of the genome - i.e. HIV) |
| The viral genome can have 3 basic morphologies |
linear, circular, segmented |
| The viral genome can be ______ or ______ stranded |
double, single |
| The ability of viruses to pass through ______ is used to ID an unknown
infectious agent as a bact or virus. |
filter |
| The largest virus |
poxvirus (300 nm) |
| The smallest virus |
parvovirus (20 nm) |
| viruses are _____-_____ times smaller then the cells they infect |
100-1000 |
| A virus is an __________ parasite |
intracellular |
| One (complete) virus particle |
Virion |
| A virus is made up of ________ & _________ |
genes (RNA or DNA) & protein-containing coat |
