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Chapter 10 Viruses
Chapter 10 vocabulary r/t viruses
67
Microbiology
Not Applicable
11/12/2013

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Term
Obligate intracellular parasite
Definition
Organisms that MUST use a cell to replicate.  Includes: viruses, chlamydias, rickettsias
Term
Capsid
Definition
A viral component made of protein and that surrounds the virus' nucleic acid. 
Term
Envelope
Definition
A membrane that surrounds some viruses made of lipid bilayer.
Term
Virion
Definition
A complete virus particle, which includes an envelope, if it has one.
Term
Genome
Definition
Genetic information
Term
Capsomeres
Definition
Protein subunits that are part of the protein capsid that surrounds a virus.  
Term
Enveloped viruses
Definition
Viruses that have a bilayer membrane outside their capsids.  Viruses that have no bilayer membrane are "naked".
Term
Nucleocapsid
Definition
Comprises the viral genome together with its capsid.
Term
Naked
Definition
A virus with only a nucleocapsid but no envelope, or non-enveloped viruses
Term
Glycoproteins
Definition
The substance that makes up the spikes that are projections found on the envelopes of certain enveloped viruses.
Term
Spikes
Definition
Projections on the envelope of certain enveloped viruses.  Certain spiked viruses cause RBCs to clump.  Useful in virus identification.
Term
Complex viruses
Definition
Viruses with more elaborate coats or capsids.
Term
Bacteriophages
Definition
Viruses that infect bacterial cells.  They have specialized heads, tails, and tail fibers.  The tail fibers are the spikes that the virus uses to attach to the host bacterium.
Term
Host range
Definition
The spectrum of hosts that a virus can infect.
Term
Viral specificity
Definition
Refers to the specific type of cells that a virus can infect.
Term
Positive (+) sense RNA
Definition
One of two types of single-stranded RNA viruses.  Positive sense RNA acts like mRNA and can be translated by the host's ribosomes.
Term

Negative (-) sense RNA

 

Definition
One of two types of single-stranded RNA. Negative sense RNA acts as a template during transcription to make a positive (+) sense RNA (acts like mRNA) AFTER a host cell has been entered.  From there it can be translated by host ribosomes just like positive (+) sense RNA can.
Term
Enteroviruses
Definition
entero, Greek for "intestine", are viruses that can live in the intestine of the host.  
Term
Hepatoviruses
Definition
hepato, Greek for "liver", viruses that infect the liver.
Term
Rhinoviruses
Definition
rhino, Greek for "nose", is one genera of viruses responsible for the common cold.
Term
Reverse transcriptase
Definition
The enzyme used by retroviruses to do reverse transcription where they use their RNA to make dsDNA.  It's called reverse transcription because it is the reverse of the typical transcription step where normally DNA -> RNA in protein synthesis.
Term
Retroviruses
Definition
Enveloped viruses that have two complete copies of (+) sense RNA with which they can do reverse transcription.
Term
Provirus
Definition
Viral DNA that has been incorporated into the chromosomes of the host DNA.
Term
togaviruses
Definition
small, enveloped, polyhedral, (+) sense RNA viruses that multiply in the cytoplasm of many mammalian and arthropod host cells.
Term
Flaviviruses
Definition
Enveloped, polyhedral, (+) sense RNA viruses that are transmitted by mosquitoes and ticks. 
Term
paramyxoviruses
Definition
medium-sized, enveloped, (-) sense RNA viruses with a helical nucleocapsid.
Term
Rhabdoviruses 
Definition
medium-sized, enveloped viruses, whose capsids are helical and so are rod or bullet shaped.
Term
orthomyxoviruses
Definition
medium sized, enveloped, (-) sense RNA viruses that vary in shape and whose genome is segmented into eight pieces.  i.e. influenza virus A.
Term
filoviruses
Definition
Enveloped, filamentous, single (-) sense RNA viruses that can be transmitted from person to person by close contact with blood, semen, and other secretions and by contaminated needles. I.e. ebola.
Term
Bunyaviruses
Definition
Enveloped, (-) sense RNA viruses whose genome has three segments.  Transmitted by arthropods.
Term
Arenaviruses
Definition
Enveloped, (-) sense RNA viruses, but their genome has two segments.  Carried by rodents.  Passed among humans via aerosols or exposure to rat bites or excrement.  
Term
Reoviruses
Definition
naked, polyhedral capsid, medium-sized dsRNA viruses that replicate in the cytoplasm and form distinctive inclusions that stain with eosin.  Includes: orthoreoviruses, orbiviruses, rotaviruses.
Term
Adenoviruses
Definition
Medium-sized, naked, viruses with linear dsDNA that are resistant to chemical agents and are stable from pH 5 to 9 and from 36 degrees celsius and 47 degrees celsius
Term
Herpesviruses
Definition
herpes, Greek for "creeping", relatively large, enveloped viruses with linear dsDNA that cause a broad spectrum of diseases.  Tendency to go latent between relapses.
Term
Latency
Definition
The ability of viruses, like the herpes virus, to remain in host cells, usually in neurons, for long periods and to retain the ability to replicate.
Term
poxviruses
Definition
A group of enveloped viruses with linear dsDNA that are the largest and most complex of all viruses.  Can infect nearly every animal species.  They replicate in parts of the host cell's cytoplasm called viroplasm.
Term
Papovaviruses
Definition
Small, naked, polyhedral dsDNA viruses that replicate in the nuclei of the host cells.  Includes: papilloma, polyoma, vacuolating viruses
Term
Hepadnaviruses
Definition
Small, enveloped, mostly dsDNA (partially ssDNA) viruses.  They cause liver infection.
Term
parvoviruses
Definition
Small,naked, linear ssDNA viruses.  Their genetic information is so limited that they must enlist the aid of an unrelated helper virus or a dividing host cell to replicate.  Three genera: dependovirus, parvovirus, erythrovirus.
Term
Emerging viruses
Definition
Recently discovered and unexpected viruses that were previously endemic but that has expanded its host range to become potential pandemic.
Term
Phage therapy
Definition
The use of phages aka bacteriophages (viruses that infect bacteria) to treat bacterial disease.
Term
Replication cycle
Definition

1. Absorption - virus attaches to host cell

2. Penetration - entry of virions or their genome into host cell

3. Synthesis - Use of cell machinery to make new parts

4. Maturation - assembly of viral the synthesized components

5. Release - departure of new virions from host cell.

Term
Virulent (lytic) cycle
Definition
Phages that lyse its host cell upon release of new viruses.
Term
Lytic cycle
Definition
The replication process of the type of viruses that end with the lysing of the host cell.
Term
Burst time
Definition
Time from absorption to release of a virus' lytic cycle.
Term
Viral yield aka burst size
Definition
The number of new virions released from each bacterial host.
Term
Replication curve
Definition
Curve that describes and represents viral growth which includes an eclipse period (penetration through biosynthesis) and a latent period (from penetration through phage release).  
Term
Plaque assay
Definition
A way for virologists to estimate phage number using serial dilutions and inoculating them onto a series of plates containing a susceptible bacterial lawn (a layer of bacteria).  After incubation the plaques are counted since they represent the areas where viruses have lysed host cells.
Term
Plaques
Definition
Each plaque represents the progeny from one infectious phage... such counts are reported as plaque-forming units (pfu).
Term

Plaque forming units

(PFU)

Definition
The estimate count of phages based on the number of plaques seen on a plate
Term
Temperate phages
Definition
Bacterial attacking viruses that do not necessarily undergo a lytic cycle with its host
Term
Lysogeny
Definition
A stable, long-term relationship between a phage and its host in which the phage nucleic acid becomes incorporated into the host nucleic acid
Term
Prophage
Definition
Is the viral DNA within the bacterial chromosome placed there by the phage during its lysogenic state
Term
Lysogen
Definition
The combination of a bacterium and a temperate phage
Term
Lysogenic conversion
Definition
When "immunity" is given to a lysogen by its phages that "protects" it from other phages of that same type (same DNA) 
Term
Lysogenic cycle
Definition
The growth of lysogens, meaning, when a bacterial host with phage DNA in its chromosomes undergoes its binary fission the phage DNA gets replicated along with its own and passed down this way.  If the phage activates the lytic cycle in any of the daughter cells will by lysed by these phages when they break out.
Term
Induction
Definition
The term used for when a dormant phage becomes active and initiates the lytic cycle.  Reasons: lack of nutrients, presence of chemical toxins, or some other reason for the virus to seek greener pastures elsewhere
Term
Uncoating
Definition
When the viral genome of an animal virus separates from its protein coat so it can enter the host
Term
Monolayers
Definition
a layer of cells one cell thick that is spread on a plastic surface.  It is used for culturing animal viruses.
Term
Subculturing
Definition
The process by which cells from an existing culture are transferred to new containers with fresh nutrient media
Term
Tissue culture
Definition
AKA cell culture: The technique of sub-culturing animal tissue for the study of animal viruses
Term
Primary cell cultures
Definition
are cultures obtained directly from the animal and are not subcultured
Term
Cell strain
Definition
What is produced from a primary cell culture when it is repeated and one type becomes dominant
Term
diploid fibroblast strains
Definition
Immature animal cells that produce collagen and other fibers as well as the substance of connective tissues, such as the dermis of the skin...  derived from fetal tissue they retain the ability to divide rapidly
Term
continuous cell line
Definition
cells that will reproduce for an extended number of generations, i.e. the HeLa cell line which has been maintained and grown in culture since 1951 and has been used in research world wide
Term
cytopathic effect (CPE)
Definition
The visible effect viruses have on cells
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