Sections
                          Key Terms
                      Key Terms
- acellular
 - lacking cells
 
- acute disease
 - disease where the symptoms rise and fall within a short period of time
 
- asymptomatic disease
 - disease where there are no symptoms and the individual is unaware of being infected unless lab tests are performed
 
- attenuation
 - weakening of a virus during vaccine development
 
- AZT
 - anti-HIV drug that inhibits the viral enzyme reverse transcriptase
 
- back mutation
 - when a live virus vaccine reverts back to it disease-causing phenotype
 
- bacteriophage
 - virus that infects bacteria
 
- budding
 - method of exit from the cell used in certain animal viruses, where virions leave the cell individually by capturing a piece of the host plasma membrane
 
- capsid
 - protein coating of the viral core
 
- capsomere
 - protein subunit that makes up the capsid
 
- cell necrosis
 - cell death
 
- chronic infection
 - describes when the virus persists in the body for a long period of time
 
- cytopathic
 - causing cell damage
 
- envelope
 - lipid bilayer that envelopes some viruses
 
- fusion
 - method of entry by some enveloped viruses, where the viral envelope fuses with the plasma membrane of the host cell
 
- gall
 - appearance of a plant tumor
 
- gene therapy
 - treatment of genetic disease by adding genes, using viruses to carry the new genes inside the cell
 
- group I virus
 - virus with a dsDNA genome
 
- group II virus
 - virus with a ssDNA genome
 
- group III virus
 - virus with a dsRNA genome
 
- group IV virus
 - virus with a ssRNA genome with positive polarity
 
- group V virus
 - virus with a ssRNA genome with negative polarity
 
- group VI virus
 - virus with a ssRNA genomes converted into dsDNA by reverse transcriptase
 
- group VII virus
 - virus with a single-stranded mRNA converted into dsDNA for genome replication
 
- horizontal transmission
 - transmission of a disease from parent to offspring
 
- hyperplasia
 - abnormally high cell growth and division
 
- hypoplasia
 - abnormally low cell growth and division
 
- intermittent symptom
 - symptom that occurs periodically
 
- latency
 - virus that remains in the body for a long period of time but only causes intermittent symptoms
 
- lysis
 - bursting of a cell
 
- lysogenic cycle
 - type of virus replication in which the viral genome is incorporated into the genome of the host cell
 
- lytic cycle
 - type of virus replication in which virions are released through lysis, or bursting, of the cell
 
- matrix protein
 - envelope protein that stabilizes the envelope and often plays a role in the assembly of progeny virions
 
- negative polarity
 - ssRNA viruses with genomes complementary to their mRNA
 
- oncogenic virus
 - virus that has the ability to cause cancer
 
- oncolytic virus
 - virus engineered to specifically infect and kill cancer cells
 
- pathogen
 - agent with the ability to cause disease
 
- permissive
 - cell type that is able to support productive replication of a virus
 
- phage therapy
 - treatment of bacterial diseases using bacteriophages specific to a particular bacterium
 
- positive polarity
 - ssRNA virus with a genome that contains the same base sequences and codons found in their mRNA
 
- prion
 - infectious particle that consists of proteins that replicate without DNA or RNA
 
- productive
 - viral infection that leads to the production of new virions
 
- prophage
 - phage DNA that is incorporated into the host cell genome
 
- PrPc
 - normal prion protein
 
- PrPsc
 - infectious form of a prion protein
 
- replicative intermediate
 - dsRNA intermediate made in the process of copying genomic RNA
 
- retrovirus
 - virus with an RNA genome that must be reverse transcribed into DNA before being incorporated into the host cell genome
 
- reverse transcriptase
 - enzyme found in Baltimore groups VI and VII that converts single-stranded RNA into double-stranded DNA
 
- vaccine
 - weakened solution of virus components, viruses, or other agents that produce an immune response
 
- vertical transmission
 - transmission of disease between unrelated individuals
 
- viral receptor
 - glycoprotein used to attach a virus to host cells via molecules on the cell
 
- virion
 - individual virus particle outside a host cell
 
- viroid
 - plant pathogen that produces only a single, specific RNA
 
- virus core
 - contains the virus genome