Micro Lecture 4 Flashcards
General charact. of viruses?
Contain DNA or RNA, protein coat, few or no enzymes for metabolism
Virion
Complete, fully developed, capable of infection
Parts of virion
Nucleic acid, capsid, envelope, spikes
What is capsid composed of?
Capsomeres (proteins), promotes virus’ attachment to host cell
Envelope
Covers capsid in some viruses, lipid/protein/carb coating
Spikes
Allow viral attachment to host, means of identification, enables hemagglutination
Name general morphology of viruses:
Helical: rabies, ebola
Polyhedral: adenovirus, poliovirus
Enveloped: influenza, herpes
Complex: bacteriophages, poxviruses
What is cytopathic effect?
Observed deterioration of virally infected cells (normal cells grow in monolayer, transformed cells fuse), stops cell synthesis
How are viruses identified?
Serological: Western blot
Nucleic acids: Restriction Fragment Length Polymorphisms, PCR
What occurs during lytic cycle?
Phage causes lysis and death of host cell
What occurs during lysogenic cycle?
Dormant/latent phase. Phage DNA incorporated into host DNA, specialized transduction.
What are the results of lysogeny?
Immunity of lysogenic cells to reinfection by same phage.
Phage conversion.
Specialized transduction (bact. genes transferred to another bacterium via phage).
What are stages of multiplication of animal viruses?
Attachment –> entry –> uncoating –> biosynthesis –> maturation –> release
Adenoviridae
dsDNA, nonenveloped ***EYE INFECTIONS / VIRAL CONJUNCTIVITIS
Poxviridae
dsDNA, enveloped (smallpox)
Herpesviridae
dsDNA, enveloped, ***Epstein-Barr
Papovaviridae
dsDNA, noneveloped, **HPV
Hepadnaviridae
dsDNA, enveloped, Hep B ***uses reverse transcriptase
Picornaviridae
ssRNA, + strand, nonenveloped, poliovirus
Togaviridae
ssRNA, + strand, enveloped, rubella
Rhabdoviridae
ssRNA, - strand, enveloped, rabies
Reoviridae
dsRNA, nonenveloped, rotavirus
Retroviridae
ssRNA, enveloped, HIV, ***uses reverse transcriptase
What are oncogenes responsible for?
Transforming normal cells to cancer cells
What is in transformed cell?
TSTA- tumor specific transplant antigen on surface or T antigen in nucleus
What are some cytopathic effects?
Stops cell synthesis
Loss of contact inhibition (transformation)
Interferons (alpha, beta) to protect uninfected cells
Antigenic changes on cell surface
What is a fusing of cells?
Synctium
What are interferons? What are the 3 types?
Cytokines produced by lymphocytes and macrophages; are antiviral. IFN alpha/beta cause cells to make antiviral proteins. IFN gamma cause neutrophils/macrophages to kill bact.
Give an example of cell-mediated immunity.
Cytotoxic T-lymphocyte: kills self-cells altered by infection
What are 3 things a vaccine does?
- primary immune response
- antibodies and memory cells
- rapid, intense secondary response
What are antimicrobial biocides effective against?
Lipid-soluble, enveloped host viruses
What do entry and fusion inhibitor antivirals do?
Block receptors on host cell that bind to virus / block fusion of virus and cell
What do nucleic acid inhibitor antivirals do?
Analogs inhibit DNA/RNA synthesis
What do protease inhibitor antivirals do?
Block cleavage of protein precursors
What do exit inhibitor antivirals do?
Inhibit enzyme required for virus to bud from host. ***Tamiflu
Define antiretroviral
RNA, requires reverse transcriptase
What are viroids?
Short pieces of naked DNA
What is a virion?
A complete infectious particle
