Concepts of Viruses Flashcards
Define virus
Infectious agent of small size
Multiply only in living cells of animals, plants, bacteria
Obligate parasites - metabolically inert when outside host
All rely on metabolic processes of host to reproduce
Viral disease = interaction b/w virus and host
What does a mature virus particle consist of?
Central core of NA covered with protein rich coat
What is required for viral reproduction?
Host cell + DNA or RNA
reproduce solely from their NA
Why can’t a virus grow and multiply outside the host cell?
Lack metabolic activity = metabolically inert
Does a virus have ribosomes?
No
viral genome is capable of utilizing normal cellular machinery for synthesis of viral components
What are two ways a virus can manipulate the host cell?
- integrate their DNA genome into the host genome
2. some lead to transformation of the host cell
What are some important concepts generated from virus involvement?
- Role of animal virus in understanding basic concepts of eukaryotic gene expression
- Role of animal virus in recombinant DNA tech
- Role of animal viruses in oncology
- Vaccine development
- Gene therapy
Capsomere
individual protein of a capsid
Capsid
protein shell that encloses the viral NA
procapsid
capsid w/o viral genome
core
central part of virus containing the genome
Nucleocapsid
NA surrounded by capsid protein/s
genome + capsid
Envelope
Bi-lipid membrane containing virus derived proteins enclosing the capsid
Not all viruses have one
Composed of proteins, lipids, and CHO
Some proteins from the host cell and some from the virus
Peplomer
glycoprotein spike protruding from virus capsid.
Bind to specific receptors on a host cell
Reverse transcriptase
What virus group has this?
enzyme that generates DNA from RNA template
Retroviruses
Virion
Virus particle (virus is made up of different things… it is one component of the virus that can infect a host) – just the viral protein or just the genome
What are the different capsid symmetry? Briefly explain
- Icosahedral - polyhedron (20 faces)
- Helical Symmetry - RNA has helical confirmation surrounded by protein capsid. Hollow center - like cylinder
- Complex symmetry
What are the complex symmetry components?
- DNA vs. RNA
- ss vs ds
- or + sense (RNA)
- linear (DNA or RNA) vs circular (DNA)
- single (DNA or RNA) vs segmented (RNA)
What is the capsid symmetry for Filovirus, Adenovirus, and Poxvirus?
Filovirus - Helical
Adenovirus - Icosohedral
Poxvirus - complex symmetry
What do virion proteins do?
Protect NA Attach to receptors Penetrate cell membrane Replicate NA (some viruses) Begin program for replication (some viruses) Modify host cell (some viruses)
T/F
All animal viruses with helical nucleocapsids are envoloped
True
Briefly describe the composition of an influenza virus.
RNA virus
Envelope
Helical symmetry
Glycoprotein peplomers = hemagglutinin and neuraminidase
What are the 9 basic virion properties used in taxonomy?
Morphology Physiochemical and Physical properties Genome Proteins Lipids CHO Genome organization and replication Antigenic properties Biologic properties
T/F
All nonenveloped viruses are Icosohedral
True
