1.03 - Virology Flashcards
• Understand the basic structure and function of bacteria and viruses o What is a virus o Diversity and classification of viruses • Understand basic microbiology and concepts in the context of health and disease o Virus-host interactions • Cellular level to whole animal o Topism o Interactions with the immune system • How can we study microorganisms o How this can limit knowledge
What is a virus?
An obligate parasite with no metabolic processes
Do viruses encode genes for mitochondria?
No. Must steal energy from the host in form of ATP
Do viruses encode genes for ribosomes?
No. Bacterial ribosome is a common target for antibiotics
Can viruses form their own membrane?
No. They steal it from the host cell
Define: Virion/Viral Particle
The physical structure that is transmitter between hosts. May or may not be infectious.
Define: Capsid
Protein shell that surrounds a virus genome in the virion
Define: Infectious unit
The amount of virus required to cause infection
Define: Specific infectivity
The ratio of visions to infections units
What classifications are used to groups viruses in families?
Type of Nucleic Acid Genome Architecture (Linear, Circular, Segmented) Symmetry of capsid Presence of envelope/enzymes Baltimore class (replication strategy) Antibody cross reactivity Genome sequence (more recently)
What are the two types of capsid symmetry?
Icosahedral
Helical
What are the basic stages of Viral Replication in cells?
Attachment Entry Viral gene expression Virus genome replication Assembly of new virions Exit
What are the cellular outcomes of Virus Infection
Cell death (Rapid productive infection)
Medium term cell survival (slower persistent productive infection)
Long term cell (and virus) survival (latent infection)
Transformation –> Tumour cell
How do enveloped viruses exit the cell?
They can “bud” out of the host cell
How do non-enveloped viruses exit the cell?
They must lyse the cell.
What are the stages of viral infection?
Entry to the host
Incubation and primary spread
Replication (sometimes followed by secondary and tertiary spread)
Development of symptoms (direct virus or host response)
Development of an immune response (T cells first –> antibodies)
Virus shedding
