Lecture 3 - Viral Pathogenesis Flashcards
What are some important features of viruses?
- non living
- rely on a host cell to replicate
- non-motile
- no metabolism
- obligate parasites
Which two technologies allow us to visualise viruses?
X ray
Electron microscope
What are the two forms of capsid symmetry?
Helical symmetry
Icosahedral
Which viruses types have envelopes?
Helically symmetrical viruses
Some icosahedral viruses
What are the subunits of the capsid called?
Capsomeres
What is the symmetry of influenza virus?
Helical
What is the symmetry of adenoviruses?
Icosahedral
What is the symmetry of mumps?
Helical
What is the symmetry of herpes virus?
Icosahedral
What is the symmetry of papillomavirus?
Icosahedral
What is the symmetry of poxviruses?
Complex symmetry
All helically symmetrical viruses have a … genome
RNA
Describe how viruses gain access to cells
- Molecules (RECEPTOR BINDING PROTEIN) on the surface of the virus binds to the host’s receptor
- RME or / fusion of envelope with host cell
What determines the tropisms of viruses for cells, tissues, species etc.
- Receptor Binding Proteins
- Enzymes released by host cells (think Tryptase clara)
- Temperature
- Ability to get ‘free ride’ by replicating inside certain cells
What happens once the virus has penetrated the host cell?
Uncoating of the capsid to reveal the genome
What are the ways that a virus can leave the host cell?
1/ LYSIS: Non-enveloped: build up, lyse the cell
2/ EXOCYTOSIS: enveloped viruses, from plasma membrane / golgi
Which is the most common route of entry into the human body for viruses?
Mucosal epithelium
What are the defence mechanisms of the respiratory tracts?
Mucous Ciliated elevator in the trachea Tears Alveolar macrophages Surfactant
Which viruses infect the respiratory tract and remain localised?
Rhinovirus
RSV
Influenza
Which viruses invade via the respiratory tract and then invade further?
Measles
Mumps
Rubella
How does Herpes invade?
To where does it then spread?
Via the oro-pharynx
It remains localised
How does Rotavirus invade?
To where does it then spread?
Invades via the oro-pharynx
Then goes further –> enteritis
How does HIV invade?
Rectal route
What are the defences of the alimentary tract?
Mucous
Acid and Bile
