Mycobacteria and Viruses Flashcards
What organism would you stain the Ziehl-Neelsen?
Mycobacteria e.g. TB
What is an example of a slow-growing bacteria?
TB
What method can tell you if someone has had previous exposure to TB?
1) Interferon gamma release assays
2) Tuberculin skin test (Mantoux)
What special ability does mycobacterium TB have?
It is able to grow intracellularly
Why are mycobacteria both hard to diagnose and treat?
D: They are hard to culture
T: Lipid rich cell wall so difficult to treat with antibiotics
What are the 3 stages of TB?
1) Primary TB
2) Latent TB
3) Pulmonary TB
What happens at each TB stage?
1) P: Initial contact by alveolar MP, bacilli taken to hilar lymph nodes
2) Cell-Mediated Immune Response whilst Primary infection
3) P: Granulomas around bacilli in apex, more air and less blood, necrosis forms with caseous material coughed up
Do viruses contain an outer cell wall?
They contain a protein rich coat, and sometimes a lipid envelope
How are viruses able to attach to a host cell?
Protein on surface that are able to interact with receptors on surface membrane of host cells
What are main stages of viral replication?
1) Attachment
2) Cell Entry
3) Interaction with host cell
4) Replication
5) Assembly
6) Release
Which portion of viral cell will enter the host cell?
Viral Core: Contains cell nucleic acids so will enter the host cells cytoplasm,
By what methods do viruses interact with host cells?
By uses of cell materials and nucleotides, are able to replicate and evade host cell defence mechanisms
Where in a cell does viral replication occur?
Nucleus, cytoplasm or both
How do viruses escape from cells?
1) Lysis: Bursting from a cell
2) Exocytosis: Leaking from a cell overtime,
What 5 methods do viruses cause cell damage?
1) Lysis: Damage by direct cell destruction
2) Cell Structure Modification
3) Immuno-Pathological: “Over-reactivity” of the host as response to infection
4) Cell proliferation and immortalisation
5) Evading host cell defence mechanisms
