Viral and bacterial pathogenicity Flashcards
What is a cytocidal infection
Infection that results in cell death via cell lysis, apoptosis or accumulation of cytopathic effects
What are the 4 possible outcomes following viral infection of a cell
1) cell death
2) chronic/persistent infection
3) Latency
4) transformation
Describe chronic viral infection
Give an example of this type of virus
Continuing viral replication within cell
Cell survives
Virus particles leave cell and enter blood stream
Specialised functions of host cell may be impaired
Example - Hep B
Describe latent viral infection
Give an example of this type of virus
No virus replication ; no production of viral proteins
Once infection , infection cannot be removed
Virus replication can be reactivated later ( called a secondary infection)
Primary and secondary infections will have different symptoms
Herpes viruses
Describe cell transformation following viral infection
Name 2 examples
Immortalisation of cell - dividing uncontrollably leading to cancer
E.g Epstein-Barr virus can lead to lymphomas and nasopharyngeal carcinoma
Hep B and C viruses can cause hepatocellular carcinoma
Describe the ways viral infections can spread
Cell to cell
Via lymphatics
Via the bloodstream
Axonal pathways
Acid fast bacteria
Neither gram positive or negative
Extensive cell wall and no outer membrane
Glycolipids embedded in cell wall
Main example are mycobacteria
What are the different types of bacteria
Symbionts - beneficial
Commensals - neither beneficial or pathogenic
Opportunistic pathogens - causes disease in immunocompromised individuals
Primary pathogens - always cause disease in healthy individuals
Accidental pathogens -
What are the different types of bacteria That interact with the human body
Symbionts - beneficial
Commensals - neither beneficial or pathogenic
Opportunistic pathogens - causes disease in immunocompromised individuals
Primary pathogens - always cause disease in healthy individuals
Accidental pathogens - when commensals bacteria enter parts of the body where they are not usually found
Many opportunistic bacteria are
Commensal
What are zoonoses ?
Pathogens that can infect a wide variety of animals
What are fimbrial adhesions
Pili that allow attachment of bacteria to cells
Describe bacterial survival factors
Immune evasion molecules :
Complement binding proteins - prevent binding of comp proteins
Antibody binding proteins
Capsules prevent antibody binding/phagocytosis = can be made from protein or polysaccharide
Nutrient scavenging systems:
Siderophore binding proteins are Iron-binding protein receptors - important as there is little free extracellular iron
What is quorum sensing
Virulence factors only switched on when a chemical released by a type of bacteria reaches high conics ; permits coordinated response of bacteria
What is a bacterial biofilm ?
When a colony of bacteria becomes embedded within a self produced slimy ECM that adheres to a surface
Often form around inserted medical devices such as catheters and pacemakers
Harder to treat via antibiotics - dangerous
And less easily accessed by immune system
