Module 5: Immune System Flashcards
What are bacteria?
Prokaryotes (free living organisms)
What are viruses?
Non-cellular entities that are parasites of cells
Do viruses have a nucleus?
No
Do viruses have a genome?
Highly variable, in terms of DNA or RNA, single- or double-stranded
Do viruses have ribosomes?
No
Outer structure of viruses?
Envelope (membrane) or nucleocapsid
Replication strategy of viruses?
Rely on host cell for replication
What is a bacteriophage?
Viruses that infect bacteria (lytic or lysogenic)
What does lytic mean?
Capable of destroying/rupturing cell
What does lysogenic mean?
Nucleic material attaches to host’s DNA and remains dormant
What is the matrix/tegument of a virus?
Structure between the envelope and nucleocapsid of herpesvirus particles - stabilisation of viral envelope
What is a icosahedral capsid?
20 sides with 12 corners
What is a nucleocapsid virus?
Genome + capsid
What is a helical capsid?
Continuous helix of capsomers forming a cylindrical nucleocapsid
What is an enveloped virus?
Virus with additional membranous covering over the capsid in some animal viruses - do this by budding off host cell
What is difference between matrix and tegument?
Matrix = for stabilisation off of plasma membrane
Tegument = for stabilisation off of nuclear membrane
What are viral enzymes?
Enzymes contained within nucleocapsids, which aid in viral replication
What is negative RNA?
Single-stranded RNA not recognised by ribosomes; viruses carry this RNA into host cells to turn into positive RNA
What are rod (bacilli) bacteria?
Rod-shaped bacteria
What are spiral bacteria?
Curve-shaped bacteria
What are sphere (cocci) bacteria?
Spherically shaped bacteria
What is the periplasmic space?
Space between outer and inner membrane
What is a lipopolysaccharaide?
Large complex molecule comprised of polysaccharides linked to lipid molecules
Why are pilli/fimbrae important for bacteria?
Allow bacteria to attach to gut wall
How do bacterial flagella stay attached?
Have a flared foot that anchors inside cell
Structure of gram-positive bacterial cell wall?
Peptidoglycan (cell wall), periplasmic space, plasma membrane
Structure of gram-negative bacterial cell wall?
Thin peptidoglycan + outer membrane containing lipopolysaccharide, periplasmic space, plasma membrane
What is a gram stain?
Test to determine if bacteria is gram positive or gram negative
What is a cytopathic effect?
Structural changes in host cells caused by viral invasion
What is shedding?
Release of infectious virus from infected host by any means
What is a reservoir?
A place or organism where microorganisms survive, multiply, and await transfer to a susceptible host
What are virulence factors?
Properties of pathogen that allow it to successfully invade and cause disease in a host
5 transmission pathways?
- Respiratory
- Faecal-oral
- Zoonotic
- Blood-borne
- Sexually transmitted
What is cholera?
Disease that causes fatal diarrhoea and dehydration
What do cholera bacteria look like?
Kidney-shaped bodies with long flagella tail
Transmission type of cholera?
Faecal-oral
How is cholera treated?
Self-limiting disease; can be treated through oral rehydration therapy
What is influenza?
Highly contagious orthomyxovirus
Structure of influenza virus?
Single-stranded, enveloped, negative RNA virus (8 segments of genome)
Transmission type of influenza?
Respiratory (sneezing, coughing, droplets)
What are reservoirs of influenza?
Humans, pigs, birds
How is influenza treated?
Generally self-limiting by an immune response; or, oseltamivir (Tamiflu)
What does tamiflu do?
Inhibits neuraminidase, which is attachment of infected cells
What is antigenic shift?
Process by which two or more different virus strains, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains
What is antigenic drift?
A mechanism for variation in viruses involving accumulation of mutations within the genes that code for antibody-binding sites
What is listeriosis?
Serious infection caused by food contaminated with Listeria monocytogenes
What do listeriosis bacteria look like?
Gram positive, motile, rod-shaped bacteria
What are reservoirs for listeriosis?
Humans, animals, soil, water; however, contamination actually comes from food
What is transmission type of listeriosis?
Eating contaminated foods (often soft cheeses and meats)
How does listeriosis act like a virus, despite being a bacteria?
Invades gut cells by having sipper-like interactions with surface proteins that causes endocytosis; then produces proteins that dissolve capsule and bacteria proliferates; excess bacterium have actin filaments that help then invade neighbouring cells
What is whooping cough caused by?
Bacteria called bordetella pertussis
Structure of bordetella pertussis?
Gram negative, non-motile, coccobacillus
Reservoirs of whooping cough?
Humans - particularly asymptomatic adults
Transmission of whooping cought?
Aerosols and direct contact
Catarrhal stage of whooping cough?
Lasts 2 weeks, may be mistaken as a cold; culture will be positive during this stage
Paroxysmal stage of whooping cough?
2 to 4 weeks, intense coughing and characteristic whooping cough upon inhalation; fatal in infants
Convalescent phase of whooping cough?
After 4 weeks; paroxysms decline and confers lasting immunity, though pneumonia, otitis media may occur after