Intro to Microbial Pathogens (Feldman) Flashcards Preview

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Flashcards in Intro to Microbial Pathogens (Feldman) Deck (15):
1

Virus

Protein capsid surrounds either RNA or DNA

Some have lipid bilayer "envelope"

2

Viruses are not cells, they are obligate intracellular parasites. What does this mean?


Computer analogy: a computer virus must be in a computer in order to be destructive

Viruses can't synthesize proteins, can't generate energy, and can't maintain ionic potential across membrane. They need OUR cells' mitochondria, etc. to act

3

Enveloped Viruses

Lipid bilayer surrounding capsid contains viral attachment proteins

When alcohol, etc sprayed on virus, membrane dissolves and virus has no way of infecting cells

Less stable than non-enveloped

Transmission host-to-host

Ex: HIV (but HIV is resiliant! Conformational masking, etc)

4


Non-Enveloped Viruses


Tough protein capsid contains viral attachment proteins

Resistant to alcohol, low pH, etc.

More stable than enveloped viruses

Transmission is fecal-oral

Ex: Polio, HepA, HPV

5


Bacteria


No nucleus

One chromosome (usually circular)

70S Ribosomes

Cell wall

6


Gram positive cell wall


(Two layers)

Plasma membrane

Thick peptidoglycan cell wall

Teichoic acid on peptidoglycan cell wall

Ex: Streptococcus, staphylococcus

7

Gram negative cell wall


(Three layers)

Plasma membrane

Thin peptidoglycan layer

Outer membrane

LPS on outer membrane

Ex: Neisseria

8


Targets of anti-bacterial drugs


Cell wall (because humans don't have one)

Protein synthesis (humans have 80S and bacteria have 70S)

DNA gyrase (humans don't have it)

9


Viral infection


1) Viral glycoprotein binds specific receptor on cell

2) Virion uncoats

3) Virus replicates by synthesizing nucleic acid and empty capsids

4) Virus inserts viral glycoproteins into cell's membrane

5) Viral egress: capsids full of nucleic acid emerge from cell, picking up envelope and inserted viral glycoproteins on the way out

10


CD8 T cells


Differentiate to cytotoxic T cells (IL-2 helps) that kill viral infected cells by secreting granzymes

11

CD4 Th2 cells


Activate B cells to become plasma cells that secrete antibodies to kill/neutralize/opsonize extracellular pathogens or toxins

12

CD4 Th1 cells

Activate macrophages (engulf) and NK cells (which can activate lysosomes) to kill intracellular pathogens replicating in phagosomes or lysosomes

13


Pattern Associated Molecular Pattern (PAMP)


Molecule on pathogen that is seen as foreign and activates the immune system

Ex: LPS on gram negative bacteria; Teichoic Acid on gram positive bacteria

14


Toll-Like Receptor (TLR)

On immune cells, recognize PAMPs on pathogen and trigger immune response

15


Complement pathways


MB-Lectin Pathway (Innate)

Alternative Pathway (Innate)

Classical Pathway (Adaptive)