Quiz on Anthrax/Strep

Question 1

Anthrax

Answer 1

Gram positive bacteria

usually lives in blood and tissues of host

Question 2

anthrax transmission

Answer 2

inhale
ingest infected meat
abrasion on skin

Question 3

why is anthrax so virulent

Answer 3

It can kill off its host and lie dormant

Question 4

Anthrax infection

Answer 4

targets macrophages

• once phagocytosed it kills macrophage
• ->no presentation by MHC

Question 5

Anthrax PA protein

Answer 5

PA binds to host cells, and also carries toxins

1. Edema Factor
2. Lethal factor

Question 6

Anthrax study method

Answer 6

used primate model (macaques)

control: wild type parental strain (PA, EF and LF)
Variables: mutant "knockouts"
1. PA & EF
2. PA & LF
3. LF & EF

Question 7

Anthrax study results

Answer 7

Higher doses of parental Ames strain = higher mortality rates

LF & PA deletion only at very high doses

-EF deletion (only lethal factor) showed highest rates of mortality (lowest ld50 value)

Question 8

Anthrax-why use deletion mutants

Answer 8

see what each factor does (mechanism of pathogen) and how lethal they are

Question 9

Conclusion of Anthrax study

Answer 9

Lethal toxin is a key factor in inducing virulence

Question 10

LD50

Answer 10

the number of microbes needed to kill 50% of infected hosts

*the smaller the number, the more virulent

Question 11

ID50

Answer 11

number of microbes needed to kill 50% of the population

Question 12

Strep (GAS)

Answer 12

gram positive bac teria

Question 13

Strep virulence factors

Answer 13

M1 proteins bind to host cells–>prevents phagocytosis

capsule prevents phagocytosis

Question 14

Transmission of Strep

Answer 14

infects skin or respiratory tract

Question 15

SpeB

Answer 15

• virulence factor produced by bacteria to infect host
• ->blocks production of cytokines and can break down host cells

BUT
-can also break down its own M1 proteins and its own cell

Question 16

M1 proteins in strep

Answer 16

prevents phagocytosis

Question 17

GRAB proteins strep

Answer 17

hijacks host cells way of protecting itself from SpeB

Question 18

Strep mechanism

Answer 18

GRAB inhibits SpeB
SpeB inhibits M1
M1 inhibits phagocytosis

So…
increased GRAB–>Decreased SpeB
–>no inhibition of M1
–>no phagocytosis

Question 19

Observations of Strep & SpeB

Answer 19

1. less severe cases have higher levels of SpeB
2. cells that did not produce SpeB had M1 proteins
3. Cells treated with protease inhibitor, M1 proteins remained intact

Question 20

Conclusion of Strep paper

Answer 20

correlation b/w SpeB, GRAB, and M1 proteins

• shows only one possible way this works
• many differing conclusions from other papers