inteferons and how viruses evade them

Question 1

CpG and ZAP

Answer 1

viruses that have a high level of CPG are detected in the body by a ZAP protein in our body, which cuts the CPG- CPG needed for replication, so they can’t replicate

Question 2

type 1 interferons- what they are and functions

Answer 2

polypeptides released from infected cells- cause an antiviral state in infected and neighbouring cells (ie they produce interferon stimulated genes), and enhanced innate and adaptive response

Question 3

types of type 1 interferons- cells that produces them, what triggers them, and how many types

Answer 3

IFN beta produced by all cells, triggered by IRF-3, IFN alpha produced by dendritic cells, triggered by IR-F7: only 1 type of IFN beta, 13 types of IFNalpha

Question 4

type 2 interferons

Answer 4

INF gamma- produced by T cells and NK cells, which affect adaptive immune response

Question 5

type 3 interferons

Answer 5

interferon lamda (upside down Y)- important at epithelial cells

Question 6

how innate immune system senses pathogens and types of PRR’S

Answer 6

PAMPS (pathogen associated molecular patterns), detected PRR’S (pattern recognition receptors), such as RLRS (RIG like receptors), TLRS (toll like receptors), which sense foreign RNA in cytoplasm, as well as cGAS (senses foreign DNA)

Question 7

how RLRS work

Answer 7

sense foreign RNA, and activates MAVS, which phosphorylates IRF3, which goes from cytoplasm into nucleus to switch on INF beta gene ie IRF3 acts as a T.F

Question 8

how TLRS work

Answer 8

they work in ENDOSOMES (viruses can enter via endosomes)- when they sense viral RNA, TLR3 activates IRF3, TLR7 activates IRF7, which produces both INF beta and alpha gene

Question 9

DNA sensor- CGAS

Answer 9

senses foreign DNA, which activates IRF3 via STING pathway= switches on INFalpha/beta

Question 10

effect of type 1 IFN

Answer 10

bind to IFNAR (IFN alpha) receptors on both its OWN cell (autocrine signalling) and neighbouring cells (paracrine), switching on MANY IFN stimulated genes

Question 11

what occurs in herpes simplex encephalitis

Answer 11

lack of INF alpha/beta within CNS in response to HSV

Question 12

inteferon stimulated genes-

Answer 12

protein kinase R- inhibits translation (thus virus can’t replicate), serpine (activates proteases), IFITM3 (inhibits viruses entering via ENDOSOMES)

Question 13

issue with IFN stimulated genes and solution

Answer 13

these genes are toxic to the cell, but MORE toxic to virus- SOCS gene turns off these genes

Question 14

how viruses evade IFN response with examples of INF induction blockage

Answer 14

hide their PAMP, activate SOCS, affect protein synthesis (ie can’t produce INF stimulated gene proteins), stop INF production eg Hep C cleaves MAVS using NS3 protease, influenza binds to RLR using NS1 protease

Question 15

POX viruses

Answer 15

large DNA viruses which have accessory genes that modify immune response- they do this by producing cytokine receptors, which bind to cytokines like IFN, preventing them from working

Question 16

cytokine storm- mediators particularly produced

Answer 16

effect of IFNs not preventing viral replication- body continues producing more IFNS,IL-6, and TNF alpha particularly

Question 17

IFN as treatment- IFN alpha/beta vs IFN lambda

Answer 17

IFN alpha/beta cause bad side effects due to cell toxicity, and may cause immune cells be overactive= AUTOIMMUNITY, where IFN lambda is not on all cells (only epithelial), so less toxic, thus may be beneficial

Question 18

viruses and vaccines

Answer 18

viruses that can’t control inteferon ie don’t have proteases can be used as LIVE ATTENUATED vaccine

Question 19

oncolytic viruses

Answer 19

cancer cells don’t produce INF, thus these viruses can damage cancer cells without immune system clearing them, without damaging healthy cells