3 - antivirals

Question 1

what are viruses

Answer 1

obligate intracellular parasites

Question 2

what does it mean to be an obligate intracellular parasite

Answer 2

they rely on host biosynthetic machinery to reproduce

they dont make their own proteins

Question 3

what is a virion

Answer 3

when viruses are not inside a cell, they are independent particles

Question 4

what do virions consist of

Answer 4

double or single stranded DNA
protein coat
lipid envelope(derived from host cell)

Question 5

what is a capsid

Answer 5

protein coat to keep genetic material inside

Question 6

what are the antigenic glycoproteins

Answer 6

important to determine which cells the viruses will affect

in the lipid envelope

Question 7

what is viral range

Answer 7

the group of cell types that a virus can infect

Question 8

what is a bacteriophage

Answer 8

virus that only infects bacteria

Question 9

what are animal and plant viruses

Answer 9

viruses that infect animals and plants

Question 10

why are animal viruses able to cross phyla

Answer 10

they cant, they often only infect closely related species (humans and primates)

Question 11

what are the three shapes of viruses

Answer 11

helical
icosahedral
complex (bacteriophages)

Question 12

what is pathogenicity

Answer 12

ability of virus to cause disease and replicate within host

Question 13

what is virulence

Answer 13

degree of virulence (how sick host gets)

Question 14

what is latency

Answer 14

the concept that some viruses can remain dormant in organisms for a long time
(ex: chicken pox)

Question 15

what are carriers

Answer 15

people that chronically infected and serve as reservoirs of infectious virus

Question 16

where does the chicken pox virus stay in the body

Answer 16

dorsal root ganglia

Question 17

what are the 4 steps of lytic cycle of viral replication

Answer 17

absorption(into host cell), penetration(of genetic material into cytoplasm or host cell), replication(make DBA or RNA), release (virions released into environment)

Question 18

what determines the host range of a virus and begins the infection process

Answer 18

the surface of viruses (proteins that bind to receptors proteins on host cell)

Question 19

what are the classifications of viruses (not structure)

Answer 19

RNA, DNA, single stranded, double stranded

Question 20

do DNA viruses come with their own DNA

Answer 20

yes

Question 21

what happens once DNA viruses enter the host cell

Answer 21

their DNA is transcribed into mRNA by host cell polymerase, then translated into proteins

Question 22

what makes poxviruses so special

Answer 22

they carry their own RNA polymerase and replicate in the host cell cytoplasm
but they use host cell to translate

Question 23

how can RNA viruses replicate

Answer 23

either the mRNA can be transcribed from RNA to mRNA (using enzymes in virion)
or the viral RNA itself can act as mRNA

Question 24

how do RNA viruses get RNA polymerase

Answer 24

they make it themselves (they use host machinery to make it from their own RNA)

Question 25

where do most RNA viruses complete their replication

Answer 25

in the host cell cytoplasm

Question 26

where do influenza viruses complete their replication

Answer 26

transcribed in the host cell nucleus

Question 27

what are special about retroviruses

Answer 27

have RNA genome that directs the formation of a DNA molecule

Question 28

how does RNA go to DNA with retroviruses

Answer 28

using reverse transcriptase (RNA dependent DNA polymerase)

Question 29

what happens to the dsDNA made from retroviruses

Answer 29

it is integrated into the chromosomal DNA of host cell

Question 30

how is retroviral DNA transcribed

Answer 30

by host machinery into RNA

Question 31

how do most retroviruses kill their host cells

Answer 31

they dont kill their host cells initially, they infect them and create a lot of infected daughter

Question 32

what can vaccines consist of

Answer 32

live attenuated or killed viruses | or viral proteins

Question 33

where can anti-viral drugs exert actions

Answer 33

viral entry nucleic acid synthesis protein synthesis and processing viral packaging and release

Question 34

what does virustatic mean

Answer 34

it does not kill the virus, they just impede infection/ stop replication

Question 35

are antivirals virustatic or cidal

Answer 35

static

Question 36

what is acyclovir

Answer 36

nucleoside analog which viruses use for replication

Question 37

why does acyclovir result in DNA chain termination

Answer 37

it lacks OH group which is important for forming the backbone of the DNA molecule

Question 38

what infection is acyclovir used for

Answer 38

herpes

Question 39

what is thymidine kinase

Answer 39

made by herpes virus that phosphorylates acyclovir

Question 40

what must happen before acyclovir can be incorperated into DNA

Answer 40

it must be phosphorylated

Question 41

how is acyclovir phosphorylated

Answer 41

by thymidine kinase

Question 42

why does acyclovir mess up human DNA

Answer 42

because thymidine kinase has a affinity for acyclovir 200x than that of mammalian enzyme

Question 43

what is the major excretion route of acyclovir

Answer 43

renal excretion

Question 44

how can acyclovir be administrated

Answer 44

topical, oral, intravaneous, butt

Question 45

what is the oral bioavailability of acyclovir | how does it change with dose

Answer 45

10-30% and decreases with increasing dose

Question 46

what is the half life of acyclovir

Answer 46

2.5h

Question 47

how does acyclovir resistance happen

Answer 47

impaired production of thymidine kinase or altered specificity

Question 48

what does amantadine do (broad)

Answer 48

inhibits viral uncoating (early step in replication)

Question 49

what virus does amantadine affect

Answer 49

influenza A

Question 50

what does amantidine do (specific)

Answer 50

blocks H+ transfer through M2, blocking acidification and initiation of transcription

Question 51

what is the M2 protein

Answer 51

a proton ion channel which allows acidification of the virus core (activates viral RNA transcriptase)

Question 52

what does RNA transcriptase require to be activated

Answer 52

acidification of the virus core

Question 53

what happens to the viral core at the onset of infection

Answer 53

it becomes acidic

Question 54

does amantidine protect against influenza A

Answer 54

yes | but there are resistant strains

Question 55

does amantidine protect against influenza B

Answer 55

no

Question 56

what is the alternative if someone is not able to get vaccine (immunocompromised)

Answer 56

seasonal prophylaxis using anti-virals

Question 57

what is zanamivir

Answer 57

anti influenza drug

Question 58

how does zanamivir work

Answer 58

inhibits neuroaminidases produced by influenza A and B (works after replication) to impede viral spread

Question 59

what do neuroaminidases do

Answer 59

cleave sialic acid residues from viral proteins which enables virus to be released from the host cell

Question 60

what kind of virus is HIV

Answer 60

lentivirus (retrovirus)

Question 61

what are special about lentiviruses

Answer 61

they lead to chronic persistent infection with gradual onset of clinical symptoms

Question 62

what kind of cells does HIV attack

Answer 62

CD4+ T cells

Question 63

what happens to the CD4+ T cells when infected to HIV

Answer 63

the levels decline below a critical level, leading to AIDS (lose cell mediated immunity)

Question 64

how does replication change after HIV infection

Answer 64

it doesnt, replication is constant

Question 65

what is HAART

Answer 65

highly active antiretroviral therapy | target multiple pathways alone the infection route

Question 66

what does maraviroc do

Answer 66

CCR5 receptor antagonist | blocks HIV from binding to the CD4 receptor on T cell

Question 67

how does HIV infection begin (what attaches)

Answer 67

attachment of HIV envelope proteins (gp120) to CD4 and CCR5 receptors on the surface of T cells

Question 68

what do HIV entry inhibitors intefere with

Answer 68

binding fusion and entry into cell

Question 69

how does HIV reverse transcriptase enzymes work

Answer 69

synthesize DNA from HIV RNA using nucleosides in the host T-cells (RNA dependent DNA pol)

Question 70

how do nucleoside reverse transcriptase inhibitors work

Answer 70

they are incorperated into the HIV DNA but lack 3'OH so it causes chain termination

Question 71

why dont nucleoside reverse transcriptase inhibitors work on human cells

Answer 71

mammalian RNA and DNA polymerases are sufficiently distinct to permit a selective inhibition of viral reverse transcriptase rather than host cells

Question 72

what are non nucleoside reverse transriptase inhibitors

Answer 72

drugs that block the transcription of viral DNA but they dont compete with nucleoside triphosphates

Question 73

how do non nucleoside reverse transriptase inhibitors work

Answer 73

they bind to a different site than NRTIs (they bind to reverse transcriptase) and inhibit the activity of reverse transcriptase

Question 74

what are integrase strand transfer inhibitors

Answer 74

blocks the integration of viral DNA into the host gene

Question 75

what is integrase

Answer 75

viral enzyme that inserts viral genome into the DNA of the host cell

Question 76

what is raltegravir

Answer 76

integrase strand transfer inhibitors

Question 77

what are protease inhibitors

Answer 77

at latest stage of viral transcription process, blocks final maturation and release of HIV virion into the enviro blocks aspartate proteases so that virion particles never reach their mature form

Question 78

what is aspartate protease

Answer 78

a viral enzyme that cleaves precursor proteins to form the final structure proteins of the mature virion core