Week 21: (B) introduction to Virology

Question 1

What are the main sites of entry for a virus?

Answer 1

respiratory tract (what you beat in)
alimentary tract
urogenital tract

Can also…
conductive (eyes)
Anthropod (insect)
Urinogenital tract)

Question 2

What is the alimentary tract?

Answer 2

things that go in from you mouth ( what you eat)

Question 3

What virus replicate in the brain?

Answer 3

Rabbies
HIV
measles
mumps

Question 4

What viruses replicate in the mouth?

Answer 4

HSV

coxachie virus

Question 5

What viruses replicate on the skin & mucous membranes?

Answer 5

HSV, measles, papilloma

Question 6

What viruses replicate in the liver?

Answer 6

hepatitis A, B,C,D, E, F

yellow fever

Question 7

What virus replicates in the heart?

Answer 7

coxachie virus

Question 8

What can the human Herpes Virus do?

Answer 8

go latent in the host

lay dormant for a period of time and nit showing symptoms

Question 9

What type of virus is herpes?

Answer 9

icosahedral virus
ds DNA genome
wrapped up in a capsid
enclosed in a lipid membrane studded with glycoproteins (lipids)

Question 10

What is the area called between the membrane and the varian?

Answer 10

tegument
solid viral proteins
ask the viral proteins get delivered int the cell

Question 11

What is the function of the viral proteins in the tegument space?

Answer 11

turn off theist cells innate immune response, allow the virus to get going
block the hosts response

Question 12

What type of herpes is picked up in childhood?

Answer 12

type 1
e.g. primary gingivostomatitis
herpes simplex virus

Question 13

What virus causes chickenpox and shingles?

Answer 13

varicella zoster (VSV)

Question 14

Why does shingles happen in limited areas?

Answer 14

it travels downtime nerves

the areas are where the nerves innervate the body

Question 15

How does Herpes simplex virus spread in the body?

Answer 15

herpes simplex infection around mouth
travels down the nerves and goes into the trigeminal ganglia (located tieback of the neck) where they are latent.
The virus doesn’t make any proteins which can be detected by the host immune system.

Question 16

What brings about a recurrent herpes infection?

Answer 16

stress or ultraviolet light

Question 17

How does shingles (VSV) occur?

Answer 17

fever
sunlight to face menstruation
immune system
occurs in older people
weaker, unable to completely suppress virus
travels foes periphery nerve erupts at nerve endings

Question 18

What nerve does herpes simple and VZV travel down?

Answer 18

peripheral nerve

Question 19

What effects the severity of a virus?

Answer 19

target tissue 
viral pathogen (strain, some strains are more pathogenic) 
immune status (immune system can over shoot, cause 
-->competence of the immune system 
--> prior immunity to the virus 
immunopathology) 
cytopathic ability of the virus 
immunopathology 
virus inoculum 
general health oath individual 
genetic make-up of the individual 
genetic make-up of the individual 
age

Question 20

What is epidemiology?

Answer 20

study of how viruses are transmitted

Question 21

What are factors of epidemiology?

Answer 21

critical community size
Mechanisms of virus transmission
Geographical season

Question 22

How does critical community size effect hoe a virus is transmitted?

Answer 22

need big enough community to start spending the virus around
R number

Question 23

What is the R number?

Answer 23

How many people 1 person will effect on average
eg. R=3
1 person infects 3 people on average

Question 24

What are some mechanisms of virus transmission?

Answer 24

respiratory or salivary spread 
Formites (e.g.tissues, clothes)
sexual contact 
zoonoses (animals, insects called arboviruses) 
Blood transfusions, organ transplant
needle sharing (drug abusers)

Question 25

How does geography/ season effect how a virus is spread?

Answer 25

Presence of cofactors or vectors in the environment
Habitat and season for arthropod vectors (mosquitos)
School/uni session; close proximity
Climate conditions

Question 26

What is the fatal-oral route?

Answer 26

rotavirus

poor sanitation

Question 27

What is venereal spread a virus?

Answer 27

genitalia
HIV
papilloma virus

Question 28

What are the conditions needed for zoonoses spread?

Answer 28

vector: insect to human- human cannot spread to another human

Vertebrate reservoir: e.g. rabies spread from vertebrate to vertebrate and vertebrate to Hunan but human cannot spread to another human

vector-vertebrate : e.g. yellow fever
vector to vertebrate and visa verse. only the vector can spread to another human but human cannot spread to a human and neither can the vertebrate.

Question 29

How do we control virus diseases?

Answer 29

1) public health care (social distancing, washing hands, good sewage system)
2) vaccination
3) chemotherapy (drugs)

Question 30

What do we not have a vaccine to?

Answer 30

HIV
RSV
rotavirus

Question 31

Why don’t we have a vaccine to HIV?

Answer 31

we need a sterilising immunity

Question 32

What are difficulties associated with design and the use of anti-viral drugs?

Answer 32

1) few biochemical pathways unique to viruses
2) therapeutic index often very low
3) selection of drug resistant mutations
4) many viruses which cause similar disease have very different modes of replication and mayn’t be sensitive to some drugs
5) by the time symptoms appear ofter chemotherapy is too late to make much of a difference to clinical course of disease.

Question 33

What do we need to make anti-viral successful?

Answer 33

need an enzyme which is not present in Hunans
e.g HiV has revise transcriptase
doesn’t have a target in humans but the virus