Week 21: (B) introduction to Virology Flashcards
What are the main sites of entry for a virus?
respiratory tract (what you beat in)
alimentary tract
urogenital tract
Can also…
conductive (eyes)
Anthropod (insect)
Urinogenital tract)
What is the alimentary tract?
things that go in from you mouth ( what you eat)
What virus replicate in the brain?
Rabbies
HIV
measles
mumps
What viruses replicate in the mouth?
HSV
coxachie virus
What viruses replicate on the skin & mucous membranes?
HSV, measles, papilloma
What viruses replicate in the liver?
hepatitis A, B,C,D, E, F
yellow fever
What virus replicates in the heart?
coxachie virus
What can the human Herpes Virus do?
go latent in the host
lay dormant for a period of time and nit showing symptoms
What type of virus is herpes?
icosahedral virus
ds DNA genome
wrapped up in a capsid
enclosed in a lipid membrane studded with glycoproteins (lipids)
What is the area called between the membrane and the varian?
tegument
solid viral proteins
ask the viral proteins get delivered int the cell
What is the function of the viral proteins in the tegument space?
turn off theist cells innate immune response, allow the virus to get going
block the hosts response
What type of herpes is picked up in childhood?
type 1
e.g. primary gingivostomatitis
herpes simplex virus
What virus causes chickenpox and shingles?
varicella zoster (VSV)
Why does shingles happen in limited areas?
it travels downtime nerves
the areas are where the nerves innervate the body
How does Herpes simplex virus spread in the body?
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.
What brings about a recurrent herpes infection?
stress or ultraviolet light
How does shingles (VSV) occur?
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
What nerve does herpes simple and VZV travel down?
peripheral nerve
What effects the severity of a virus?
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
What is epidemiology?
study of how viruses are transmitted
What are factors of epidemiology?
critical community size
Mechanisms of virus transmission
Geographical season
How does critical community size effect hoe a virus is transmitted?
need big enough community to start spending the virus around
R number
What is the R number?
How many people 1 person will effect on average
eg. R=3
1 person infects 3 people on average
What are some mechanisms of virus transmission?
respiratory or salivary spread Formites (e.g.tissues, clothes) sexual contact zoonoses (animals, insects called arboviruses) Blood transfusions, organ transplant needle sharing (drug abusers)
How does geography/ season effect how a virus is spread?
Presence of cofactors or vectors in the environment
Habitat and season for arthropod vectors (mosquitos)
School/uni session; close proximity
Climate conditions
What is the fatal-oral route?
rotavirus
poor sanitation
What is venereal spread a virus?
genitalia
HIV
papilloma virus
What are the conditions needed for zoonoses spread?
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.
How do we control virus diseases?
1) public health care (social distancing, washing hands, good sewage system)
2) vaccination
3) chemotherapy (drugs)
What do we not have a vaccine to?
HIV
RSV
rotavirus
Why don’t we have a vaccine to HIV?
we need a sterilising immunity
What are difficulties associated with design and the use of anti-viral drugs?
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.
What do we need to make anti-viral successful?
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
