L23 Viruses and Diseases Flashcards
types of infection
acute
persistant
transformative
types of persistant infection
latent
chronic
characteristics of acute infection
short incubation
host cell dies
clinical symptoms present
virus is cleared quickly from host
characteristics of persistent infection
long incubation period
can persist for life
what occurs during latent infection
progeny are not produced, few proteins and genome is present
no clinical symptoms
what is meant by chronic infection
progeny are produced, and can be passed to offspring
symptoms present
what can a latent infection turn into and how
acute infection
stress and hormonal changes can trigger it
what is transformative infection
causes cells to become cancerous
what are cancer causing genes called?
viral oncogenes
how do viral oncoproteins cause cells to become cancerous
- inactivate host tumour suppresser proteins
- hyperactivity host proto-oncogenes
both result in uncontrolled cell division
what happens to the host cell in the lytic cycle and lysogenic cycle
lytic = death lysogenic = survives
what kinds of viruses follow a lytic cycle
virulent phage
-T4 bacteriophage
what kind of viruses follow a lysogenic cycle
temperate (slightly subdued) phage
-lambda phage
in lysogeny what is the host bacterium referred to as
lysogen
what form of the phage remains in the lysogen
prophage (viral genome)
how is the prophage present in the lysogen
integrated into the lysogen genome
what is lysogenic conversion
when the prophage changes the lysogen phenotype
use Diptheria as an example of lysogenic conversion
C. diphtheria only causes diptheria when in lysogeny, the prophage encodes for the toxin
Use salmonella as an example of lysogenic conversion
prophages remove the receptor on salmonella to make it immune to superinfection
what causes the induction of a temperate phage to become a virulent phage
growth conditions
UV irridation
five ways of viral transmission
aerosol faecal-oral blood, semen zoonotic vecters
what is the aerosol transmission
respiratory droplets and secretions
what is feacel-oral transmission
contamination of water/ food
what is transmission of direct contact with bodily fluids caused by
contact with blood, semen
what causes zootonic transmission
direct contact with an infected animal
what is vector transmission caused by
vectors (insects, nematodes)
five categories of viral diseases
air-borne diseases food and water-borne diseases Direct contact zootonic anthropod-borne
examples of airborne diseases
Flu chicken pox measles mumps rubella smallpox covid
these are the disease not the viruses
examples of food-water borne diseases
viral gastrointendinitis
viral hepatitis
poliomyelitis
these are the diseases not the viruses
