Virus & Fungi Flashcards
what is a virus?
need host to replicate
- little cellular machinery, no cell division - just self assembly - mutuates to adapt to host better.
viral classification
- dna vs rna
- linear, circular, segmented
- ss/ds +/- sense
- enveloped or not**
General life cycle of virus
1 attachment
- entry – uncoating
- replication, translation
- assembly
- release
lytic cycle
step 3. translation focused on viral proteins, not cellular proteins = weakens cell.
- self-assembly
- weak cell - can lyse out our budd off. both ways weakening the cell further. bud off = keep intact factory for viral growth.
lysogenic cycle
- no repln, transln = instead, integrate pro-virus into host DNA. duplication of host will allow pro-virus to duplicate too. more cells have viral in DNA. slowly propagates self. viral DNA reemerges when immunocompromised. opportunistic.
ex: Dna virus
ex: rna virus
dna = vzv = chicken pox rna = mmr
transmission : airborne
best for droplets. both DNA and RNA transmitted. large or small droplet
transmission: GI, fecal-oral
transmitted by aerosols. high concentration can spread well. mostly RNA.
transmission: contact
probs have membrane - need close contact to pass on & not die. mostly DNA ex: VZV.
transmission: sexual
RNA - mostly DNA
transmission: blood -borne
needle-stick injury in hospital.
insect vecotr
mosquito malaria
disease manifestation- latency
virus may co-existwith human cells without disease, viral replication coincides with host cell division
diseas manifestation- active infection
cell dmaage and disease, acute cell necrosis, cell hyperplasia and proliferation
fungal - target of antifungals
ergosterol and cell structure.
yeast
single cell - bud by asexual reproduction. round.
human disease, yeast infections are typically from our GI flora
moulds
filamentous, multicellular branching.
aspergillus. environmental - conidia bud off easily.
asexual spores, easily airborne, transmission: allergy, infection
infection source is environmental
superficial infection
dermatophyte = fungi parasatize skin, hair nails.
eX: ringworm, dermatophystosis, cutaneous mycosis
subcutaneous infection
gardeners thumb - spore in thumb = deep ulcerated skin lesion
opportunistic infection
not true pathogen, low virulence. need immuno-compromised = aspergillus
invasive
true pathogens cause severe disease. dimorphic types.
host defines mechanisms
cytokines, interferons, humoral immunity (Ab), vaccine
antiviral agents
DNA/RNA synthesis
prevention of protein coating
activation of host responses (interferon)
What is fungus?
eukaryotic microorganisms, 50 species cause human disease, larger than bacteria
Three main fungal forms
yeast - single cell, asexual budding
mould- multicellular, filamentous, asexual
dimorphic form- mold at RT, yeast at body temp
