Unit 3: Virus Infection Flashcards
what is a virus genotype?
difference in the gene sequence within viral species
distinguished by differences in genetic sequence etc
what is a virus serotype?
difference in antibody recognition within viral species
share similar antigen epitopes
what viral proteins determine the serotype?
- surface proteins involved with virus entry or antibody reactions
what are the different mechanisms that lead to amino acid changes/ variation in viral protein?
- mutations
- reassortment
- recombination
where in the influenza HA protein can variation occur?
- mostly loop regions = can tolerate changes
- at secondary structure sites
what are the two theories for genetic recombination?
- copy choice model = template switching
- non-replicative RNA recombination (via ligation) - only seen in polio, BVDV and HCV
what is FMDV and how does it vary?
- foot and mouth disease virus
- variation in gene sequence = VP1
- different strain recombination
what makes FMDV VP1 region highly variable?
- GH loop contains major immunodominant sites + receptor binding site
- variation driven by host immune response
- anitbody escape mutants
what does HIV infect?
- CD4+ T cells
- integration into hosst genome = long persistant infection
what is the advantage of env protein variability in HIV?
- act as decoys = focus on variable regions instead of conserved
- epitope masking via glycosylation sites
what is the general advantage of pathogen variability?
escape of vaccine induced and naturally acquired immunity
what is an antisera?
blood serum containing antibodies that is used to spread passive immunity to many diseases
what can monoclonal antibodies be used to type?
type and react to one virus epitope
what can Mab I be used to type?
type and react with a conserved epitope on all virus strains
what can Mab II, III + IV be used to type?
type and react with only some virus strains
