1 COPY CHOICE RECOMBINATION+ strand + strand
2 Other methods recombinationTake advantage quirks in virus replication eg. Coronaviruses (include SARS virus)
3 RECOMBINATION - SOME USESmapping by recombination frequency mapping by marker rescue
4 RECOMBINATION - SOME USESmarker rescue TK - mt TK mutant HSV TK - wt TK - wt TK wt HSV
5 RECOMBINATION - SOME USESmapping by recombination frequency mapping by marker rescue development of recombinant viruses for vaccines and therapeutic reasons
6 RECOMBINATION - SOME USESTK vaccinia virus T K rabies G rabies G vaccinia virus for use as rabies vaccine
7 raccoon eating bait with rabies vaccine in it
8 REASSORTMENT
9 REASSORTMENT form of recombination (non classical) very efficientsegmented viruses only can occur naturally used in some new vaccines eg for influenza and rotaviruses
10 INFLUENZA VIRUS cold adapted temperature-sensitive attenuatedlive vaccine intranasal delivery approved 2003 adapted fromTreanor JJ Infect. Med. 15:714
11 NON-SEGMENTED NEGATIVE STRAND RNA VIRUSESno classical recombination no copy choice no reassortment least ability to exchange genetic material
12 other aspects of viral genetics
13 COMPLEMENTATION ts M ts N wt N wt MInteraction at the functional level, NOT the nucleic acid level ts N wt M ts M wt N ts mutant 1 ts mutant 2 Progeny virus assembled using wt N and wt M proteins Genomes in progeny are either ts M or ts N mutants which can complement are generally in different genes
14 DEFECTIVE VIRUSES genomelack gene(s) necessary for a complete infectious cycle ‘helper’ virus provides missing functions package me! copy me! genome package me! copy me!
15 DEFECTIVE VIRUSES some examples of defective virusessome retroviruses (use related helper) hepatitis delta virus (uses unrelated helper)
16 DEFECTIVE INTERFERING (DI) VIRUSES (PARTICLES)decrease replication of helper virus compete for viral precursors, etc. may modulate wt infections occur naturally eg. DI measles virus in subacute scelerosing panencephalitis - SSPE
17 PHENOTYPIC MIXING no changes in genome possibly altered host rangepossibly resistant to antibody neutralization
18 PHENOTYPIC MIXING PSEUDOTYPE
19 Antigenic variation 1-Antigenic shift 2- 1-Antigenic driftOccur in some viruses such as Influenza virus
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