Virology review session: first midterm By Philippe Perron Savard

Lecture 1 Don’t bother. No questions will be asked.

Lecture 2: replication cycle Cells provide: ribosomes, nucleotides & aa, ATP (energy), membranes. Consequences of virus replication on the cells: –Diverts cell metabolism –Fill up the cells –Escape (lysis for example) –Apoptosis induction

Lecture 2: virus structure Some viruses affect the behaviour of their host to improve transmission A lot of viruses do not cause disease

Lecture 2: virus structure Techniques used to detect and measure viruses: –Electron microscopy –Hemagglutination –Plaque assay –Foci formation Replication cycle

Finding the pfu/ml If a dilution (1/10000) is made and 1 ml of this dilution is plated: we get 50 plaques. How do we solve this: 50 plaques in 1 ml of the dilution= 50 pfu/ml in that dilution. 50 pfu/ml * = pfu/ml in the original solution.

Lecture 3: virus structure One step growth curve Baltimore classification Basics of virus particles Icosahedral and helical symmetry

Lecture 4: ssRNA phages Gene regulation dependent mostly on RNA secondary structure Replication Vs translation problem Replication Transcription of maturation gene

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Lecture 5: ssDNA phage (  X174) Displays extensive overlapping in genes. How do we regulate transcription? Concept of frames in transcription Entry Replication through rolling circle Formation of the capsid

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Different frame ACG ATG GGG CCC TAT GCT -1 AC GAT GGG GCC CTA TGC -2 CGA TGG GGC CCT ATG CT +1 TGG GGC CCT ATG CT +2 GGG GCC CTA TGC

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T7 phage Entry and DNA winching by RNA pols from the host and the virus. How it regulates transcription of its genes How the T7 RNA pol functions Problems with replication of linear dsDNA pET vectors for protein expression

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Lambda phage Genome organisation Understanding gene regulation is crucial How do we repress the lytic cycle? How do we decide between lysis or lysogeny Integration into the bacterial genome and its regulation

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