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Fundamentals of Virology BIOT 316 Dr Natasha Anwar Tues, Thurs 11.00 – 12.15 s416 Course Outline • We will address the fundamentals of: – properties, – multiplication, – molecular mechanisms, – process of infection, and – how viruses pose new threats to human and animal health through emergence and evolution. – we will focus primarily on viruses that are pathogenic to animals. Grading • • • • • • Think and learn principle Quizzes 15% Mid Term 30% Final 30% Presentations 15% Written Assignment 10% I am Virus Viruses Infect.... • • • • • • • Humans Other vertebrates Invertebrates Plants Fungi Bacteria ....they infect all cellular life forms Can they be found anywhere else? • Found in: – soil, – air and – water (high conc in aqueous environments). Nature • Pathogenic • Non pathogenic Is the study of viruses important? • Diseases – Infections: can spread rapidly in a susceptible population. – Cancer • Veterinary and plant virology? Are they useful? • Phage typing of bacteria. Some groups of bacteria, such as some Salmonella species, are classified into strains on the basis of the spectrum of phages to which they are susceptible. • Sources of enzymes. A number of enzymes used in molecular biology are virus enzymes. • Pesticides. Some insect pests are controlled with baculoviruses and myxoma virus has been used to control rabbits. • Anti-bacterial agents. In the mid-20th century phages were used to treat some bacterial infections of humans. Interest waned with the discovery of • Anti-cancer agents. Genetically modified strains of viruses, such as herpes simplex virus and vaccinia virus, are being investigated for treatment of cancers. • Gene vectors for protein production. Viruses such as certain baculoviruses and adenoviruses are used as vectors to take genes into animal cells growing in culture. • Gene vectors for treatment of genetic diseases. Discoveries thanks to viruses • A famous experiment carried by Alfred Hershey and Martha Chase, and published in 1952, used phage T2 and E. coli to provide strong evidence that genes are composed of DNA. • The first enhancers to be characterized were in genes of simian virus 40 (SV40). • The first transcription factor to be characterized was the transplantation (T) antigen of SV40. • The first nuclear localization signal of a protein was identified in the T antigen of SV40. • Introns were discovered during studies of adenovirus transcription. Are Viruses Alive • • • • Yes = No = Somewhere in between = Don’t know = Basic Properties • Size – small – The units in which virions are normally measured are nanometres (1 nm = 10−9 m). – 20-400nm – Amongst the smallest are parvoviruses, with diameters about 20 nm, while the microbemimicking virus (mimivirus), isolated from an amoeba, is amongst the largest. • Virions are not cells. They do not contain organelles. • Except for the virions of the arenaviruses, which contain cell ribosomes that were packaged when the virions were assembled. Viruses have genes • The virion contains the genome of the virus. • Whereas the genomes of cells are composed of double stranded DNA, there are four possibilities for a virus genome: – double-stranded DNA – single-stranded DNA – double-stranded RNA – single-stranded RNA.