tailieunhanh - Ebook Rapid review microbiology and immunology (3th edition): Part 2

(BQ) Part 2 book "Rapid review microbiology and immunology" presents the following contents: Viral structure, classification and replication, viral pathogenesis, diagnosis, therapy, and prevention of viral diseases, nonenveloped dna viruses, enveloped DNA viruses, arge enveloped RNA viruses, infectious diseases clinical correlations,. Invite you to consult. | Section III Virology ___12 X Chapter 1 Viral Structure Classification and Replication The following characteristics genome type enveloped or naked capsid and relative size large medium or small allow you to predict many of the properties of the virus. Parvoviruses only DNA viruses with singlestranded genome All - RNA viruses are enveloped and must carry their RNA-dependent RNA polymerase as part of the nucleocapsid. DNA except pox and RNA not retro do not need to carry a polymerase into the target cell and their genomes are sufficient to infect a cell. Reoviruses doubledouble double-capsid double-stranded segmented genome Be able to recognize viruses with characteristic shapes Fig. 18-2 An icosahedron or icosadeltahedron is the basic capsid shape and looks like a soccer ball. I. Structure and Classification of Viruses A. Overview 1. A virion or viral particle consists of a genome DNA or RNA packaged within a protein coat the capsid which may or may not be surrounded by a membrane envelope. 2. Essential enzymes or other proteins are carried within some viruses. 3. The major virus families can be classified based on their genome structure size and whether they are enveloped or not enveloped. B. Genome structure 1. DNA genome Fig. 18-1A Single-stranded linear DNA parvoviruses Double-stranded DNA a. Linear genome adenoviruses herpesviruses and poxviruses b. Circular genome polyomaviruses and hepadnaviruses 2. RNA genome Fig. 18-1B Positive-sense RNA a. Same sequence as messenger RNA mRNA b. Directly translated into protein Exception is the retroviruses in which the RNA genome is not translated but is converted into DNA which then acts as a template for production of mRNA. Negative-sense - RNA a. Sequence complementary to mRNA b. Must be copied into strand to generate mRNAs for protein synthesis Double-stranded - RNA copying of - strand generates mRNA for protein synthesis 3. Segmented genome Found in the reoviruses a - RNA genome and in three families of - RNA viruses