The document summarizes key aspects of virology. It describes that viruses are small infectious agents that contain either DNA or RNA and use the machinery of host cells to replicate. Viruses infect cells and program them to produce new viral components for assembly of new virus particles. The document then discusses viral structure, morphology, replication cycles involving attachment, entry, uncoating, production of components, assembly and release. It also covers pathogenesis, diagnosis, cultivation, and methods for prevention and treatment of viral infections including vaccines, interferons and antiviral drugs.

1. Dept. Microbiology, Medical Faculty Padjadjaran University VIROLOGY SUNARYATI SUDIGDOADI

8. Virus structure & Morphology The basic design of all viruses places the nucleic acid genome on the inside of a protein shell  capsid Two basic types of virions : 1. Enveloped viruses  have a nucleocapsid of nucleic acid complexed to protein 2. Naked capsid viruses  have a nucleic acid genome within a protein shell

9. Virus structure & Morphology Schematic drawing of two basic type of virions

11. Basic viral forms

12. The structure and relative sizes of a number of DNA

13. The structure and relative sizes of a number of RNA

18. The main groups of human viruses

20. The outcome of the infection depend on : the particular virus-host combination other factors : - the extracelullar environment - multiplicity of the infection - physiology & developmental state of the cell

21. ADSORPTION Adsorption is the first step in every viral infection. Adsorption involves : - virion attachment proteins - cell surface receptor proteins Examples of viral receptors

24. The two basic modes of entry of an enveloped animal virus into the host cell

25. Entry by direct fusion

26. Viropexis

28. Schematic of receptor-mediated endocytosis ulitilized by poliovirus for entry into host cell

29. Insertion of glycoprotein into the cell’s membrane structures and formation of the viral envelope

30. Viral release by Budding

31. VIRAL LIFE CYCLE ATTACHMENT PENETRATION HOST FUNCTIONS ASSEMBLY (MATURATION) Transcription REPLICATION RELEASE UNCOATING Translation MULTIPLICATION Click after each step to view process

33. Recombination Homologous recombination is common in DNA viruses There are 2 mechanisms : 1. Which is unique to the viruses with segmented genomes, involves reassortment of the segments during a mixed infections involving 2 different viral strains. 2. Exemplified by the genetic recombination between different forms of poliovirus Recombination occurs during replication by a “copy choice” type of mechanism Poliovirus replicase switches templates to generate recombinants

38. Cultivation in cell cultures

51. Questions ?