Subject: Molecular Virology Instructor: Dr. Sobia Manzoor VIRUSES AN INTRODUCTION Subject: Molecular Virology Instructor: Dr. Sobia Manzoor Lecture: 1

INTRODUCTION TO VIROLOGY Virology: study of small biological entities : Viruses Living organisms: consists either of viruses; 1: Parasites 2: Viral genes incorporated in the genome of a living organism. Viruses; the smallest of creatures have a great impact on the molecular mechanisms of a living organism. Since viruses are parasitic in nature therefore the study of viral genome, viral processes of gene expressions in host cells and viral replication provides fundamental information regarding the cellular processes in general. .

Viral Entry Viral Persistence Pathogenesis of Viral Infections Host Virus Interactions Viral Immunopathogenesis Tumor Biology of Viruses Definition: Simplest of all definitions quoted by the author S. E. Luria states that “Viruses are submicroscopic entities, capable of being introduced into specific living cells and of reproducing inside such cells only”.

Viruses differ from each other on various bases. They differ on the basis of type of host they infect. On the other hand viruses they may be distinguished from one another: Morphology Genome type or Mode of replication.

There are some unifying principles which all viruses follow: Viral genome is always packaged inside the core of a particle in order to ensure safe transfer from one host to another In order to survive, all viruses establish themselves in a host population. The viral genome consists of all the information required for the initiation and completion of an infectious cycle within a host cell that is rendered susceptible to that specific infection.

Study of Viruses - Virology Five Kingdoms Plantae Animalia Fungi Protista Monera

Five Characteristics of Life 1. Cells. 2. Grow and maintain their structure by taking up chemicals and energy from the environment. 3. Respond to their external environment 4. Reproduce and pass on their organization to their offspring. 5. Evolve and Adapt to their environment.

Viruses are: Acellular. Obligate intracellular parasites. No ATP generating system. No Ribosomes or means of Protein Synthesis.

Typical Virus Two parts 1. Nucleic Acid 2. Capsid (Coat Protein) DNA or RNA (But never both) 2. Capsid (Coat Protein) Some Viruses: Envelope Enzymes

Host Range Spectrum of host cells that a virus can infect Some viruses only infect: Plants Invertebrates Protists Fungi Bacteria (bacteriophages)

Host Range Most viruses have a narrow host range Polio virus - nerve cells Adenovirus - cells in upper Respiratory Tract

Course Outcomes: At the end of the course the student will have a good understanding of fundamental concepts of structure and replication of virus. The course will help student to understand fundamental aspects on the effect of virus on eukaryotic and prokaryotic organisms. After reading the course the student will have elaborate knowledge of morphology, taxonomy, mechanisms of replication, strategies of viral gene expression, diseases and biological control of viruses. 

Course Contents: 200 years of discoveries General aspects of virology Viral Classification and Structure Modes of infection Cellular Models of virus propagations Replication and pathogenesis in a comparative fashion. Host-virus interactions Transformation and oncogenesis Immunopathology Host defense mechanisms Antiviral pharmacology and applied virology Bacteriophages Plant viruses and their associated diseases What is next for Virology?