* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download PowerPoint Presentation - Introduction to viruses
Survey
Document related concepts
Transcript
CHAPTER-II Introduction to viruses R.KAVITHA, M.PHARM, LECTURER, DEPARTMENT OF PHARMACEUTICS, SRM COLLEGE OF PHARMACY, SRM UNIVERSITY, KATTANKULATHUR . Definition of a Virus Sub microscopic entity consisting of a single nucleic acid surrounded by a protein coat and capable of replication only within the living cells of bacteria, animals or plants. Definition of a Virus Obligate Intracellular Parasite Virion Structure Lipid Envelope Nucleic Acid Protein Capsid Virion Associated Polymerase Spike Projections Virion Morphology • Simple Structure • Repetitive Structure • High Level of Redundancy Virus Morphology Helical Icosahedral Virus Replication 1 Virus attachment 2 3 1 5 4 5 6 4 2 3 7 8 7 6 8 and entry Uncoating of virion Migration of genome nucleic acid to nucleus Transcription Genome replication Translation of virus mRNAs Virion assembly Release of new virus particles Cytopathic Effect (cpe) Adenovirus Herpes virus Transmission of Viruses • • • • • Respiratory transmission 9 Influenza A virus Faecal-oral transmission 9 Enterovirus Blood-borne transmission 9 Hepatitis B virus Sexual Transmission 9 HIV Animal or insect vectors 9 Rabies virus Virus Tissue Tropism • Targeting of the virus to specific tissue and cell types • Receptor Recognition 9 CD4+ cells infected by HIV 9 CD155 acts as the receptor for poliovirus In vivo Disease Processes • Cell destruction • Virus-induced changes to gene expression • Immunopathogenic disease Acute Virus Infection Amount of virus Symptoms Virus Time Generation of Novel Influenza A Viruses Human H2N2 ANTIGENIC SHIFT Genetic Reassortment Avian H3N8 Point mutation of HA and NA genes ANTIGENIC DRIFT Human H3N2 Viruses and Human Tumours • Epstein Barr Virus 9 Burkitt’s Lymphoma • Human papillomavirus 9 Benign warts 9 Cervical Carcinoma • Human T-cell Leukaemia Virus (HTLV-1) 9 Leukaemia • Hepatitis C virus 9 Liver carcinoma Virus-induced tumours Virus Infection [ ] Uninfected Cell ? Uncontrolled cell growth and tumour formation Virus-induced transformation Normal cells Transformed cells Virus-Induced Tumours • • • • Virus infects cell. Virus nucleic acid, as DNA, integrates into cellular genome. Virus causes changes in cellular gene expression. Uncontrolled cell multiplication and tumour formation. Treatment and Prevention of Virus Infections • Antivirals • Vaccines and immunisation Antiviral Targets • Attachment/Entry • Nucleic acid replication • Virus protein processing • Virus maturation Problems with Antivirals • Identification of virus-specific target. • Generation of resistant variants.