Virus morphology
•
2 likes•106 views
This document discusses virus morphology and structure. It begins by defining key virus terminology like capsid, capsomer, nucleocapsid, and virion. It then describes the basic virus structure, which can be naked or enveloped. Viruses vary greatly in size but are generally 20-300nm. They display one of three symmetry patterns: icosahedral, helical, or complex. The document outlines different virus components like the genome, proteins, and envelop. It concludes by discussing factors that impact virus stability like temperature, pH, and detergents.
More Related Content
What's hot
What's hot (19)
Similar to Virus morphology
Similar to Virus morphology (20)
More from Muhammad Amir Sohail
More from Muhammad Amir Sohail (20)
Recently uploaded
Recently uploaded (20)
Virus morphology
- 1. VIRUS MORPHOLOGY BY DR JAWAD NAZIR ASSISTANT PROFESSOR DEPARTMENT OF MICROBIOLOGY UNIVERSITY OF VETERINARY AND ANIMAL SCIENCES, LAHOREUNIVERSITY OF VETERINARY AND ANIMAL SCIENCES, LAHORE
- 2. Contrasting features of microorganisms and viruses g g Property Bacteria Rickettsiae Mycoplasma Chlamydia Virus > 300 nm in diameter* + + + + ‐ Growth on non living + ‐ + ‐ ‐g media + + Binary fission + + + + ‐ DNA and RNA + + + + ‐* Infectious nucleic acid ‐ ‐ ‐ ‐ ‐ Functional ribosomes + + + + ‐ Metabolism + + + +Metabolism + + + + ‐ Sensitivity to antibiotics + + + + ‐ Virus Morphology
- 4. Virus? A protein capsid with nucleic acid Capable of self replication inside the host cellCapable of self replication inside the host cell Envelop may or may not be present Virus Morphology
- 5. Virus structure Capsid protein Nucleocapsid Naked capsid virus DNA or =+ protein virus RNA Nucleocapsid Lipid membrane, glycoproteins Enveloped virus+ Virus Morphology
- 6. Virus structure Size: in the range of 20 ‐ 300 nmSize: in the range of 20 ‐ 300 nm (Size of S. aureus: ~ 1000 nm) Genome: DNA or RNA G i i th f 3000 300 000 bGenome size: in the range of 3000 ‐ 300,000 bps Gene number: 1 to > 200 Virus Morphology
- 9. Virus symmetry y y The arrangement of capsomers to form the capsidThe arrangement of capsomers to form the capsid give rise to virus symmetry h d lIcosahedral symmetry Helical symmetryHelical symmetry Complex symmetry Virus Morphology
- 10. Icosahedral symmetry y y 12 vertices (corners) 30 edges30 edges 20 faces Virus Morphology
- 21. Virus envelopp Several viral families contain an outer envelop Viruses acquire their envelop from cellular membranes during the process of budding If t l i fIf present, envelop is necessary for infectivity Lipids of envelop are cellular origin whileLipids of envelop are cellular origin while proteins are virus encoded Virus Morphology
- 25. Virus structure All th DNA i h i h d l tAll the DNA viruses have icosahedral symmetry except “Poxviridae” All RNA viruses with helical symmetry are enveloped viruses Virus Morphology
- 26. Chemical composition of virus p Virus Genome Can be RNA or DNA Can be single stranded or double strandedCan be single stranded or double stranded Genome can be linear or circular Monoparatite: All genes on single nucleic acid molecule Multiparatite: Genes distributed on various segments Viral genome is haploid except retroviruses RNA viral genome can be positive sense or negative sense Virus Morphology
- 27. Viral genome g All DNA viruses are double stranded (except circoviruses and parvo viruses) All DNA viruses have a single molecule of nucleic acid (not segmented) RNA viruses may be a single molecule or segmented Virus Morphology
- 29. Structural proteins p Include capsid, spikes or peplomers or otherInclude capsid, spikes or peplomers or other components Function of the structural proteinsFunction of the structural proteins Protect the fragile nucleic acid genome from Physical damage ‐ Shearing by mechanical forces Chemical damage‐ UV irradiation leading to chemical modification Matrix proteins give rigidity to the virion Glycoproteins responsible for virus attachment to the cellsGlycoproteins responsible for virus attachment to the cells Structural proteins are immunogenic Virus Morphology
- 30. Non‐structural proteins p Include replicases, transcriptases, ligases etc.Include replicases, transcriptases, ligases etc. Function of the structural proteins Begin program for replicationBegin program for replication Transcription and translation of viral genome Virus replication processVirus replication process Shut down of cellular function Virion assemblyVirion assembly Virus Morphology
- 31. Stability of virus infectivity y y TemperatureTemperature Viruses are highly sensitive to temperature inactivation As a thumb role virus infectivity can be measured inAs a thumb role virus infectivity can be measured in Seconds at 60 °C minutes at 37 °Cminutes at 37 C Hours at at 20 ° C days at 4 ° Cdays at 4 C Years at ‐70 ° C or lower Virus Morphology
- 32. Stability of virus infectivity y y pH p Infectivity is best preserved at isotonic pH (7.00‐7.80) Tolerate a wide range of pH g p pH tolerance is high in non‐enveloped viruses as compared to enveloped viruses d l d dLipid solvents and detergents Enveloped viruses are more sensitive to lipid solvents than the naked virusesthan the naked viruses Virus Morphology