2. WHAT IS PURPOSE OF CLASSIFICATION
❖Grouping of biological entities according to their resemblances
and differences
❖To make structural arrangement for easy comprehension
❖To enable prediction of properties of new viruses
❖Possible evolutionary relationships
❖To be able to communicate with each other
3. VIRUSES
❖Viruses are ‘Sub-microscopic’infective entities that multiply only
intracellularly and are potentially pathogenic
❖ Nucleic acid either-RNA or DNA
❖Genome enclosed within protein coat-Capsid
❖Different shapes (Helical,polyhedral,isometric,rod like or
filamentous ) -size vary from 20-300nm
❖Nucleic acid 5-40% and protein 60-95%
❖These may enveloped or non enveloped
4. CRITERIA USED FOR CLASSIFYING PLANT VIRUSES
❖Structure of the virus particle (monopartite,bipartite,tripartite)
❖Physiochemical properties of the virus particle
❖Properties of viral nucleo-protien
❖On the basis of symmertry ( eg.helical viruses)
❖Number and arrangement of protein sub-units (eg.isometric
viruses)
❖Size of viruses
5.
6. CLASSIFICATION OF VIRUSES
• Virus classification starts at the levels of order and continues as
follows ,with the taxon suffixes given in italics:
▪Order (-virales)
▪Family (-viridae)
▪Sub-family (-virinae)
▪Genus (-virus)
▪Species
✓Species –English common name