Classification of virus
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The document classifies viruses according to their nucleic acid, capsid, and envelope. Viruses are classified based on whether they contain DNA or RNA, if it is single or double stranded, segmented or not, and positive or negative stranded for RNA viruses. Capsids are classified as icosahedral or helical. Envelopes are naked or enveloped. DNA viruses like herpes, hepatitis, adeno, papilloma, parvo, and pox viruses are usually double stranded, icosahedral, and replicate in the nucleus, with some exceptions. RNA viruses are generally single stranded, enveloped, helical, and replicate in the cytoplasm, though some are double stranded, non-enveloped, or
Classification of virus
- 2. Classification of Medically important virus Viruses are classified according to their 1)Nucleic acid: Type of nucleic acid: DNA, RNA Double- vs. single-stranded Single or segmented pieces of nucleic acid Positive (+) or negative (-) stranded RNA Complexity of genome 2) Capsid: Icosahedral Helical 3) Envelope: Naked Enveloped
- 3. DNA Viruses Sometimes referred to as the HHAPPPy viruses: Herpes Hepadna Adeno Papova Parvo Pox Most DNA viruses are double-stranded, show icosahedral symmetry, and replicate in the nucleus.
- 4. DNA Viruses Two DNA viruses break these rules: 1) Parvoviridae: This virus is so simple that it only has a single strand of DNA 2) Poxviridae: This virus is at the opposite end of the spectrum and is extremely complex. Although it does have double-stranded DNA, the DNA is complex in nature, coding for hundreds of proteins. This virus does not have icosahedral symmetry. The DNA is surrounded by complex structural proteins looking much like a box ( POX IN A BOX). This virus replicates in the cytoplasm
- 5. DNA Viruses Three of the DNA viruses have envelopes: Herpes Hepadna Pox Three are naked: A woman must be naked for the PAP smear exam. PApova Adeno PArvo
- 7. RNA Viruses There are certain generalities about RNA viruses, most of which are the opposite of DNA viruses.Most RNA viruses are single- stranded (half are positive [+1 stranded, half negative [-1), enveloped, show helical capsid symmetry, and replicate in the cytoplasm: Toga Corona Retro Picorna Calici Reo Orthomyxo Paramyxo Rhabdo Bunya Arena Fibo
- 8. RNA Viruses Exceptions: 1) Reoviridae are double-stranded 2) Three are nonenveloped: Picorna, Calici, and Reoviridae 3) Five have icosahedral symmetry: Reo, Picorn ,Toga, Flavi, Calici (Rhabdo has helical symmetry but shaped like a bullet). 4) Two undergo replication in the nucleus: Retro, Orthomyxo.