1 / 24

Classification of Medically Important Viruses @ Two components of virus are used

Classification of Medically Important Viruses @ Two components of virus are used in classification : 1. Molecular weight & structure of nucleic acid 2. Size, symmetry ,& envelope of capsid. DNA VIRUSES 3 nonenveloped, icosahedral virus families:*parvoviruses,

stephanie-gutierrez
Download Presentation

Classification of Medically Important Viruses @ Two components of virus are used

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Classification of Medically • Important Viruses • @ Two components of virus are used • in classification : • 1. Molecular weight & structure of • nucleic acid • 2. Size, symmetry ,& envelope of • capsid

  2. DNA VIRUSES • 3 nonenveloped, icosahedral virus • families:*parvoviruses, • *papovaviruses, *adenoviruses • 2. 3 enveloped virus families : a) hepadnavirus family, eg : • hepatitis B virus – icosahedral b) herpesviruses - icosahedral . c) pox viruses - complex symmetry

  3. Papovaviruses • @ Nonenveloped (naked) icosahedral viruses , with double-stranded circular DNA. • @ Known: papilloma, polyoma, simian viruses • @ 3 human papovaviruses known : • JC virus, isolated from progressive multifocal leukoencephalopathy cases . • BK virus, isolated from urine of kidney transplant patients . • Human papillomavirus

  4. Adenoviruses @ Naked icosahedral, Ds. linear DNA viruses @ Cause pharyngitis, URT & LRT diseases . @ There are at least 40 antigenic types .

  5. Parvoviruses • @ Very small, nonenveloped, icosahedral, Ss. , linear DNA. • @ 2 types of parvoviruses: Defective & nondefective : • Defective require a helper virus for replication. • Nondefective ,e.g. B 19 virus

  6. Hepadnaviruses @ These are double-stranded viruses with an icosahedral capsid covered by an envelope. @ Hepatitis B virus is the human pathogen in this family.

  7. Herpesviruses @ Enveloped, icosahedral, Ds., linear DNA viruses @ Cause latent infections. @ The 5 important pathogens: *herpes simplex types I & 2, *varicella-zoster, *CMV *Epstein-Barr cause of IM.

  8. Poxviruses @ Largest virus with a bricklike shape, an envelope, & a complex capsid symmetry. @ Cause skin lesions, or "pocks" @ Smallpox & vaccinia are the two important members. @ Vaccinia virus is used in smallpox vaccine.

  9. RNA VIRUSES @ 14 families of RNA viruses . @ 3 naked icosahedral viruses : 1. Picornavirus 2. Calicivirus 3. Reovirus @ 3 enveloped icosahedral viruses: 1. Flavivirus 2. Togavirus 3. Retrovirus

  10. @ 8 are enveloped helical viruses: * 5 have Ss. linear RNA, e.g: (1) orthomyxovirus (2) paramyxovirus (3) rhabdovirus (4) filovirus (5) coronavirus * 3 have Ss. circular RNA, e.g: (1) arenavirus (2) bunyavirus (3) deltavirus .

  11. Picornaviruses @ The smallest RNA viruses. @ Have Ss, linear, nonsegmented RNA within a naked icosahedral capsid. @ "picorna" is derived from pico- small @ Divided into 2 groups of pathogens: (I) enteroviruses : poliovirus, echovirus coxsackievirus, hepatitis A (2) rhinoviruses.

  12. Caliciviruses @ Naked , icosahedral viruses. @ Have Ss, linear, nonsegmented, RNA. @ 2 human pathogens: * Norwalk virus * hepatitis E virus.

  13. Reoviruses @ Naked viruses with 2 icosahedral capsid coats. @ Have 10 segments of Ds. linear RNA. @ Main pathogen is rotavirus, causing diarrhea in infants.

  14. Flaviviruses • @ Enveloped, icosahedral, Ss, linear, nonsegmented, RNA viruses • @ Include : • hepatitis C virus, • yellow fever virus, • dengue virus, • St. Louis encephalitis viruses. • Japanese encephalitis viruses.

  15. Togaviruses @ Enveloped, icosahedral, Ss, linear, nonsegmented RNA viruses @ 2 groups of human pathogens: * Alphaviruses: include : eastern & western encephalitis viruses * Rubiviruses: contain only rubella virus

  16. Retroviruses • @ Enveloped, icosahedral, with 2 strands of Ss , linear RNA viruses • @ "retro" pertains to the reverse transcription of RNA into DNA. • @ 2 medically important groups: • oncovirus group, contains the sarcoma & leukemia viruses, e.g. • (human T cell leukemia virus-HTLV) • 2.lentivirus group includes human immunodeficiency virus (HIV) .

  17. Orthomyxoviruses @ Enveloped, with a helical capsid & 8 segments oflinear, Ss RNA. @ "myxo" means affinity formucins. @ Influenza virus is the main human pathogen.

  18. Paramyxoviruses @ Enveloped, helical, Ss , linear, non segmented RNA viruses @ Human pathogens are : *measles, *mumps, *parainfluenza, *respiratory syncytial (RSV).

  19. Rhabdoviruses @ Bullet-shaped enveloped viruses with a helical, Ss , linear, nonsegmented RNA viruses @"rhabdo" refers to bullet shape. @ Rabies virus is the only important human pathogen.

  20. Filoviruses @ Enveloped, helical, Ss , linear, nonsegmented RNA viruses. @ Pleomorphic, long filaments . @ "filo" means "thread" . @ 2 human pathogens are : *Ebola virus *Marburg virus.

  21. Coronaviruses @ Enveloped, helical, Ss , linear, nonsegmented RNA viruses . @ "corona" refers to crown of spikes protruding from envelope. @ Cause respiratory tract infections (e.g. common cold) .

  22. Arenaviruses @ Enveloped, helical, Ss, circular, 2 segments RNA viruses @ "arena" is "sand“, refers to ribosome granules on virus surface @ 2 human pathogens are known : *lymphocytic choriomeningitis virus *Lassa fever virus.

  23. Bunyaviruses @ Enveloped, helical, Ss, circular 3 segments RNA viruses . @ "bunya" refers to the place in Africa where it was isolated. @ Cause encephalitis & fevers e.g Korean hemorrhagic fever.

  24. Deltavirus @ Hepatitis delta virus (HDV) is the only member of this genus. @ Enveloped, helical, circular, Ss, RNA virus @ It is a defective virus “cannot replicate unless hepatitis B virus (HBV) is present within the same cell”

More Related