8. virus classification
• host specification: plant, animal, bacteria
• DNA a RNA virus: ds DNA, ss DNA, ds RNA,
pos ss RNA, neg ss RNA, rev trans diploid ss
RNA, rev trans circular dsDNA
• structure: symmetry helical, complex, icosahedral,
capsid, envelope, number of capsomer
9. ds DNA, ss DNA, ds RNA, ss RNA, rev trans diploid
ss RNA, rev trans circular dsDNA
10.
11. Reverse transcriptase
= enzyme overwriting RNA to DNA
transcription
replication
reverse
transcription translation
RNA Protein
DNA
14. Viruses can reproduce only within a host cell
• Obligate intracellular parasites
• lack enzymes and ribosomes …
• only a limited range of host cells
– host specificity
• eukaryotic viruses
are tissue specific
• Lytic cycle – virulent viruses
15. Lytic cycle of virus reproduction
• adsorption virus to cell
• penetration virus or viral NA into cell
• replication, transcription and translation
•assembling new virus particles (self-assembly)
• transfer to daughter cells: effect on the cell:
death of the cell – lyses (hundreds or thousand)
cytopathy effect (exocytose)
16.
17. Lysogenic - virogenic cycle
= integration of the viral nucleic acid into
the host genome as provirus (prophage)
• replication with the DNA of the host cell
• latent viruses – the cell is not damaged
• virus is transferred to daughter cells
• viruses as vectors of oncogeny
21. Prion protein
- occurrence in two isoforms:
normal PrPC (C=cellular)
abnormal PrPSC (SC=scrapie)
– PrPC – prevalence of alpha helix a little beta
structure
– PrPSC – prevalence of beta structure
– presence of PrPSC induces PrPC change =
normal protein to abnormal - runs as chain
22.
23.
24. • hereditary disease
= gene mutation → abnormal protein
• transfer between species is rare,
but might be possible with a long period
of latency
• transfer from human to human: by
growth hormone, brain electrodes
25. Disease
They cause an infection in sheep
called scrapie and cattle
bovine spongiform encephalopathy
("mad cow" disease).
26. Human diseases
– Creutzfeld-Jacob disease: affection of the grey
brain cortex, severe neurological symptoms with
quickly proceeded dementia)
– kuru: Papua-New Guinea: disability of
movement coordination, paralysis, dementia –
disease is extension by ritual cannibalism
27. Neural degeneration in a
prion infection.
a slice from the brain of a
person who died of kuru
The large fluid-filled holes
are places where neurons
have died.
31. Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson,
Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings
Publishing Company, 1996 –2010.
Notas do Editor
Spherical virus
A virus which, upon infection of a host , does not necessarily cause lysis but whose genome may replicate in synchrony with that of the host
Germen measles Group: Group IV ( (+)ssRNA ) Family: Picornaviridae Genus: Enterovirus Species: Poliovirus Group: Group IV ( (+)ssRNA ) Order: Picornavirales Family: Picornaviridae Genus : Rhinovirus Group: Group V ( (-)ssRNA ) Family: Orthomyxoviridae Genera Influenzavirus A Influenzavirus B Influenzavirus C Group: Group IV ( (+)ssRNA ) Family: Flaviviridae Genus: Flavivirus Species: Tick-borne meningoencephalitis virus Group: Group IV ( (+)ssRNA ) Family: Togaviridae Genus: Rubivirus Species: Rubella virus Group: Group V ( (-)ssRNA ) Order: Mononegavirales Family: Paramyxoviridae Genus: Rubulavirus Type species Mumps virus Group: Group V ( (-)ssRNA ) Order: Mononegavirales Family: Paramyxoviridae Genera Subfamily Paramyxovirinae Avulavirus Henipavirus Morbillivirus Respirovirus Rubulavirus Subfamily Pneumovirinae Pneumovirus Metapneumovirus Group: Group V ( (-)ssRNA ) Order: Mononegavirales Family: Rhabdoviridae Genus: Lyssavirus Species: Rabies Group: Group VI ( ssRNA-RT ) Family: Retroviridae Genus: Lentivirus Species Human immunodeficiency virus 1 Human immunodeficiency virus 2
Group: Group I ( dsDNA ) Family: Adenoviridae Genera Atadenovirus Aviadenovirus Ichtadenovirus Mastadenovirus Siadenovirus Group: Group I ( dsDNA ) Family: Herpesviridae Subfamily: Alphaherpesvirinae Genus: Simplexvirus Species Herpes simplex virus 1 (HWJ-1) Herpes simplex virus 2 (HWJ-2) Group: Group I (dsDNA) Family: Herpesviridae Subfamily: Gammaherpesvirinae Genus: Lymphocryptovirus Species: Human herpesvirus 4 Variola virus (Smallpox) Virus classification Group: Group I (dsDNA) Family: Poxviridae Genus: Orthopoxvirus S pecies: Variola vera Group: Group I (dsDNA) Order: Unranked Family: Papillomaviridae