Microbiology - Viruses Flashcards
What is the only single stranded DNA virus?
Parvovirus
What are the two types of RNA viruses?
Positive(+) stranded RNA viruses - being just like mRNA
Negative(-) stranded RNA viruses - carrying RNA polymerase which transcripe the negative strand into a positive(+) strand, making it ready for translation.
Difference between positive(+) and negative(-) stranded RNA viruses?
Positive(+) RNA viruses are ready for translation immediately after infecting host cell.
Negative(-) RNA viruses carry RNA polymerase that transcribe the negative strand into a positive(+) strand before it is able to translate its genome into structural proteins.
What are the two types of capsids?
1 Icosahedral - capsomers are first arranged in triangles. 20 triangles are placed together to form an icosahedron.
2 Helical capsids - protein capsomers are bound to RNA(always RNA) and coiled into a spherical nucleoprotein capsid.
Viruses that do not have membranes are called?
naked viruses
Viruses that have a membrane are called?
enveloped
What are the HHAPPPy viruses?
Herpes Hepadna Adeno Papova Parvo Pox
All are DNA viruses
Virus that replicates in the cytoplasm?
Poxviridae
Singlestranded DNA virus?
Parvoviridae
Three naked DNA viruses?
Papova
Adeno
Parvo
= PAP
Six positive(+) stranded RNA viruses?
TOGA FLAVI CORONA RETRO - CALICI PICORNA
What are the four steps of viral replication?
1 Adsorption and penetration - virus enters host cell
2 Uncoating - nucleic acid is release from capsid into cytoplasm
3 Synthesis and assembly - production of viral proteins
4 Release of virions from host cell
Four outcomes(for host cell) of viral infection?
1 Death - host cells own function shuts down
2 Transformation - infection activate oncogenes = uninhibited growth
3 Latent infection - virus survive in a sleeping state.
4 Chronic slow infection - disease after many years of indolent infect.
Orthomyxoviridae causes this famous disease?
The flu
What is the role of Neuraminidase and Hemagglutinin in the pathogenesis of infleunza?
Neuraminidase cleaves neuraminic acid and disrupts the mucin barrier.
Hemagglutinin attach to host sialic acid receptors = adsorption.
What is antigenic drift?
During viral replication mutations occur in HA or Na, due to poor proofreading. The antigenic drift is the reason for why influenza reccurs every year. The small alterations makes so that host immune system do not recognize orthomyxoviridae = sesonal flu.
What is antigenic shift?
Co-infection of host cell with two different influenza viruses. When the two viruses undergo replication, their proteins “mix” and creates a new virus that has never before been exposed to human immune system.
Reye’s syndrome?
Giving aspirin to children with viral infection may induce severe hepatitis and encephalopathy.
H5N1?
Avian influenza
H1N1?
Swine flu
Croup?
Parainfluenza infection of larynx an upper respiratory tract. Swelling of these structure produce airway narrowing.
Fusion (F) protein?
protein present in paramyxovirus that causes infected cell to fuse into multinucleated giant cells.
Respiratory Syncytial Virus?
Paramyxovirus. Number one cause of pneumonia in young children, especially in infants less than 6 months.
Measles clinical picture?
1 Prodrome - fever, photophobia, conjunctivitis, rhinitis ++
2 Koplik’s spots - red-based lesions in mouth, 1or 2 days before the rash.
3 Rash - starts on the head and spreads downward
What is the Dane particle?
Active, Intact and infective HBV