Virus Genome Diversity Flashcards
What is the largest virus called?
Mimivirus
What is error-catastrophe?
Too many mutants within the viral genome, it is too far from the optimum so the virus self-destructs.
What two subcategories can single-stranded RNA genomes be split into?
Positive and Negative sense
What is the purpose of the 5’cap?
Resistance to exonucleases and recognition by translational machinery.
When can positive sense RNA be translated?
Immediately, RNA has a very short half-life
What structures do positive-sense RNA viruses have?
5’cap (m7G)and a polyA tail to mimic the host’s mRNA
What initiates cap binding?
eIF4A - RNA can cap snatch
What is the IRES?
Internal ribosome binding entry site, the genome can H-bond to itself making secondary structures that mimic the cap
Name 5 +sense RNA viruses
- Flavivirus
- HepC
- Picornavirus
- Alphavirus
- Coronavirus
Give 3 examples of the Flavivirus
- Dengue fever
- Yellow Fever
- West Nile
How is HepC different to Flavivirus?
Has an IRES site instead of an m7G cap
Give 4 examples of picornavirus
- Polio
- Rhinovirus
- HepA
- FMDV
How many open reading frames does alpha virus have?
2
Give 2 examples of coronavirus
- SARS
2. MERS
What are the features of a retrovirus?
Single-stranded Positive sense RNA 5'-cap and a 3'-polyA tail Integrates into host cell genome Multiple and overlapping ORFs
What are the two subgroups of negative sense RNA viruses?
Segmented and non-segmented
Give 3 -sense RNA viruses
- Rhabdovirus
- Filovirus
- Orthomyxovirus
Two examples of rhabdovirus
- Rabies
2. Vesicular stomatitis
2 examples of filovirus
- Ebola
2. Marburg
1 example of orthomyxovirus
Influenza
Give 3 DNA viruses
- Adenovirus
- Herpesvirus
- Papillomavirus
What is an inverted terminal repeat?
A single stranded sequence of nucleotide followed downstream by its reverse compliment
Is the papillomavirus genome linear or circular?
Small circular
What charge do capsid proteins have and rich in what amino acids?
Positively charged and rich in arginine and leucine
What are glycoproteins for?
Recognition of host cell receptors (setting the tropism)
When are matrix proteins present?
In enveloped viruses, interact with both capsid and envelope proteins
What is the tegument?
A cluster of proteins which line the space between the envelope and nucleocapsid of herpesvirus
What do lipid envelopes contain?
Glycosylated proteins which can recognise specific receptors.
What is maturation of viral glycoproteins for?
Avoiding tangling
What directions are polyproteins cleaved in?
Cis and Trans
