M2-Group 5 (Non-segmented) Flashcards
Are Paramyxoviridae enveloped or non enveloped and what capsid do they have?
-Enveloped
-helical
What group are Paramyxoviridae in?
Group 5–> (-) ssRNA
Are Paramyxoviridae segmented or non-segmented?
Non-segmented
What does it mean to be segmented or non-segmented
Non-segmented: Only 1 strand of RNA
Segmented: Multiple strands of RNA that makes up genome
What pathogens are in Paramyxoviridae?
-Measles & mumps
-Parainfluenza
-Nipah & Hendra
-Rabies–>Rhabdoviridae
True or false: Before the measles vaccine, it did not kill many people
False
-Before vaccine measles killed 2 million kids per year
True or false: Measles has a low R0 value compared to other viruses
False
-Measles has the HIGHEST R0 value for a virus
-R0 = 12-18
What are the reservoirs and amplifying host for Nipah and Hendra
Reservoir: bats
Nipah host: Pigs
Hendra host: Horses
True or false: Nipah, Hendra, and Rabies can easily pass human to human
False
-usually dead end host because of high fatality rate
Explain Paramyxovirus life cycle
- Enters through fusion–>neutral pH
- Polymerase is brought with virus
- Buds off plasma membrane–>syncytia
True or False: In Paramyxoviridae the genome is not bound by proteins
False
-Since helical genome is always wrapped in viral proteins
-Genome size is divisible by 6
Differences between Icosahedral and Helical capsids
Icosahedral: Genome is not associated with proteins–>naked RNA
Can be immediately translated
Helical: Genome is bound by proteins –>Nucleocapsid, phosphoprotein, polymerase
Must be transcribed to make mRNA
Where are structural and non structural proteins found on mRNA?
-Structural (nucleocapsid) at the beginning 3’ end –> N
-Non-structural (polymerase)–> 5’ end –>L
What does polymerase stuttering do?
-Pol stutters at polyU to form polyA so that pol can reinitiate at start in intergenic region or go back to the beginning at 3’end
What determines the switch from making short mRNA transcription to the whole genome replication
Levels of N protein –> nucleocapsid proteins
-when there is enough N proteins to coat the genome, pol will stop reinitiating & read the entire genome
The expression of what protein cause infected cells to fuse with uninfected cells forming a?
-fusion (F) proteins
-form syncytia
-Paraymyxovirus
Filoviridae: group, enveloped/non, capsid, segmented/non
-Group 5–>(-)ssRNA
-Enveloped
-Helical
-Non-segmented
What pathogens are in Filoviridae?
Ebola and Marburg
Filovirus life cycle
- Entry through endosomes –> Low pH triggers
- Viral polymerase is always brought with virus
- Virus buds off plasma membrane–>secretes 2 types of glycoprotein from polymerase stuttering
What is Ebola’s host receptor that is used to access cytoplasm?
NPC1
True or false: Once viruses spillover they adapt to humans and replicate less in original reservoir
True
-Ex: virus binds better to human NPC1 than bat NPC1
What does the P/C/V gene do?
Polymerase stuttering that causes “editing” or insertion of either 1 or 2 As
-changes frameshift–>causes overlapping reading frames & alternative starts
In Filoviridae, how are 2 alternative versions of GP made?
-Full length GP is made ONLY when polymerase stutters & adds an extra base
-secreted sGP is made in high conc to be a decoy for antibodies–>nothing happens when it binds
Ebola viral protein?
Glycoprotein
Difference in stuttering for Paramyxoviridae and Filoviridae
-Paramyxoviridae: addition of As not essential for making proteins, happens occasionally
-Filoviridae: Glycoprotein is ONLY made when there is stuttering