21. Rhabdovirus/Paramyxovirus Flashcards
4 types of genomes in RNA viruses
- +RNA
- -RNA
- dsRNA
- ssRNA retroviruses
3 properties of -RNA virus
- genomic RNA is not mRNA
- genomic RNA is template for mRNA and genomic RNA
- package RdRP in virion
are -RNA viruses non-enveloped or enveloped?
enveloped
how do -RNA viruses enter the cell? how do they exit?
enter cells by fusion, exit by budding
when do -RNA viruses become infectious?
once they have budded
what 2 things are -RNA viruses sensitive to?
- lipid solvents
- drying
what 2 diseases does rhabdovirus cause?
- rabies
- vesicular stomatitis
what 2 diseases does paramyxovirus cause?
- mumps
- measles
what is the shape of rhabdovirus?
bullet
5 proteins in rhabdovirus
- nucleocapsid protein
- matrix protein
- L and P proteins (RNA pol)
- glycoprotein
6 proteins in paramyxovirus
- nucleoprotein
- matrix protein
- polymerase
- phosphoprotein
- fusion protein
- hemagglutinin-neuraminidase
when is rabies fatal?
once clinical symptoms are observed
5 symptoms of rabies
- excitement or agitation
- hypersalivation
- acute encephalomyelitis
- coma
- death
progression of rabies infection (6 steps)
- virus enters tissue from saliva from animal bite
- virus replicates in muscle near bite
- virus moves up peripheral nervous system to CNS
- virus ascends spinal cord
- virus reaches brain to cause fatal encephalitis
- virus enters salivary glands and other organs
what is the only way that rabies can travel? why?
can only travel in saliva bc virus cannot survive in open air/dry conditions
describe the first artificially produced virus vaccine
Louis Pasteur dried rabbit spinal cords after rabies infection to make attenuated virus –> inoculation into animals protected them from disease
are human rabies cases common in Asia, Africa, North America?
common in Asia and Africa but very rare in North America
describe what happens to people exposed to bats
prophylactically vaccinated against rabies when exposed to bats
what is mumps?
salivary gland and testicular infection
what does RSV stand for?
Respiratory Syncytial Virus
what does RSV cause?
bronchiolitis and pneumonia in infants and children
what is the 2nd most common cause of respiratory tract disease in infants and children?
Human Parainfluenza Viruses (HPIV)
What are 5 diseases that paramyxoviruses cause in other animals?
- Canine distemper virus
- Phocine distemper virus (seals)
- Cetacean morbillivirus (dolphins)
- Newcastle disease virus (birds)
- Rinderpest virus (cattle)
what are henipaviruses?
type of paramyxovirus that is a zoonotic pathogen –> occurs naturally in animals but also infects humans
what does measles cause?
disseminated rash
what is the most common cause of sterility?
mumps
describe the processing of -RNA genomes
- transcribed to make mRNA
- translation of mRNA makes proteins for replication from +RNA to -RNA
- new -RNA undergoes secondary transcription to make more viral proteins
what were the 2 proposed models of transcription?
- MULTIPLE PROMOTER
- SINGLE ENTRY
describe the multiple promoter model
there are multiple transcription promoters along the genome, each at the 3’ end of each cistron –> RNA pol transcribes, falls off, jumps to the next one
describe the single entry model
RNA pol binds 1 promoter and transcribes each cistron in sequence
which transcription model is correct? how do we know?
the SINGLE ENTRY model is correct
using UV radiation that makes dimers and stops transcription –> found that all protein production was blocked –> must be single entry
describe the assay looking at molar abundance of RNA complementary to probe DNA
made oligonucleotide probes complementary to the 3’ and 5’ ends of the first 3 genes
allow for hybridization –> both ends were synthesized at the same rates but 3’ end made in greater molar abundance than 5’ end
what did they find from the assay looking at molar abundance of RNA complementary to probe DNA? 2 main things
found the time when transcription began –> let you find the RATE of transcription
at intergenic region:
1. Pausing - polyadenylation at poly(U) tract by repetitive retranscription
2. Attenuation - polymerase falls of template during “stuttering” process
why is VSV a good vaccine vector? (6)
- it is a weak pathogen that cannot undergo recombination/reassortment/transformation
- no integration
- can elicit strong humoral and cellular immune responses
- naturally infects at mucosal surfaces
- recombinant VSVs can be made with large gene insertions into their genome
- grows to high titers in vitro, allowing rapid purification of large amounts of virus/viral proteins
what is the strategy for vaccination with VSV?
ring vaccination
was VSV vaccine successful?
extent of efficacy was uncertain bc trial design and adverse effects occurred
side effects of VSV vaccine
- headache
- fatigue
- muscle pain
