Test 2 Flashcards
What are the three upper respiratory viruses?
adenovirs, coronavirus (SARS), Rhinovirus
What anatomical features are included in the upper respiratory?
nasal cavity throat nostril mouth voice box (larynx)
Where was the adenovirus first isolated?
in human adenoids
What percentage of viral respiratory infections do adenoviruses cause
5-10%
What is the size in diameter of adenoviruses
80-100nm
The adenovirus is classified as what size in easy terms
medium
What is the shape of the adenovirus
icosohedral
How many protein subunits is the capsid of the adenovirus made up of
252 capsomeres
How many sides are to the adenovirus capsid
20
The 20 sides of the adenovirus form what
12 vertices
What extends from each vertice
binding protein spike fibers
Are adenoviruses enveloped or non-enveloped
non-enveloped
How many serotypes does the adenovirus have
49 serotypes
What is the largest of non-enveloped viruses
adenovirus
Each type of serotype infects what
only 1 type of species
Why do upper repiratory typically go unreported
they are minor symptoms similiar to the common cold
Why is the adenovirus good for gene therapy
It has a DNA genome which replicates in the nucleus of the cell where the human genome is
How does the adenovirus get entry into the cell
protein spikes bind to receptor on cell surface and the virus in endocytosed
what occurs directly after the adenovirus enters the cell
the virion is released and the viral genome enters the nucleus
What type of genome does the adenovirus have
ds DNA
How many base pairs does the adenovirus have
38kb
How many genes does the adenovirus code for
30 genes
What is the first step of the adenovirus replication
early genes are transcribed first and spliced into individual mRNAs
What are the early genes transcribed from
9 promoters
How many non-structural proteins are translated
12
What are the functions of early genes
regulatory enzymes
- upregulate expression of host cells DNA replication machinery
- activate other viral genes
- inhibit cell death
Why are early genes typically involved in regulatory while late genes are structural
- a necessary order
- efficiency issue (what needs to happen to drive replication process and then express the structural proteins from the replicated genomes
What is the second step of adenovirus replication
DNA replication
What type of polymerase is used for DNA replication
virus expressed DNA polymerase
What is the third step of adenovirus replication
late genes are expressed
What is the fourth step of adenovirus replication
assembly
where does assembly occur
in the nucleus
What is the fifth step of adenovirus replication
release
What happens to the cell in order for release of the virus
transcription and translation shut down and the cell dies
What serotypes cause disease in early childhool
1,2
What serotype causes disease later in life
3,5
What are adenovirus infection symptoms
“stuffy nose” and cough
pharyngitis
pneumonia
GI infection
What serotypes cause pneumonia
3,7
What serotypes cause GI infection
40,41
What serotypes cause pharyngoconjunctival fever
3,4,7
What is pharyngoconjunctival fever typically associated with
swimming pools
How is the virus transmitted
aerosol, direct contact, fecal-oral
What are some characteristics of the adenovirus
can resist pH and chemical stresses
What is the vaccine for adenovirus
there is none
What does corona mean
latin for crown
what percentage of common colds do coronoviruses account for
2-10%
What is the diameter of corona virus
60-220
Is the corona virus enveloped or not
enveloped
What is the capsid shape of the coronavirus
helical
Why is this shape weird for the corona virus
because its unusual for a + stranded virus
What comes off the surface of the coronavirus
large dub-shaped protein spikes
How many serotypes of the corona virus infect humans
3
how many serotypes of the corona virus infect other animals
15
What type of genome does the corona virus have
ss RNA positive
how many base pairs does the corona virus have
30kb
What is the largest RNA virus infecting humans
coronavirus
What are the 5 main proteins of the genome
R1/2, S, HE, M, N
What is the R1/R2 protein
replicase
What is the S protein
surface trimer
What is the HE protein
virus exit
What is the M protein
structural membrane protein
What is the N protein
nucleocapsid protein
How does the corona virus gain entry to the cell
attaches to host cell through S spike proteins, virus is endocytosed into the cell
Where does viral replication occur for corona virus
cytoplasm
How is the corona virus replicated
directly translated into 2 polyproteins that are cleaved into 16 smaller proteins
What type of replicase is used
RNA polymerase
What does the replicase do
transcribes a full length RNA strand (negative)
What does the negative strand serve as
transcribed to make positive strands, yield many smaller mRNAs which are translated into smaller proteins
What is the RNA polymerase prone to
errors
What is the ratio for errors
1/10000 nucleotides
What does the high rate of recombination between RNA strands equal
rapid change in virus host range and disease
Where does assembly of the corona virus occur
in cytoplasm
How does assembly occur
virions bud from the RER, virions accumulate in the Golgi and are released when vesicles leave the golgi and fuse with plasma membrane
What is the incubation period for corona virus
3 days
where is the corona virus confined to in the body
upper respiratory tract
What are the symptoms of the corona virus
nasal discharge, malaise, no fever, no coughing, no sore throat
How long do the symptoms last
1 week