Virology exam 4

non-segmented neg sense viruses

rhabdo

paramyxo

pneumo

filo

rhabdo disease

rabies

families in mononegavirales

all:

rhabdo

paramyxo

pneumo

filo

what is the L protein for paramyxo

it is the RdRp complex

contains:

C-terminal domain, methyl transferase

RdRp domain

capping domain

methyl ttransferase domain

connecting domain, methyl transferase

this L protein is a single polypeptide that has these 5 functional domains

do mononegavirales have poly-a tails?

yes because they also have the poly-u tract that transcribes into a poly-a tail

measles appear first on?

forehead, then spreads ti the rest of the body

pneumo disease

RSV

mild respiratory illness in children

can cause bronchitis and pneumonia

T/F: there are segmented members of mononegavirales

falseee

T/F: rhabdo, filo, pneumo, and paramyxo all use the nested mRNA polymerase jumping mechanism to create multiple mRNAs

false: they use the start stop mechanism

who uses nested mRNA polymerase jumping mechanism to create multiple mRNAs?

corona

T/F: RNA editing is used to create a new mRNA that will translate a second ORF

True:

allows expression of an overlapping ORF by inserting a G which causes a frame shift mutation which leads to a slightly different mRNA and a different protein

look at slide 10 on lecture 23

T/F: RNA editing is only observed in mononegavirales

True,

paramyxo, pneumo, and filo do this.

RHABDO DOES NOT

a local importer of monkeys reports that several of them died in quarantine. you perform electron microscopy of a liver sample from one of the monkeys and find a shepherd’s crook-shaped virus particle. what is it most likely to be?

filovirus

filamentous virus, they have this shape

the L protein of paramyxo possess a:

RdRp

methyl transferase

mRNA capping

mRNA polyadenylation

The L protein has 5 domains which allows all this activity

which mRNA is typically the most abundantly produced by neg strand RNA viruses

nucleocapsid

The N gene is always the first structural gene in their genome

where does RNA editing occur in paramyxo

mRNA

why doesnt cedar virus cause disease?

it does not have an mRNA editing site V or W

T/F: most deaths from Ebola virus are because of hemorrhagic disease

False, its the vomiting and diarrhea that kills people

T/F: ebola virus VP35 disrupts…?

RIG-I- is blocked because VP35 binds to 5’-PPP of viral dsRNA

TBK-1- VP35 binds to active site of TBK-1/IKK epsilon

filo disease

ebola 

two types of ebola viruses we are focusing on

Nipah and Hendra viruses

orthomyxoviridae characteristics

neg sense ssRNA

segmented (8)

nuclear replication

enveloped

spherical

cap snatcher

splices mRNA

myxo means

mucus

(paramyxo and orthomyxo)

influenza c virus

host=humans

respiratory disease

least severe

7 segments, single-stranded, neg sense RNA genome

caused by orthomyxo

influenza b virus

host= humans

respiratory disease

moderately severe

8 segments, single-stranded, neg sense RNA genome

caused by orthomyxo

influenza a virus

reservoir= water fowl

infects a wide range of species

respiratory disease

world-wide distribution

8 segments, single-stranded, neg sense RNA genome

caused by orthomyxo

4 important proteins in orthomyxo

1. HA

2. NA

3. M1

4. M2

HA function in orthomyxo

glycoprotein in viral envelope

occurs in groups of 3

it is the VIRAL ATTACHMENT protein

binds to SA residues on the cell’s surface

19 different HA molecules

NA function in orthomyxo

glycoprotein in viral envelope

serotype determinant

11 different NA molecules (N1-N9 in water fowl and N10-N11 in bats)

FUNCTION: cleaves SA residues to help with viral maturation and exit

if NA cleaves SA, how does influenza enter the cell?

enters quickly, before NA functions. Exit is slow, so NA has an opportunity to cleave the SA on the cell’s surface

M1 function in orthomyxo

M2 function in orthomyxo

its an ion channel that pumps protons into the virion to acidify the interior so M1 can release viral RNA

what is the function of cap snatching in ortho myxo?

primer for transcription and provides ribosome binding site

how does orthomyxo start replication?

de novo synthesis

RdRp self starts

when does the cap bind to orthomyxo during cap snatching?

When RdRp reads the neg sense and makes it a pos sense RNA

what is PB1 in orthomyxo?

RdRp

what function did orthomyxo evolve to replicate in the nucleus to achieve because it is ONLY done there?

to splice its mRNA

which of the following can perform reassortment?

a and b

are there any pos sense RNA or DNA viruses that do reassortment?

NO only neg sense RNA viruses

what does inhibiting the M2 ion channel do in orthomyxo?

inhibit endocytic vesicle envelope fusion

antigenic drift

rapid mutations

antigenic shift

segmented viruses, someone infected with 2+ viruses and they undergo reassortment

what does inhibiting NA do in orthomyxo?

inhibit exit from the cell

a friend of your parents subacute sclerosing panencephalitis. what infection did this friend most likely have as a child

measles virus

Your friend develops COVID and has a cough, fever, body aches, but their blood oxygen levels are normal and they do not require hospitalization yet. They were reading about possible treatments and wants their doctor to start them on anti-inflammatory steroids right away. Should the doctor start anti-inflammatory steroids now?

A. Yes it has been shown to reduce progression to severe disease

B. No steroids will not be effective at this stage

C. No steroids will never be effective

B.

Steroids like dexamethasone only help once a patient is in the hyperinflammatory phase, typically when they require oxygen support. Early in infection, the virus is still replicating and the immune system needs to respond—giving steroids too early can worsen outcomes by suppressing immunity. They only become effective later, if the patient develops severe disease with hypoxia.

You isolate a virus that is transmitted to humans by contact with bats or an amplifying host that contracted infection from bats, what type of genome could this virus have

A. Positive sense RNA

B. Negative sense RNA non- segmented

C. dsRNA

D. A or B

E. A, B or C

D.

A (corona)

B (paramyxo and Rhabdo)

which of the following are most likely to splice their RNA? DNA or RNA viruses

DNA because they need to enter the cell’s nucleus to use the host machinery to slice the RNA

bunyavirales (order) characteristics

families: arena, peribunya, phenu, hanta, nairo

negative sense RNA

may have amisense segments

replicate in cytoplasm

cap snatching

helical and enveloped

uses CELLULAR protease

SEGMENTED

which families in Bunyavirales have ambisense segments?

arena and phenu

which families in Bunyavirales do NOT have ambisense segments?

hanta, nairo and peribunya

what is the vector for nairo

tick

what vector is for phenu

mosquito, but can also be sandflies and ticks

what vector is hanta

rodent

what vector is arena

rodent

amisense segments allow the virus to?

make more than one mRNA per segment

how does cap snatching in viruses in the order Bunyavirales differ from orthomyxo?

orthomyxo snatch caps in the nucleus

you isolate a new virus that has an ambisense genome and is transmitted by ticks. which family would you predict this virus most likely belongs to?

phenui

you isolate a virus that is neg sense RNA segmented with 3 segments. it is transmitted by ticks. what family would you predict this belongs to

nairoviridae

T/F: most viruses in the order of bunyavirales other than hanta and arena are transmitted by mosquitoes/ticks

true

peribunya virus

lacrosse encephalitis

nairo virus

crimean congo hemorrhagic virus

phenu viruses

mosquito- rift valley fever

sandfly- sandfly fever naples virus

tick- heartland virus

hanta virus

hantaan virus, sin nombre virus

arena virus

hemorrhagic fevers (many)

which of these viruses do not cross the placetna and cause congential infections?

adenovirus 52

which of these viruses is sexually transmitted?

all of the above:

zika flavu also Hep C

ebola filo

Hep B hepadna

T/F: most RNA viruses that carry RdRp in their virion splice their mRNA

false, only orthomyxo can

T/F: segmented neg sense RNA viruses that are NOT ambisense create subgenomic mRNAs

false

each of the segments create an mRNA that is the length of the segment

which of the following is a way a neg sense RNA virus creates a subgenomic mRNA?

polymerase stop start mechanism AND ambisense genomes

yes or no: there are neg sense RNA viruses that create subgenomic mRNA from a neg sense strand antigenome internal promoter

no

no neg sense or ds RNA viruses, pos sense (toga, calici, and matona do this)

T/F: all of the viruses with ambisense genomes are also segmented

true

T/F: viruses with ambisense segments in their genomes have more segments than those with neg sense or ds RNA genomes

false

they have less (2-3) vs 7-12 (like orthomyxo)

T/F: all neg sense RNA viruses that are NOT segmented and replicate in the cytoplasm use the start stop mechanism for creating multiple mRNAs

true

viruses that carry RdRp in their virion either have segmented genomes or do start stop mechanism to make many mRNAs

if they have only a few segments they may have ambisense segments so they make more than 1 mRNA per segment

which of the following viruses is found to have segmented genomes?

neg sense RNA and dsRNA

T/F: some neg sense viruses use viral protease to cleave polypeptide to individual proteins

False:

all pos sense RNA do this

neg sense RNA use cellular protease*

T/F: all the families of segmented neg sense viruses that replicate in the cytoplasm use CELLULAR protease to cleave polypeptides to individual proteins?

true

all members of bunya do this

T/F: in both prion and prion like diseases, formation of fibrils of misfolded protein are observed.

true

which of the following best describes the changes seen in misfolded prion proteins (and the proteins of prion like diseases)?

B and C

what is one piece of evidence that BSE was transmissible to other species of animals?

its similar glycosylation patterns between prion proteins found in diseased tissues

Is scrapie disease transmissible?

yes, all prion diseases are infectious and transmissible

what virus replicates using palindromic ends and end nicking on ssDNA genome?

parvo

which virus replicates using de novo synthesis with no primer via RdRp?

most RNA viruses

RNA viruses that dont do de novo synthesis to start replication?

picorna and calici- 5 VPg primes replication

Retro- mRNA genome transcribed from long terminal repeats (LTR) by cellular DdRp. it doesnt use RdRp and only RdRp does de novo

T/F: cap snatching is used to prime RdRp replicase activity

false

they cap snatch to gain a 5 cap for their mRNA for translation

who does this: arena, phenui, orthomyxo, hanta, nairo

RNA neg sense segmented viruses

does neg sense rna get translated?

NO

which of the following viruses will use RT that is primed with a tRNA?

HTLV I

caused by retroviridae

Hep B uses RT but primes with protein

which of the following viruses will have to make their own DdDp?

CMV (herpes), pox, and adeno

CMV/herpes= replicates in nondividing cells

Adeno= uses a protein primer cell DdDp wont recognize

Pox= replicates in cytoplasm

which of the following viruses is found in south america?

a and b

which of these virus families causes tumors?

all of the above

herpes- EBV

polyoma- merkel cell carcinoma

flavi- hep C

also:

papilloma, hep B, and retroviruses cause tumors

which of the following is used to create more than one ORF or protein per mRNA?

A. Leaky Scanning

segmented genomes lead to more than one ORF per genome as each segment has an ORF

IRES is how viruses without 5’ cap initiate translation

which of the following viruses uses an IRES?

a and b

hep c (flavi)- no 5’ cap, needs IRES

polio (picorna)- Vpg 5’ end so no 5’ cap, needs IRES

not noro virus (calici) because it does have Vpg 5’ end but uses the Vpg to bind the ribosome, so NO IRES