Virology Dengue - Dengue Virus in Detail

Virology

1. z
K. Gayathri
BP231506
1
st
M.ScMicrobiology
Deparmentof Microbiology
Sacred Heart College (Autonomous), Tirupathur
Dengue Virus

2. zIntroduction
Dengueisamosquito-transmittedvirusandtheleadingcauseof
arthropod-borneviraldiseaseintheworld.
Itisalsoknownasbreakbonefeverduetotheseverityofmuscle
spasmsandjointpain,dandyfever,orseven-dayfeverbecauseofthe
usualdurationofsymptoms.
Dengueisfoundintropicalandsubtropicalclimates,mostlyinurban
andsemi-urbanareas.
It'saprobleminmanytropicalandsubtropicalpartsoftheworld,including
Africa,Asia,SouthAmerica,andsomepartsofnorthernQueensland
In1943,RenKimuraandSusumuHottafirstisolatedthedenguevirus
whilestudyingbloodsamplesofpatientstakenduringthe1943dengue
epidemicinNagasaki,Japan.

3. zDengue Virus
Denguevirus(DENV)isasingle-stranded,positive-senseRNAvirus
thatbelongstotheFlaviviridaefamily.
It'sanenvelopedviruswith10,700bases.DENVisamemberofthe
Flavivirusgenus,whichalsoincludesotherarthropod-borneviruseslike
Zika,WestNile,andyellowfever
DENVistransmittedbythebiteofAedesmosquitoes.It'scategorized
asanarbovirus(arthropod-bornevirus)becauseit'stransmittedby
mosquitoes.

4. zStructure
Denguevirusis40-60
nanometersinsize,
withanisometric
nucleocapsidof25-
30nanometers.The
dengue virus's
structureisroughly
spherical,witha
diameter of
approximately 50
nanometers.

5. zTypes of Dengue Virus
ThefourdenguevirusserotypesareDENV-1,DENV-2,DENV-3,and
DENV-4.Theyarecalledserotypesbecauseeachhasdifferent
interactionswiththeantibodiesinhumanbloodserum.
In2013,afifthvariant,DENV-5,wasisolated.Thisserotypefollows
thesylvaticcycleunliketheotherfourserotypeswhichfollowthe
humancycle

6. zReplication of Dengue Virus

7. zReplication
The replication cycle of the dengue virus (DENV) includes the following steps:
1.The virus binds to host cell receptors.
2.The virus enters the host cell via receptor-mediated endocytosis.
3.The virus is internalized into a clathrin-coated endosome.
4.The viral genome is transported to the endoplasmic reticulum (ER).
5.The viral genome is replicated and viral proteins are synthesized.
6.The viral proteins are assembled into a nucleocapsid.
7.The virus matures and egresses.
8.The newly synthesized dengue viruses are released and go on to infect
other host cells.

8. zPathogenesis
InfectionofDendriticCells
Denguevirusentersdendriticcellsintheskinviamosquitobites.
Denguevirus(DENV)candirectlyinduceDC-apoptosisthrough
replicationinsideinfectedcells

9. zPathogenesis
DisseminationviaLymphatics
Thevirusthendisseminatesviathelymphaticstoothertissues.
Afteramosquitobite,cellsintheskinareinfectedanddeliver
Denguevirus(DENV)tothedraininglymphnodes.
Thelymphnodescontainresidentmacrophagesandotherunknown
cells.Thesecellsinfectanddeliverthevirustothelymphaticand
vascularsystem,whichcanleadtotheinfectionofbonemarrow

10. zTransmission
1.MosquitoBites
Thedenguevirusisspreadthroughthebiteofan
infectedfemalemosquito,primarilytheAedesaegypti
mosquito.OtherspecieswithintheAedesgenuscan
alsoactasvectors,buttheircontributionissecondary
toAedesaegypti.
2.BloodTransfusion
Theviruscanbetransmittedthroughbloodtransfusion
ororgantransplantation.

11. zClinical Symptoms
1.Fever:Ahighfeverof104°F(40°C)
2.Headache:Asevereheadache
3.Pain:Painbehindtheeyes,muscle,bone,orjointpain,or
extremeachinginthelegsandjoints
4.Rash:Arashthatappearstwotofivedaysaftertheonset
offever
5.Othersymptoms:Nausea,vomiting,fatigue,swollen
glands,leukopenia,andapositivetourniquettest

12. zLaboratory Diagnosis
1.Serologicaltests-ELISA
2.Moleculartests-PCR
3.Completebloodcount
4.Electrolytetest(includingNa+,K+,Cl-)
5.Liverfunctiontests(includingAST,ALT,GGT)
6.Albumintest
Treatment
Thereisnospecificmedicinetotreatdenguefever.

13. z
Prevention
1.EliminateMosquitoBreedingSites
2.UseMosquitoRepellents
3.WearProtectiveClothing
4.MosquitoNets
5.StayIndoorsduringPeakMosquitoActivity

14. z