Download Arboviruses

Chair of Medical Biology, Microbiology, Virology,
and Immunology
Arboviruses
Lecturer Prof. S.I. Klymnyuk
Arthropod-Borne (Arbo) Viral Diseases
The arthropod-borne viruses, or arboviruses, are a group of infectious
agents that are transmitted by blood-sucking arthropods from one
vertebrate host to another. They can multiply in the tissues of the arthropod
without evidence of disease or damage. The vector acquires a lifelong
infection through the ingestion of blood from a viremic vertebrate. All
arboviruses have an RNA genome, and most have a lipid-containing
envelope and consequently are inactivated by ether or sodium
deoxycholate.
Current taxonomic status of some arboviruses
Current Taxonomic
Classification
Arbovirus Members
Togaviridae
Genus Alphavirus
Aura, Chikungunya, eastern equine
encephalitis, Getah, Maygro, Mucambo,
Ndumu, O'Nyong-nyong, Ross River,
Semliki Forest, Sindbis, Venezuelan and
Western equine encephalitis
Flaviviridae
Genus Flavivirus
Dengue, Israel turkey
meningoencephalitis, Japanese B
encephalitis, Kunjin, Kyasanur Forest
disease, Murray Valley encephalitis,
Ntaya. Omsk hemorrhagic fever.
Powassan, St. Louis encephalitis, tickborne encephalitis, Uganda S,
Wesselsbron, West Nile fever, yellow fever,
Current taxonomic status of some arboviruses
Current Taxonomic
Classification
Arbovirus Members
Bunyaviridae
Genus Bunyavirus
Bunyamwera, Bwamba, C, California, Capim,
Guama, Koongol, Patois, Simbu, and Tete;
7 unassigned viruses
Genus Uukuniemi
Uukuniemi, Anopheles A, Anopheles B, Bakau,
Crimean-Congo hemorrhagic fever, Kaisodi,
Mapputta, Nairobi sheep disease, Phlebotomus
fever, and Turlock; 8 unassigned viruses
Reoviridae
Genus Orbivirus
African horse sickness, bluetongue, and Colorado
tick fever viruses
Rhabdoviridae Genus Cocal, Hart Park, Kern Canyon, and vesicular
Vesiculovirus
stomatitis viruses
Current taxonomic status of some arboviruses
Current Taxonomic
Classification
Arbovirus Members
Arenaviridae
Genus Arenavirus
Junin, Lassa, Machupo, and Pichinde viruses
Nodaviridae
Nodamura virus
Sindbis virus
Structures of Alphaviruses
Principal medically important alphaviruses
Virus
Antigenic
Clinical
Syndrome
Vector
Host
Distribution
Eastern
equine
encephalitis
Encephalitis
(EEE)
Mosquito
Birds
Americas
Western
equine
encephalitis
Encephalitis
(WEE)
Mosquito
Birds
North
America
Venezuelan
equine
encephalitis
Febrile
illness,
encephalitis
(VEE)
Mosquito
Rodents,
horses
Americas
Virus
Antigenic
Clinical
Syndrome
Vector
Host
Distribution
Chikunguny
(CHIK)
Africa,
Febrile
illness, rash,
arthralgia
Mosquito
Primates,
humans
India,
Southeast
Asia
O’nyongnyong
(ONN)
Febrile
illness, rash,
arthralgia
Mosquito
Primates
Africa
Sindbisc
(SIN)
Febrile
illness, rash,
arthralgia
Mosquito
Birds
Nothern
Europe,
Africa, Asia,
Australia
Semliki
Forest
Febrile
illness, rare
encephalitis
Mosquito
Birds
Africa
The scheme of Alphavirus replication
Pathogenesis of alphaviruses
FIGURE Alphavirus transmission. Virus abbreviations:
Chik, chickungunya; RR, Ross River; May, Mayaro; ONN,
O'nyong-nyong; SIN, Sindbis; EEE, eastern equine
encephalitis; VEE, Venezuelan equine encephalitis.
Rubellaviruses
Rubella (German measles) is a common mild disease
characterized by a rash. It affects children and adolescents
worldwide and can also affect young adults. When rubella
virus infects susceptible women early in pregnancy, it may
be transmitted to the fetus and may cause birth defects.
Therefore, accurate diagnosis is critical in pregnancy. The
rubella virus is a member of the genus Rubivirus in the
family Togaviridae.
Rubella virus
Rash
FIGURE. Clinical findings, virus shedding, and serologic response
in postnatally acquired rubella.
Abnormalities Associated with Congenital Rubella Syndrome
Type of defects
Examples
Ocular defects
Cataracts
Microphthalmia
Glaucoma
Retinitis
Heart defects
Patent ductus arteriosus
Atrial septal defect
Ventricular septal defect
Peripheral pulmonic artery stenosis
Hearing impairment
Sensorineural deafness
Abnormalities Associated with Congenital Rubella Syndrome
Type of defects
Examples
Central nervous system
Mental retardation
Meningoencephalitis
Progressive rubella panencephalitis (rare)
Microcephaly
Other
Growth retardation
Radiolucent borne disease
Hepatosplenomegaly
Hemathologic abnormalities:
Thrombocytopenia, purpura
Pneumonitis
Endocrine dysfunction:
Insulin dependent diabetes mellitus,
thyroididtis
Cataract
Glaucoma
Structure of Flaviviruses
Flavivirus
Tick-born encephalitis virus
Tick-born encephalitis virus
Figure 5. The scheme of Flavivirus replication
Virions are formed in perinuclear regions of the cytoplasm in
association with Golgi or smooth membranes (Figure 6). Virions
appear within cytoplasmic vacuoles and appear to exit the cell as
vacuoles fuse with the plasma membrane. Unlike alphaviruses, no
evidence of budding has been seen in flavivirus-infected cells, and the
mechanisms of virion assembly and release remain obscure.
FIGURE 6.
Morphogenesis
of flaviviruses
Principal medically important flaviviruses
Virus
Antigenic
Clinical
Syndrome
Vector
Host
Dengue
(DEN)
Febrile
illness, rash,
hemorrhagic
fever, shock
syndrome
Mosquito
Humans
Tropics,
worldwide
Yellow fever Hemorrhagic
(YF)
fever,
hepatitis
Mosquito
Primates,
humans
Africa,
South
America
St. Louis
encephalitis
(SLE)
Encephalitis Mosquito
Birds
Distribution
Americas
Principal medically important flaviviruses
Virus
Antigenic
Clinical
Syndrome
Vector
Host
Distribution
Japanese
encephalitis
(JE)
Encephalitis
Mosquito
Pigs, birds
India, China,
Japan,
South-East
Asia
Febrile
illness
Mosquito
Birds
Africa,
Middle East,
Europe
Encephalitis
Tick
Rodent
Europa, Asia
West Nile
Tick-borne
encephalitis
(TBE)
Principal medically important flaviviruses
Virus
Antigenic
Clinical
Syndrome
Vector
Host
Distribution
Omsk
Hemorrhagic
hemorrhagic
fever
fever
Tick
Muskrats
Siberia
Kyasanur
Forest
disease
(KFD)
Tick
Rodents
India
primates
Hemorrhagic
fever
Human infection with both mosquito-borne and tick-borne
flaviviruses is initiated by deposition of virus through the skin via
the saliva of an infected arthropod (Fig 7).
Figure 7. Pathogenesis of flaviviruses.
Tick
Yellow fever virus
Yellow fever
Dengue fever virus
Dengue fever
Bunyaviridae is a family of arthropod-borne or rodent-borne,
spherical, enveloped RNA viruses. Bunyaviruses are
responsible for a number of febrile diseases in humans and
other vertebrates. They have either a rodent host or an
arthropod vector and a vertebrate host.
Rift Valley Fever virus
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distribution
Bunyavirus
Anopheles A
Tacaiuma
Fever
Mosquito
South
America
Bunyamwera
Bunyamwera
Fever
Mosquito
Africa
Germiston
Fever
Bwamba
Bwamba
Fever ,
Rash
Mosquito
Africa
C
Apeu
Fever
Mosquito
South
America
Africa
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distribution
Bunyavirus
California
Simbu
California
encephalitis
Encephalitis
Mosquito
North
America
Snowshoe
hare
Encephalitis
Mosquito
North
America,
Asia
Tahyna
Fever
Mosquito
Europe
Shuni
Fever
Mosquito
Africa, Asia
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distribution
Phlebovirus
Phlebovirus
fever
Alenquer
Fever
Naples
Fever
Rift Valley
Fever
Fever,
encephalitis,
hemorrhagic
fever, blindness
Sicilian
Fever
Unknown South
America
Sand fly
Europe,
Asia, Africa
Mosquito Africa
Sand fly
Europe,
Africa, Asia
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distribution
Hemorrhagic
fever
Tick
Africa, Asia
Fever
Tick
Africa, Asia
Nairovirus
CrimeanCongo
CrimeanCongo
hemorrhagic
fever
Nairobi sheep Nairobi sheep
disease
disease
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distribution
Hantavirus
Hataan
Hantaan
HFRS
Rodent
Asia
Puumala
HFRS
Rodent
Asia
Sequl
HFRS
Rodent
Asia, Europe
Human diseases Caused by Viruses of the Family Bunyaviridae
Genus and
Group
Virus
Disease
Vector
Distributi
on
Genus unassigned
Bangui
Fever, rash
Unknown Africa
Bhanja
Fever,
encephalitis
Tick
Africa,
Europa,
Asia
Issk-kul
Fever
Tick
Asia
Kasokero
Fever
Unknown
Africa
Nyando
Fever
Mosquito Africa
Tataguine
Fever
Mosquito Africa
Wanowrie
Fever,
hemorrhage
Tick
Middle
East, Asia
FIGURE 3. Pathogenesis of bunyavirus infections. Humans are dead-end hosts
of most bunyaviruses; however, the blood of Crimean-Congo hemorrhagic fever
patients may be highly infectious.
FIGURE 5. La Crosse encephalitis transmission cycle
Signs of Crimean-Congo Hemorrhagic Fever
Clinics of Hataan virus infection