Bunyavirales order Flashcards
La Crosse virus
Family: Peribunyaviridae
Genus: Orthobunyavirus
3 (-)ssRNA genome segments - Small, Medium, Large
Baltimore: V
California serogroup - Jamestown Canyon virus, snowshoe hare virus, and La Crosse
Vector- Aedes mosquito
Symptoms- Fever, myalgia, arthralgia, ENCEPHALITIS with lifelong neurological sequelae
Mortality < 1%
Heartland virus
Order: Bunyavirales
Family: Phenuivirdae
Genus: Bandavirus
(-)ss RNA with 3 part segmented genome - Small, Medium, Large
Closely related to RVF, SFTS, Toscana
Baltimore: V
Vector- Amblyoma ticks
Clinical syndrome - Fever, arthralgia, myalgia, thrombocytopenia, transaminitis
Diagnosis: PCR, virus specific plaque reduction - 4 fold titre increase
Phlebovirus genus groups
- Tick borne- Uukuniemi group- Uukuniemi virus & precarious point virus
- Tick borne - SFTS group- SFTS, Heartland, Hunter island, Malsoor (India)
- Tick borne - Bhanja group - Bhanja virus, Palma virus, lone star virus
- Mosquito borne - RVF
- Sandfly - Toscana, Punta Toro virus
SFTS/ Dabie bandavirus
Family: Phenuiviridae
Genus: Phlebovirus
Enveloped (-)ss RNA in segments
Baltimore: V
Vector: Ixodid ticks, blood transfusion
Epidemiology: central China, Japan, South Korea, Vietnam and Taiwan
Mortality: 12-30%
Clinical features: SFTS, VHF
Diagnostics: In Japan, conventional one-step RT-PCR, ELISA and the isolation of SFTSV are performed to diagnose human SFTS cases.
Treatment: Favipiravir & ribavirin trialled
NO vaccines
Toscana
Family: Phenuiviridae
Genus: Phlebovirus
Enveloped (-)ss RNA with 3 segments
Baltimore: V
Fourr structural proteins:
- two outer glycoproteins encoded by the M segment;
- a nucleocapsid protein and a nonstructural protein encoded by the S segment
- an RNA-dependent viral polymerase encoded by the L segment.
Vector: Phlebotomus sandfly
Toscana virus can present serological cross-reactions with other phleboviruses, particularly those included in the Naples phlebovirus species (sandfly fever Naples virus, Granada virus, and to a lesser extent Arrabida, Balkan, Fermo, Saddaguia viruses) or Punique phlebovirus.
Incubation 3-7 days.
Majority asymptomatic. high fever, headache, rash, nausea, vomiting, malaise and/or myalgia. Neck stiffness is reported in nearly 90% of the cases and encephalitis is observed in nearly 40% of the cases.
Cases of Toscana virus infection are reported exclusively during the period of sand fly activity, from April through November in the Mediterranean, with a peak observed during the hottest period (July to September)
Direct diagnosis: The virus can be detected at the acute phase of infection in CSF and in blood. ELISA/IFA - 4 fold increase.
No treatment or vaccines
Oropouche
Family: Peribunyaviridae
Genus: Orthobunyavirus
(-)ss RNA virus in SEGMENTS
Baltimore: V
found to circulate in Central and South America and the Caribbean.
Vector: Culicoides paraensis midge, & certain Culex mosquitos.
Symptoms are similar to dengue and start between 4 to 8 days (range between 3-12 days) after the infective bite. The onset is sudden, usually with fever, headache, joint stiffness, pain, chills, and sometimes persistent nausea and vomiting, for up to five to seven days. Severe clinical presentation is rare, but it may result in aseptic meningitis. Most cases recover within seven days, however, in some patients, convalescence can take weeks.
RIPL has a PCR - done on all dengue negative samples from south & Central America with compatible clinical picture.
There is no specific antiviral treatment or vaccine for Oropouche virus disease.
RVF
Family: Phenuiviridae
Genus: Phlebovirus
Enveloped (-)ssRNA with 3 segments
Baltimore: V
Vector: Aedes & Culex but also blood of livestock and butchering.
Incubation: 2-6 days
Clinical: mild flu-like illness to severe haemorrhagic fever
Mortality: 1%
Diagnosis: EIA 4 fold increase, RT-PCR
No specific treatment. Ribavirin trialled.
Vaccine: inactivated human vaccine not licensed nor commercially available. It has been used experimentally to protect veterinary and laboratory personnel at high risk of exposure to RVF
CCHF classification & structure
Order: Bunvyavirales
Family: Nairoviridae
Genus: Nairovirus
3 segmented (-)ssRNA
Its genome of three single-stranded RNA segments is encapsidated by the nucleocapsid protein (CCHFV N) to form the ribonucleoprotein complex
Baltimore: V
Vector & reservoir - Hyalomma/Ixodid ticks
Increased tick & animal surveillance in the UK given cases in south of France and existence of these ticks here.
Bakir scale
CCHF severity scoring
CCHF treatment
Ribavirin unclear effectiveness - works in vitro. RCT from turkey shows no effect.
Ongoing trial with ribavirin + favipiravir in Turkey
Tocilizumab/Anakinra if HLH.
Ribavirin is offered as PEP.
Mabs being developed.
CCHF diagnostics
RT-PCR
serology - ELISA
LAMP
CCHF vaccine
ChAdOX2 vaccine in trials
California serogroup
- California encephalitis virus
- Jamestown Canyon
- La Crosse
- Tahyna
Bunyavirales families
Here it is:
Bunyavirales order has 5 families that cause human infection:
- Arenaviridae - Old world (Lassa, Lujo, LCMV) & New world (Junin, Guanarito, Chapare, Sabia, Machupo, Whitewater Arroyo).
- Nairoviridae - CCHF
- Peribunyaviridae - Oropouche, California serogroup (California encephalitis virus, Jamestown Canyon, La Crosse & Tahyna).
- Phenuiviridae - Phleboviruses (Tick borne Uukuniemi group- Uukuniemi virus & precarious point virus, Tick borne SFTS group- SFTS, Heartland, Hunter island, Malsoor, Tick borne Bhanja group - Bhanja virus, Palma virus, lone star virus, Mosquito borne - RVF & Sandfly - Toscana, Punta Toro virus
- Hantaviridae - New world (Sin Nombre, Andes, Choclo, Laguna negra, Rio manmore) & Old world (Hantaan, Dobrava, Seoul, Puumala)
