Rhabdoviridae Flashcards
Rabies structure & classification
Family: Rhabdoviridae
Genus: Lyssavirus
Species: rabies virus genotype 1 (classical rabies) or less commonly by rabies-related lyssaviruses
(-)ss RNA virus, bullet shaped with lipid envelope
Baltimore: V
Replicates in the cytoplasm.
Important lyssaviruses
Human bat-associated rabies cases in Europe are caused by European bat 1 lyssavirus (EBLV-1) and European bat 2 lyssavirus (EBLV-2). EBLV-1 is hosted by the European serotine bat Eptesicus serotinus, whilst EBLV-2 has been detected in two bat species: Myotis bats.
Both 1&2 found in UK bats.
In Africa, Duvenhage virus (DUVV) and Mokola virus (MOKV) have been implicated in human rabies. MOKV is particularly noteworthy, as vaccines against RABV do not confer protection against MOKV
The Australian bat lyssavirus (ABLV) is the only endemic lyssavirus in Australia. There have been three fatal human cases since its discovery in 1996. Pteropus is the host.
Irkut virus (IRKV) is a bat-associated lyssavirus that has been isolated in China and Russia from Murina bats.
Important rhabdoviridae
Lyssaviruses.
Cluster of three cases of VHF in a forest region of the Democratic Republic of the Congo (DRC) in 2009. The virus was named Bas-Congo virus (BASV) after the province where it was isolated. Genus TIBROVIRUS.
Chandipura virus (CHPV) was first isolated in 1965 from two patients with a mild illness characterised by fever and myalgia in the Indian city of Nagpur. It sits within the genus VESICULOVIRUS alongside the well-characterised VSV and demonstrates the canonical genome arrangement conserved across the Rhabdoviridae. Causes encephalitis.
Rabies incubation
Median 1-3 months
Range 1 weeks to 19 years
If the animal is observed, remains well and behaves normally 15 days after the date of an exposure it will not have had rabies infection at the time of exposure.
HRIG indications and when not to give
The total antibody level induced by vaccine is many orders of magnitude greater than can be provided by passive immunisation (HRIG). For this reason HRIG is not given more than 7 days after the first dose of rabies vaccine or to an individual who is already partially or previously immunised.
HRIG is not indicated if the person has already received 2 doses of rabies vaccine, (that is, d0 and d3 doses) or if the exposure was more than 12 months previously. HRIG is manufactured from non-UK human blood products.
The final formulation is a liquid and the potency of the material is assessed in international units (IU/ml). The maximum dose is 20 IU/kg, adults and children (all ages), and should not be exceeded as it may inhibit the immune response to rabies vaccine.
Rabies vaccine
There is currently one rabies vaccine licensed for intramuscular use in the UK – INACTIVATED purified chick embryo cell rabies vaccine (PCEC, 2.5 IU/ml) (Rabipur®).
FLURY LEP strain.
Other WHO approved cell culture-derived vaccines are available in other countries and may contain different concentrations of rabies antigen.
The cell-culture derived rabies vaccines may be used interchangeably
Always given INTRAMUSCULAR/INTRADERMAL (off-label). It should not be used in those taking chloroquine for malaria prophylaxis as this drug suppresses the antibody response if the vaccine is given by the intradermal route (chloroquine does not suppress the antibody response if the vaccine is given by the intramuscular route).
PREP: primary pre-exposure immunisation, three doses of rabies vaccine (2.5 IU; one vial) should be given intramuscularly on days 0, 7 and 28. The third dose can be given from day 21 if there is insufficient time before travel.
ACCELERATED PREP: Three doses of rabies vaccine (2.5IU) should be given intramuscularly on days 0, 3 and 7, with an additional dose at one year if they will continue to travel to high risk
PEP: based on composite risk (see pics in album): Category of exposure + country risk + immunity status
Rabies diagnostics
No tests exist to diagnose before onset of symptoms
Post mortem - FAT - Fluorescent antibody test on brain tissue, IHC on brain tissue, H&E for naegri bodies
FAT can be done on saliva, peripheral nerves etc in late stages of disease
LN34 pan-lyssavirus RT-PCR offered by CDC can be done on brain tissue or nape of neck tissue biopsy
Chandipura
Family: Rhabdoviridae
Genus: Vesiculovirus
(-)ssRNA enveloped Bullet shaped
Codes for 5 proteins - Nucelocapsid N, phosphoprotein P,M matrix, G glycoprotein, L large protein.
Animal host: cattle, goats, frogs, lizards
Vector- Phlebotomus Sandfly but also was found in Aedes
NO human to human or livestock to human cases identified yet
Epidemiology: middle & western & Eastern India
Incubation - 5 to 6 days
Clinical- encephalitis & VHF
Diagnostics:
IFA on brain tissue,
RT-PCR on blood/CSF available at NIV, Pune & Gujarat Biotech
Therapeutics: Ribavirin & Favipiravir no benefit in case reports
Mortality - 50 to 80%
Vaccine: A Vero cell based vaccine candidate was developed and evaluated for immunogenicity in mice in 2010 but no human data
Rabishield
Mab- Immunoglobulin G1 monoclonal antibody that binds to the surface protein of the rabies virus
