Transcript Rhabdoviridae by Michelle Rodriguez

Rhabdoviridae
Michelle Rodriguez
MCB5505
Taxonomy
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Group V
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Order: Mononegavirales
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Family: Rhabdoviridae
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Genus: Lyssavirus
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Species: Rabies
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Virus Properties:
 -ssRNA genome
 Enveloped, bullet shaped
 ~180 nm in length
 Slow, progressive, zoonotic
 neurotropic
Rabies Facts
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Responsible for approximately 60,000 annual deaths worldwide
 10th most common lethal disease
 Rabies means “rage” or “anger”
 Lyssa is greek goddess of rage, madness
 Transmission by humans and animals
 Genus Lyssavirus comprises rabies
virus and 3 rabies-like viruses
 Each capable of causing rabies-like
disease in humans
http://www.bristol.ac.uk/biology/research/behaviour/batlab/members/harris.s.html
Epidemiology
http://www.travelhealth.ie/Diseases/rabies.php
Virion Structure
• linear -ssRNA molecule encodes 5 viral proteins
• Spiked outer envelope: composed of glycoproteins
• Middle region consists of matrix protein M, and inner ribonucleocapsid
complex
http://www.cdc.gov/rabies/transmission/virus.html
Genome
Genome of rabies virus (ERA strain). This contains single-stranded RNA (12
kilobases); N, NS, M, G, and L genes; a leader sequence at the 3' end; and four
intergenic regions.
http://www.cdc.gov/rabies/transmission/virus.html
Protein Translation
Negative-stranded RNA linear genome, about 11 kb in size. Encodes for 5 proteins, plus 4 by
alternative initiation. The viral RNA dependent RNA polymerase binds the encapsidated genome
at the leader region, then sequentially transcribes genes by recognizing start and stop signals
flanking viral genes. mRNAs are capped and polyadenylated by the L protein during synthesis.
http://viralzone.expasy.org/all_by_species/2.html
Viral Protein Functions
http://www.austincc.edu/microbio/2993s/rab.htm
Replication Steps
CYTOPLASMIC
1. Attachment of the viral G glycoproteins to host receptors mediates clathrinmediated endocytosis of the virus into the host cell.
2. Fusion of virus membrane with the vesicle membrane; ribonucleocapsid is released
into the cytoplasm.
3. Sequential transcription of viral mRNAs are capped and polyadenylated by
polymerase stuttering in the cytoplasm.
4. Replication presumably starts when enough nucleoprotein is present to encapsulate
neo-synthetized antigenomes and genomes.
5. The ribonucleocapsid binds to the matrix protein and buds via host ESCRT pathway
occurs at the plasma membrane, releasing new virions.
http://imgbuddy.com/rabies-virus-replication.asp
Neurotropism of Rabies
The cycle of rabies infection begins with viral entry at a peripheral site and proceeds through retrograde axonal
transport. Viral replication occurs in the cell body of the primary neuron. Infection proceeds by transsynaptic spread
through several neurons before spreading to the acinar cells, which then shed the virus into the saliva
http://www.bio.davidson.edu/courses/immunology/students/spring2006/jameson/rabies.html
Rabies virus entry into neurons and intra-neuronal transport.
• Nicotinic acetylcholine receptor (nAchR) is located at the
postsynaptic muscle membrane
• It has been suggested that nAchR enriches rabies virus at
the neuromuscular junction or synaptic cleft
•Enables more efficient infection of the connected
motor neurons.
•Rabies virus enters the neurons using neural cell adhesion
molecule (NCAM) or another, unknown receptor.
•Two different mechanisms have been proposed for the
transport of rabies virus through the axon to the cell body:
•the transport of either the rabies virus capsid
•or the whole rabies virus virion within the vesicle
•The evidence favors the transport of intact virions.
http://www.nature.com/nrmicro/journal/v8/n1/fig_tab/nrmicro2260_F4.html
Comparative Analysis of Rabies Virus Reverse Transcription-PCR and Virus Isolation
Using Samples from a Patient Infected with Rabies Virus
http://jcm.asm.org/content/48/8/2960/F1.expansion.html
Transmission
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Diagnostic Methods
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ELISA specific antibody detection
PCR
Viral sample from brain taken after death
Rabies-specific fluorescence
Standard pre-mortem test
• Fluorescent antibody to demonstrate presence of
viral antigen
Molecular Imaging/Identification
Rabies-specific fluorescence
This transmission electron micrograph
http://synapse.koreamed.org/DOIx.php?id=10.4142/jvs.2012.13.1.43&vmode=PUBREADER
The Future of Rabies Expression Vectors
http://journal.frontiersin.org/article/10.3389/fncir.2013.00002/full
An overview of the numerous tools that could, in the future, be developed using RABV ΔG vectors. Such possibilities include the expression of
genetically encoded tools to aid imaging/microscopy approaches and tools to examine loss-of-function (knockdown) or gain-of-function of a
gene/protein of interest. Other possibilities involve retargeting using engineered envelope proteins or the possibility of transfection using naked
ribonucleoprotein (RNP) complexes. Some approaches are not possible with RABV ΔG vectors including the integration of lox P sites, cell specific
promoters or tet-regulatory sequences, or expression of shRNA. RNP, Ribonucleoprotein, core of the RABV; EM, Electron microscopy; PALM,
Photo-activated localization microscopy; VSD, Voltage-sensitive dye; miRNA, micro RNA; shRNA, short hairpin RNA
Prevention
•Vaccinate your pets. Cats, dogs and ferrets can be vaccinated against
rabies
•Keep your pets confined
•Protect small pets from predators
•Report stray animals to local authorities
•Don't approach wild animals
•Keep bats out of your home
•Consider the rabies vaccine if you're traveling (immune globulin)
References
Dietzschold, B, M Schnell, H Koprowski. (2005). Pathogenesis of Rabies. Current Topics in
Microbiology and Immunology. 292: 45-56.
Thoulouse, MA, M Lafage, M Schachner, U Hartmann, H Cremer, M Lafon. (1998). The Neural Cell
Adhesion Molecule Is a Receptor for Rabies Virus. Journal of Virology. 72(9): 7181-7190.
Warrell, MJ and DA Warrell. (2004). Rabies and other lyssavirus diseases. The Lancet. 363(9413): 95969.
Bassin SL, Rupprecht CE, Bleck TP. Rhabdoviruses. In: Mandell GL, Bennett JE, Dolin R, eds. Principles
and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap
163.
Tuffereau C., Benejean J., Blondel D., Kieffer B., Flamand A. Low-affinity nerve-growth factor receptor
(P75NTR) can serve as a receptor for rabies virus. EMBO J. 1998;17:7250–7259