Lyssavirus
Encyclopedia
Lyssavirus is a genus of virus
es belonging to the family Rhabdoviridae
, in the order Mononegavirales
. This group of RNA virus
es includes the Rabies virus
traditionally associated with the disease.
.
The structure consists of a spiked outer envelope, a middle region consisting of protein M, and an inner ribonucleocapsid complex region, consisting of the genome associated with other proteins.
s consist of a negative-sense, single-stranded RNA
molecule that encodes five viral proteins: polymerase
L, matrix protein
M, phosphoprotein
P, nucleoprotein
N, and glycoprotein
G.
Based on recent phylogenetic evidence, Lyssaviruses are categorized into seven major genotype
s. In addition, there have been four genotypes recently discovered, and these are West Caucasian Bat virus, Aravan Virus, Khujand virus, and Irkut virus. The major genotypes include Rabies virus
(genotype 1), Lagos bat virus
(2), Mokola virus
(3), Duvenhage virus
(4), European Bat lyssaviruses 1 and 2 (5 and 6), and Australian bat lyssavirus
(7). Based on biological properties of the virus
es, these genotypes are further subdivided into phylogroups 1 and 2. Phylogroup 1 includes genotypes 1, 4, 5, 6, and 7, while phylogroup 2 includes genotypes 2 and 3. The nucleocapsid region of lyssavirus is fairly highly conserved from genotype to genotype across both phylogroups; however, experimental data has shown that lyssavirus strains used in vaccinations are only from the first genotype of the first phylogroup (i.e. classic Rabies).
, is prevalent throughout the world and can be carried by any mammal. The other genotypes (types 2 through 7) have much less diversity in carriers. Only select host
s can carry each of the genotypes. Also, these other genotypes are particular only to a specific geographic area.
Bats are known to be an animal vector for all but one of the seven genotypes, the one exception being Mokola virus.
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es belonging to the family Rhabdoviridae
Rhabdoviridae
Rhabdoviruses are viruses belonging to the family Rhabdoviridae, which is in the order Mononegavirales. The name is derived from the Greek rhabdos meaning rod referring to the shape of the viral particles. Rhabdoviruses infect a broad range of hosts throughout the animal and plant kingdoms...
, in the order Mononegavirales
Mononegavirales
The order Mononegavirales is the taxonomic home of numerous related viruses. Members of the order that are commonly known are, for instance, Ebola virus, human respiratory syncytial virus, measles virus, mumps virus, Nipah virus, and rabies virus. All of these viruses cause significant disease in...
. This group of RNA virus
RNA virus
An RNA virus is a virus that has RNA as its genetic material. This nucleic acid is usually single-stranded RNA but may be double-stranded RNA...
es includes the Rabies virus
Rabies virus
The rabies virus is neurotropic virus that causes fatal disease in human and animals. Rabies transmission can occur through the saliva of animals....
traditionally associated with the disease.
Structure
Viruses typically have either helical or cubic symmetry. Lyssaviruses have helical symmetry, so their infectious particles are approximately cylindrical in shape. This is typical of plant-infecting viruses. Human-infecting viruses more commonly have cubic symmetry and take shapes approximating regular polyhedraRegular polyhedron
A regular polyhedron is a polyhedron whose faces are congruent regular polygons which are assembled in the same way around each vertex. A regular polyhedron is highly symmetrical, being all of edge-transitive, vertex-transitive and face-transitive - i.e. it is transitive on its flags...
.
The structure consists of a spiked outer envelope, a middle region consisting of protein M, and an inner ribonucleocapsid complex region, consisting of the genome associated with other proteins.
Genome
Lyssavirus genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s consist of a negative-sense, single-stranded RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
molecule that encodes five viral proteins: polymerase
Polymerase
A polymerase is an enzyme whose central function is associated with polymers of nucleic acids such as RNA and DNA.The primary function of a polymerase is the polymerization of new DNA or RNA against an existing DNA or RNA template in the processes of replication and transcription...
L, matrix protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
M, phosphoprotein
Phosphoprotein
Phosphoproteins are proteins that are physically bonded to a substance containing phosphoric acid . This category of organic molecules includes Fc receptors, Ulks, Calcineurins, K chips, and urocortins....
P, nucleoprotein
Nucleoprotein
A nucleoprotein is any protein that is structurally associated with nucleic acid .Many viruses harness this protein, and they are known for being host-specific...
N, and glycoprotein
Glycoprotein
Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
G.
Based on recent phylogenetic evidence, Lyssaviruses are categorized into seven major genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
s. In addition, there have been four genotypes recently discovered, and these are West Caucasian Bat virus, Aravan Virus, Khujand virus, and Irkut virus. The major genotypes include Rabies virus
Rabies virus
The rabies virus is neurotropic virus that causes fatal disease in human and animals. Rabies transmission can occur through the saliva of animals....
(genotype 1), Lagos bat virus
Lagos bat virus
Lagos bat virus is a lyssavirus of southern and central Africa that causes a rabies-like illness in mammals. It was first isolated from a fruit bat from Lagos Island, Nigeria in 1956. Brain samples from the bat showed poor cross-reactivity to rabies antibodies but the virus was found to be closely...
(2), Mokola virus
Mokola virus
Mokola virus is one of four members of the lyssavirus genus found in Africa, the others being Duvenhage virus, Lagos bat virus and classic rabies virus. Mokola virus was first isolated from shrews from Mokola forest, Nigeria in 1968. It has caused two human deaths in Nigeria, in 1969 and 1971...
(3), Duvenhage virus
Duvenhage virus
Duvenhage virus is a member of the lyssavirus genus which also contains rabies virus. The virus was discovered in 1970 when a South African farmer died of a rabies-like encephalitic illness after being bitten by a bat...
(4), European Bat lyssaviruses 1 and 2 (5 and 6), and Australian bat lyssavirus
Australian bat lyssavirus
Australian bat lyssavirus is a zoonotic virus closely related to rabies virus. It was first identified in a 5-month old juvenile Black Flying Fox collected near Ballina in northern New South Wales, Australia in 1996 during a national surveillance program for the recently identified Hendra virus...
(7). Based on biological properties of the virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, these genotypes are further subdivided into phylogroups 1 and 2. Phylogroup 1 includes genotypes 1, 4, 5, 6, and 7, while phylogroup 2 includes genotypes 2 and 3. The nucleocapsid region of lyssavirus is fairly highly conserved from genotype to genotype across both phylogroups; however, experimental data has shown that lyssavirus strains used in vaccinations are only from the first genotype of the first phylogroup (i.e. classic Rabies).
Epidemiology
Genotype 1, classic rabiesRabies
Rabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...
, is prevalent throughout the world and can be carried by any mammal. The other genotypes (types 2 through 7) have much less diversity in carriers. Only select host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
s can carry each of the genotypes. Also, these other genotypes are particular only to a specific geographic area.
Bats are known to be an animal vector for all but one of the seven genotypes, the one exception being Mokola virus.