Rhabdoviridae

Are bullet-shaped RNA viruses, whose most famous

member is rabies virus, which causes one of the oldest

.and most feared disease of humans and animals

Rhabdoviridae encompasses more than 175 viruses of

.vertebrates, invertebrates, and plants

 

 


Introduction

 

Taxonomy

 

Rhabdoviridae is a virus family within the Mononegavirales order, which also contains the Bornaviridae, Filoviridae, and Paramyxoviridae families. Rhabdoviridae contains six genera: vesiculovirus, lyssavirus, ephemerovirus,norvirhabdovirus,cytorhabdovirus, and nucleorabdovirus. The Rhabdoviridae family contains only two viruses that infect humans, however, which are rabies virus (RABV) and vesicular stomatitis virus (VSV .

 

Morphology

 

Virions consist of an envelope and a nucleocapsid. Virions are in unfixed preparations bullet-shaped, or bacilliform or pleomorphic. Virions measure 45-100 nm in diameter; 100-430 nm in length. Surface projections are densely dispersed, distinctive spikes. Capsid consists of an RNA and N protein . The nucleocapsid contains transcriptase activity and is infectious.

Nucleic Acid

The genome is not segmented and contains a single molecule of linear; usually negative-sense.The complete genome is 11000-15000 nucleotides long.

Lipids

Lipids are present and located in the envelope and protein.Virions are composed of 15-25% lipids by weight (their composition depends on the host cell membrane. Generally phospholipids represent about 50-60%, sterols and glycolipids about 35-40% of the total lipids. G protein has a covalently associated fatty acid proximal to the lipid envelope). The composition of viral lipids and host cell membranes are similar.

Polyamines:Other compounds that have been detected in the virus particles are 3% carbohydrates. The carbohydrates are present as N-linked glycan chains on G protein and as glycolipids.

Plant Rhabdoviruses :Enveloped. 180 nm long and 75 nm wide. Certain plant rhabdoviruses are bacilliform in shape.

Nucleorhabdovirus

GENOME

 

Negative-stranded RNA linear genome, about 11-15 kb in size. Encodes for 5 to six proteins.

Transmission:Transmitted by a vector Aphididae , or Cicadellidae , or Delphacidae . Transmitted in a persistent manner.Virus retained when the vector moults, or lost by the vector when it moults ; multiplies in the vector; transmitted by mechanical inoculation, or not transmitted by mechanical inoculation; transmitted by grafting; transmitted by contact between plants, or not transmitted by contact between plants ; not transmitted by seed ; transmitted by pollen to the seed, or not transmitted by pollen .

REPLICATION

  1. Virus attaches to host receptors though G glycoprotein and is endocytosed into vesicles in the host cell.
  2. Fusion of virus membrane with the vesicle membrane; ribonucleocapsid is released into the cytoplasm.
  3. sequential transcription, viral mRNAs are capped and polyadenylated in the cytoplasm.
  4. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
  5.  The ribonucleocapsid interacts with the matrix protein under the plasma membrane M protein and buds from the plasma membrane, releasing the virion.

(Iranian maze mosaic virus (IMMV

Random polymerase chain reaction (rPCR) followed by filling of gaps by the use of specific primers (designed from the rPCR data) was used to sequence and subsequently analyze the genome of Iranian maize mosaic virus (IMMV). Complete nucleotide sequence of genes and intergenic regions and partial sequence of leader and trailer regions comprising 12381 nucleotides were determined. Based on these data IMMV had six open reading frames (ORF) on complementary viral RNA (vcRNA). All ORFs were estimated as a region from the first methionine to a stop codon between two junctions. The proposed IMMV genomic map is 3¢ l-N-P-3-M-G-L-t 5¢. N, P, 3, M, G and L are genes for proposed nucleocapsid, phosphoprotein, a protein of unknown function, matrix protein, glycoprotein and transcriptase. T and l are the trailer and the leader sequences, respectively. Pairwise and multiple alignments and phylogenetic tree analysis showed IMMV closer to MMV than to other plant rhabdoviruses. The results of this study, including sequence analysis in agreement with the results of previous works including absence of serological relationship between IMMV and maize mosaic virus (MMV), difference in host range, difference in size of proteins, difference in particles size and transmission by different vectors show that IMMV is a distinct virus in the genus Nucleorhabdovirus. However, the closest virus to IMMV appears to be MMV.

Cytorhabdovirus

Transmission

  • Transmitted by a vector ; an insect ; Aphididae , or Delphacidae .
  • Transmitted in a persistent  . Virus retained when the vector moults ;
  • multiplies in the vector;
  • transmitted by mechanical inoculation , or not transmitted by mechanical inoculation ;
  •  transmitted by grafting ;
  • not transmitted by contact between plants;
  • not transmitted by seed ;
  • not transmitted by pollen.

GENOME

Negative-stranded RNA linear genome, about 13 kb in size. Encodes for six (LNYV.

Cytopathology

Virions found in cytoplasm, or in the perinuclear space . Inclusions present in infected cells , or absent from infected cells ; are membranous bodies , or viroplasms , or unusual in shape ; they contain virions , or they do not contain virions .

(Soybean Blotchy Mosaic Virus (SbBMV

A previously unidentified plant Rhabdovirus sp. associated with a blotchy mosaic symptom of soybean (Glycine max), prevalent in the lower-lying, warmer soybean production areas of South Africa, was isolated and partially characterized. The virus was shown to be transmitted by mechanical inoculation and at least one species of leafhopper (Peragallia caboverdensis Lindberg (Cicadellidae, Agalliinae)). To determine the morphology and virion size, as well as intercellular accumulation, negative-stained preparations or embedded ultrathin sections of infected plant samples were observed under a transmission electron microscope. The distribution of the virions within the cytoplasm and its bullet-shaped morphology and size (338 to 371 nm by 93 nm) suggested that it is a putative member of the genus Cytorhabdovirus.

References:                                                          

  1. http://www.vet.ksu.edu/depts/rabies/index.htm
  2. http://www.cdc.gov/ncidod/dvrd/kidsrabies/TheVirus/rabvir.htm
    1. Lamprecht. R.L, Kasdorf. G. G. F, Stiller. M, Staples. S. M, Nel. L, Pietersen. H, Soybean blotchy mosaic virus, a New CytorhabdovirusFound in South Africa, Plant Disease, November 2010, Volume 94, Number 11, Pages 1348-1354
    2. A.Massah,K.Izadpanah,A.R.Afsharifar,S.Winter.2008.Analysis of nucleotide sequence of Iranian maze mosaic virus its identify as a distinct nucleorhabdovirus.Virology.2008.153:1041-1047
    3. Matthews,R.E.F.2002.Plant virology.Academic press,New York,1029pp