Properties of Rhabdoviridae

Rhabdoviruses are approximately 70 nm wide and 170 nm long, and consist of a lipid envelope with glycoprotein peplomers surrounding a helically wound nucleocapsid, which gives the viruses their distinctive bullet-shaped or conical morphology (Fig. 29-1). The viruses contain a single linear molecule of minus sense ssRNA, 11-12 kb in size. Rhabdovirus virions contain five major proteins which, for the genus Lyssavirus, are designated as follows: L [transcriptase, with 5'-cap methylase, 3'-poIy(A) polymerase, and protein kinase activities]; G (glycoprotein peplomer with hemagglutinin activity, target of neutralizing antibodies); N (nucleoprotein); NS, or P, or Ml (phosphoprotein, binds to L and promoter); and M, or M2 (matrix protein).

Table 29-1

Properties of Rhabdoviruses

Two genera include human pathogens Li/ssavtrus (rabies virus) and Vesiculovirus (vesicular stomatitis virus)

Bullet-shaped enveloped virion, 170 x 7(1 nm, with glycoprotein peplomers, matrix protein under lipoprotein envelope

Nucleocapsid with helical symmetry

Linear minus sense ssRNA genome, 11-12 kb

Cytoplasmic replication; viral transcriptase transcribes five monocistronic mRNAs which are translated into five proteins transcriptase (L + P), nucleoprotein (N), matrix protein (M), glycoprotein peplomer (G), and phosphoprotein (P or NS)

Maturation by budding through plasma membrane

Vesicular stomatitis causes rapid cytopathology; rabies virus is noncytopathogenic

Classification

Two genera, Vesiculovirus and Lyssavirus, have been defined among the rhabdoviruses of animals; within each genus, species are distinguished by neutralization tests, which recognize epitopes on the G glycoprotein. The genus Vesiculovirus includes some 35 serologically distinct viruses, only one of which causes human infection. The genus Lyssavirus comprises rabies virus and three rabies-like viruses from Africa: Mokola, Lagos bat, and Duvenhage viruses. Each of these viruses is capable of causing rabies-like disease in animals and humans.

Mokola Virus
Fig. 29-1 RhaMovrrtdae (A) Section of fox salivary gland infected with rabies virus (B, C) Negatively stained preparations of (B) vesicular stomatitis virus and (C) rabies virus. Bars, 100 nm (Courtesy Dr F A. Murphy)

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