Rhabdoviridae

Rhabdoviridae is a family of negative-strand RNA viruses in the order Mononegavirales. Vertebrates (including mammals), invertebrates, plants, fungi and protozoans serve as natural hosts. Diseases associated with member viruses include rabies encephalitis caused by the rabies virus, and flu-like symptoms in humans caused by vesiculoviruses. The name is derived from Ancient Greek rhabdos, meaning rod, referring to the shape of the viral particles. The family has 62 genera, most assigned to four subfamilies.

The individual virus particles (virions) of rhabdoviruses are composed of RNA, protein, carbohydrate and lipids. They have complex bacilliform or bullet-like shapes. All these viruses have structural similarities and have been classified as a single family.

The virions are about 75 nm wide and 180 nm long. Rhabdoviruses are enveloped and have helical nucleocapsids and their genomes are linear, around 11–15 kb in length. Rhabdoviruses carry their genetic material in the form of negative-sense single-stranded RNA. They typically carry genes for five proteins: large protein (L), glycoprotein (G), nucleoprotein (N), phosphoprotein (P), and matrix protein (M). The sequence of these protein genes from the 3 'end to the 5' end in the genome is N–P–M–G–L. Every rhabdoviruses encode these five proteins in their genomes. In addition to these proteins, many rhabdoviruses encode one or more proteins. The first four genes encode major structural proteins that participate in the structure of the virion envelope.

The matrix protein (M) constitutes a layer between the virion envelope and the nucleocapsid core of the rhabdovirus. In addition to functions in virus assembly, morphogenesis and budding off enveloped from the host plasma membrane, additional functions, such as in regulation of RNA synthesis and in establishing balance between replication and transcription products, for M protein were found through reverse genetics experiments with rabies virus, a member of the family Rhabdoviridae. The large (L) protein has several enzymatic functions in viral RNA synthesis and processing. The L gene encodes this L protein, which contains multiple domains. In addition to RNA synthesis, it is thought to be involved in methyl capping and polyadenylation activity.

P protein plays important and multiple roles during transcription and replication of the RNA genome. The multifunctional P protein is encoded by the P gene. P protein acts as a non-catalytic cofactor of large protein polymerase. It is binding to N and L protein. P protein has two independent binding regions. By forming N-P complexes, it can keep the N protein in the form suitable for specific encapsulation. P protein interferes with the host's innate immune system through inhibition of the activities of interferon regulatory factor 3 (IRF3)  and signal transducer and activator of transcription 1 (STAT1), thus eliminating the cellular type 1 interferon pathway. Also, P protein acts as an antagonist against antiviral PML function.

In contrast to paramyxoviruses, rhabdoviruses do not have hemagglutinating and neuraminidase activities.

Transcriptase of rhabdovirus is composed of 1 L and 3 P proteins. Transcriptase components are always present in the complete virion to permit rhabdoviruses to begin transcription immediately after entry.^{[citation needed]}

The rhabdovirus transcriptase proceeds in a 3' to 5' direction on the genome and the transcription terminates randomly at the end of protein sequences. For example, if a transcription finishes at the end of M sequence; leader RNA and N, P and M mRNAs are formed separately from each other.^{[citation needed]}