Rabies Microbiology

Rabies:

Microbiology

Structure

Rabies virus belongs to Lyssavirus genus, Rhadboviridae family. It is a negative-sense, non-segmented, single-strand RNA and 180 nm long* 75 nm wide bullet-shape virus. All rhabdoviruses have two main structural components: a helical ribonucleoprotein (RNP) complex and a surrounding viral envelope. The rabies virus genome encodes five functional proteins: L (transcriptase), N (nucleoprotein), and NS (transcriptase-associated) protein with viral RNA are composed of the RNP complex. This complex adds up in the cytoplasm of neurons that are infected by rabies virus and makes up Negri body that is an indicator of rabies for histopathologists. Another two proteins are M (matrix) and G (glycoprotein) proteins that are associated with the lipid envelope. The G protein shapes the protrusions that are spikes-shape surface antigen on the virion envelope and induce virus-neutralizing antibody.

Replication

Like other negative-stranded RNA viruses, the G protein of rabies virus binds to the host cell membranes and penetrates into the host cytoplasm by pinocytosis. The virions are composed of cytoplasmic vesicles, fuse to cytoplasmic membrane and release RNP into the cytoplasm. The core starts primary transcription of the five complementary monocistronic messenger RNAs by using the virion-associated RNA-dependent RNA polymerase. Each mRNA is translated to an individual viral protein. After synthesis and replication of the genomic RNA, the full length, positive-stranded RNA is completed and becomes the template for the next negative-stranded RNA. In the assembly process, the N-P-L complex encapsulates negative-stranded genomic RNA to be made up of RNP core and the M protein consists of a capsule or matrix that su...

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...at in domestic animals, which indicates wild animals cause a higher risk to humans. Controlling the disease in susceptible wild free-ranging animal populations is implemented by oral vaccination and recombinant rabies vaccine by use of vaccine-containing bait. The best prevention is decreasing chances to expose to the disease. Once a patient is suspected as a rabies case, the physician and local health administrator should decide whether infection actually occurs and whether a risk of rabies exists in the geographic area. Once the identification is completed, the patient should receive post-exposure prophylaxis immediately, which contains the combination of local wound cleansing, human rabies immune globulin (HRIG) and rabies vaccine. The population such as veterinarians, animal handlers that have higher risk to be infected should receive pre-exposure immunization.