Rhabdoviruses

Q: What are the main stages of the rhabdovirus replication cycle inside an infected cell?

The replication cycle includes five main stages: Adsorption and penetration — binding of viral glycoproteins to receptors and entry via clathrin-mediated endocytosis.Uncoating — release of the ribonucleocapsid from the endosome directly into the cytoplasm.Biosynthesis — transcription of incomplete positive strands (mRNA) and replication of full-length positive-sense RNA using the viral RNA-dependent RNA polymerase.Translation and processing — synthesis of viral proteins on ribosomes and modification of glycoprotein G in the endoplasmic reticulum and Golgi apparatus.Assembly and release — formation of the ribonucleocapsid and exit of new virions by budding through the cell membrane.

Q: What is the mechanism of rabies virus spread through the human nervous system following a bite?

Spread of Rabies virus through the nervous system occurs strictly via neurogenic pathways: Centripetal transport — the virus moves retrogradely along motor neuron axons from the inoculation site to the CNS at a rate of 50–100 mm/day, driven by minus-end directed motor proteins of the dynein family.Centrifugal spread — following replication in neuronal cell bodies of the brain and spinal cord, the virus disseminates via efferent peripheral nerve fibers to internal organs, primarily the salivary glands.

Q: What laboratory diagnostic methods are used to confirm a rabies diagnosis?

Diagnostic methods include: Direct fluorescent antibody (DFA) test — examination of corneal smears and skin biopsies.Enzyme-linked immunosorbent assay (ELISA) and complement fixation test (CFT) — serological detection of antibodies.Neutralization test — in mice using antirabies immunoglobulin.Biological assay — isolation of the virus from saliva, tear fluid, or cerebrospinal fluid via intracerebral inoculation of suckling mice.Indirect immunofluorescence is also utilized.

Q: What products are used for specific post-exposure rabies prophylaxis?

Active and passive immunization products are used: Rabies vaccine — a concentrated, purified, inactivated cell-culture vaccine administered intramuscularly in a 6-dose series for prompt immunity induction.Rabies immunoglobulin (RIG) — provides immediate passive immunity for severe exposures or high-risk bites. Administered at 20 IU/kg, with a portion infiltrated around the wound and the remainder given intramuscularly.

Rhabdoviridae

For medical students2 min readUpdated 2026-10-10

Rhabdoviruses are a large family of enveloped RNA viruses distinguished by their characteristic bullet-shaped virion morphology. This group of pathogens infects both animals and plants, with its most notable medical representative being the causative agent of rabies.

Specific shapeBullet-shaped (a cylinder with one rounded and one flat end)

Virion dimensionsLength of 120–300 nm and a width of 60 to 80 nm

Outer envelopeSupercapsid formed by a bilayer lipoprotein membrane

Genetic materialSingle-stranded linear unsegmented negative-sense RNA molecule

General Characteristics and Classification

The family Rhabdoviridae represents a massive group of infectious agents. To date, approximately one hundred and eighty species belong to this family. A unique feature of this group is its extremely wide host range: various species can infect both diverse animal organisms and plant crops.

In medical and veterinary microbiology, several key genera have the greatest epidemiological and economic importance:

Genus Lyssavirus — critical for human medicine, as it includes the rabies virus, which causes a fatal disease.
Genus Vesiculovirus — a prominent and typical representative is the vesicular stomatitis virus.
Genus Ephemerovirus — includes the specific pathogen causing bovine ephemeral fever.

Morphology and Etymology

Under an electron microscope, members of the family display a highly specific appearance. Virions possess a characteristic bullet shape. The structure of the viral particle is asymmetric and resembles a cylinder with one smoothly rounded pole and one completely flat (truncated) end.

This unique visual feature served as the basis for the family's nomenclature. The name originates from the ancient Greek word rhabdos, meaning "rod" or "stick." The physical parameters (dimensions) of virions vary widely: their length ranges from 120 to 300 nanometers, and their width typically spans 60 to 80 nanometers.

Ultrastructure and Viral Envelope

The complex structure of the virion is ensured by several key structural components. The outer protective barrier is the supercapsid — a specialized envelope consisting of a bilayer lipoprotein membrane with a precisely ordered spatial organization:

Inner layer: Facing the center of the virion, the lipoprotein membrane is densely lined with matrix protein, designated in microbiology as the M protein.
Outer layer: The outer surface of the supercapsid is densely covered with specialized spikes formed by glycoprotein G. Each spike measures approximately 5 to 10 nanometers in length and about 3 nanometers in diameter.

Ribonucleocapsid and Genome Organization

Beneath the lipoprotein supercapsid lies the internal component — the ribonucleocapsid, which exhibits helical symmetry. The core contains genetic material represented by a single-stranded, strictly linear, unsegmented RNA molecule. Crucially, this is a negative-sense RNA (negative polarity) molecule.

The viral genome functions in close association with specific nucleocapsid proteins, each performing a unique task:

N protein (nucleocapsid) — performs a structural function, forming a tight protective protein shell around the genomic RNA.
L protein (large) and P protein (phosphoprotein) — associate to form a vital polymerase complex functioning as a transcriptase, which is essential for initiating and driving viral replication inside the infected cell.

Mnemonic

To remember the components of the rhabdovirus polymerase complex, use the association: to start replication, the virus needs a Leader (L protein) and a Partner/Phosphoprotein (P protein).

Frequently asked questions

Which target cell receptors does rabies virus glycoprotein G bind to during infection?

Rabies virus glycoprotein G binds to specific nicotinic acetylcholine receptors (nAChR) in neural tissue, ensuring adsorption. The p75NTR receptor also participates in transporting the virus to the neuronal cell body.

What are the main stages of the rhabdovirus replication cycle inside an infected cell?

The replication cycle includes five main stages:

Adsorption and penetration — binding of viral glycoproteins to receptors and entry via clathrin-mediated endocytosis.
Uncoating — release of the ribonucleocapsid from the endosome directly into the cytoplasm.
Biosynthesis — transcription of incomplete positive strands (mRNA) and replication of full-length positive-sense RNA using the viral RNA-dependent RNA polymerase.
Translation and processing — synthesis of viral proteins on ribosomes and modification of glycoprotein G in the endoplasmic reticulum and Golgi apparatus.
Assembly and release — formation of the ribonucleocapsid and exit of new virions by budding through the cell membrane.

What is the mechanism of rabies virus spread through the human nervous system following a bite?

Spread of Rabies virus through the nervous system occurs strictly via neurogenic pathways:

Centripetal transport — the virus moves retrogradely along motor neuron axons from the inoculation site to the CNS at a rate of 50–100 mm/day, driven by minus-end directed motor proteins of the dynein family.
Centrifugal spread — following replication in neuronal cell bodies of the brain and spinal cord, the virus disseminates via efferent peripheral nerve fibers to internal organs, primarily the salivary glands.

What laboratory diagnostic methods are used to confirm a rabies diagnosis?

Diagnostic methods include:

Direct fluorescent antibody (DFA) test — examination of corneal smears and skin biopsies.
Enzyme-linked immunosorbent assay (ELISA) and complement fixation test (CFT) — serological detection of antibodies.
Neutralization test — in mice using antirabies immunoglobulin.
Biological assay — isolation of the virus from saliva, tear fluid, or cerebrospinal fluid via intracerebral inoculation of suckling mice.
Indirect immunofluorescence is also utilized.

What products are used for specific post-exposure rabies prophylaxis?

Active and passive immunization products are used:

Rabies vaccine — a concentrated, purified, inactivated cell-culture vaccine administered intramuscularly in a 6-dose series for prompt immunity induction.
Rabies immunoglobulin (RIG) — provides immediate passive immunity for severe exposures or high-risk bites. Administered at 20 IU/kg, with a portion infiltrated around the wound and the remainder given intramuscularly.

What shape do members of the Rhabdoviridae family have?

They have a bullet shape, forming a cylindrical structure with one rounded and one flat (truncated) end.

What type of genome do rhabdoviruses have?

Their genetic material is represented by a single-stranded, linear, unsegmented negative-sense RNA molecule.

Which components form the supercapsid?

The supercapsid consists of a bilayer lipoprotein membrane lined internally with M (matrix) protein and covered externally with spikes made of glycoprotein G.

What is the function of the L and P proteins in the viral structure?

The L and P proteins together form a specific polymerase complex (transcriptase) critical for viral replication in the host cell.

Go deeper

Pathogenesis of diseases caused by rabies virus (genus Lyssavirus)
Life cycle of negative-sense RNA viruses
Epidemiological significance of vesicular stomatitis virus (genus Vesiculovirus)
Mechanisms of formation and functions of glycoprotein G in cell interaction
Features of ribonucleocapsid helical symmetry