Arenavirus - Introduction, Classification, Morphology, Genome

Classification of Arenavirus

Realm: Riboviria

Kingdom: Orthornavirae

Phylum: Negarnaviricota

Class: Ellioviricetes

Order: Bunyavirales

Family: Arenaviridae

Some medically important genus includes: Antennavirus, Hartmanivirus, Mammarenavirus, Reptarenavirus

Introduction of Arenavirus

Arenavirus is a member of the family Arenaviridae containing 23 viral species among which cause human disease. They are categorized into two complexes- based on Antigenic properties and genetic analysis. These groups correspond to geographic distribution and rodent reservoirs thus known as “Old World” or “New World” Arenaviruses. These viruses infect rodents and occasionally humans.

Arenaviruses include lymphocytic choriomeningitis virus (LCMV) and hemorrhagic fever viruses such as:

• Guanarito virus (GTOV)Junin virus (JUNV)

• Lassa virus (LASV)

• Julo virus (LUJV)

• Machupo virus (MACV)

• Sabia virus (SABV)

• Whitewater Arroyo virus (WWAV)

As arenaviruses and bunyaviruses are associated with rodent reservoirs and vectors, they are designated as roboviruses.

Morphology of Arenavirus

Arenavirus is enveloped (50-300 nm typically 110-130nm), slightly pleomorphic/spherical viruses that have a sand-like appearance. The surface GP (Glycoproten) spikes are distinct i.e. club-shaped and extend 7-10 nm from their surface. These spikes are in small no. and are dispersed evenly over the surface.

Genome of Arenavirus

Arenavirus virions not only contain a virus genome but also host ribosomes (both 28s and 18s ribosomal RNA) which give the virus its characteristic grainy morphology.

Arenavirus genome is a negative sense, single-stranded RNA with 2 sub-genomic segments, namely, S (small segment, measuring 1.3 million bases) and L (large segment, measuring 2.4 million bases) separated by a short hairpin configuration.

• The (L) segment in the Arenavirus genomic sense encodes viral polymerase and in the antigenomic sense encodes zinc-binding matrix protein (Z)

• The (S) segment in the Arenavirus genomic sense encodes nucleoprotein (NP) and the antigenomic sense encodes glycoprotein precursor (GPC). GPC is post-translationally cleaved by cellular proteases into 2 envelope proteins- GP1 and GP2.