Arenaviridae

The Arenaviridae (from Latin arenosus = sandy) are a family of enveloped RNA viruses whose sole member is the genus Arenavirus (see also Viruses, Classification). The viruses of this genus are generally associated with human diseases transmitted by rodents. Each virus is usually associated with a particular rodent host species in which it occurs. Arena virus infections are relatively common in humans in some areas of the world and can cause severe disease.

Arenaviruses are divided into two groups: the New World or Tacaribe complex and the Old World or LCM/Lassa complex. Viruses in these groups that cause mild or severe disease in humans are listed below by date of discovery:

Human arenavirus species

• Lymphocytic choriomeningitis virus (LCMV) Lymphocytic choriomeningitis 1933
• Junin virus(Argentine hemorrhagic fever, 1958)
• Machupo virus (Bolivian hemorrhagic fever, 1963)
• Lassa virus(Lassa fever, 1969)
• Guanarito virus (Venezuelan hemorrhagic fever, 1989)
• Sabia (Brazilian hemorrhagic fever, 1993)
• Chapare (Chapare hemorrhagic fever, 2004)
• Lujo (Lujo hemorrhagic fever, 2008)

The genome consists of two single-stranded ambisense RNA molecules (linear ss(-)RNA), L and S, with lengths of approximately 7.5 kb and 3.5 kb, respectively. Variable amounts of full-length viral complementary RNAs (predominantly S) and viral subgenomic mRNA species have been detected in virus preparations. The most abundant structural protein is nucleoprotein (N or NP), a nonglycosylated polypeptide (approximately 63 kDa) that is closely associated with viral genomic RNA in the form of a ribonucleoprotein complex or nucleocapsid structure. Lipids constitute about 20% of the dry weight of the virion and are similar in composition to those of the host plasma membrane. Carbohydrates in the form of complex glycans on GP1 and GP2 account for about 8% of the virion dry weight.

Replication: The infection process involves attachment to cell receptors. The particles are taken up by endocytosis. The two RNA segments are subsequently released into the cytoplasm by fusion of the viral envelope with the endosomal envelope . Both the L segment and the S segment encode 2 proteins each. The viral envelope glycoproteins are synthesized in the cell as a single mannose-rich precursor molecule that is proteolytically cleaved and processed into complex glycans during transport to the plasma membrane.

Animal hosts: Arenaviridea are zoonotic, which means that they occur naturally in animals. Each virus is associated either with a species or with some closely related rodents that form the natural reservoir of the virus. Tacaribe complex viruses are generally associated with New World rats and mice (family Muridae, subfamily Sigmodontinae). LCM/Lassa complex viruses are associated with Old World rats and mice (family Muridae, subfamily Murinae). Collectively, these species of rodents are distributed over most of the Earth's landmass, including Europe, Asia, Africa, and the Americas. A notable exception is Tacaribe virus, which occurs in Trinidad and has been isolated from bats and mosquitoes.

Spread of arenavirus infections: Rodent hosts of arenavirus species are chronically latently infected with the virus. Some arenavirus species appear to be passed from rodents to their offspring during pregnancy and thus remain in the rodent population generation after generation. The viruses are released into the environment in the urine or feces of infected hosts.

Human infection with an arenavirus occurs incidentally in the natural cycle of viruses and occurs when a person comes into contact with the excreta or materials contaminated with the excreta of an infected rodent, such as ingestion of contaminated food or direct contact of scraped or broken skin with rodent feces. Infection can also occur by inhalation of minute particles contaminated with rodent urine or saliva (aerosol transmission). The types of incidental contact depend on the habits of both humans and rodents. For example, where the infected rodent species prefers a field habitat, human infection is associated with agricultural work. In areas where the rodent species' habitat includes human dwellings or other buildings, infection occurs in the domestic environment.

Some arenaviruses, such as Lassa, Machupo, and Lujo viruses, are associated with secondary human-to-human and nosocomial (healthcare setting) transmission. This occurs when a person infected by exposure to the virus from the rodent host transmits the virus to other people, for example, through direct contact with the blood or other body fluids of infected persons that contain virus particles. Aerogenic transmission has also been reported in the context of certain viruses.

Prophylactically , the use of protective clothing and disinfection procedures (barrier care) is necessary to prevent further spread of the disease.

1. Ayres JS (2020) Immunometabolism of infections. Nat Rev Immunol 20:79-80.
2. Gonzalez JP et al (2007) Arenaviruses. Curr Top Microbiol Immunol 315:253-288.
3. Hof H et al (2019) Special virology. In: Hof H, Schlüter D, Dörries R, eds Dual series medical microbiology. 7th, completely revised and expanded edition. Stuttgart: Thieme pp 237-239.
4. Sarute N et al (2017) New world arenavirus biology. Annu Rev Virol 4:141-158.