Arenavirus taxonomy: a review

Despite a late beginning, the construction of the arenavirus taxon and its placement in the scheme of the International Committee on Taxonomy of Viruses has now been completed. The bringing together of the member viruses has already provided valuable indications of promising laboratory and field study approaches. The morphologic, physicochemical, and serologic data became the basis for a formal proposal and definition of the arenavirus group (from the Latin arena, sand). This name reflects the characteristic fine granules seen within virions by thin section electron microscopy (Ernest Borden). At present, 10 arenaviruses are known: LCM (the prototype virus; world wide), Junin (Argentina), Machupo (Bolivia), Amapari (Brazil), Pichinde (Columbia), Parana (Paraguay), Tamiami (Florida), Latino (Bolivia), Tacaribe (Trinidad), and Lassa (West Africa) viruses. The definition of the taxon is described. The virions have a unique morphology in thin section; they are spherical or pleomorphic and range in diameter from 50 to 300 nm (mean 110-130 nm). The particles have a unit membrane envelope covered with club shaped projections of electron dense granules within an otherwide unstructured interior. These granules, 20-25 nm in diameter, have been shown to be ribosomes. Viral constituent synthesis takes place in the cytoplasm, often with inclusion body formation; maturation occurs via budding, primarily from plasma membranes. The viruses of this group variably cross react in indirect immunofluorescent tests, and to a lesser extent in complement fixation tests, but not in neutralization tests.