Propagation of Junin Virus, the Etiological Agent of Argentinian Hemorrhagic Fever, in HeLa Cell Cultures

The propagation of the virus of epizootic hemorrhagic disease of deer in newborn mice and HeLa cells

The New Jersey strain of EHD virus has been propagated in newborn Swiss mice by the intracerebral route and is regularly lethal beyond the first serial mouse passage. A complement-fixing antigen prepared from the brains of infected mice reacts positively with the sera of deer recovered from infection with either the New Jersey or South Dakota strain of virus, but not with the serum of normal deer. The mouse-passaged virus induced an inapparent infection in an experimental deer. The virus can also be grown serially in HeLa cell culture and induces a characteristic cytopathic effect. It is neutralizable in such cultures to high titer by the sera of deer recovered from EHD (New Jersey strain) and to lower titer by the serum of a deer recovered from EHD (South Dakota strain). Normal deer serum does not neutralize the virus in tissue culture. The HeLa cell-passaged virus induced typical lethal EHD in an experimental deer and virus could be recovered from most of the tissues of this animal in HeLa cell culture. An unexplained prozone of inhibition of cytopathogenicity at low dilutions was observed in cultures of some of the organs. The fact that EHD virus exhibited a limited sensitivity to sodium desoxycholate suggests that it may belong in the arbor virus group.

Arenoviruses in Vero cells: ultrastructural studies

Thin-section electron microscopy was carried out on Vero green monkey kidney cell cultures infected with some viruses of the newly constituted arenovirus group. Junin, Machupo, Amapari, Pichinde, Parana, Tamiami, and Latino viruses were morphologically identical and indistinguishable from lymphocytic choriomeningitis virus, the prototype virus of the group. Virus particles were round, oval, or pleomorphic, 60 to 280 nm in diameter, and matured via budding from plasma membranes. Most characteristically, particles contained various amounts of homogeneous, 20- to 25-nm, dense granules; these granules in large masses also formed distinctive intracytoplasmic inclusions. In negative-contrast preparations from infected Vero cell culture supernatant fluids, several of the viruses appeared as pleomorphic membrane-bound forms with rather pronounced surface projections. Most particles were between 90 and 220 nm in diameter, although some reached 350 nm in their longest dimension. Internal structure was not resolved by negative-contrast electron microscopy. All observations supported the current delineation of a distinct arenovirus group.