PRIMARY VIRUS-CELL INTERACTIONS IN THE IMMUNOFLUORESCENT ASSAY OF VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS
FORT DETRICK FREDERICK MD
Pagination or Media Count:
The conditions under which Venezuelan equine encephalomyelitis VEE virus attached to host cells markedly influenced the assay of virus by the fluorescent cell-counting technique. When virus inoculum was centrifuged onto McCoy cell monolayers, approximately 97 of virus was attached to cells within 10 minutes in contrast to 34 after stationary incubation at 35 C for 2 hours. Maximum binding of virus occurred only in the presence of 0.1 to 0.15 M NaCl. This salt requirement, added to evidence of pH dependence and temperature independence of VEE virus attachment to cells, indicated that the initial union involved electrostatic forces. Virus penetration, measured by the insensitivity of virus-cell complexes to viral antiserum, was complete in 30 minutes at 35 C. The process was temperature-dependent and unaffected by the ionic content of medium. For assay of VEE virus by the fluorescent cell-counting technique, infected cells may be enumerated as early as 12 hours after infection of cell monolayers. The relationship between virus concentration and cell-infecting units was linear the distribution of fluorescent cells was random. Virus assay by the fluorescent technique was equivalent in sensitivity but more precise and rapid than that by intracerebral inoculation of mice.