DENSITY AND BIOLOGICAL HETEROGENEITY IN EASTERN EQUINE ENCEPHALITIS VIRUS
FORT DETRICK FREDERICK MD
Pagination or Media Count:
Experiments in which partially purified eastern equine encephalitis EEE virus was centrifuged to equilibrium in CsCl revealed three bands. These consisted of a hemagglutinating particle, rho 1.18 a major infectious band, presumed to be the complete virion, rho 1.20 and a minor infectious band, rho 1.22 to 1.23. Analysis of radioactive profiles of CsCl-fractionated EEE labeled with either P32O4 or uridine-H3 indicated that most of the hemagglutinin was stripped from the complete virion. The viral origin of the hemagglutinin was verified by inhibition with specific antiserum. Attempts to differentiate between EEE rho 1.22 to 1.23 and the complete virion rho 1.20 showed that the denser particle was neither a viral contaminant nor a density mutant. No evidence for its being an immature form of the virus was obtained. Results from a comparison of the kinetics of neutralization of EEE rho 1.20, rho 1.23, or unfractionated EEE with antiserum showed that the three virus populations were indistinguishable antigenically. Furthermore, all three preparations sedimented at about 250S in sucrose gradients. These results and those obtained from CsCl rebanding experiments suggest that the denser infectious species results from a CsCl-induced alteration or breakdown of the virion and that it arises as the hemagglutinin is stripped from the surface of the complete virion.