ELECTRON MICROSCOPY OF LATENT PSITTACOSIS VIRUS IN MCCOY CELLS.

Kajima, Masahiro (University of Notre Dame, Notre Dame, Ind.), Nehama Sharon, and Morris Pollard. Electron microscopy of latent psittacosis virus in McCoy cells. J. Bacteriol. 88:709-715. 1964.-Replication of psittacosis virus in McCoy cells was observed periodically by electron microscopy, and was correlated with the appearance of inclusion bodies in infected cells stained by acridine orange fluorochrome. Three well-defined morphological stages characterized the replication cycle: (i) noninfectious initial body, (ii) noninfectious intermediate body, and (iii) infectious mature or elementary body. When replication of virus was interrupted by aminopterin, the virus failed to develop beyond the noninfective initial body stage; however, after treatment of such cultures with folinic acid, intermediate and mature virus particles appeared in the cells. Latent psittacosis virus, as described here, represented a virus in which the replication process was interrupted at a noninfective (eclipse) stage of the developmental cycle.