Viruses of Entamoeba histolytica II. Morphogenesis of the Polyhedral Particle (ABRM ₂ →HK-9)→HB-301 and the Filamentous Agent (ABRM) ₂ →HK-9

Abstract

The intracellular development of two morphologically different amoebal viruses has been studied by electron microscopy. One is a polyhedral agent which was observed as early as 24 hr after infection in the perinuclear cytoplasm. Subsequently, cell lysis occurred and particles were found in large number bound to membranes of disrupted amoebae. Other particles were found in phagocytic vacuoles suggesting a possible portal of entry into amoebae. The other virus is a filamentous particle which is first seen in small clusters in the nucleus after 24 hr of infection. The number of particles increases such that by 72 hr massive whorls of particles occupy a substantial part of the nucleus. After rupture of the nuclear membrane, clusters of filaments are widely dispersed throughout the cytoplasm. Still later, the cytoplasmic membrane disintegrates and clusters of filaments are found extracellularly, but free of cell membranes. The morphology of these agents is discussed in comparison with a variety of plant, animal, and bacterial viruses.

Viruses of Entamoeba histolytica IV. Studies on the Nucleic Acids of the Filamentous and Polyhedral Viruses

“…Other infected cells whose nuclei had lysed contained large yellowish-green fluorescent inclusions in the cytoplasm. This appearance is compatible with previous investigations in which cytoplasmic inclusions of filaments were identified by electron microscopy subsequent to rupture of the nuclear membranes (11).…”

“…In infected cells, however, the labeled DNA appears to be largely associated with the cytoplasmic fraction. This result was consistent with the observation by electron microscope that this polyhedral virus assembled in the perinuclear cytoplasm (11). It could be argued, however, that the labeled DNA in the cytoplasmic fraction results from an unusual fragility of nuclei of infected cells.…”

“…One was the filamentous agent which to date has only been obtained from the ABRM strain of amoeba. This virus isolate is known to be contaminated with a polyhedral virus and was originally designated (ABRM,)-HK-9 (4,11). Hereafter, it is simply referred to as VABRM.…”

“…Since the identification of two morphologically different viruses, one filamentous and the other polyhedral, in axenically cultivated strains of Entamoeba histolytica (4,11), and the investigation of a number of biological and chemical properties of the polyhedral virus (9), we have concentrated our attention on determining whether these viruses contained DNA or RNA. We have made only preliminary and unsuccessful attempts to purify the filamentous virus, VABRM, because it has not yet been separated from a contaminating polyhedral virus previously described (4,11). Purified polyhedral virus was impossible to prepare, despite an intensive effort, because the virus became irreversibly bound to the cell debris of lysed amoebae and because of the extraordinary lability of the virus in concentrations of salts and nonionic substances ordinarily employed in gradient purification procedures (9).…”

Viruses of Entamoeba histolytica. VII. Novel beaded virus

“…If the donor contains a virus to which the recipient is susceptible, the latter will become infected and lyse. The virus can pass 0.22-Im membrane filters, be continuously passaged in recipient amoebae, and be read-ily identified with an electron microscope as a viruslike entity (1,3,6).…”