Virus-like particles in the scaly green flagellate Mesostigma viride

Abstract

Icosahedral virus-like particles (VLPs) have been found in cells of the freshwater scaly green flagellate Mesostigma viride Lauterborn. VLPs occurred in about 5% of the cell population as judged from sections of the fixed sample. The VLPs measure 130 nm in diameter, appear hexagonal in section and consist of a quadrilamellate coat (20 nm thick) and a dense fibrillar core. In infected cells different stages of cell degeneration have been observed. In early infection stages the nucleus is largely intact, VLPs occur in a cytoplasmic area adjacent to the nucleus. Evidence is presented that dictyosomes may be involved in the assembly and maturation of the VLP-coat.