DSRNA ASSOCIATED WITH VIRUS-LIKE PARTICLES IN EIMERIA SPP OF THE DOMESTIC-FOWL

RNA segments, identified as double-stranded, were found in sporozoites of the Guelph strains of Eimeria acervulina, E. brunetti, E. maxima a nd E. necatrix and in 8 of 11 strains of E. acervulina obtained from p oultry houses across the United States. These RNAs were resistant to R Nase A digestion in the presence of high salt concentrations (0.3 M Na Cl). On agarose-gel electrophoresis, E. acervulina had one obvious ban d at 1.7 kb and a faint band at 3.5 kb; E. brunetti had two bands at 2 .1 and 3.3 kb, respectively; E. maxima had one band at 4.5 kb; and E. necatrix had two major bands at 4.5 and 5.6 kb, respectively. No dsRNA band was seen in the three strains of E. tenella examined. Virus-like particles were purified by cesium chloride density centrifugation of homogenates of E. necatrix sporulated oocysts. The fraction at peak vi rus concentration had a buoyant density of 1.39 g ml(-1). These virus- like particles were icosahedral, had no envelope and measured 42-44 nm in diameter. Only one RNA band at 5.6 kb was observed when nucleic ac ids from gradient fractions containing virus were subjected to electro phoresis. The 4.5-kb dsRNA segment of E. necatrix was not associated w ith a virus-like particle.