Demonstration of a reovirus in helicopter disease of broilers

: A reovirus was isolated from 5-13-day-old broiler birds with signs of the so-called helicopter disease--one of the forms of the malabsorption syndrome. A number of organs were investigated (trachea, liver, spleen, bursa of Fabricius, proventricular stomach, and tendon sheath of musculus gastrocnemius). The virus was isolated from the proventricular stomach and the tendon sheath in cell cultures of chick embryo kidney as well as in 5-7-day-old chick embryos inoculated in the yolk sac. The remaining organs proved virologically negative. All organs, including the primarily positive ones, were shown to be virologically negative upon the inoculation of chick embryo fibroblast cultures and of chorioallantoic membranes of 10-11-day-old chick embryos. The isolate was identified as an avian reovirus, and was denoted with the initials R-85--on the grounds of its biologic and physico-chemical properties, of its morphology (negative-contrast electron microscopy), and of its morphogenesis (ultrathin electron-microscopic cross sections). Investigated were the histopathologic changes in chick embryos inoculated with the R-85 reovirus and the pathologic changes in the liver of spontaneously affected birds.