“…These RNAs include cellular mRNA and its heterogeneous nuclear precursors (Kates, 197o;Darnell, Wall & Tushinski, I97I ;Edmonds, Vaughan & Nakazoto, 1971 ; Lee, Mendecki & Brawerman, I971), virus particle RNA (Armstrong et al 1972;Eaton & Faulkner, 1972;Yogo & Wimmer, 1972), and virus-specified RNA (Kates, 197o;Philipson et al I97I;Eaton, Donaghue & Faulkner, 1972;Pridgen & Kingsbury, 1972;Weinberg, Ben-Ishai & Newbold, 1972;Galet & Prevec, 1973;Soria & Huang, 1973). In this paper we use several different procedures to examine the virus-specific RNA from cells infected with Semliki Forest virus, an alphavirus, for the presence of poly A tracts.…”