Abstract
A method was described for isolating the helical nucleocapsid of the parainfluenza virus SV5 from infected [Rhesus monkey kidney and baby hamster kidney] cells in mg quantities. The length distribution of nucleocapsid shows a sharp peak with a mean of 1.02 /x, suggesting that this is the length which contains one SV5 genome. Chemical determinations indicate that the nucleocapsid is a ribonucleoprotein with an RNA content of 4.1%.