Mathes L E, Yohn D S, Olsen R G
J Clin Microbiol. 1977 Mar;5(3):372-4. doi: 10.1128/jcm.5.3.372-374.1977.
Feline leukemia virus from tissue culture fluids was concentrated 100 times by continuous-flow molecular filtration. Virus concentrates retained 100% of their original infectivity. Further purification was accomplished by a single sucrose density gradient centrifugation.