The use of polylysine during negative staining of viral suspensions

The use of 0.1% aqueous solution of polylysine (poly-L-lysine) is proposed as a prior step to negative staining of viral or particle suspensions. Particles spread better on films precoated with polylysine than with other substances used for the same purpose. This applies particularly to samples from sucrose or CsCl gradients. The use of negative contrast substances is discussed.