Abstract
Various methods have been reported for purifying non-occluded viruses of insects but they have seldom been compared. We find that one we use to purify acute beeparalysis virus (crytogram† R/1:2/(25):8/3:I/O) and sacbrood virus (R/*:*/(35):S/S:I/O) (Bailey, Gibbs & Woods, 1963, 1964) is suitable for many other viruses, and is as effective but simpler than other methods. For example, we have used it to purify Galleria dense nucleus virus (GDNV) (D/*:*/37:S/S:I/*) (Meynadier et al. 1964). Larvae of Galleria mellonella that had been injected with the virus and kept at 30° for 7 to 14 days were ground in a 4/1 mixture of water and carbon tetrachloride (1 larva/ml. of water) and centrifuged at 8000 g for 10 min. The supernatant fluid contained about 1013 virus particles/ml., which separated in the analytical centrifuge into two components with S20,w values of 120 and 60 (Fig. 1b); the median lethal doses, by injection, of these two components, separated by centrifuging in sucrose density gradients, were about 102 and 105 particles respectively.