Improvement on the Sharp Technique: A Method for Virus Retrieval from Agar with Negative Staining,by Which Changes in Form are Shown for the Coliphage T2L.

摘要

A procedure is described by which virus particles, at low concentration in salt solution, can be enumerated as negative-stained images in the electron microscope. It is based on the Sharp technique of concentrating virus by centrifuging onto agar but the method for retrieving the virus is easier. Since virus is simply washed onto a Formvar film as fluid flows down from the agar, negative staining can be done simultaneously, if stain is incorporated in the agar. With the layer of fluid deposited uniform and very thin, drying is virtually instantaneous, ensuring uniform distribution of the particles and stain. Damage to the particles is also minimized and observation can even be made of structural alterations occurring in solution. Using the technique a change in shape of the coliphage T2L head has been observed which has long been suspected to occur when pH is lowered from 7 to 5. Moreover, the particle shape can be manipulated by varying the conditions of the negative staining.