Basic electron microscopy of aquatic viruses

Hans-W. Ackermann and Mikal Heldal

Full Citation: Ackermann, H.-W., and M. Heldal. 2010. Basic electron microscopy of aquatic viruses, p. 182-192. In S. W. Wilhelm, M. G. Weinbauer, and C. A. Suttle [eds.], Manual of Aquatic Viral Ecology. ASLO. [DOI 10.4319/mave.2010.978-0-9845591-0-7.182]

ABSTRACT: For identification and structural studies, viruses are concentrated and purified by differential or density gradient centrifugation, stained with phosphotungstate (PT) or uranyl acetate (UA), and examined by transmission electron microscopy. Both PT and UA produce artifacts. PT yields negative staining only; UA produces both negative and positive staining and often gives excellent contrast. Fixation is normally not necessary. UA-stained preparations can be stored for years. Virus particles may be sedimented directly from water samples onto grids by means of special centrifuge tubes and subsequent staining. Positively stained particles are highly contrasted and easy to count at low magnification. Positive staining also provides information on bacteria containing viral particles and rough estimates of burst sizes in individual bacteria. Isometric, filamentous, and pleomorphic viruses are identified after negative staining.