Electron microscopic identification of Zinga virus as a strain of Rift Valley fever virus.

Electron microscopic examination of a negatively stained suspension of Zinga virus showed particles 90-100 nm in diameter, enveloped with spikes 12-20 nm in length and 5 nm in diameter. Further identification of the virus by immune electron microscopy showed the reactivity of human Rift Valley fever virus-positive serum with Zinga virus. Results of this study are in agreement with earlier reports that Zinga virus is a strain of Rift Valley fever virus.

Carbon-based immunocytochemistry. A new approach to the immunostaining of epoxy-resin-embedded material.

A carbon-based immunocytochemistry (CarBIC) method, whereby the epoxy resin is completely removed from a section prior to immunocytochemistry (IC), is described. The resulting absence of embedding medium allows for an optimal access of both primary antibodies and marker systems to structures at various levels throughout the depth of the section. A carbon film evaporated onto the surface of the section before extraction of the resin forms a base to which the section adheres and maintains structural integrity during subsequent processing. The conventional and accepted electron microscopical (EM) appearance for epoxy-resin-embedded material is regained by re-embedding in Epon before contrasting in the normal manner. The technique is demonstrated using human cytomegalovirus (HCMV)-infected human fibroblasts. HCMV+ serum is the source of primary antibodies and 10-nm protein A-gold (pA-G10) together with rabbit anti-human IgG + IgM is the marker for IC.

Electron microscopical particle counting in virology. III. Parameters governing the efficiency of sedimentation techniques and its improvement with the application of poly-L-lysine.

In the preceding study the degree of adsorption of virus to electron microscope grids has been shown to be an important parameter governing the efficiency of sedimentation techniques used for particle counting. In the present study the application of poly-L-lysine not only improves the binding ability but makes it more reproducible. In addition the distribution of adsorbed particles between grid bars and holes is characterized and its importance as an additional parameter for such techniques discussed. For accurate particle titre estimation and for assessing the efficiencies of sedimentation techniques in virus diagnostics the product of these parameters represents a correction factor which must be taken into consideration. Furthermore it could be demonstrated, using the technique here described over the surface of a poly-L-lysine treated grid after drying. This phenomenon makes possible the estimation of a titre through particle counting on gravimetrically determined volumes.

Antigen controlled immuno diagnosis-- 'ACID test'.

A test for the presence of antibodies in sera is described in which the binding of the antibody to a morphologically identifiable antigen, visualized using staphylococcal protein A-coated gold, serves as the criterion for specificity. This 'Antigen Controlled Immuno Diagnosis' (ACID test) as applied to T4 bacteriophage, vaccinia virus and Enterobacterium Yersinia has proved to be reliable and simple to carry out.