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and the pathway taken by specific viral proteins in 

 infected cells (Green et al. , 1981; Griffiths et al . , 

 1982, 1983). It has also been used to reveal the 

 antigenic sites in different cellular compartments of 

 infected cells (Garzon et al., 1982; Roth, 1983, 1984). 

 These studies have demonstrated that the protein A-gold 

 technique represents a valuable approach for medical 

 diagnosis (Garzon et a_l. , 1982). It has also been 

 introduced as an alternative to other techniques for the 

 ultrastructural localization of antigenic sites (Bendayan, 

 1984). In plant virology, immunogold labelling was first 

 applied to barley stripe mosaic virus by using gold- 

 immunoglobulin ( IgG ) complexes for Lowicryl-embedded 

 tissues (Lin and Langenberg, 1983). It was also used to 

 identify viral antigens in suspensions (Giunchedi and 

 Langenberg, 1982; Lin, 1984; Louro and Langenberg, 1984). 

 However, some complexity is involved in using Lowicryl and 

 the gold-IgG complex (Causton, 1984; Newman and Jasani, 

 1984, Louro and Lesemann, 1984). The problems associated 

 with the use of Lowicryl can be circumvented by using LR 

 White resin instead. The polymerization of LR White does 

 not require the very low temperatures and ultraviolet 

 light necessary for the polymerization of Lowicryl 

 (Causton, 1984). This study demonstrates that the higher 

 temperature for polymerization of LR White does not 

 interfere with the specificity of immunogold labelling 



