FIG. 4.

Example of a standard curve used to quantitate EIAV gag DNA in tissues by PCR. Plasmid copy number is plotted against densitometry units. R², regression coefficient. Portions of agarose gel, stained with ethidium bromide, show PCR bands in triplicate from serial dilutions of EIAV gag-containing plasmid. cc, copies of plasmid.