These include northern hybridisation, quantitative RT-PCR, Western blot, immunofluorescence, ELISA and phenotypic analysis. Differential display, RNase protection assay and northern blot. Proteins can be detected using the Western blot and immuno dot blot tests. Alternatively, immunocytochemical, western blot, and immunoprecipitation-mass spectrometry screening can also be used. Granzyme secretion can be detected and measured using Western Blot or ELISA techniques. A similar hybridization technique is called a zoo blot. The sample is detected on a western blot. For this reason, primary antibodies must be well-validated in a Western Blot or similar procedure. Development of the blot is then stopped by washing away the soluble dye. Using ELISA is more specific than using a Western blot or Arc2 immunodiffusion. This technique is extensively used in Southern blot analysis of DNA samples. Similarly, detection of RNA is termed as northern blot. Any positive test result should be confirmed by a lab using the western blot. The brainstem tissue, but not lymph nodes, was positive for CWD (confirmed with Western Blot). One method is the Terminal Restriction Fragment (TRF) southern blot.