Immunodiffusion in agar

Immunodiffusion test A serologic test similar to the precipitin test but carried out in agar gel medium. 

Figure 6-4. Double immunodiffusion. Antigens about the concentration and size of the antigen and antibodies are loaded into two wells cut at the number of precipitin bands indicates the opposite ends of the agar gel. The position and number of distinct antigens in the mixture, intensity of the precipitin lines gives information...

Agar gel immunodiffusion methods have been produced as commercial kits and a further development is dipstick assays for meat species identification. The immunoreagents are immobilized on a dipstick and a color change, occurring in less than 1 h, identifies the presence of a particular meat species, with a detection limit of 1 % lean meat. 

Fig. 2. Radial immunodiffusion pattern of HPL standards. Antiserum to HPL is mixed with the agar. Decreasing concentrations of HPL standards in wells 1 to 3 are reflected by smaller immunoprecipitln rings.

More recently, Zalitis and Feingold (1969) have purified the enzyme from beef liver extensively and studied its mechanism of action. The purified enzyme was homogeneous in polyaciylamide gel electrophoresis, Immunoelectrophoresis, and agar immunodiffusion. It sedimented as a symmetrical peak in the ultracentrifuge at pH 7.0 with an sso.w of 12.8. The molecular weight calculated from the sedimentation data was 3-4 X 10. Further experiments indicated that the enzyme could be dissociated... 

---