Serological Properties of Turnip Mosaic Virus

Abstract

The sensitivities of some serological methods such as tube precipitin, ring interface, bentonite flocculation and agar gel immunodiffusion tests were compared by using antiserum prepared with purified turnip mosaic virus (TuMV) and various antigen preparations of the virus. When crude sap from infected plants or partially purified virus preparation was used as an antigen, the tube precipitin, ring interface and bentonite flocculation tests showed almost similar sensitivities. When purified TuMV or its degraded protein was used, however, the sensitivity of bentonite flocculation test was remarkably high as compared to other methods. In agar gel immunodiffusion test, intact virus antigen did not react with antiserum. In order to prepare TuMV antigen useful for immunodiffusion test, the purified virus preparations were subjected to ultrasonication or chemical degradation. When the virus suspensions were sonicated for various periods, both mean length of the particles and infectivities were markedly reduced and the reduction correlated with increase of sonication period. The purified virus suspensions sonicated for periods over 1min formed single precipitin line with TuMV antiserum. With preparation sonicated for 5 to 10min, a sharp precipitin line was produced midway between the antigen and antiserum wells. TuMV proteins degraded by BaCl₂, ethanolamine or pyrrolidine produced a continuous single and clear precipitin line in agar gel. BaCl₂ treatment produced the highest useful amount of soluble antigen for agar gel immunodiffusion test. The products degraded by sodium dodecyl sulfate formed 2 precipitin lines; the faster-diffusing antigen was identical with those degraded with other reagents. No difference was observed in serological properties between the sonicated fragments and degraded proteins of TuMV.