Serological studies on sugar-beet yellows virus

Specific antisera have been prepared against the sap expressed from beet plants infected with beet yellows virus.

The antigen is unstable. In the sap it is destroyed by keeping for 2‐3 days at room temperature or by heating for 10 min. at 52d̀C. It is unaffected by pH changes between 5 and 9. In detached leaves at room temperature it remains unchanged for at least 6 days, whereas the ability of aphides to transmit from these leaves fell considerably in 4 days.

The antigen can be reversibly precipitated by ammonium sulphate or sedimented by high‐speed centrifugation. However, all the attempts to isolate it from other sap constituents or concentrate it have failed.

The precipitin reaction is of value for diagnosis, and works successfully with crude sap.