IMMUNOLOGICAL PROPERTIES OF PLANT VIRUSES^ 



J. M. Wallace 



University of California Citrus Experiment Station, 



Riverside, California 



Serological reactions — It is now well established that plant viruses 

 are antigenic and evidence obtained from many studies, particularly 

 those dealing with purified virus preparations, strongly favors the view 

 that the specific antigens found in virus-affected plants are the viruses 

 themselves, rather than products of the host plant produced as a result 

 of virus infection. Most of the evidence of the antigenicity of plant 

 viruses has been obtained from precipitin reaction and complement 

 fixation tests. With these techniques the results appear to be clear cut 

 especially in the case of the more stable viruses that exist in host plants 

 in relatively high concentrations. Certain plant viruses, which have not 

 given antigenic reactions when crude or clarified sap of affected plants 

 was used, have been shown to be antigenic when purification or con- 

 centration procedures were followed. 



Studies of anaphylactic reactions have been quite meager and those 

 reported have dealt chiefly with the tobacco mosaic virus. The con- 

 clusion drawn from this work is that purified tobacco mosaic virus 

 induces anaphylactic shock "in vivo" although it is much less anaphy- 

 lactogenic than animal proteins. 



A fourth test of antigenicity of plant viruses and one which at first 

 sight would seem to be the simplest means of demonstrating serological 

 activity of plant viruses is that of neutralization of infectivity. How- 

 ever, it has been found that both normal and heterologous antisera 

 inhibit infectivity. Thus accurate tests and adequate controls are nec- 

 essary to measure the specific effect of homologous sera in reducing 

 infectivity. From the reported studies on neutralization of infectivity 

 the following facts seem to be established: 



A. Normal sera and heterologous sera have a non-specific effect in 



'For more detailed discussion of this subject and for specific literature citations the 

 reader is referred to the following: 



Bawden, F. C. Plant viruses and virus diseases. Chronica Botanica Co., Waltham, 

 Mass., U. S. A. 1943. 



Price, W. C. Acquired immunity from plant virus diseases. Quart. Rev. of Biol- 

 ogy, 15:3- 1940- 



. Generalized defense reactions in plants. The Amer. Naturalist, 74: 117- 



128. 1940. 



