Herpes Simplex and Pseudorabies Viruses

many must be the result of using impure systems and of secondary effects or else they are the product of a multiplicity of phenomena with similar end results. Dr. Vilcek is a splitter; he gives the impression that no unifying principle exists in the interferon system, but that there are several physically diverse interferons produced by the same cell and that cells may be induced to produce these by a variety of dissimilar substances. In taking this stand, the author of this monograph stands with the majority of scientists who are actually working with interferon. Interferon is only defined by a few stability characteristics, and by its action in inducing resistance to a wide variety of viruses in cells of the same species as produced it. It may vary threefold in its molecular weight; it varies in its requirements for synthesis and it varies in its kinetics of production. It may be induced by some but not all live viruses, some but not necessarily the same killed viuses, and an heterogeneous group of non-viral chemicals and cell products. It is more effective against some viruses than others, quite independent of their metabolic patterns. Vilcek does an excellent job of guiding the reader through all these intricacies with a prose that is lucid and coherent. Most impressively he studs his text with a large number of references and yet avoids the impression that he is simply listing citations. There is, however, another approach to the subject of interferon that Dr. Vilcek eschews. Some workers would try to find a common mechanism that might tie together most if not all the experimental data. There is no agreement on just what this mechanism might consist of. Interferon does absorb very readily to many substances and there can be no guarantee that the observed physical differences are not due to association with variously firmly bound contaminants. Of the various interferon inducers, double stranded RNA is much the most potent and recent findings suggest that this substance is much more commonly encountered than originally believed. To this reviewer, it seems incompatible with the laws of evolution that cells should exhibit such redundancy of interference producing mechanisms, and he looks hopefully to the day when a unifying theorem can be expounded. Dr. Vilcek's monograph is not the only recent reference that is available to the student of interferon, but it is probably the best for the beginner who wishes for the first time to delve into this important field. There is an excellent chapter with a more molecular orientation on interferon by Levy in his book, The Biochemistry of Viruses. There are also two recent symposia edited by Wolstenholme and by Finter, but these provide no synthesis of the divergent points of view which they present.