UNIVERSITY OF ILLINOIS DEPARTM2NT OF PACTERIOLOGY November 12, 1951 Dear, al, Joshua, Mark, and Max (and respective coharts): I imagine you have received a copy of a MS (in press) by Lwoff including a proposed nomenclature of bacteria and phage according to their mutual relations, Bertani and I, after discussion at our seminar, have summarized our objections and criticisms in the enclosed pages. Page 0 comes to you only. Pages 1 ~ Q are sent also to Iwoff, I should make it clear that we feel strongly, not only against the proposed system of nomenclature, but against any such system at this time. ‘e see no need for it, no use in it, anc several dangers, Cordially yours, SO (tk S, E, luria SELsoz Comments on proposing the nomenclature, One of the outstanding features of phage work from 1940 till 1951 has been its cooperativeness and the absence of deliberate attempts to "scoops," priorities und "ownership," Questions of nomenclature, coordination of publications and the like have been handled by consultation and agreement, we dislike the policy of foreing a nomenclature és an accomplished fact, by publishing it before asking for comments and announcing one's intention to use it, irrespective of any comments, General cowments on the nomenclature. ‘Ne have two main objections: first, the nomenclcture is restrictive und formalistic rather than flexible and aduntable, Second, it attempts to define bacteria as such snd phare as guch in term of situationel interactions between phage end bacterium, Thus, a bacterium, as we shall see below, can be sensitive or immune, euphazic or disnhagic towards the same phage in different phases of its life cycle (for example, B towards T2, depending ons hether P his previously been infected with another phage or not, or whether T2 was irradiated with UV, x-rays, etc,), "Situational" definitions are dangerous because they confuse the yeater as to the extent of their vilidity and tend to make the property deseribed apnear as an intrinsic one instead of an interactive one, The best example is that of “virulent” versus “Lemnercte”® phages. The definition of virulent as "absolutely ineapable of lysogenic condition" is bound to collapse in most cases upon thorough search, anc is contrary to the biologically sound presumption that every existant phage is carried lysogenicelly in nature, An exunaple in point is that of phase P2, carried by E, coli lisbonne anc Correre: on the one hand, Pe on sensitive ih, dysenteriae lyses most cells and establishes lysogenesis on a few; on the other hand, the mutant P2hp,, active on &, coli, does not estublish simil.r lysogenesis on this host. The disadvantages intrinaie in any supcosedly ratimal new syston of nomenclature @Y illustrated in the abandonment of the clearly definable, well-established term “lysorenie™ in favor of “merophagic? specific criticisms. 1, the "non-recevtive” term is ambicuous, in view of Garen and Puck's resuits, which show some "resistant" bacteria to be blocked in otep 1 (reversible), some in step = (irreversible adsorvtion). The definition of resistance as fiven in the Syllabus (Viruses 2950) is much mere preferable for the time being, 2, As mentioned under General Comments, the distinction between euphagic, dysphagic, and anaphagic collapses «ithin ihe course of infection. Moreover, there seems to be little use for 4 nomenclature according to which a bacterium is suphagie for Th, dysphagic for UV-TA and immune (anaphagic 7?) for A-rayed T4, Similar objections can be raised concerning B + T5 in absence of Ca++, These evomples 4llustrate better than words the pitfalls of « method based on designing the reactants in term of the end results of one specific reaction, 3, The supposed correlation between UV sensitivity anc virulence or tenpersnce of phages (footnote 3), based apparently on two cuses, does not hold for the phages Pl, P2, P3 of iB, coli Lisb, end barr. They are about as UV sensitive as Th, See also Genera] Comments on "virulence and temperance," he be 6. The admission made in footnote 4 negates by itself the pr:sumed absolute nature of the distinction between "virulent" and “temperate” phage. uhere would a case be placed, in which a bueterium permits the develonment Lut not the fuli mituration of a phige? Such cases exist in Luria and liuman's work on B/4 mutants end are cuoted to show how @ nomerncluture of this type is restrictive rtoer than heuristic, he abbreviation system is probably the most dangerous aspect of the proposs1, since it is the one most likely, if used in forth- coming srench publications, to generite long years of confusion. (a) The fact that any "virulent" phage is likely to be ultin.tely found to be “hemperate” will cause chenges in nomeneluture, whose dangers are vell known to geneticists (see then ~ 45 T1-T2 confusion), (b} The capital vs, lower case systan is inapplicable to rumbers and to several Greek letters, «without generating confusion. (ce) The princinle of genelic nomenclabure, by whieh the symbol should as far as possible deseribe the cenotype ratucr than the previous history of an organism, is openly flouted in the proposed nomonclature for the bacterial hosts. (4) Priorities, Like that of usirg parentheses for Lysorerjecclly carried phages (see sillian Smith, d. Gen, Microbe, 52458, : wy a Hf - neo vethhs , and Bertani, 7.1.5, #6) are disregarded without reason. we are more opposed to the proposul for abbrevitions, especially insofar as it concerns vhages, than to the nomenclature itself, which is likely to fade axay in any exse, like most restrictive systens of definitions.