4 nowrt of L&s. Avery r;xL EurtitiLll (tLasitited by l&s. ~am&Binkley, Curnen, Goub~l, t;:cCtrty, iuiirick, Ptirlm;n, stillmi;n, anti Ziegler). Ltu:.y on the chemicnl n;.ture of the subtitcnce iniUCing tranuformti- tion of buucific types of 0neumococcus (Avery LLr-iC dcC;kzty). i3iologie ts, es- ptrci&lly the gcn6ticists, h&vo long sttempte:'l by cher,Lc;i mans to inc;uce in higher organisms prec.ict;,51e &ni specific chagcs which thereafter coulli be transmit&C in tierics trs herutiittiry charzturs. Among microorg#.nisms the most titriking anC yurftips the only known ex;.wplo of inhcrittiblc nnci specific iLt2r~tion0 in c&l structure tini! i'unct.ion thc+t cxn be tixperimtint2lly inoucod LnG thr.t ix3 ruyrowt:i.Llt-t uniter ViCll wfinw tnd &quLtel;r controlicc. con- c.itionr; is the trtnsforolltion of spcifis typis of' Pneumococcuti. This phen- o&r&n w&;i first c.c:;cribal ij;{ Griffith who ~UCC~~I.CC: in irr~.nsforning tin sttonul;Lcc! and nun-onclysuLtc;c (1,) v:.ri::nt tleriv& from une sp,scific tyde into fully enct..ytiulhtti(? LnL. virult;nt (b) cells of i. hzterclogbus specific type of Amuwcoccus. H typiccl instr;nce will buffice to illusLrr.te the ttichniques: origirally used mci serve to incAiwta tho wide vcziety of Was- formations thut iire possible within the &ctqritil species. For example, Griffith found that mice injectad s&cutaneously with c small &mount.of a living & culture aerivsci frun i?neumococcus Type II together with L: large inoculum of heart kill& l'ype III (S) cells frequently succumbed to infection an& thcrt heat'& blood of these wlimuls yiol&d Type III p%nococci in pure' culture. The fat th&t the ri s&An W(LI #*virulent tnci incapable by itself of c&using fcrtal septicemia und the ncUtionc1 fact that the ho&ted suspen- sion of Type III cells cc,ntsin& no vitible orgclniums brought convincing evicance thtit the H forms &Towing uncer these cofiditions herd newly acquired the cc+suLr abructure ani; biA&cul spcfficity of Type III yneumococci. 1 ! i boyunc suggesting that the cie~*c: btictcria in the inoculum might furui%b SOIIE s+cific prutein thot encbles the ii forms to manuf6cturc ii capsulr;r CC&W- hyar;Ptc of t hc same sgecific type LS thz.t of the 3 cells which sorve~ ~p3 initi:.i LLUYZ~ of th*; incucing subs'vilnca. i,ithough the ex+rirn~nt~ in mice: VJCZ'~ succosjlful, Griffith ~8 un&bib to r'bprucuco the ghe:numt;ndn withuut muse p,bSSJ~ge Lno on the: 'bzsis of nrgc-tivc results conciuucci that incu'aticn of the h&tc?rial mixture in vitrb failtld to iniuca tr:.nsf3rm:itii)n. -- Those vrigirlL.l cb;crv:Atibns v:ere Lter confirmed by i~eufcld hnd Levinthci JX-...a~. ano by L'r..rtson ano ailcway in this labcrr;Lry. subsequent- ly bi wbn WLY the first t u succecti in incucing transf~,rmation in vitro. This -- he acc~mplishu~ by grdiing h ctills in ti fluiL moiium containing tLnti-ri sorum I*nci hci.t iriiluu cnci:ysti:,too ;i colis. in the: test tube I*Y in the aniutal &ooy hc sr~cvfeci that trJ+nsftirmation c&n bo solcctively uetormincd c+enuing bn the ty,~a specificity of the ti cells ubed in the reacting system. Later aliovuy was Lblt? t \: c&use bpctcific trkcsformLtion in vitro using sterile -- oxtriLcts sf rj cells frum which ~~11 form& elements and celiular debris had been rcwva~ by Btirkefeld filtrtltion, He thus showed t&t crtie exticucts con- taining the &CtiVd materilil in soluble formclre effective, intiucing the SkUW specific trtineformationu as do the intact cells from which the extracts were The pessnt report is cuncurnec with a m&o wtuilod analysis of this #onUmen\m. c)ur mt+jor interest hr;o centored in attempts tu isol&te the ilctivc princi& from crutie oxtrc&cts c.no to itientify if Ixissibie its chcmictl nature d at least tu chtLractoriz0 it ~;s belonging to ;i gonoral. @oUp of PJnorm chtjmicdl subst;inces. For purpose jf study, the typical exrqle of trLnsform;tion cho,stin L;S t vrbrking mvuol WAS the roncting system with which 145 we hl+ve hi,&a most experience ;.na which consequently seem& best uuitea t'or further knnlysis. T!,is pi.rticuler ex;z&e retiresents the trLnsformc;tion of Type II to 'i'yG;e III ~neumococcus through the intermekzy K form. E'..ch constituent of the ret.cting system grescnteti probioms which requirea clui- :. Y f'ic&tion before it wtAs gossibiti to obkin consistent tinc. rcprociucible re- suits. The various comgontint:, ot' the system will Lx briufiy c;iscusbei; in the foilwing ox-tier: 1) Lulture mtiium; 2) 'i'he n-strain; 3) Yiepr:tion of trLns:`orming extracts of Type III cells; 4) Purification of the active mttcrihlj 5) ChemicLl nt,ture ;:na biologic[A 4,ctivity of the $rifiod sub- iulture meaium: 'i'ho z-sic mkium convists of' the sttinc~rd nei;t infusion oro'uh routinely uscc. in th: cultivttion of gneumococci. Girlier stuaies ruvutlec; chtt in oracr to oi?ii,in trknsform:;tton it is neccssar;J to ~,cti buruiil to th:: &sic moaiu:;,. Hnti-11 ri.bbit :;erm ws usoa in tho first succussful experiments in vitro. -- it satin bcci.:mc ttviacnt, hoaovcr, t1Lt the ei'factiveriess of aiffsrent lots of ~rum vLri8u i;nci tktilt the cifferencos observe6 were not nocusskrily deyenaent upon the content of H untit%lies, since winy 8era of high titer were fcsund to be inca;wblc of supporting trbnsfcrfition. This suggestou t&t f&ctor& other thkn H antibodies ~8 involvoa in the system. I&cLoti first showed t&t trcrk from various r&ma1 species ir- rtisductive of their immune jzopertios, &nd inaeed norraul sera of divarse 11 (" origin cat&n tn enzyue.ccrt>nble of uetitrciying tho k&n&forming principle in 1 potent extracts. (The na.ture of this enzyme cnti the spucific ~Ubtitrabe Upon which it acts vrill bc referred to later in this ra&rt). It w~is found t&t this enzyme w~is intictiv;ltod by heating the serum ht 600-65%. and k&t tiera urcviously heated tt tcmger~.turoo known to destrtiy thci enzyme were then 'or&h conttiining Type II LLntissrum for 36 serial pssugca and isolating the h w&at thuu intruced. The strtiin (~36H) iw lost the type-asecific chwac- tcribtics of tho parent culture anti conuists only of tttenuuted, non-crimp- suiikiGt% h ceilu. The chmge S+ri is often u ruverrsible one, provided the ri celis LTB not too fkr %iegrsded8t. Tht: reversion of the h form to it6 ori&niii s-pecific t;rpv my i!requmtly be axom@ished by buccestjivr: ani.m.1 p.sstt~cs vr by repcatud growth in anti-h serum. Under these ca&itions, hopaver, the ri cuitura ixm;ric&~ rr)verta to thti saae s+cific type i;ti thut frolii wnich it WE clerivc%. ;itr&in rt36~ h&b tmxme rci&tively fixeti in the ft phLcbe encl bus never been i'wnc to revert spontaneously to tho Type II S i'wm. . i . II!+7 1 u C;onversion oi 3--$ r( ;>.nt.. vice vers?. within the liaits of L given t/>e is quite i. c.,if`fsrent iai.tter thdl 1 `Y the tr::nd'orrstion of orgmisms Of one specific type into those of ,nother specific type. `i'hc Ltter hi;s never ueen o!jjbbri'eL to occur stjont;deousiy ant; inc.t?ec. cm iw incuced exyerirtien thlly otllj' by Liie specii.1 tcchniqut2s outlinei~ emlier in this report. Uncrcr these contiitions, Lhe enzimtic s:.Tthesis of L chedcdly atid irnnunologicdLy c.il'r'srel;t ci;+u~iir >oljmcch~d-icle is sp2cificallf oricnteu mu selectively c~terwined c;eperdi.n& on the tfge tigecificity of the L cells used ns the source of' the trtnsforming drincigie. Tn thr? course of Lhc present stuuy it was notm thtit the btock CULLLU~ 01' 1~36 on Sbri:i:L trxnsf'er s in blo;3<: broth udergoes SgOnthneOUS ai~~~,(:ii.t.im ami givsti rise to i nwlber of other ii vl:ri;nts uhic;h can be c:isG.l?&bhm one from anti iher cl;' codmy i'orm. The significCj.nce of this in the &tsarlt instmce lies in the r';ct tbt of L, uifferunt v&ritints iboic*ted l'ro111 the G&rent cuLture only one strdn, Lesignbteb h3bi, is susceytiblc to the tr;ntiLorrning bction of potent extrc;icts, whlie the others Laiied to rebycm2 tncl htrve since rcinainec inactive in this regard. `l'he knowledge of Ufferences In the responsiveness or' Different h vwiants to the same spep- ific stimulus emphasizes the cbre th&t mutrt be exercised in the'selection of ti aui%bie ti variant for use in trrnaformetion experiments. Although the significance of the following fact will become apparent later on, it must be mentioned here that pneumococcctl cells possess an enzyme cs*ble of destroying the rsctivity of transforming extracts. In- deed, ciutolysetes of d36~ we highly active in this respect. EArlier workers found thut it is essential to use u s;ntili inoculunt of young md rcctively ero.wing ir cultures in trtnsformtltion tests. This rtquirement m&y berit be ex- yltiineti on the t;bsumption th;t when l&rge inoculti irre used encrugh enzyme my be relzs:sed bj' autolysis to inactivate the tk-aforming principle present in / 148 thr? system. i+cwrttion of tr&nsforminE extracts fiord Two III 0neUGoCocCi: The prustz~t 1:rcthod of prspr;ration of extracts from yneumococc&l cells rep%- SorrtS tht3 and r~sulss of nurirarous axperinontr;. .: t+pror;ches ckrried out over i yariod c;f yazs. The proccdurtiti usud in uxtrirction Lna +rii'icrticrn hrrve been evolvd gr;,duily L:, evkunce ht& Lean rjbkinod concerning the nsture tnti pro+rti.i'b of the c.ctivu SU'bSti.IlCf:. FJi2a III colib i.rti i;rown in ic*rgc qzntitios (50-75 liters) i..nd ccGit;cteo by c;ontrifuC;kti~n in (. ~,t,titt~ arivan ;Ih,q.Lk;s cc;ntrit`ugti. The mkteriirl incurrac; in the VJWhing ~rcjcess is slight cotlparcd to the @lrificc;- { i , tiun r;chieveu. 'Ihe vrrrshtid calls; &ro then extrc;cte$ twice by shaking in Saline con"&ining 0.5 pr oont souium deuoxychtilrzto. Extracts yrtqared in *his manner tifter remcrval crf the doeoxychol~te by &lcohol CuntcLin the major por- tion of the'active princi&.e titi~metsurer: by their c&p&city to in&we trans- r'oriwtitin. . i [ i 1 l?urifict:tiun pi' tictivo Yubtii&ncc: nqrecipi.ttLtion of the cru&o i oxtrtrct with 4 vcjluws tf alcoh~rl flocigitatorr the uctSve mcWri&l L&A re- . wvas the last trtLcbb of dttsowclGktrJ vrhich rewin soluble in the t;lctihc;l. 'I'hs t)l'ecigitute is rouiuwivod in btiino rAnti the grctit buik tif ;Jrutein is i bicillus captlble of dcconpoving 'i'y~ III polysaccharide is then employed 8 5 f j tti digest the ctipsular pulysaccharide remaining in the extract. After di- gesti;n of' ctpsulur pdySECCh~iriW3 is c~npletec! 68 c,etormincd by loss tif reactivity vrith Ty+ III Lntib0dy klutL>n, the cxtrcl.ct is &g&in tr&.ted by the bcvq metha to rcmovc the enzyme grotoin ;.nd any remaining pneu- mococccJ protein. This pr~ccss is rcyeatud until the sugernattnt fails to give the biuret reaction. The finril ate2 in prificatiou iti the reieated peciLAkti.on of the extract by the drop&e aiolysacchr,rido together with t`ne somrLtic C carb&ydrate, ribs- nucleic acid and remaining traces of protein t.re loft in the residue. nfter several repecipitatiuns, the material is finally aissulved in distilled water and Dialyzed against distilled water to remove free stilts and other ciiffusible substances. Chemical nature and biologic&l activity of the mrif%& &ubH&nce: In tho oourse of chemical fractionation of active marteritrl it WCS reyeatedly found th&t biological activity was always aseociatad with that frkctlon which gave a strongly positive reaction in the diphewlwnine test, sugge8ting that the active substance might be &esoxyribonucleic acid (tbyztu8 ty+). Further evidence for this view was found on elementary analysis of several preprations isolated by the .pocedures outlined above. In the following table analytical figures on two highly purified prepartitions are compared with the theoretical values for the sodium salt of deso-xyribonuclei~ rcid on the basis of the totrtinucleotiue structure of the mdocule. Theory for des~x~- i5i, Yreslirttion A(37 i?re&ration rir42 ribotetranucleotide phoadhorous 8.57 per cent 9.U4 tier cent 9.05 per cent Nitrcr;i'on U.21 ,*r cent 15.36 per cent 15.32 per, cent N/P ratio 1.66 1.69 1.69 , Carbon 34.27 ;rcr cent 35.50 pr cent 34.20 ller cent Hydrogen 3.89 tJer cent 3.76 lxr cent 3.21 tier cent ' tect frorJ theory. These figures by thclmaclvcs co not establish that the substw~~ isolirted is t @rc chemictil entity. However, on the basis of the h/p rirtio it WUUh hype&r th:,t littlo prutt;in c)r other substances containing r&tia ~ulcl be conoiuerz&Ay altered. l)n enzyWtic an&lysio of the active tiatorial it was found that crystalline tql2sin or cmotrydsin ant! combinutirms'of both causad no atipruciob10 1os.s in cicti.vitiJ. Moreover, digestion with crystalline ribo- nucloase duos not iq+ir biological rctivity. Amung various crude 2re+ra- tions of enz;yoles derived from sciurces such as bone, kidney, ~eum~cocccrl cells, pancretitin and'uerit only thuse which atttsck authentic ssPryle8 of desoxyrihonucleic acid have been.found to cause w Getecttble loss in thu activity of potent peprations of the transforming princi&~. This Ah . . _' further evitience of the chemical relationship suggested bjr the analytical figures ubve. Preliminary inveotigatiuns in collaboration with Dr.T Rothen irLict;te that the substince in highly purified form is ;Jrc)&Itiiy highly &ymerizcsd anti has a nol,ecuLr weight of ~~iJjmxc~tely 0.5 - 1 million. Uther stuuies of the &pica1 chemical pru,Jerties of the active substance ure now in progress. St clhould also be pointed out that as the crude extracts are puri- fied, serological activity with Type III antiserum progressively deoreasee. Solution6 of the purified substance itself give only faint trace reaction6 with high titer Type III antipneumococcus rabbit serum. In view of the fact that the Type III capsular polysacchsride and the somatic C carbohydrate react with homologous antisera in &ilutions as high tis 1 ytrt in 5 million, this loss of bcrologicel activity reflects the almost complete removql of all sorologic&liy reactive substances from the final preparations. The fuct th&t the transforming substance in purified skte 8x- hibits iittle or no immunological reactivity is in titriking contrbet to its biologi&i function in inducing highly specific changes in living pnoutno- cocci1 cells. ke little as 0.02 clgr., representing a final dilution in the reacting system of 1 prt in 1oO,OOO,OOO has sufficed to bring about the trtinsformcition of tho b variant (H36k) into un~qsulirtcd Type III pneumococci. Assuming thLt the sodium desoxyribonuclefc acid and the active principle are one irnd the sqne substr;nca, thon the trun+formation frpm H--)SIII represents a change that is chemically induced anti specifically direoted hy a known chemical compound. Lloroover, this substsnco selectively determines a differentiation of cellular function and structUre corresponding in type to that of the 8 organisms from which the agent was derived; The interaction between the R cell and the transforming principle initiatoa a series of complex reactions which c&ninate in the synthesis of the Type III capsular polysaccharide. Thus, the transforming principle - a nucleic acid - and the end product of the synthesis it evokes - the Type III pcrlysnccharicie - are each chemici;lly distinct and both ark requisite in the type specific differentiation of the ceil of which they form a psrt. The.former has been likened tu a gene, the latter to a gene product, the accession of which is mediated thruugh enzymatic synthesis. The go&tic interpretation of this L 1% phenomenon is supported by the fact thzLt once trhnaformttion is induced, theretifter without further addition of the inciting agent both capsule forma- tion Lnd the gene-like substance are reduplicated in the daughter cells. The ci,cnges inuuced are therefore not bansient nooific&tions but c;re +a transmitted through innumerable trcnsfers in ordinary cuiture media. , Ii' the present studies are confirmed and the biologically active substance isolated in highly purified form L;S the sodium salt of dcsoxy- ribonucleic acid actually proves to be the transforming principle, ati the avhiltble evidence now suggests, than nucleic acids of this type must be rogttrood not merely as structurally important but as functionally active in determining the biochomicol activities and specific ch&ractcristics of pneumococcul cells. Leathes has pointed out that in the chemical make up of proto- . plasm proteins are not the only essentiz.1 s?Jbstsnces. Among the other con- stituents he ranks the nucleic acids ts preeminent, and reforring to their occurrence as major comp&onts of nuclear chromcrsomes he raises the question "whether the virtuas of nucleic acids may not rival the amino acid chains e. in their vital importance." . btwiies on nrimay t;t~icUl DIMBIW~~~ (Horsfall, Curnen, Mirick, and Ziegler). In 1930 it was first recugnised cletily that there &fisted L common clinic&l form of yneumuniu which differed from.the usual bacterial * pneumonias. In the intcxvenirg yetas this illness, nuw termed "priapary ktypical,pneumonian, has been encountered with incretising frequency. Inter- est in the condition stems frcru the-ftats tb:t it is, L;t tho present time, about as often seen as is birctrjrial pneumonic tend that the cause .or ~8~808 of it hbvo not been definitely oslxblished. Thore is good reason to believe that thiv clinical syndrome lo 153 not a new disease. It W&8 probablg recognised OCCa8iOlMd~ during the 8OC- ond half of the last century and undoubtedly was observed not infrequently 8 during each of the first three decacres of this century. `l'he recent marke& increase in the use of the x-ray in acute reb&%tory aiseaties, the establishment of active full-time heaith units in some schools, colleges and camps and the ineffectiveness of sulfonamide chemotherapy in the illness seem to have been the most important factOr in bringing this syndrome into c+zar relief. There can `be no doubt that this condition, ciuring the past three . years, has been incret;oing in incioencs more r&pidly than can be accounted for on the basis merely of increased Lwareness and recognition of it by physicians. In certr;in Army camps in the continental United titates the incidence of the illness has been GS high ati 1.3 per cent of the total commana. It is recognized both bjr the hrmy end the Navy as res~nsible for T[rore mtm-days lost from duty thun almost my other acute infectious disease. The frequency with which the illness occurs r;Idong civiliana cannot now be estimated due to the fact that, with the exception only of New York City, the disease is not reportable. Almost all investigators who have studied ctr8ek of primary criiypiosl. pneumonia think that the illness Lo not the result of bacterial. infection. / &me workm8 have &uggeoted the pss$bility that the syndrome was caused hq e a virus and as a result the term %irus pneumonia" has come into conmon ,' U8ii@. There is cviaence that the syndrome is not a singlo disease en- tity. At lelist three different infectious agents have such been shown to be otiologically reli+tod to certain small groups of ~0~8. Those arc the i.WithCOSiS group of viruses, Hickettsia di:iRoriCa, and & viru8 infG&ticu8 . 154 for the mongoom. &iditiont;l infectious ogbnts have bcon suggested LB posscbsing ;r CLUX,~ r&&tionship to other c&se3 although the evitience upon which th&c; suggestions hLve been 'b~iscd scdm8 insufficient to Frmit of crl.*,Ackl assousment. thio hirspitcrl one ytxz &go. The primary objoctivcs of the study were two- fcrld; firstly, t dsttiiled tituay of all the clinic&l manifuatutions of the iU.neus, &nd secondly, an investig&tion of the nrcture of the infectious egunts reeponsiblo for'thc ayndromc. During this year 112 patients .wero &droittod tc, this hospittil with auto respiratory dibeirses. Of these pktiento 80 wtxc found to lava primzy atypical pneumtinilr. Specimens obtained from thbbe ijutient3 cunstituted the ~mrct: mtori&l fur the l&borLitory 8tUdie8~ - In uaiitim, syticimms wart ~leo obthined from 511 pf.ti~nts with the syn- drmo in other ha@tuls, hth civil&n Lnd military. nil trpecinens have J been stxed at -70%. mc consequently ure c~n3tantly available for bttiy. This large Library of ptitcntially infectious SVUTCB W~tcrial ha3 blI%aCy proven cd grunt value. The Laboratory stu&ie,s were faci.litated Iy fund8 ovrde uvrrilable through G contract b3~weea the ciffice of Mientific tieSearCh and Deve+p- ment tnd The Htickefellcr Institute. Comylete laboratories and animal quart- er3 SUitible for the Vtudy of Virus di&8aS88 were f&tted GUt Wld t@Ed.&~ equipped for this investigntiofi. kdditimrrl technic% iresisbnts were ., engtgso. . (;lini.cr;l studies. As ii result of the detailed studies of 80 patients vfith @mry L;typ.ic&i pneumcinis it WLY possible to forimll.ato a f&irly ticcur&tc clinical piCtIII?e of the syndrrjras. The illnass ciffered strikingiy frum thu bttctorial @neumonins. The clinictil hfst&y, pwtlic~l b 0 examination, chest x-ray, hnd clinicei course had hut little in common with those encountered in the bacterkl pneumonias. The most common finding6 were fever, rel;rtive bradycnrdia, cough, headache, blight tlterntion in the phys- ictrl signs over the chest, d.ef initt x-r&y evicence of consolidk tion, a norral luucocyte count und normA urine. Four chaructarivtic observations were common; (1) tht: patient selaom ayge~rou ;rb ii1 ab the: chut would lend one tc expect, (2) the gul, se rctf.2 wt~s s~ldor:~ i:s rrcpio (:s the temperature wouiu incfikte, (3) the &r;icti cxkLline.tion r&rely suggested thitt conboli- Ltion ~1' the extent dcmoraLrt'ole by x-ri.y WLIS prcsc)nt, hnd (4) the clinical sovurit;r of the illness w&s ofton unrel&tai tu tho extent of puinmnriry in- volvaent. hn knaiybis of the clinic:..1 dak reveCloci the f ollcwing cvorirge fiaiings; i'cver $erbidtc?c for 10 (iCAys :,nd Wiichad 103.50F., the- pulse rrzte was 23 beats por r&nub sluwur tha the tempaature inciict$ed, thu retlpira- tory rtte wi.8 25 *r minute, lacocytta aere,7,800 per cu. ma. md the . erythrocyte sedimcnktion r;Lte W&Y 38 mm. pur hour. In 75 per cent of ins;taces the consolidation occurred in the lower lobes, tnd more cowreonly on the left thm the right side. In 70 per cent of instances only one lobe was consolidated. LVldence of beginning rosoiution of the pneumonic process could be discerned by x-r&y on the 10th tiy but complete resolution did not vccur until the 17th c&y. CLmpILications were uncommon, although recrudes- ceqcc or' fever ffcs not infrequent. Either extoncian of the cmsuiicktim or recurrence of it uccurred in sWati ckeeb. Pleuritis associated with small collections or` i'luid anti a mild fbrm bf meningismus, or transient encephalitis, cl*ch occurred in &+ut 5 per cznt of cases. Slight splenomegaly, arthrtclgia and tranbi,mt Clttz&tias in the electrocarcii~grc wore each ftiunii in, &me CEsab. This group of unus~l $hcnaena ir;d to the h;'p&hesis th;Lt the ti.,n. c,uiI',m.dib~ chal;iothorr;py seened nut to ;;ltor the clinical course of the illness. The wrtelity rtto was zero. fLchenicr+l studies w yrimry atypical pneumonia (B&son, Haag- ltnd, Curnon, tiirick and Ziegler). Through the cGoporution of other services in the hoa&tal numertius biochemical stuoios were ccirricd out on aolectod p;ltients. It was found that tho icteric indicts, prothrcmbin lavels, serum CC, and serum chloride levels wore within normal limits. Plasma carotene anti vitamin A lt~els were reduced but only to an extant commonly encountered in many other tcute infectious diseases as well. Plasma 2 amino acfds urre within nurmal limits and chloride balance studios inAcr,t.eG that there was no striking abnormality in chloride metabolism. These latter findings are notliworthy since they serve uuditianclly to cifferenticte this syndrome from those associated with the bacteritl pneumonits. As is well known, the plasma g amino acid levels are Gofinitely roducod in bacterial pneumonia and chloritie metabolism is distinctly abnormal in moot cases. Bacteriological studies on nrimary atydcal cnewnia+ (Curnen, Mirick, Ziegler, &cl McCarty). The bacterial flora of the nose, throat and sputum was studied in each case and an effort was made'to obtain both quali- dative and qu&itative data. The sputa usually contained relatively few btLct;eria and in no instance was it possible to determine the type of pneu- mococcus by the direct Quellung technique. &waver, by mouse inoculation one or another type of pneumococcus was obtained from 60 per cent of the sputa. It is noteworthy that neither Type I nor Type II Pneumococcus was isolated. The clistribution of pneumococcuo types was not dissimilar to that which has boen found in the throats of healthy individuals. & hemolytic strqptococci, hemolytic staphylococci and Ii. influenzae, though occasionally i57 found were nut encountered with suffi'cient frequency or in numbers sufficient to make them seem of etiological significance. None of the strains of fl` influenzae isolatti were smooth and none could be typed. Numerous other species of bacterial micro-organisms were also isolated from specimens ob- twined from the respiratory tracts of patients. All of these organism8 are known to be present commonly in the upper respiratory tract of healtw persons. in no instance was any evidence obtained which suggested that any of tha bucterial species isolated/were causally related to the illness. Blood cultures were done on alb patients and none showed bxterial growth. tioruover, pleural fluid and cerebrospinal fluid obtained from patients faiieci to revetl the presence of btrctoria on culture. Sorologicol studies on nrimary atypical mewnonia (Horsfall, Thorms, Curnon, rilirick and Ziegler). Acute phase tilxi convalescent 8erb from patients were tested for the presence of antibodios against a numbor of viruses known to be caprble'of inciting acute respiratory disease in human beings. The agents selected for those tests were, psittacosis virus, lymphocytic choriomeningiiis virus, influenza A virus, influenza B virus and swine influenza virus. In no instance was a significant increase in specPfic antibodies against any of theve viruses demonstrable during convalescence of patients admitted to this hospital. Acute phase and convalescent sera from patients were also teeted for the presence of the so-called C reactive protein. It will be,recalled a that notcrbly in pnmmococcus pnmnonie but also In other acute infectious diseases there is present in the serum Wring the acute phase of the ill- ness an abnormal protein which has the peculiar property of reacting with the C or somatic polysaccharicie of pneumococcus to form TV precipitate. It was found that this protein was almost invariably present in the acute 1 phase sera of patients with primly atypical pneumonia and t&t it disl;ppeared during early convalescence. In the course of certain serological tests a peculiar and unex- pected phenomenon was encountered. It was found thz.t approximately 35 per cent of yatiants with primary atypical pneumonic cevelopcd in their S~IWII during early convalescence the caLyt.city to fi,x complement with a wide variety of apparently unrelated antigens. The cunvclesccnt serum in high dilution of some patients ratcted with many of those untiguns cLlthough the &cute p&se serum from the same patients did not. Similar reactions were not observed when convalescent serc from other acute infectious diseases, either of bac- terial or virus etiology, wr6 tested. The reaction could bo domunstratad with antigens prcparec. frc;m a vcriaty of organs obtuined from L number of unreltited species ant it is not yet apparent what cr;mpcnent common to these antigens m&y cxylitin the yhenomcnun. In general, tissues infectec with one tir kinither virus provkod mtire cctive antigens tin dia normal tiasuesi This ghcnomenon seriously complicates tho interprut+tLn of complement fixa- tion tests in this sync&me. aoraover, it serves.to cast s&me ti.oubt on the significance of certain studies which have been based wholly or largely upon the results obtiined rith the complement fixation technique in this illness. Etiolonical studies on nrimary atynical nneumoni.8 (Horsfall, C-en, Miriok, Thomas, Ziegler). Specimens of sputum, throat washings, plasma, pleural fluid and cerebra-spinal fluid obtained during the acute phase of ilhese from a number of patients with prm atypic& pneumonia were testsd for the presence of infectious agents. In numerous instances .these specimens were inoculated in mice, guinea-pigs, hamsters, rabbits, cotton rats, white rets, hooded rats and monkeys by a variety of routes incluciing the intranasal, intrutracheal, intraperitoneal, intravenous, sub- cutaneous and intracerebral. Many specimens were also inoculated in chick- embryos of various ages by the following routes; intra-. i5'3 allantoic, intraamniotic, and on the chorio-allantoic membrane. berial passages were carried out in all species with the exception of monkeys. In no instance were obvious signs of infection produced which could be repro- duced on transmission in -series. Indeed in only two of 21 sputa tested w&s pulmonary consolidation grociuced repe&tedly in cotton rcrts following prim- ury intrtlnasai inocuilition. However, it wu8 not possible :n either insknce to reproduce this lesion on serial passage in this species 'despite r%ny varittions in experiment&l procedure. Although no obvious signs of infection, trsnsmissible in series, were encountered in eny of the species tested, it wus diocovertid that ani- ~1s inocultted with certain specimens or with p~~usi~ge material derived from thetie specimen s subsequently developed in their serum, tintibodies which vrem ccp&ble of specific&lly n3utrcilizing a hetorologous virus. This hetero- logous virus was pruviouvly ehv.vn to be present, though latent, in the lungs of mny apparently healthy mice and hiis been termed "pneumonic, virus of mice". B&uve of this unexpected obsorv&tion that an-18 inoculated with speci- . mens obtained from cusos of priw atypicel pneumonia produced antibodies which completely n+utrsliaod large &mounts of u heterologoua virus derived from the lungs of nrice, the possibility tirose that thare might be in the agent recovered from patients and in the QxwaatonicL vizws of mice" minor common antigens. Moreovar, 3.f such trll stccidental antigenic relation&&p actu&Lly existed, means would become avaLl.able of detecting the presence of the hum&n cigont even though it were not cawble of producing ObVioUS Si@M of infection in &viilable c;;nimcrl ciyecies. This hypothesis has proven fruit- ful hind h&s m&e possible the development of experimental procedures, brrsed . almost entirely upon syacific immunologictil tests, by means of which certcrti charccteristica of the human &gent hkive been defined. Bvidenco has oeen obtained which in&icste& that 15 strclins of & virus hz`ve been recovereii from ssecimeno ob+G&led f'rom a tot&l or" twenty-two tj(Ltienty, TWO CtrhXi WAY? recovered frOti thrO&t-WbhingS, eight f'rOIfl f3,~I.h snti five i'rou citr~tocl pLi.Lsma. sil 15 strbino eppcured to possasb: minor ontigunic components; also prc;aent in the heterologouu pneumonii: virus of mice, hereinkiter rcfbrrecl to t& PVti.. irlthough none of thitso Strains w:rS cap2'bic of proaucing obvious signs of infection on sex%1 pWW.~go in t.ny tnimcl byacie!s tested, neverthclctis, immunologictl tiviclence has been ob- Wined th&t the ugant could bcr pascd in seristi in both chick embryos iind cotton rtts. It could clso be pased stiricilly in chick umbryo solid tissue cUltUre:, was sntigunic for rabbits ana cf.utiod :a inapp;rent infection in I&X?. The virus ws filter&bla ttiough B.?rkcfelG V candles, ciici not lo&e activity c.ftsr storqe c.t -73%. for morz th;a eight months, withstood rq)id freezing Lnci thtiwing 10 tina, and uz..ti in;ctivLted by 56% for 30 minutos. Evidence inciicuting the prcacnce of this &gent in specimens from patients with primary ~~tyyia.1 pneurdonic huu been obt&ined in t vtiriaty of wuys . Cotton ratv wore inoculutud and ri;bbits were injected with sputum, throat-wtiehings, or plas~a~~ from yLtients t+s well GD with a&al or tissuk culture -p&&sags mtericl derived from thob;e sr-pecimena. Sera obtained front theee cmimals before ancI nt interv&ls r+f'tur inoctition were tested for tlie presence of neutrrlizing sntihudies ag;inst PVbi. Mice inoctitud with * eimilr;r specimens were subsequently tasted for active immunity r@wt &I- fection by PW. C)ne of three filtered throat wt;si;ings tested co&&nod an &gent which followi& serial passage in chick abryos WCS cqabls of otimul.&ting the production of trpocific neutrulizing antibodico aglrinst &%I in rsbbits. c)f 15 acute pti;su pti~sraa toetod 5 wore fcund- to con&in tin a&gent which was ,. . c;+b.Le d stimulating the ~rA.xi;i\m of neutralizing mtibodias bgdnut Pild either fd1wi.n~ inir~venous inj6ctJ.a of rtibbit.5 (jr intrkni.stl inocu- ?VIp ited.f it 'rr.,s fcunc; tht:t this virus Liii.;xd.i:toti the prductia uf neu- ~~UUYC virus thun riic; tither dce which ktiru givun the hutuzn iigmt. The quuntitc;tive mcc ternpal ciiff&encorr in the mdfoet~tionti of immunity yY'o- ducod by the&o two viruses intiicuted thtit trhereas they p~sessd,tintigen&~ in comma they were not'antigonicelly iauntic&l. A aumber of etrtiincl uf the hum&n virus were p?daoC in series either in cotton rut lungs or in ChiCK e~&rjws t.a rrell w on the chorio- dluntoic mem'brma ur in tissue culture. E@icrtaco for thu srttsonco uf the agent in pmsup mterid WA ubttinbc; by the c.uaonstrutLn ~f.n~utrdizing This I'inaing ww oT borne interest Yinco it seams prokbla that tha h-n injection itoelr' is trtrnsmissible :.T contirct. ili~t~olc~ictr 1 sections of itli BC tt?ci rb t iUtlEY ;itlti itdec t@d egg uomtxxnes stuiwu by the Giemsc method irncI impression i'iims tit&cd uy the kcchitiveilo or Cirsn method f&ilod to rtses~l the grasace oi' dwtentary aooties, inclusion bwictb, tiLGke%tsitie or bkcterit.. Thtl iuct that +,ho qent recoveroci from current cksc* of primary atypicui pneillrlus antigens are removed. Wien the absorption is cr;lrriLd out with the hetorologous 2 polyssccharide, the homologous antibodies remain and only the hoterologou3 agglutinins and pre- cipitins are removed. kiince these cell froc antigens represent pure or nearly pure chemical entities, $t seems not unlikely that their Wological crossing and that of the organisms from which they ark derived is not cautied by a multiplicity of antigenic constituents but may be rrtbributed to Sin- ilarities in the chemical constitution of the polysaccharide portion of the respective bacterial antigens. Bc hope to eskrblish this hypothesis by more extensive work and tc( explain the immunologiccrl roktionship of the organisms of the Flexner group strictly on the basis of chemical similurities of the type q3ecific antigens. Studies tin the bacterial flora in acute resDiratorv diseases (~tillmnn). In the lnstqanaemic of influenza the high mortality rate was largely due to the frequent occurrence of highly fatul pleumonius caused by pathogenic microorganioms which the mticnt had newly acquired or hap- penod to be carrying ut the time in the upper ruspiratory tract. Those opportunistic pathogens, notably the various typos of influenza bacilli, hemolytic streptococci, and pncumococci, are also frequently found as sectindury invaders in the purulcnt ccmplicttiwls asoociLtcd with the common coid. If infiusnza and tho common cold ;re in fact duo to viruses, it seems not unlikely th.t these primary agents m&y so alter the defense reactions of the patient as tc permit socondirry invasion by microorganisms which can be carried with impunity by the healthy individual for considcrcblo priticifi of time. If this hypothesis is curroct then the Lctorial pneumonias and the suppur&tivo lesions &scribed above must be rogardsc! not as primary disoases but iis scconrisry comiAicutions 03 the initial virus infection. In a study ma& in 1920-21 un the occurrence of ti. influ,,neke - in cuses of Qneumoccccal lobar pneumonia, this organism was WA&ted from 85 per cent of the piiticnts studied. Although homophilic bacilli are only rarely present in nasal cultures from healthy individuals, thuy have been found in similar ckiltures in 23 per cent of cm388 of lohr pnaurwnfa. At the time these studies were made the Uifferentiation between the encapsula- ted (S) and the non-encapwltited (kc) forms of this group of ~giinism had nut 'been recognized and no serological ciassification of specific types h& b&n developea.' When it was found that a large number of patients with atypical (virus) pneumonia also harbor in their nasopharynx H. influenzae our in- terest in this organism was reawakened, particularly since it is now possible by means of immune sera to classify strains into known specific types. Type specific immune sera have been prepared by the immunization of rabbits with strains of H. influensao of known specific types. ii study of the kcterii;l flora; of patients stifering from various mild upper resipir- atory a&eases is being continued with the hope thtt the results may serve us c. 'oxkgrodnd in the event of tin epidemic of rcspir;tory infection of viral origin, complicated by secondaq~ bacterial invasion cs occurred in the last p6.ndernic of influenza. Speck1 attention is directed towtird &he occurrence of type-specific strains of H. infiucnzas. Studies ire now in progress on experimentcl pneumonia induced in mice by the mothod of inhal:Ation which simulates more closely the natuxl pathwzy ol' infection. It h:,s been found that pulmonccry consolidation occtsionclly occurs in mice sprayed vGth H. influonzne followed by inhalation of pnouinococci :.nri cht.t this lesion does not occur v;hen tither organism is usoci clone. Ex+rimonts :.rc being ctrried out to cietk:rmina whether the combinttion of these two orgen,,, terns is the etscntirl fxtor or v;hether in L:ssoci:-tion togcthcr they serve ks a provoct:tive stimuius to the pneumonia virus of mice which is knovm to be htrbored in 1, l&tent statt: by many animals of this species. Publics tions Adams, bn. H., The reaction between the enzyme tyrosinase and its specific antibody, J. Ike. i&d.. 1942, 76, 175. Horsfall, F. L. Jr., The present sttrtus of the influenza problem, J. ml. Me& Assn., 1%2,~, 2&6. Horsfall, F. L. Jr., Human influenza, Cornell University Press, New York, 1942 Horsfall, F. L. Jr., The effect of sulphonunides on vitience of pneumococc$.,. J. Clin. Invest.. 194.2, 21, 647 (abstr.) Horsfal.1, F. L; Jr., Curnon, E. C., Mirick, G. S., Thorn&s, L., t;nci Ziegler, Jr A virW recovered from patients with priory utypic&l pneumonis., SC ienca , 1943, 97, 289. UacLeod, C. a., and PcCarty, ti., Helution of ii somatic factor to virulence of pneur;:ococci, J. Cl&. Invest., 1942, Xl., 647 (zbstr.) o ? ? , 1&+cL00a, C. Ml., ilnii Uirick, G. b., Qu.ntitc;ti.ve tiota!airation of thr? lxzter- iut&tic effect of thi: w.Lfunaii:e drugs on pneumwwxf, J. Net., 1542, d& 277. blirick, G. b., Siocle of action of the s:d@~onc!slide drug6 in vitro, 3'. BiLC'ti.) 1943, 45, 66 (ubutr.). Lirick, C. b., Enzyi:rtitic i&ntifict.tiLin of p-t mint. tvnzoic cdic! (PAa) in cultl.lres of pneumocGccus ;.nil its reLatiun to ~~~~flon~~ni~e-f:stnous, J. (;lin. Iwest.,lY42, Zl., 6~8 (cbstr.) Thaws, l,., Curtlcn, E. C,, dirick, G. k., Zicglcr, J. E., Jr., a-k Horuf;dl, F, L., Jr., Gcrmplemunt fixt&tion with dissimilrsr atigena in primuy atypical pncuwnie, Proc. SW. Ekp. Mol. Mod., 1943, z, 121.