Antibody Responses inRabbits toInjections ofWholeCell, Flagella, andFlagellin Preparations ofCholera andNoncholera Vibrios

Seraprepared bytheinjection ofliving cells, killed cells, flagella, orflagellins ofvibrios intorabbits were examined forantibodies whichcross-reacted with cholera andnoncholera vibrio strains. Antisera to Vibrio cholerae strains agglutinated heterologous V.cholerae strains. Theydidnotagglutinate strains of noncholera vibrios. Seratononcholera strains agglutinated homologous strains only. There was no evidence that a common antigen was present intheorganisms tested. Theproposal for a "cholera groupofvibrios" based upon sharing ofan H antigen between cholera andsome noncholera vibrios isheld asuntenable. Itis indicated, however, thattheuse ofserotyping ofvibrios couldbeusedas an addedtoolforbetter identification ordescription ofvibrios. WhenVibrio cholerae isisolated fromhuman orenvironmental specimens, a considerable responsibility isplaced onhealth officials becauseoflocal, national, andinternational implications. Thelaboratory thatinitiates this process bases identification oftheorganisms on biochemical andserological tests. Sakazaki et al.(3)andmanyothers havenoted thesimilarities inbiochemical tests between various kinds ofvibrios. Forthisreason, thesetests are generally usedmerely toindicate thatthe organism might beV.cholerae. Serological tests areemployed bymostlaboratories asthedefinitivecriterion inidentification. Cholera vibrios agglutinate inthespecific serum; those organismswhichdonotareoften termed"nonagglutinable" (NAG)ornoncholera vibrios (NCV). Sakazaki etal.(4)foundthatserafrom rabbits receiving 25ormoreinjections ofkilled cholera orNAG vibrios cross-reacted withheterologous vibrio strains. Theirworkindicated that acommonflagellar antigen wasresponsible forthereactions. Onthisbasis, itwasrecommendedthatvibrios withbiochemical reactions described bySakazaki etal.(3)whichwere motile should beplaced inasingle species, V. cholerae. Further differentiation wouldbe based onserotyping of0 antigens. SmithandGoodner (5), intheir methodfor serotyping NCV,usedlive organisms asinocula forrabbits andlive organisms asagglutinogens intesting thesera.A single injection-single bleed method wasusedtoprepare thesera.No mention ofcross-reactions wasmadebythese authors. Because thepresence orabsence ofacommon flagellar antigen hasepidemiologic aswellas taxonomic importance, studies wereconducted toseekanexplanation forthedivergent results obtained bythetwogroups ofworkers.