Thep35kDproteinofthespiRocheteborreliaburgdorferiisbeinginvestigatedforuseasanearlydiagnosticMarkerofLymeDisease.Borreliamaychangeitscompositioninitsneedforadaptationtostressesimposedbychangesinconditionsfromcyclingbetweenitsarthropodandmammalianhosts.ThisgroupofB.burgdorferiproteinsmaybeinducedinthetickmidgutduringthefeedingevent.Thep35proteinelicitsaprotectiveimmunityfromwildtypeB.burgdorferi.Ithasbeenshownthatp35expressioninB.burgdorferiisupregulatedinthestationarygrowthphase,andthatatemperatureof34°Cbutnot24°Cinfluencedtheexpression.TheexpressionofamajorityoftheproteinsexpressedinearlyLymediseaseisaffectedpH,beingabundantlyexpressedatpH7.0(resemblingthetickmidgutpHof6.8duringfeeding)butonlysparselyatpH8.0(aconditionclosertothatoftheunfedtickmidgutpHof7.4).Theencodinggenesmaybecoregulated.The35kDhasbeenshowntobeastatisticallysignificantmarkerinIgGimmunoblotsinastudyofpatientswithearlyLymediseasewhopresentedwitherythemamigrans.Recombinantp35proteinmaybeusefulasadiagnosticreagent,especiallyincombinationwithotherantigensthathavebeendeemedrelevantinSEROdiagnosisofearlyLymedisease.