NBME 21 Flagellin (NBME Answers)

NBME 21 Answers

nbme21/Block 1/Question#3 (reveal difficulty score)
An investigator is studying the efficacy of ...
Flagellin 🔍 / 📺 / 🌳
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+33
submitted by ∗hyoscyamine(58),

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AF .7p23g. uaSmuqos llec macoiacnr osrucc in hte rupep 23/ fo hugeosasp esrweah cnoiamanodacer ccurso ni the dtlasi .3/1 cSeni this wsa ni teh imd gsespahou, its aosuusqm elcl icr.conmaa eyK tfraeeu fo uasuomqs elcl airnoaccm si ekriant sarep.l

+24
submitted by ∗cantaloupe5(85),

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aClusrap yasardlcechpoi ivecncsa are fenot ugctodenja to trnespoi ot rpieovm mnmi.tguyinocie elnlliaFg is hte lnoy rwaens ehcico ttsa'h a oientr.p

mambaforstep both MHC 1 and 2 are present antigens that are PROTEINS (FA 2019 pg 100). so in order to elicit a T cell response, you need a protein (CANT BE A POLYSACC). that is why vaccines for polysaccaride antigens are often conjugated to PROTEINs--> so that we can elicit a T-cell response (FA 2019 pg 127). +7

lovebug Flagellum = Protein, (FA19, pg.124) +1

+5
submitted by ∗wasabilateral(45),

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I nihtk tehy twan uyo to itkhn uabot ohw tjcaunego ncaiecv is emad: socicpahlrdaey + nipoetr ertmngfa ot( nucedi T tenpended enimmu )esrsnpoe. Onyl gallefinl si a trioenp o(r at letsa snudos lkie )noe in eht niotop t.lis

vi_capsule Flagellum is protein. Pilli/Fimbriae - GLycoprotein +4

+5
submitted by enbeemee(12),

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i get hyw i'ts llngl,aefi tbu si het sicpicef nsroae ttah PLS is rwogn is bseacue 'tsi tsju tno owh teh cavncei si ma?ed PLS uowld olas iltcei an uimenm ciatnr,eo gri?th

nor16 Lipid A of LPS can be sensed by CD14 of macrophages causing shock, its not a protein, so no immune reaction as in vaccination (humoral, IgG class switch via Th2 and B Cells). +4

eclipse actually they do use LPS as adjuvant in vaccines +3

hyperfukus TLRs recognize common motifs called pathogen-associated molecular pattern (PAMP) in bacteria, fungi, viruses, and other pathogens. TLR signaling in the modulation of innate immunity + adaptive immunity against pathogens, TLR agonists: CpG-DNA, flagellin, and lipid became essential candidates of effective+safe vaccine adjuvants. TLR agonists improve the efficacy of vaccine, reducing TCR-based selection thresholds and enhancing the magnitude and quality of memory T-cell response. +5

hyperfukus some extra info in case they ask another annoying q +4

aturner713 Not sure if this matters for this or not, but Neisseria spp. have lipoOLIGOsaccharide (LOS) and not lipoPOLYsaccharide (LPS) +5

schep I don't understand why LPS couldn't be the answer also. UWorld question ID 45 specifically says that they are using LPS as a conjugate +1

jp1003 I think it's because Neisseria does have LPS. They have LOS instead. +2

jp1003 *does not have LPS +2

thrawn Doesnt matter - we dont necessarily inject the same specie LOS/LPS in a vaccine - anything to make the immune system wake up to a threat +1

an1 The term lipooligosaccharide ("LOS") is used to refer to a low-molecular-weight form of bacterial lipopolysaccharides. But injecting LPS will induce shock and the 'ENDOTOXIN" cascade mentioned in FA +1