Medical Microbiology

420 8 VirusesasHumanPathogen

lion.Aswithallherpesviruses,thepathogenremainsinthemacroorganism

permanentlyaftertheprimaryinfection.Followingreactivation(endogenous

recidivation),thevirusesfollowthesameroutebacktotheperiphery,where

theycausethefamiliarvesicularexanthem(“feverblisters,”herpeslabialis,

Fig.8. 5 ).Despiteestablishedimmunity,suchrecidivationscanmanifestre-

peatedlybecausetheviruseswanderwithinthenervecellsanddonotenter

Herpesviruses

1 00 nm

a b 200 nm

Fig.8. 4 aWithenvelope,binthenucleusofthehostcell;envelopeformationat

thenuclearmembrane.Thenakedvirionmeasures 100 nmandtheviruswithits

envelopeupto 200 nm.

Herpeslabialis

Fig.8. 5 Followingthein-

itialinfection,herpessim-

plexviruses(HSV)persist

inthelatentstateinnerve

cells of the CNS. When

reactivated, they travel

downtheaxonsofthese

cells to the periphery,

wheretheycausethetypi-

calvesicularexanthem.

8

Kayser, Medical Microbiology © 2005 Thieme