Effects on exocytosis by two HSV-1 mutants unable to block autophagy.Herpes simplex virus 1 (HSV-1) is a prominent human pathogen that manipulates host responses to support the infection.  HSV-1 infection triggers an increased release of extracellular vesicles (EVs) through the CD63 biogenesis pathway that contains the DNA sensor STING and exerts an antiviral effect on recipient cells.  ΔICP34.5 virus induced a greater release of EVs as compared to HSV-1(F), whereas ΔICP0 virus did not.  EVs released by ΔICP34.5-infected cells differ in origin from those released by HSV-1(F)-infected cells as they contained markers of microvesicles and apoptotic bodies, but lacked major tetraspanins (CD63 or CD81) or lysosomal membrane proteins.  EVs released by ΔICP0-infected cells are generated through the CD63 biogenesis pathway activated by HSV-1(F) but displayed reduced amounts of cargo.  Herpes simplex virus 1 (HSV-1) infection stimulated EV biogenesis through a CD63 tetraspanin biogenesis pathway and these EVs activated antiviral responses in recipient cells restricting the infection.  HSV-1 inhibits autophagy to evade the host, and increased CD63 exocytosis could be a coping mechanism, as CD63 is involved in both cargo delivery to lysosomes during autophagy and exocytosis.  We analyzed exocytosis after infection with two HSV-1 mutants, a ΔICP34.5 and a ΔICP0, that could not inhibit autophagy.  Unlike HSV-1(F), neither of these viruses stimulated increased EV biogenesis through the CD63 pathway. 
HSV-1
ΔICP34.5 virus induced a greater release of EVs as compared to HSV-1(F), whereas ΔICP0 virus did not.  EVs released by ΔICP34.5-infected cells differ in origin from those released by HSV-1(F)-infected cells as they contained markers of microvesicles and apoptotic bodies, but lacked major tetraspanins (CD63 or CD81) or lysosomal membrane proteins.  EVs released by ΔICP0-infected cells are generated through the CD63 biogenesis pathway activated by HSV-1(F) but displayed reduced amounts of cargo.  Unlike HSV-1(F), neither of these viruses stimulated increased EV biogenesis through the CD63 pathway. 
HSV-1(F)
Considering that autophagy and exocytosis are interwoven processes regulating intercellular communication, we sought to determine changes in EV biogenesis after infection with a ΔICP0 and a ΔICP34.5 virus that displayed defects in blocking autophagy compared with wild-type virus.  ΔICP34.5 virus induced a greater release of EVs as compared to HSV-1(F), whereas ΔICP0 virus did not.  EVs released by ΔICP0-infected cells are generated through the CD63 biogenesis pathway activated by HSV-1(F) but displayed reduced amounts of cargo.  We analyzed exocytosis after infection with two HSV-1 mutants, a ΔICP34.5 and a ΔICP0, that could not inhibit autophagy.  ΔICP34.5 stimulated production of microvesicles and apoptotic bodies that were CD63-negative, while ΔICP0 displayed an overall reduced production of EVs. 
ΔICP0
Considering that autophagy and exocytosis are interwoven processes regulating intercellular communication, we sought to determine changes in EV biogenesis after infection with a ΔICP0 and a ΔICP34.5 virus that displayed defects in blocking autophagy compared with wild-type virus.  ΔICP34.5 virus induced a greater release of EVs as compared to HSV-1(F), whereas ΔICP0 virus did not.  EVs released by ΔICP34.5-infected cells differ in origin from those released by HSV-1(F)-infected cells as they contained markers of microvesicles and apoptotic bodies, but lacked major tetraspanins (CD63 or CD81) or lysosomal membrane proteins.  We analyzed exocytosis after infection with two HSV-1 mutants, a ΔICP34.5 and a ΔICP0, that could not inhibit autophagy.  ΔICP34.5 stimulated production of microvesicles and apoptotic bodies that were CD63-negative, while ΔICP0 displayed an overall reduced production of EVs. 
ΔICP34.5