Vaccinia virus extracellular enveloped virion antigens (EEV antigens)

Vaccinia virus produces two infectious forms: intracellular mature virus (IMV) and extracellular enveloped virus (EEV), with EEV antigens on the outer envelope enabling virus spread within the host. Key EEV antigens include B5R (a transmembrane glycoprotein related to complement regulators, targeted to Golgi), A33R, A34R, A36R (involved in actin tail formation), A56R, and F13L (palmitylated protein for morphogenesis). EEV incorporates host proteins like CD46, CD55, CD59 (RCA family) into its fragile outer membrane, conferring resistance to complement-mediated neutralization when grown in matching host species, but sensitivity otherwise. This protects EEV during dissemination, distinct from IMV properties. Antibodies against B5R neutralize EEV via opsonization and complement activation, preventing cell binding, while anti-B5 IgG enables complement-dependent lysis of infected cells expressing surface B5. EEV enters cells silently at the plasma membrane without actin signaling, unlike IMV.

Other names

EV antigensextracellular virion antigens