Novel antigen delivery systems

Table 2 Preclinical studies based on E2 formulations

E2 construct	Description	Route	Immune response	Ref.
Gag(p17)-E2	HIV-1 Gag p17 matrix protein	sc	Mice immunized with Gag(p17)-E2 mounted a strong and sustained Ab response; the isotype of induced Abs was biased toward IgG1; CD8+ T cells primed with E2 particles were able to exert lytic activity and to produce IFN-γ	[65]
BS1-E2	Mimotope 1 from HIV-1 bridging sheet domain (BS)	IM1/sc1	The E2-BS1 fusion peptide showed good antigenic results; a moderate neutralizing antibody response was found against two HIV-1 clade B and one clade C primary isolates	[67]
Env(V3)-E2	HIV-1 SF162 Env V3 loop peptide 291-336 from gp120 (HXB2 numbering)	Env-E2: IM1;pDNA2: ID1	Env(V3)-E2 induced potent binding Ab and T-cell responses in mice, as well as autologous NAbs in rabbits, when co-immunized with pDNA; co-immunization with pDNA and E2 multimers generated potent immune responses after only two immunizations	[19]
Env(MPER)-E2	HIV-1 SF162 Env MPER peptide 649-689 from gp41 (HXB2 numbering)	Env-E2: IM1;pDNA23: ID1	MPER (membrane proximal external region) displayed on E2 focused Ab responses toward conserved region of HIV-1 Envelope when co-administered with pDNA lacking hypervariable loop regions	[66]
(1-11)-E2	Peptide 1-11 of beta-amyloid	sc	(1-11)E2 vaccine induced fast-rising, robust and persistent Ab responses to beta-amyloid; the Ab response was characterized by a marked prevalence of IgG1 over the IgG2a isotype	[68,69]

¹Routes of administration for rabbit immunizations;

²pDNA: codon-optimized HIV-1 SF162 plasmid DNA encoding gp160 full-length;

³Lacking hypervariable regions. sc: Subcutaneous; IM: Intramuscular; ID: Intradermal administration; Env: Envelope; gp: Glycoprotein; Ab: Antibody; NAbs: Neutralizing antibodies.