A Phase 1 Human Immunodeficiency Virus Vaccine Trial for Cross-Profiling the Kinetics of Serum and Mucosal Antibody Responses to CN54gp140 Modulated by Two Homologous Prime-Boost Vaccine Regimens

Abstract

A key aspect to finding an efficacious human immunodeficiency virus (HIV) vaccine is the optimization of vaccine schedules that can mediate the efficient maturation of protective immune responses. In the present study, we investigated the effect of alternate booster regimens on the immune responses to a candidate HIV-1 clade C CN54gp140 envelope protein, which was coadministered with the TLR4-agonist glucopyranosyl lipid A-aqueous formulation. Twelve study participants received a common three-dose intramuscular priming series followed by a final booster at either 6 or 12 months. The two homologous prime-boost regimens were well tolerated and induced CN54gp140-specific responses that were observed in both the systemic and mucosal compartments. Levels of vaccine-induced IgG-subclass antibodies correlated significantly with FcγR engagement, and both vaccine regimens were associated with strikingly similar patterns in antibody titer and FcγR-binding profiles. In both groups, identical changes in the antigen (Ag)-specific IgG-subclass fingerprint, leading to a decrease in IgG1 and an increase in IgG4 levels, were modulated by booster injections. Here, the dissection of immune profiles further supports the notion that prime-boost strategies are essential for the induction of diverse Ag-specific HIV-1 responses. The results reported here clearly demonstrate that identical responses were effectively and safely induced by both vaccine regimens, indicating that an accelerated 6-month regimen could be employed for the rapid induction of immune responses against CN54gp140 with no apparent impact on the overall quality of the induced immune response. (This study has been registered at under registration no. NCT01966900.)

Immunoglobulin G1 Allotype Influences Antibody Subclass Distribution in Response to HIV gp140 Vaccination

“…To pursue this, we developed novel PCR (Figure S1 in Supplementary Material) and ELISA protocols and combined them in a dual approach to determine the IgG1 allotype identity (G1m3 and/or G1m1) of clinical trial participants, using both human serum and mRNA. The optimized protocol was applied to determine the IgG1 allotype identity of 14 clinical trial participants from an HIV vaccine study utilizing a Clade C gp140 envelope protein (Figure 1 ; Figure S2 in Supplementary Material) ( 21 ). IgG1-allotyping X001 study participants revealed that 3/14 (21%) were homozygous for G1m1 and 6/14 (43%) homozygous for G1m3, with 5/14 (36%) carrying both alleles (heterozygous).…”

“…This study mainly builds upon findings from the previously published X001 clinical trial ( 21 ), registered at under no. NCT01966900, EudraCT 2013-001032-22.…”

“…Serum antibodies from clinical trial participants were assessed for the presence of the IgG1-allotype G1m3 via a novel ELISA protocol adapted from a previously published ELISA platform ( 21 ). This antibody recognizes both the G1m3 allele prevalent in Caucasian populations and the G1m1,3 allele prevalent in those with Asian ancestry.…”

“…For the G1m1 ELISA the commercially available detection antibody anti-IgG1-Hinge-HRP (Cat: 9052-08, Southern Biotech) was used at a 1:5,000 dilution. Except for the detection antibody, the G1m1-ELISA is identical to the anti-IgG1-ELISA protocol previously published ( 21 ). This antibody does not bind to G1m3 allele, but does show cross reactivity with G1m1,3 allele prevalent in those with Asian ancestry, suggestive of recognition of the common G1m1 allotype.…”

“…Biotinylated dimeric Fc-gamma-Receptors (FcγRIIa-H131, FcγRIIIa-V158) were produced as previously described ( 26 ). The dimeric FcγR multiplex method has been previously published ( 21 ). Briefly, gp140 coupled microspheres (minimum 500 of each individual antigen bead set per well) was added to 1:100 plasma diluted in PBS + beads, incubating overnight at 4°C.…”