Selected HIV-1 Env Trimeric Formulations Act as Potent Immunogens in a Rabbit Vaccination Model

Abstract

BackgroundTen to 30% of HIV-1 infected subjects develop broadly neutralizing antibodies (bNAbs) during chronic infection. We hypothesized that immunizing rabbits with viral envelope glycoproteins (Envs) from these patients may induce bNAbs, when formulated as a trimeric protein and in the presence of an adjuvant.MethodsBased on in vitro neutralizing activity in serum, patients with bNAbs were selected for cloning of their HIV-1 Env. Seven stable soluble trimeric gp140 proteins were generated from sequences derived from four adults and two children infected with either clade A or B HIV-1. From one of the clade A Envs both the monomeric and trimeric Env were produced for comparison. Rabbits were immunized with soluble gp120 or trimeric gp140 proteins in combination with the adjuvant dimethyl dioctadecyl ammonium/trehalose dibehenate (CAF01). Env binding in rabbit immune serum was determined using ELISAs based on gp120-IIIB protein. Neutralizing activity of IgG purified from rabbit immune sera was measured with the pseudovirus-TZMbl assay and a PBMC-based neutralization assay for selected experiments.ResultsIt was initially established that gp140 trimers induce better antibody responses over gp120 monomers and that the adjuvant CAF01 was necessary for such strong responses. Gp140 trimers, based on HIV-1 variants from patients with bNAbs, were able to elicit both gp120IIIB specific IgG and NAbs to Tier 1 viruses of different subtypes. Potency of NAbs closely correlated with titers, and an gp120-binding IgG titer above a threshold of 100,000 was predictive of neutralization capability. Finally, peptide inhibition experiments showed that a large fraction of the neutralizing IgG was directed against the gp120 V3 region.ConclusionsOur results indicate that the strategy of reverse immunology based on selected Env sequences is promising when immunogens are delivered as stabilized trimers in CAF01 adjuvant and that the rabbit is a valuable model for HIV vaccine studies.

Neutralizing Antibody Response and Antibody-Dependent Cellular Cytotoxicity in HIV-1–Infected Individuals from Guinea-Bissau and Denmark

“…Hopefully, these responses can be elicited again in human or animal models if formulated into an appropriate vaccine immunogen, or cocktails of immunogens, and with the right delivery strategy. 25,63…”

Boosting of HIV-1 Neutralizing Antibody Responses by a Distally Related Retroviral Envelope Protein

“…4A). HIV-1 ITM-1_4 gp140 was selected based on comparative analyses of a large set of HIV-1 gp140s and was found to be one of the most potent for induction of neutralizing activity when given in an adjuvant without prior priming (45). However, in contrast to SIV mac239 gp140, HIV-1 ITM-1_4 gp140 was not able to boost the response against the clade B viruses HIV-1 SF162.LS and MN.3.…”

“…SIV mac239 , HIV-1 UG37, YU2, ITM1_4, NIBSC40-9 and HIV-2 (accession numbers, UG37: AY494974; YU2: M93258; ITM1_4: FM165626;NIBSC 40-9: KJ579955; HIV-2 is JN863894) (41–45) gp140 were produced following transient transfection of 293T cells cultured in multilayer Cell Bind Hyperflasks (Corning) in high glucose DMEM (Sigma) supplemented with 10% FCS (Sigma) and Penicillin-Streptomycin solution (Sigma). Two mg plasmid DNA was incubated with 3.6 mg PEI in media without FCS for 30 minutes to allow complex formation.…”

Vector optimization and needle-free intradermal application of a broadly protective polyvalent influenza A DNA vaccine for pigs and humans

“…The use of electroporation in rabbit skin has been evaluated for efficacy 40 and safety 41 and the method has been used successfully in previous studies with DNA vaccines in rabbits. 42,43 For the vaccination procedure, the rabbits were anesthetized using intramuscularadministered Hypnorm Ò (fentanyl citrate:fluanisone mix) (Skanderborg Pharmacy, Denmark) 0.3 ml/kg. 2).…”