title: Vaccination with peptide mimetics of the gp41 prehairpin fusion intermediate yields neutralizing antisera against HIV-1 isolates.
abstract: Eliciting a broadly neutralizing polyclonal antibody response against HIV-1 remains a major challenge. One approach to vaccine development is prevention of HIV-1 entry into cells by blocking the fusion of viral and cell membranes. More specifically, our goal is to elicit neutralizing antibodies that target a transient viral entry intermediate (the prehairpin intermediate) formed by the HIV-1 gp41 protein. Because this intermediate is transient, a stable mimetic is required to elicit an immune response. Previously, a series of engineered peptides was used to select a mAb (denoted D5) that binds to the surface of the gp41 prehairpin intermediate, as demonstrated by x-ray crystallographic studies. D5 inhibits the replication of HIV-1 clinical isolates, providing proof-of-principle for this vaccine approach. Here, we describe a series of peptide mimetics of the gp41 prehairpin intermediate designed to permit a systematic analysis of the immune response generated in animals. To improve the chances of detecting weak neutralizing polyclonal responses, two strategies were employed in the initial screening: use of a neutralization-hypersensitive virus and concentration of the IgG fraction from immunized animal sera. This allowed incremental improvements through iterative cycles of design, which led to vaccine candidates capable of generating a polyclonal antibody response, detectable in unfractionated sera, that neutralize tier 1 HIV-1 and simian HIV primary isolates in vitro. Our findings serve as a starting point for the design of more potent immunogens to elicit a broadly neutralizing response against the gp41 prehairpin intermediate.
authors.affiliation: Department of Peptide Chemistry, Merck Research Laboratories, Pomezia, 00040 Rome, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bianchi
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Joyce
authors.forename: Michael D
authors.initials: MD
authors.lastname: Miller
authors.forename: Adam C
authors.initials: AC
authors.lastname: Finnefrock
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Liang
authors.forename: Marco
authors.initials: M
authors.lastname: Finotto
authors.forename: Paolo
authors.initials: P
authors.lastname: Ingallinella
authors.forename: Philip
authors.initials: P
authors.lastname: McKenna
authors.forename: Michael
authors.initials: M
authors.lastname: Citron
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ottinger
authors.forename: Robert W
authors.initials: RW
authors.lastname: Hepler
authors.forename: Renee
authors.initials: R
authors.lastname: Hrin
authors.forename: Deborah
authors.initials: D
authors.lastname: Nahas
authors.forename: Chengwei
authors.initials: C
authors.lastname: Wu
authors.forename: David
authors.initials: D
authors.lastname: Montefiori
authors.forename: John W
authors.initials: JW
authors.lastname: Shiver
authors.forename: Antonello
authors.initials: A
authors.lastname: Pessi
authors.forename: Peter S
authors.initials: PS
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology*; D040761:Biomimetic Materials; D006168:Guinea Pigs; D015483:HIV Antibodies / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000276:immunology*; D015497:HIV-1 / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D007106:Immune Sera / Q000276:immunology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011817:Rabbits; D014611:Vaccination
chemical_list: D057134:Antibodies, Neutralizing; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D007106:Immune Sera; D010455:Peptides