A Multivalent Clade C HIV-1 Env Trimer Cocktail Elicits a Higher Magnitude of Neutralizing Antibodies than Any Individual Component

Abstract

The sequence diversity of human immunodeficiency virus type 1 (HIV-1) presents a formidable challenge to the generation of an HIV-1 vaccine. One strategy to address such sequence diversity and to improve the magnitude of neutralizing antibodies (NAbs) is to utilize multivalent mixtures of HIV-1 envelope (Env) immunogens. Here we report the generation and characterization of three novel, acute clade C HIV-1 Env gp140 trimers (459C, 405C, and 939C), each with unique antigenic properties. Among the single trimers tested, 459C elicited the most potent NAb responses in vaccinated guinea pigs. We evaluated the immunogenicity of various mixtures of clade C Env trimers and found that a quadrivalent cocktail of clade C trimers elicited a greater magnitude of NAbs against a panel of tier 1A and 1B viruses than any single clade C trimer alone, demonstrating that the mixture had an advantage over all individual components of the cocktail. These data suggest that vaccination with a mixture of clade C Env trimers represents a promising strategy to augment vaccine-elicited NAb responses. IMPORTANCEIt is currently not known how to generate potent NAbs to the diverse circulating HIV-1 Envs by vaccination. One strategy to address this diversity is to utilize mixtures of different soluble HIV-1 envelope proteins. In this study, we generated and characterized three distinct, novel, acute clade C soluble trimers. We vaccinated guinea pigs with single trimers as well as mixtures of trimers, and we found that a mixture of four trimers elicited a greater magnitude of NAbs than any single trimer within the mixture. The results of this study suggest that further development of Env trimer cocktails is warranted. P rotection afforded by most currently licensed vaccines is correlated with the generation of neutralizing antibodies (NAbs) (1-3). However, no HIV-1 vaccine to date has been capable of eliciting broad and potent NAbs (4-7). Difficulties in generating broadly neutralizing antibodies (bNAbs) arise from the extensive sequence diversity of circulating strains of HIV-1 (8) and from the unusual characteristics of antibodies associated with the development of breadth (9). However, 15% of HIV-1 infected individuals develop bNAbs with substantial breadth, while over 50% of people make antibodies with at least moderate breadth, typically several years into chronic infection (10-13). Moreover, multiple broadly neutralizing monoclonal antibodies have been reported (14-17). It is therefore important to develop strategies that improve the magnitude and breadth of vaccine-elicited NAbs.As the HIV-1 Env protein is the sole viral antigen on the surface of the virus, it is the target for NAbs. HIV-1 Env is a trimer consisting of three gp120 surface subunits, responsible for interacting with the primary receptor (CD4) and the secondary receptors (CCR5 and/or CXCR4), as well as a trimer of gp41 transmembrane subunits responsible for membrane fusion (18). Previous studies have demonstrated that soluble Env gp140 trimers more closely mimic the...

Influences on the Design and Purification of Soluble, Recombinant Native-Like HIV-1 Envelope Glycoprotein Trimers

“…In all experiments, equivalent amounts of different Env proteins were confirmed to be present on the SPR chips, allowing their reactivity with test MAbs to be compared directly. In contrast, the more commonly used SPR method in which the Env protein flows in a solution over chipimmobilized MAbs does not allow such comparisons, and in addition, this method often detects the MAb binding of only a small subset of the input proteins (2,5,26).…”

“…The 92UG037.8 and CZA97.012 gp140 UNC -Fd-His gp140s were purified via their His tags using Ni-NTA columns as described previously, followed by SEC (Ni-NTA/SEC) to isolate the trimer fraction (2,42). We used this procedure to maximize comparability between our data and what has been reported for the same proteins (2,4,5,42). We conducted pilot experiments to assess how best to purify the newly generated 92UG037.8 and CZA97.012 SOSIP.664-His trimers, in a form that was as fully native-like as possible.…”

“…ecombinant, soluble envelope glycoprotein (Env) gp140 trimers from human immunodeficiency virus type 1 (HIV-1) are being designed, developed, and produced as vaccine candidates intended to induce neutralizing antibody (NAb) responses (1)(2)(3)(4)(5)(6)(7)(8).…”

Antigenic variability: Obstacles on the road to vaccines against traditionally difficult targets

“…43 Subsequently, a number of elegant studies offered new sophisticated approaches for immunogen construction, however they failed to generate immunogens inducing broadly neutralizing Abs (bnAbs), although helped us to better understand the immune pathways behind the induction and evolution of such antibodies. [54][55][56][57][58][59] We share the opinion that reverse vaccinology, based on the combined use of genomic, structural and immunological information to select relevant protective HIV-1 epitopes with increased antigenicity, may not lead to the discovery of effective immunogens: in other words, vaccine immunogenicity can not be predicted from viral antigenicity. 60,61 Clearly, alternative innovative paradigms that could diversify the further search for vaccine candidates are needed.…”

“…60,61 Clearly, alternative innovative paradigms that could diversify the further search for vaccine candidates are needed. 59,60 Recently, an important role of viral antigenic diversity in shaping of bnAb repertoires was analyzed in detailed and systematic manner. 61 Thus, the effect of diverse HIV variant epitopes (immunotypes) on driving the neutralization breadth within a family of 33 mAbs, isolated from a superinfected patient was studied demonstrating that early viral escape at key antibodyvirus contact sites selects for antibodies that can tolerate these changes.…”