Human Ig knockin mice to study the development and regulation of HIV‐1 broadly neutralizing antibodies

Abstract

Summary A major challenge for HIV-1 vaccine research is developing a successful immunization approach for inducing broadly neutralizing antibodies (bnAbs). A key shortcoming in meeting this challenge has been the lack of animal models capable of identifying impediments limiting bnAb induction and ranking vaccine strategies for their ability to promote bnAb development. Since 2010, immunoglobulin knock-in (KI) technology, involving inserting functional rearranged human variable exons into the mouse IgH and IgL loci has been used to express bnAbs in mice. This approach has allowed immune tolerance mechanisms limiting bnAb production to be elucidated and strategies to overcome such limitations to be evaluated. From these studies, along with the wealth of knowledge afforded by analyses of recombinant Ig-based bnAb structures, it became apparent that key functional features of bnAbs often are problematic for their elicitation in mice by classic vaccine paradigms, necessitating more iterative testing of new vaccine concepts. In this regard, bnAb KI models expressing deduced precursor V(D)J rearrangements of mature bnAbs or unrearranged germline V, D, J segments (that can be assembled into variable region exons that encode bnAb precursors), have been engineered to evaluate novel immunogens/regimens for effectiveness in driving bnAb responses. One promising approach emerging from such studies is the ability of sequentially administered, modified immunogens (designed to bind progressively more mature bnAb precursors) to initiate affinity maturation. Here, we review insights gained from bnAb KI studies regarding the regulation and induction of bnAbs, and discuss new Ig KI methodologies to manipulate the production and/or expression of bnAbs in vivo, to further facilitate vaccine-guided bnAb induction studies.

Strategies for a multi-stage neutralizing antibody-based HIV vaccine

“…Significant progress has been made over the past few years in the generation of immunoglobulin (Ig) knock-in (KI) mouse models that express the pre-rearranged V(D)J-encoding inferred germline genes of HIV bnAbs precursors to evaluate candidate immunogens (Figure 2A) [29,30,32,37,47]. Much of this activity has focused on VRC01-bnAb germline-KI models, but expansion to other bnAb precursors is in progress [37,48].…”

“…However, these KI mouse models have a selective advantage over unbiased B cell repertoires, as all or at least part of the bnAb precursor genes replace the natural mouse Ig genes. While these KI mouse studies have been informative, certain limitations, such as B cell receptor editing and peripheral anergy have complicated analysis of the experimental outcomes [47]. Nevertheless, precursor B cell adoptive transfers into wild-type animal models can provide models that more closely resemble those anticipated in humans and can provide estimates of the affinities of immunogens that may be required to trigger appropriate B cell lineages [49].…”

GIBaren aurkako txertoaren bila

“…Gainera, baliteke espezie hauetan ez egotea bNab-ak ekoizten dituzten B zelula germinal aitzindariak. Horrenbestez, gaur egun garrantzia handia hartzen ari diren animalia-ereduak giza antigorputzak adierazten dituzten saguak (bNab knock-in saguak alegia, KI saguak) [53] eta sagu humanizatuak dira [54].…”

“…Eredu hauetan oinarrituta egindako ikerketak, gizakietan edo primateetan egindako azterketekin osatu behar dira, baina nahiko informazio ematen dute B zelulen aukeraketa eta eraketaren inguruan, baita immunogeno berriek antigorputzen ekoizpenean izan dezaketen erantzunaren inguruan ere [35,53].…”

Developing an HIV vaccine

“…Mice engineered to express some bnAb Ig heavy-chain variable domain (V H ) and light-chain variable domain (V L ) genes display central tolerance (deletion), receptor editing, antibody reversion (loss of reactivity to target epitope), and peripheral anergy (self-reactive T cells become nonresponsive), all of which control bnAb development (13). Immune tolerance control of bnAbs can reduce the pool of bnAb-producing B cells capable of responding to a vaccine and may increase the propensity of bnAb B cell lineages to divert “off track” during antigen stimulation and affinity maturation.…”