Antibodies and Fc-fusion antibody-like proteins have become successful biologics developed for cancer treatment, passive immunity against infection, addiction, and autoimmune diseases. In general ...these biopharmaceuticals can be used for blocking protein:protein interactions, crosslinking host receptors to induce signaling, recruiting effector cells to targets, and fixing complement. With the vast capability of antibodies to affect infectious and genetic diseases much effort has been placed on improving and tailoring antibodies for specific functions. While antibody:antigen engagement is critical for an efficacious antibody biologic, equally as important are the hinge and constant domains of the heavy chain. It is the hinge and constant domains of the antibody that engage host receptors or complement protein to mediate a myriad of effector functions and regulate antibody circulation. Molecular and structural studies have provided insight into how the hinge and constant domains from antibodies across different species, isotypes, subclasses, and alleles are recognized by host cell receptors and complement protein C1q. The molecular details of these interactions have led to manipulation of the sequences and glycosylation of hinge and constant domains to enhance or reduce antibody effector functions and circulating half-life. This review will describe the concepts being applied to optimize the hinge and crystallizable fragment of antibodies, and it will detail how these interactions can be tuned up or down to mediate a biological function that confers a desired disease outcome.
Prophylactic and therapeutic drugs are urgently needed to combat coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over the past year, ...SARS-CoV-2 neutralizing antibodies have been developed for preventive or therapeutic uses. While neutralizing antibodies target the spike protein, their neutralization potency and breadth vary according to recognition epitopes. Several potent SARS-CoV-2 antibodies have shown degrees of success in preclinical or clinical trials, and the US Food and Drug Administration has issued emergency use authorization for two neutralizing antibody cocktails.Nevertheless, antibody therapy for SARS-CoV-2 still faces potential challenges, including emerging viral variants of concern that have antibody-escape mutations and the potential for antibody-mediated enhancement of infection or inflammation. This review summarizes representative SARS-CoV-2 neutralizing antibodies that have been reported and discusses prospects and challenges for the development of the next generation of COVID-19 preventive or therapeutic antibodies.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with multiple spike mutations enable increased transmission and antibody resistance. We combined cryo-electron microscopy ...(cryo-EM), binding, and computational analyses to study variant spikes, including one that was involved in transmission between minks and humans, and others that originated and spread in human populations. All variants showed increased angiotensin-converting enzyme 2 (ACE2) receptor binding and increased propensity for receptor binding domain (RBD)-up states. While adaptation to mink resulted in spike destabilization, the B.1.1.7 (UK) spike balanced stabilizing and destabilizing mutations. A local destabilizing effect of the RBD E484K mutation was implicated in resistance of the B.1.1.28/P.1 (Brazil) and B.1.351 (South Africa) variants to neutralizing antibodies. Our studies revealed allosteric effects of mutations and mechanistic differences that drive either interspecies transmission or escape from antibody neutralization.
Aided by extensive spike protein mutation, the SARS-CoV-2 Omicron variant overtook the previously dominant Delta variant. Spike conformation plays an essential role in SARS-CoV-2 evolution via ...changes in receptor-binding domain (RBD) and neutralizing antibody epitope presentation, affecting virus transmissibility and immune evasion. Here, we determine cryo-EM structures of the Omicron and Delta spikes to understand the conformational impacts of mutations in each. The Omicron spike structure revealed an unusually tightly packed RBD organization with long range impacts that were not observed in the Delta spike. Binding and crystallography revealed increased flexibility at the functionally critical fusion peptide site in the Omicron spike. These results reveal a highly evolved Omicron spike architecture with possible impacts on its high levels of immune evasion and transmissibility.
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•Omicron S architecture differs from Delta and other variants•Tight packing of Omicron S RBDs results in unique up- and down-state arrangements•3-RBD-down Omicron S stabilizes the rearrangement of the NTD-to-RBD (N2R) linker•S2 subunit conformational changes lead to altered fusion peptide dynamics
Gobeil, Henderson, Stalls et al. identify diverse Omicron S ectodomain conformations demonstrating altered architecture that exhibits tight packing of the 3-RBD-down state, NTD-to-RBD (N2R) linker rearrangements, and changes in fusion peptide conformational dynamics. These distinct conformational features of its S protein may underlie Omicron’s higher transmissibility and immune evasion.
The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and SARS-CoV-2 in 2019 highlights the need to develop universal vaccination strategies against the broader
subgenus. ...Using chimeric spike designs, we demonstrate protection against challenge from SARS-CoV, SARS-CoV-2, SARS-CoV-2 B.1.351, bat CoV (Bt-CoV) RsSHC014, and a heterologous Bt-CoV WIV-1 in vulnerable aged mice. Chimeric spike messenger RNAs (mRNAs) induced high levels of broadly protective neutralizing antibodies against high-risk Sarbecoviruses. By contrast, SARS-CoV-2 mRNA vaccination not only showed a marked reduction in neutralizing titers against heterologous Sarbecoviruses, but SARS-CoV and WIV-1 challenge in mice resulted in breakthrough infections. Chimeric spike mRNA vaccines efficiently neutralized D614G, mink cluster five, and the UK B.1.1.7 and South African B.1.351 variants of concern. Thus, multiplexed-chimeric spikes can prevent SARS-like zoonotic coronavirus infections with pandemic potential.
The SARS-CoV-2 pandemic that causes COVID-19 respiratory syndrome has caused global public health and economic crises, necessitating rapid development of vaccines and therapeutic countermeasures. The ...world-wide response to the COVID-19 pandemic has been unprecedented with government, academic, and private partnerships working together to rapidly develop vaccine and antibody countermeasures. Many of the technologies being used are derived from prior government-academic partnerships for response to other emerging infections.
Collaboration between academic, government, and private institutions can enable the development and sustenance of a pandemic preparedness platform that can be readily deployed upon need, as is the case with the COVID-19 pandemic.
The SARS-CoV-2 spike (S) protein, a primary target for COVID-19 vaccine development, presents its receptor binding domain in two conformations, the receptor-accessible 'up' or receptor-inaccessible ...'down' states. Here we report that the commonly used stabilized S ectodomain construct '2P' is sensitive to cold temperatures, and this cold sensitivity is abrogated in a 'down' state-stabilized ectodomain. Our findings will impact structural, functional and vaccine studies that use the SARS-CoV-2 S ectodomain.
After nearly four decades of research, a safe and effective HIV-1 vaccine remains elusive. There are many reasons why the development of a potent and durable HIV-1 vaccine is challenging, including ...the extraordinary genetic diversity of HIV-1 and its complex mechanisms of immune evasion. HIV-1 envelope glycoproteins are poorly recognized by the immune system, which means that potent broadly neutralizing antibodies (bnAbs) are only infrequently induced in the setting of HIV-1 infection or through vaccination. Thus, the biology of HIV-1-host interactions necessitates novel strategies for vaccine development to be designed to activate and expand rare bnAb-producing B cell lineages and to select for the acquisition of critical improbable bnAb mutations. Here we discuss strategies for the induction of potent and broad HIV-1 bnAbs and outline the steps that may be necessary for ultimate success.
The CD4 binding site (CD4bs) of the HIV-1 envelope glycoprotein is susceptible to multiple lineages of broadly neutralizing antibodies (bnAbs) that are attractive to elicit with vaccines. The CH235 ...lineage (VH1-46) of CD4bs bnAbs is particularly attractive because the most mature members neutralize 90% of circulating strains, do not possess long HCDR3 regions, and do not contain insertions and deletions that may be difficult to induce. We used virus neutralization to measure the interaction of CH235 unmutated common ancestor (CH235 UCA) with functional Env trimers on infectious virions to guide immunogen design for this bnAb lineage. Two Env mutations were identified, one in loop D (N279K) and another in V5 (G458Y), that acted synergistically to render autologous CH505 transmitted/founder virus susceptible to neutralization by CH235 UCA. Man5-enriched N-glycans provided additional synergy for neutralization. CH235 UCA bound with nanomolar affinity to corresponding soluble native-like Env trimers as candidate immunogens. A cryo-EM structure of CH235 UCA bound to Man5-enriched CH505.N279K.G458Y.SOSIP.664 revealed interactions of the antibody light chain complementarity determining region 3 (CDR L3) with the engineered Env loops D and V5. These results demonstrate that virus neutralization can directly inform vaccine design and suggest a germline targeting and reverse engineering strategy to initiate and mature the CH235 bnAb lineage.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Engineering better bnAbs
A highly effective HIV vaccine has been the goal of vaccinologists for nearly 35 years. A successful vaccine would need to induce broadly neutralizing antibodies (bnAbs) that ...are capable of neutralizing multiple HIV strains (see the Perspective by Agazio and Torres). Steichen
et al.
report a strategy in which the first vaccine shot can lead to immune responses that generate desired bnAbs. By combining knowledge of human antibody repertoires and structure to guide design, they validated candidate immunogens through functional preclinical testing. Saunders
et al.
designed immunogens with differences in binding strength for bnAb precursors, which enabled selection of rare mutations after immunization. The immunogens promoted bnAb precursor maturation in humanized mice and macaques.
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Engineering antibodies against rare HIV mutations is required for HIV neutralizing antibody development.
INTRODUCTION
A major goal of HIV-1 vaccine development is the design of immunogens that induce broadly neutralizing antibodies (bnAbs). However, vaccination of humans has not resulted in the induction of affinity-matured and potent HIV-1 bnAbs. To devise effective vaccine strategies, we previously determined the maturation pathway of select HIV-1 bnAbs from acute infection through neutralizing antibody development. During their evolution, bnAbs acquire an abundance of improbable amino acid substitutions as a result of nucleotide mutations at variable region sequences rarely targeted by activation-induced cytidine deaminase, the enzyme responsible for antibody mutation. A subset of improbable mutations is essential for broad neutralization activity, and their acquisition represents a key roadblock to bnAb development.
RATIONALE
Current bnAb lineage–based vaccine strategies can initiate bnAb lineage development in animal models but have not specifically elicited the improbable mutations required for neutralization breadth. Induction of bnAbs requires vaccine strategies that specifically engage bnAb precursors and subsequently select for improbable mutations required for broadly neutralizing activity. We hypothesized that vaccination with immunogens that bind with moderate to high affinity to bnAb B cell precursors, and with higher affinity to precursors that have acquired improbable mutations, could initiate bnAb B cell lineages and select for key improbable mutations required for bnAb development.
RESULTS
We elicited serum neutralizing HIV-1 antibodies in human bnAb precursor knock-in mice and wild-type macaques vaccinated with immunogens designed to select for improbable mutations. We designed two HIV-1 envelope immunogens that bound precursor B cells of either a CD4 binding site or V3-glycan bnAb lineage. In vitro, these immunogens bound more strongly to bnAb precursors once the precursor acquired the desired improbable mutations. Vaccination of macaques with the CD4 binding site–targeting immunogen induced CD4 binding site serum neutralizing antibodies. Antibody sequences elicited in human bnAb precursor knock-in mice encoded functional improbable mutations critical for bnAb development. In bnAb precursor knock-in mice, we isolated a vaccine-elicited monoclonal antibody bearing functional improbable mutations that was capable of neutralizing multiple HIV-1 global isolates. Structures of a bnAb precursor, a bnAb, and the vaccine-elicited antibody revealed the precise roles that acquired improbable mutations played in recognizing the HIV-1 envelope. Thus, our immunogens elicited antibody responses in macaques and knock-in mice that exhibited the mutational patterns, structural characteristics, or neutralization profiles of nascent broadly neutralizing antibodies.
CONCLUSION
Our study represents a proof of concept for targeted selection of improbable mutations to guide antibody affinity maturation. Moreover, this study demonstrates a rational strategy for sequential immunogen design to circumvent the difficult roadblocks in HIV-1 bnAb induction by vaccination. We show that immunogens should exhibit differences in affinity across antibody maturation stages where improbable mutations are necessary for the desired antibody function. This strategy of selection of specific antibody nucleotides by immunogen design can be applied to B cell lineages targeting other pathogens where guided affinity maturation is needed for a protective antibody response.
Overcoming somatic mutation roadblocks to advance broadly neutralizing HIV-1 antibody (bnAb) development.
Vaccination of animal models with engineered HIV-1 immunogens generated antibodies that acquired functional improbable mutations critical for virus neutralization. The lack of envelope selection of improbable mutations is a roadblock for bnAb development. Vaccine-elicited antibodies exhibited neutralization activity similar to that of intermediate-stage bnAbs. Structural studies showed a vaccine-elicited neutralizing antibody bound to HIV-1 envelope in a manner similar to that of a mature bnAb.
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