Latent reservoirs of HIV-1-infected cells are refractory to antiretroviral therapies (ART) and remain the major barrier to curing HIV-1. Because latently infected cells are long-lived, ...immunologically invisible, and may undergo homeostatic proliferation, a “shock and kill” approach has been proposed to eradicate this reservoir by combining ART with inducers of viral transcription. However, all attempts to alter the HIV-1 reservoir in vivo have failed to date. Using humanized mice, we show that broadly neutralizing antibodies (bNAbs) can interfere with establishment of a silent reservoir by Fc-FcR-mediated mechanisms. In established infection, bNAbs or bNAbs plus single inducers are ineffective in preventing viral rebound. However, bNAbs plus a combination of inducers that act by independent mechanisms synergize to decrease the reservoir as measured by viral rebound. Thus, combinations of inducers and bNAbs constitute a therapeutic strategy that impacts the establishment and maintenance of the HIV-1 reservoir in humanized mice.
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•bNAbs can be used for postexposure prophylaxis (PEP) in humanized mice•bNAb PEP efficacy requires Fc-receptor binding•bNAbs plus a single inducer of HIV-1 transcription do not reduce viral rebound•bNAbs plus a combination of inducers significantly reduce viral rebound
A combination of broadly neutralizing antibodies and viral inducers reduce the frequency of viral rebound in the humanized mouse model of HIV-1 infection.
Human antibodies to human immunodeficiency virus-1 (HIV-1) can neutralize a broad range of viral isolates in vitro and protect non-human primates against infection. Previous work showed that ...antibodies exert selective pressure on the virus but escape variants emerge within a short period of time. However, these experiments were performed before the recent discovery of more potent anti-HIV-1 antibodies and their improvement by structure-based design. Here we re-examine passive antibody transfer as a therapeutic modality in HIV-1-infected humanized mice. Although HIV-1 can escape from antibody monotherapy, combinations of broadly neutralizing antibodies can effectively control HIV-1 infection and suppress viral load to levels below detection. Moreover, in contrast to antiretroviral therapy, the longer half-life of antibodies led to control of viraemia for an average of 60 days after cessation of therapy. Thus, combinations of potent monoclonal antibodies can effectively control HIV-1 replication in humanized mice, and should be re-examined as a therapeutic modality in HIV-1-infected individuals.
Effective control of HIV-1 infection in humans is achieved using combinations of antiretroviral therapy (ART) drugs. In humanized mice (hu-mice), control of viremia can be achieved using either ART ...or by immunotherapy using combinations of broadly neutralizing antibodies (bNAbs). Here we show that treatment of HIV-1–infected hu-mice with a combination of three highly potent bNAbs not only resulted in complete viremic control but also led to a reduction in cell-associated HIV-1 DNA. Moreover, lowering the initial viral load by coadministration of ART and immunotherapy enabled prolonged viremic control by a single bNAb after ART was withdrawn. Similarly, a single injection of adeno-associated virus directing expression of one bNAb produced durable viremic control after ART was terminated. We conclude that immunotherapy reduces plasma viral load and cell-associated HIV-1 DNA and that decreasing the initial viral load enables single bNAbs to control viremia in hu-mice.
Antibodies to Zika virus (ZIKV) can be protective. To examine the antibody response in individuals who develop high titers of anti-ZIKV antibodies, we screened cohorts in Brazil and Mexico for ZIKV ...envelope domain III (ZEDIII) binding and neutralization. We find that serologic reactivity to dengue 1 virus (DENV1) EDIII before ZIKV exposure is associated with increased ZIKV neutralizing titers after exposure. Antibody cloning shows that donors with high ZIKV neutralizing antibody titers have expanded clones of memory B cells that express the same immunoglobulin VH3-23/VK1-5 genes. These recurring antibodies cross-react with DENV1, but not other flaviviruses, neutralize both DENV1 and ZIKV, and protect mice against ZIKV challenge. Structural analyses reveal the mechanism of recognition of the ZEDIII lateral ridge by VH3-23/VK1-5 antibodies. Serologic testing shows that antibodies to this region correlate with serum neutralizing activity to ZIKV. Thus, high neutralizing responses to ZIKV are associated with pre-existing reactivity to DENV1 in humans.
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•Pre-existing antibodies to DENV1 correlate with high ZIKV neutralizing responses•Antibodies to the EDIII lateral ridge correlate with serum neutralization of ZIKV•Recurrent VH3-23/VK1-5 antibodies to the EDIII potently neutralize ZIKV and DENV1•The structures of VH3-23/VK1-5 antibodies with the EDIIIs of DENV1 and ZIKV were solved
Individuals with high neutralizing antibody response against Zika virus have expanded clones of B cells that express the same heavy and light immunoglobulin genes and that are cross-reactive against dengue 1 virus.
Cancer-initiating translocations such as those associated with lymphomas require the formation of paired DNA double-strand breaks (DSBs). Activation-induced cytidine deaminase (AID) produces ...widespread somatic mutation in mature B cells; however, the extent of “off-target” DSB formation and its role in translocation-associated malignancy is unknown. Here, we show that deregulated expression of AID causes widespread genome instability, which alone is insufficient to induce B cell lymphoma; transformation requires concomitant loss of the tumor suppressor p53. Mature B cell lymphomas arising as a result of deregulated AID expression are phenotypically diverse and harbor clonal reciprocal translocations involving a group of Immunoglobulin (Ig) and non-Ig genes that are direct targets of AID. This group includes miR-142, a previously unknown micro-RNA target that is translocated in human B cell malignancy. We conclude that AID produces DSBs throughout the genome, which can lead to lymphoma-associated chromosome translocations in mature B cells.
Chromosomal translocations involving the immunoglobulin switch region are a hallmark feature of B-cell malignancies. However, little is known about the molecular mechanism by which primary B cells ...acquire or guard against these lesions. Here we find that translocations between c-myc and the IgH locus (Igh) are induced in primary B cells within hours of expression of the catalytically active form of activation-induced cytidine deaminase (AID), an enzyme that deaminates cytosine to produce uracil in DNA. Translocation also requires uracil DNA glycosylase (UNG), which removes uracil from DNA to create abasic sites that are then processed to double-strand breaks. The pathway that mediates aberrant joining of c-myc and Igh differs from intrachromosomal repair during immunoglobulin class switch recombination in that it does not require histone H2AX, p53 binding protein 1 (53BP1) or the non-homologous end-joining protein Ku80. In addition, translocations are inhibited by the tumour suppressors ATM, Nbs1, p19 (Arf) and p53, which is consistent with activation of DNA damage- and oncogenic stress-induced checkpoints during physiological class switching. Finally, we demonstrate that accumulation of AID-dependent, IgH-associated chromosomal lesions is not sufficient to enhance c-myc–Igh translocations. Our findings reveal a pathway for surveillance and protection against AID-dependent DNA damage, leading to chromosomal translocations.
MicroRNAs (miRNAs) are small noncoding RNAs that regulate vast networks of genes that share miRNA target sequences. To examine the physiologic effects of an individual miRNA-mRNA interaction in vivo, ...we generated mice that carry a mutation in the putative microRNA-155 (miR-155) binding site in the 3′-untranslated region of activation-induced cytidine deaminase (AID), designated
Aicda
155
mice. AID is required for immunoglobulin gene diversification in B lymphocytes, but it also promotes chromosomal translocations.
Aicda
155
caused an increase in steady-state
Aicda mRNA and protein amounts by increasing the half-life of the mRNA, resulting in a high degree of
Myc-Igh translocations. A similar but more pronounced translocation phenotype was also found in miR-155-deficient mice. Our experiments indicate that miR-155 can act as a tumor suppressor by reducing potentially oncogenic translocations generated by AID.
To explore the influence of genetics on homeostatic regulation of dendritic cell (DC) numbers, we present a screen of DCs and their progenitors in lymphoid and non-lymphoid tissues in Collaborative ...Cross (CC) and Diversity Outbred (DO) mice. We report 30 and 71 loci with logarithm of the odds (LOD) scores >8.18 and ranging from 6.67 to 8.19, respectively. The analysis reveals the highly polygenic and pleiotropic architecture of this complex trait, including many of the previously identified genetic regulators of DC development and maturation. Two SNPs in genes potentially underlying variation in DC homeostasis, a splice variant in Gramd4 (rs235532740) and a missense variant in Orai3 (rs216659754), are confirmed by gene editing using CRISPR-Cas9. Gramd4 is a central regulator of DC homeostasis that impacts the entire DC lineage, and Orai3 regulates cDC2 numbers in tissues. Overall, the data reveal a large number of candidate genes regulating DC homeostasis in vivo.
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•Collaborative Cross and Diversity Outbred mice show dendritic cell (DC) frequency variation•QTL mapping reveals the highly polygenic and pleiotropic architecture of DC homeostasis•Gramd4 and Orai3 regulate DC frequency
Oliveira et al. use quantitative trait locus (QTL) mapping in Diversity Outbred mice to find candidate genes linked to dendritic cell (DC) homeostasis. Site-directed mutagenesis using CRISPR-Cas9 confirms two candidate genes, Gramd4 and Orai3. Overall, the data represent a resource for interrogating the mechanisms governing DC homeostasis in tissues.
Antibody-mediated immunotherapy is effective in humanized mice when combinations of broadly neutralizing antibodies (bNAbs) are used that target nonoverlapping sites on the human immunodeficiency ...virus type 1 (HIV-1) envelope. In contrast, single bNAbs can control simian-human immunodeficiency virus (SHIV) infection in immune-competent macaques, suggesting that the host immune response might also contribute to the control of viremia. Here, we investigate how the autologous antibody response in intact hosts can contribute to the success of immunotherapy. We find that frequently arising antibodies that normally fail to control HIV-1 infection can synergize with passively administered bNAbs by preventing the emergence of bNAb viral escape variants.
Zika virus (ZIKV) causes severe neurologic complications and fetal aberrations. Vaccine development is hindered by potential safety concerns due to antibody cross-reactivity with dengue virus and the ...possibility of disease enhancement. In contrast, passive administration of anti-ZIKV antibodies engineered to prevent enhancement may be safe and effective. Here, we report on human monoclonal antibody Z021, a potent neutralizer that recognizes an epitope on the lateral ridge of the envelope domain III (EDIII) of ZIKV and is protective against ZIKV in mice. When administered to macaques undergoing a high-dose ZIKV challenge, a single anti-EDIII antibody selected for resistant variants. Co-administration of two antibodies, Z004 and Z021, which target distinct sites on EDIII, was associated with a delay and a 3- to 4-log decrease in peak viremia. Moreover, the combination of these antibodies engineered to avoid enhancement prevented viral escape due to mutation in macaques, a natural host for ZIKV.
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•Monoclonal antibodies are tested in macaques challenged with high-dose Zika virus•A single monoclonal antibody selects for Zika virus escape mutants•A combination of two antibodies suppresses viremia and prevents escape mutants•Antibodies engineered to avoid enhancement confer similar levels of protection
Passive administration of anti-Zika human monoclonal antibodies could be an efficacious and safe alternative to vaccines for at-risk populations. Keeffe et al. show that administration of a combination of two monoclonal antibodies to macaques followed by high-dose intravenous Zika challenge reduces viremia and prevents the emergence of viral escape mutations.
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