Biology subjects

Ackerman, M. E.

Publications and source records attributed to Ackerman, M. E..

3 recordsLinked to original sources

bioRxiv2022

Antibody-mediated prevention of vaginal HIV transmission is dictated by IgG subclass in humanized mice

HIV broadly neutralizing antibodies (bNAbs) are capable of both blocking viral entry and recruiting innate immunity to HIV-infected cells through their fragment crystallizable (Fc) region. Vaccination or productive infection results in a polyclonal mixture of class-switched IgG antibodies comprised of four subclasses, each encoding distinct Fc regions that differentially engage innate immune functions. Despite evidence that innate immunity contributes to protection, the relative contribution of individual IgG subclasses is unknown. Here we use vectored immunoprophylaxis (VIP) in humanized mice to interrogate the efficacy of individual IgG subclasses during prevention of vaginal HIV transmission by VRC07, a potent CD4-binding site directed bNAb. We find that VRC07-IgG2, which lacks Fc-mediated functionality, exhibits significantly reduced protection in vivo relative to other subclasses. However, even low concentrations of highly functional VRC07-IgG1 yields substantial protection against vaginal challenge, suggesting that interventions capable of eliciting modest titers of functional subclasses may provide meaningful benefit against infection.

immunology↗

bioRxiv2022

Maternally transferred monoclonal antibodies protect neonatal mice from herpes simplex virus-induced mortality and morbidity

Neonatal herpes simplex virus (HSV) infections often result in significant mortality and neurological morbidity despite antiviral drug therapy. Maternally-transferred HSV-specific antibodies reduce the risk of clinically-overt neonatal HSV (nHSV), but this observation has not been translationally applied. Using a neonatal mouse model, we tested the hypothesis that passive transfer of HSV-specific human monoclonal antibodies (mAbs) can prevent mortality and morbidity associated with nHSV. The mAbs were expressed in vivo by vectored immunoprophylaxis, or administered in vivo following recombinant expression in vitro. Through these maternally-derived routes or through direct administration to pups, diverse mAbs to HSV glycoprotein D protected against neonatal HSV-1 and HSV-2 infection. Using in vivo bioluminescent imaging, both pre- and post-exposure mAb treatment significantly reduced viral load. Administration of mAb also reduced nHSV-induced behavioral morbidity, as measured by anxiety-like behavior. Together these studies support the notion that HSV-specific mAb-based therapies may prevent or improve HSV infection outcomes in neonates. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/476098v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@175f6eaorg.highwire.dtl.DTLVardef@1a59e39org.highwire.dtl.DTLVardef@36c484org.highwire.dtl.DTLVardef@19fec96_HPS_FORMAT_FIGEXP M_FIG C_FIG Different antibody sources were used to maternally-transfer or directly administer HSV-specific mAbs to mouse pups. Neonatal mice were challenged with wild type or bioluminescent virus before or after mAb acquisition. Following infection, pups were assessed for survival, virus-induced bioluminescence and anxiety-like behavior as a measure of neurological morbidity. Efficacy was time and mAb dependent. Notably, all HSV-specific mAbs prevented nHSV-associated mortality.

immunology↗

bioRxiv2021

Engineered ACE2-Fc counters murine lethal SARS-CoV-2 infection through direct neutralization and Fc-effector activities

Soluble Angiotensin-Converting Enzyme 2 (ACE2) constitutes an attractive antiviral capable of targeting a wide range of coronaviruses utilizing ACE2 as their receptor. Here, using structure-guided approaches, we developed divalent ACE2 molecules by grafting the extracellular ACE2-domain onto a human IgG1 or IgG3 (ACE2-Fc). These ACE2-Fcs harbor structurally validated mutations that enhance spike (S) binding and remove angiotensin enzymatic activity. The lead variant bound tightly to S, mediated in vitro neutralization of SARS-CoV-2 variants of concern (VOCs) with sub-nanomolar IC50 and was capable of robust Fc-effector functions, including antibody-dependent-cellular cytotoxicity, phagocytosis and complement deposition. When tested in a stringent K18-hACE2 mouse model, it delayed death or effectively resolved lethal SARS-CoV-2 infection in a prophylactic or therapeutic setting utilizing the combined effect of neutralization and Fc-effector functions. These data confirm the utility of ACE2-Fcs as valuable agents in preventing and eliminating SARS-CoV-2 infection and demonstrate that ACE2-Fc therapeutic activity require Fc-effector functions.

microbiology↗