Betsy Herold, M.D.

Betsy Herold, M.D. directs a basic and translational research program, which focuses on virus host interactions. Projects in the lab include studies designed to identify the cellular signaling pathways that herpes simplex viruses (HSV) usurp to promote viral entry and infection. The lab uncovered a previously unappreciated paradigm associated with activation of phospholipid scramblases, which are known to catalyze the movement of phosphatidylserine lipids between the inner and outer leaflet of the plasma membrane. Surprisingly, they found that the exofacial movement of phospholipids is associated with concomitant translocation of intracellular proteins, including the master kinase Akt to the outside, where Akt becomes phosphorylated to activate an “outside-inside” signaling cascade that promotes viral entry. This pathway is also usurped by SARS-CoV-2 and is important for cellular processes including apoptosis. In collaboration with the Almo lab, they have engineered cell impermeable kinase inhibitors. These compounds block viral entry and prevent induction of apoptosis by select TNF ligands.

Serendipitously, in studying this signaling pathway, the lab identified a novel candidate vaccine for the prevention and treatment of HSV infections.  Most efforts to develop a vaccine have focused on neutralizing antibodies that target HSV glycoprotein D (gD), but all of these have failed in clinical trials. Instead, the lab (in collaboration with the Jacobs lab), engineered a virus completely deleted in gD. Glycoprotein D is required for viral entry and cell-to-cell spread, thus the deletion virus (DgD-2) is restricted a single cycle and will not spread. This candidate vaccine elicits T cell responses and high titer, polyfunctional antibodies that protect through antibody-dependent cell mediated cytotoxicity (ADCC). The vaccine prevents the establishment of latency in mice and is significantly more protective in multiple small animal models than prior vaccines that have failed in clinical trials. The lab has subsequently isolated monoclonal antibodies (mAbs) that have this protective ADCC activity and both the vaccine and the mAbs are being advanced for preclinical development.  Studies to understand why this vaccine elicits ADCC-mediating antibodies whereas gD vaccines and primary HSV infection only elicit neutralizing antibodies led to the identification of a key role for TNFRSF14 (aka HVEM) in generating and mediating ADCC responses. HVEM is an immune cell surface protein that functions in signal transduction pathways that regulate inflammatory or inhibitory immune responses but its role in shaping the B cell repertoire and in providing a second signal for ADCC had not been previously described and has implications for vaccine development and oncolytic therapies.

The third major area of basic research involves defining the molecular mechanisms underlying the HIV-HSV syndemic. Epidemiological studies have consistently demonstrated that being HSV seropositive is associated with an increased risk for HIV acquisition, replication, higher plasma viral loads and more frequent episodes of HIV reactivation.  Using primary cells from patients and HIV latently infected cell lines, the lab has identified several mechanisms by which HSV promotes HIV latency reversal and replication including upregulation of the noncoding RNA, Malat1, and downregulation of IL-32. Defining these pathways may lead to identification of new strategies to “shock and kill” or “block and lock” HIV.

Clinical studies include prevention of infectious disease complications in transplantation. Members of the research group are involved in studies to optimize pre-emptive prophylaxis for CMV and EBV, vaccine responses in transplantation recipients, and others

Studies with vaginal microbicides have resulted in the expnasion of studies to focus on soluble mucosal immunity in the genital tract. We found that .female genital tract secretions collected from healthy women provide variable, but significant protection against both HSV and HIV. Mechanistic studies suggest that this endogenous activity is mediated by defensins and other antimicrobial peptides. This endogenous activity may serve as a biomarker of a "healthy mucosal immune environment" and thus provide a surrogate marker to evaluate the safety of vaginal microbicides. In addition, identification of the mediators that contribute to this endogenous activity could lead to development of new strategies to boost this host defense and help protect against infection. These studies are being conducted in collaboration with the proteomics core facility at AECOM. Additionally, we are testing the hypothesis that HSV triggers changes in the mucosal environment, which allow it to escape cervical secretion defenses, enhance its own infectivity and facilitate HIV co-infection. Our preliminary observations support the paradigm that HSV disrupts the epithelial barrier by targeting tight junction and adherens junction proteins, and interferes with host defenses by triggering an inflammatory response and a loss in protective proteins such as SLPI. These changes could facilitate both its own infectivity and enhance HIV co-infection.

Results obtained from this bench research are critical to the laboratory's translational studies. The focus of the Translational Microbicide Research Program is to identify optimal combinations of topical microbicides that are safe and target different steps in HIV life cycle, thus reducing the risks of drug resistance and providing greater protection than could be achieved with a single agent, and also target HSV infection. Candidate combinations are evaluated using a multi-tiered approach for anti-viral activity and safety using human cervical cultures, as well as primary T cells and macrophages, in the presence of cervicovaginal secretions and seminal plasma. Leading combinations are then evaluated in human explant cultures (cervical, vaginal) and in murine genital models and a new cotton rat model for anti-viral activity and for the impact on mucosal immunity. If results of these pre-clinical studies suggest that candidate microbicides are safe and effective, the drugs are advanced for regulatory testing, and undergo evaluation in Phase I clinical studies.

Clinical research interests also include prevention of infectious disease complications in transplantation. Members of the research group are involved in studies to optimize pre-emptive prophylaxis for CMV and EBV, vaccine responses in transplantation recipients, and other related infectious complications.