Hannah Wallace, University of Manitoba

Hannah L. Wallace1, Bárbara N. Porto1, Alicia Berard2, Jason Kindrachuk1,3 1 Medical Microbiology & Infectious Diseases, University of Manitoba, Winnipeg, Canada 2 Department of Obstetrics, Gynecology & Reproductive Sciences, and Department of Immunology, University of Manitoba, Winnipeg, Canada 3 National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Canada

Damaging & Spreading

Introduction: Poxvirus infections have long been linked to adverse pregnancy outcomes and complications, from the smallpox era to more recently with cases of mpox. Programmed cell death (PCD) has been implicated in viral pathogenesis as well as pregnancy complications including preeclampsia and recurrent miscarriage. Here, we investigated the role of lytic PCD in poxvirus-induced pregnancy complications to elucidate mechanisms of pathogenesis. Methods: Trophoblasts were infected with vaccina virus (VACV; CL2 surrogate for mpox virus [MPXV]) and infection and cell death was investigated using cytotoxicity assays, microscopy, Western blotting, ELISAs, plaque assays, RT-PCR, and specific inhibitors of pyroptosis. Results: This study is the first to investigate poxvirus infection of trophoblasts, showing productive VACV infection, reaching high viral loads. VACV caused significant increases in lytic cell death which increased substantially with increasing time post-infection and increased MOIs. Inhibition of necroptosis lead to ameliorated cell death and improved cell viability with increased levels of pathway-associated markers. In contrast, inhibition of pyroptosis or treatment with IL-11, which is associated with pyroptosis-driven adverse pregnancy outcomes, led to increased lytic death and decreased cell viability. Discussion: Our data indicate that VACV productively infects trophoblasts and induces necroptosis which may provide a viable treatment target. Inhibition of pyroptosis resulted in increased levels of lytic PCD, highlighting significant crosstalk between PCD pathways. Future work includes performing these studies using MPXV, as well as characterizing pregnancy complications in a BALB/c mouse model and evaluating whether PCD-related gene knockouts and/or pharmaceutical interventions ameliorate pregnancy outcomes and disease.