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OBJECTIVES/GOALS: Maternal opioid use disorder (OUD) is linked to poor fetal outcomes. While it has been established that opioids can cross from maternal to fetal circulation, the mechanisms underlying these adverse outcomes remain poorly defined. This study aims to uncover OUD-associated immunological changes in maternal and fetal circulation. METHODS/STUDY POPULATION: To study the effect of maternal OUD on the maternal immune system at delivery, we collected maternal blood samples at delivery from healthy pregnant women (controls) and pregnant women with a diagnosis of severe OUD. To study the impact of maternal OUD on newborn immunity, we also collected umbilical cord blood (UCB) at delivery. Flow cytometry was used to determine the frequency and phenotype of circulating immune cell subsets and responses to stimulation. Isolated monocytes were stimulated with bacterial/viral agonist cocktails, while T and NK cells were stimulated with PMA/ionomycin. The impact of maternal OUD on circulating immune mediators was determined by Luminex and on monocyte activation markers sCD14 and CRP by ELISA. RESULTS/ANTICIPATED RESULTS: In maternal circulation, OUD was associated with a significant decrease in markers of inflammation, cell proliferation, and activation. Frequencies of immune cell subsets were impacted by OUD, shown by an expansion of CD8+ EMRA T cells, marginal-zone B cells, mDCs, non-classical monocytes, and CD16low NK cells. While no differences were seen in T and NK cell responses to stimulation, monocytes and pDCs had significantly lower responses to bacterial and viral agonist stimulation. Analysis of UCB revealed increased levels of pro-apoptotic/T cell exhaustion mediators and pro-inflammatory cytokines, albeit decreased levels of several chemokines and growth factors. The UCB immune landscape is altered with maternal OUD, as demonstrated by a shift from naive to memory CD8+ T cells and a decrease in pDC frequency. DISCUSSION/SIGNIFICANCE: OUD dampens maternal peripheral immunity, possibly contributing to poor placental function or premature/delayed labor. Monocytes and pDCs lack antimicrobial functionality, suggesting increased infection susceptibility with OUD. Finally, these implications extend to the fetal compartment, shown by heightened immune activation in UCB.

To obtain proof of concept for HIV vaccines, we generated recombinant multimeric particles displaying the HIV-1 Envelope (Env) third hypervariable region (V3) as an N-terminal fusion protein on the E2 subunit of the pyruvate dehydrogenase complex of Geobacillus stearothermophilus. The E2 scaffold self-assembles into a 60-mer core that is 24 nm in diameter, with a molecular weight of 1.5 MDa, similar to a virus like particle with up to 60 copies of a heterologous protein accessible on the surface. Env(V3)-E2 multimers were tested alone and in combination with Env(gp160) DNA in mice and rabbits. Following two or more co-immunizations with Env(V3)-E2 and Env gp160 DNA, all 18 rabbits developed potent autologous neutralizing antibodies specific for V3 in six weeks. These neutralizing antibodies were sustained for 16 weeks without boosting, and comparable responses were obtained when lipopolysaccharide, a contaminant from expression in E. coli, was removed. Co-immunizations of Env(V3)-E2 and DNA expressing gp160 elicited moderate CD8-specific responses and Env-specific antibodies in mice. Co-immunization with DNA and E2 was superior to individual or sequential vaccination with these components in eliciting both neutralizing antibodies in rabbits and CD8(+) T cell responses in mice. Co-immunization with DNA and multimeric E2 scaffolds appears to offer a highly effective means of eliciting rapid, specific, and sustained immune responses that may be a useful approach for other vaccine targets.