Objectives/Goals: A key strategy in generating a protective HIV vaccine is the elicitation of broadly neutralizing antibodies (bnAbs), capable of neutralizing a large diversity of HIV-1 isolates. The goal of this study is to identify molecular signatures of HIV bnAb development early in life, to guide the development of a successful pediatric HIV vaccine strategy. Methods/Study Population: We previously defined HIV neutralization breadth in 40 ART-naive children living with HIV. Single-cell RNAseq was performed utilizing peripheral blood mononuclear cells (PBMCs) from the top 5 children with highest neutralization breadth scores and compared their transcriptome to that of PBMCs from 5 children that did not develop neutralization breadth within the first three years of life. Additionally, we incorporated analysis of PBMCs from 5 healthy uninfected children, matched to our experimental groups by race, ethnicity, and gender. Results/Anticipated Results: We expect that a distinct host transcriptional profile is associated with the development of HIV-specific antibody neutralization breadth in early life. Discussion/Significance of Impact: Identifying immune cell transcriptional profiles associated with neutralization breadth will lead to more targeted vaccine approaches for eliciting the appropriate B cell responses and provide an invaluable screening tool allowing early identification of vaccine candidates with the potential to induce bnAbs.