This is a presolicitation notice for a sole-source contract to provide nucleic acid-based reagents for in vivo transient protein expression to the National Cancer Institute. The work will focus on using these reagents to investigate preventive strategies against HIV/SIV and HTLV in preclinical models. The contract is intended for award to the Trustees of The University of Pennsylvania - Penn Medicine in Philadelphia, PA. The justification for a sole-source award is to ensure consistency and direct comparability with materials used in prior studies conducted by the AMRVS.