Additional Study Information: The HIV Vaccine Trials Network, Division of AIDS, and Columbia University Irving Medical Center are conducting a trial to learn about the safety and effectiveness of two new experimental HIV vaccines. This is a first-in-human phase 1 clinical trial where we will be testing 2 study vaccines, CH505M5 N197D mRNA-gp160 and CH505 TF mRNA-gp160. The goal is to understand if the study products are safe to use in people not living with HIV, and whether they can get the study products without being too uncomfortable. We also want to understand how people's immune systems respond to the study products at different dosages, and whether people develop a certain type of cell in their lymph nodes that researchers think is important for protecting against HIV. There will be 4 groups in this study. Each group will receive the same study products across the same schedule. The only difference between the groups is the dosage of both study vaccines. The first study vaccine will be administered at three different timepoints, two months apart. The second study vaccine will be administered six months after the first injection. You will receive a total of 8 injections during the study (2 injections at each of the 4 injection visits). If you are aged 18-55, in overall good health and not living with HIV, you may be able to participate. Your participation in this study will be for about 11 months. Study procedures will include blood draws, injections, leukapheresis (a procedure to collect white blood cells), and a lymph node biopsy. Because the vaccines have not been given to people before, we do not know what all the risks may be. Common side effects from all vaccines include headache, fever, chills, rash, aches and pains, nausea, dizziness, and fatigue (feeling tired). You will receive a minimum total compensation amount of $1600 for completing all required study visits and procedures.