Particle-based Co-delivery of HIV immunogens as Next-generation HIV Vaccines: Tailored immunogens (such as Envs, monomers, native and/or native-like trimers, nucleic acids/RNA such as mRNAs, self-amplifying RNAs) combined with an effective multivalent antigenic display on nanoparticles for delivery may provide a strategy to promote strong and long-lived neutralizing antibody responses against HIV and direct affinity maturation toward HIV neutralizing antibodies. The objective of this contract is to develop, evaluate, and optimize nanoparticle-based platforms to elicit broadly neutralizing antibodies against the membrane proximal external region (MPER) of the HIV-1 gp41 protein.