Dirasantha, O. | Search bioRxiv

bioRxiv2026

Targeted Delivery of Nucleic Acid and Protein Cargos into Primary Human Hematopoietic Stem Cells Using Bacteriophage T4

Here, we report, for the first time, delivery of mRNA and/or protein payloads into primary adult human hematopoietic stem cells (HSCs) using a bacteriophage-derived nanoparticle vector. We have been developing a new category of bacteriophage T4-engineered nanoparticles, termed "artificial viral vectors" (AVVs), for delivering therapeutic nucleic acid and protein complexes into human cells. Using a defined in vitro assembly-line platform, we decorated the capsid surface with mRNA and protein complexes through two outer capsid proteins, Hoc (highly antigenic outer capsid protein) and Soc (small outer capsid protein). First, we displayed a Hoc-protein G fusion protein to which HSC-targeted monoclonal antibodies (mAbs) are attached. Then we decorated the nanoparticle with the Soc-fused HIV-TAT molecule to create a positively charged capsid surface with cell penetrating function. Reporter mRNA molecules are then displayed on the capsid surface and the nanoparticle is coated with lipids. Such T4-AVVs transduced HSCs and delivered GFP and Luciferase reporter mRNAs at levels as high as 20% efficiency and exhibited targeted Ab-dependent phenotypes. Furthermore, we demonstrate simultaneous delivery of both protein and mRNA payloads, by decorating the capsid with mRNA and [~]507 kDa tetrameric {beta}-galactosidase. The AVV-transduced HSCs maintain viability, and once optimized, the T4-AVV platform will provide enormous versatility to target various types of human cells and deliver next generation therapies for cancer and genetic diseases.

bioengineering↗

bioRxiv2023

Infection pressure in apes has driven selection for CD4 alleles that resist lentivirus (HIV/SIV) infection

Simian immunodeficiency viruses (SIVs) comprise a large group of primate lentiviruses that endemically infect African monkeys. HIV-1 spilled over to humans from this viral reservoir, but the spillover did not occur directly from monkeys to humans. Instead, a key event was the introduction of SIVs into great apes, which then set the stage for infection of humans. Here, we investigate the role of the lentiviral entry receptor, CD4, in this key and fateful event in the history of SIV/HIV emergence. First, we reconstructed and tested ancient forms of CD4 at two important nodes in ape speciation, both prior to the infection of chimpanzees and gorillas with these viruses. These ancestral CD4s fully supported entry of diverse SIV isolates related to the viruses that made this initial jump to apes. In stark contrast, modern chimpanzee and gorilla CD4 orthologs are more resistant to these viruses. To investigate how this resistance in CD4 was gained, we acquired CD4 gene sequences from 32 gorilla individuals of two species, and identified alleles that encode 8 unique CD4 protein variants. Functional testing of these identified variant-specific differences in susceptibility to virus entry. By engineering single point mutations from resistant gorilla CD4 variants into the permissive human CD4 receptor, we demonstrate that acquired substitutions in gorilla CD4 did convey resistance to virus entry. We provide a population genetic analysis to support the theory that selection is acting in favor of more and more resistant CD4 alleles in ape species harboring SIV endemically (gorillas and chimpanzees), but not in other ape species that lack SIV infections (bonobos and orangutans). Taken together, our results show that SIV has placed intense selective pressure on ape CD4, acting to propagate SIV-resistant alleles in chimpanzee and gorilla populations.

microbiology↗