# Engineering T3 and T7 host range to target protein receptors and guide bacterial evolution

## TL;DR

Researchers modified T3 and T7 phages to target a nanobody receptor, expanding their host range and guiding bacterial evolution for potential therapeutic use.

## Contribution

The study demonstrates how phage host range and evolutionary steering can be engineered using nanobody receptors.

## Key findings

- T3 and T7 phages were successfully retargeted to bind a nanobody receptor.
- Nanobody binding significantly expanded the host range of T3 and T7.
- T7's reduced efficiency of plating was rescued by nanobody expression.

## Abstract

Phage engineering holds significant potential for overcoming the challenges that limit phage therapy. A promising yet underutilized approach is engineering phage host range to target specific receptors and guiding bacterial evolution into a desirable trajectory, referred to as evolutionary steering. This requires balancing binding interactions between native and desired receptors, though it is unclear how balancing binding interactions affects host range and resulting evolutionary trajectories. To provide insights, we surveyed a suite of phage engineering methods to program protein-protein interactions between phage and bacteria and then measured host range expansion and evolutionary trajectories. We engineered T3 and T7, both LPS-targeting phages, to target a proteinaceous nanobody receptor. In addition, we discovered that the capsid plays a role in phage host range and can be a potential target for host range expansion. Together, these studies increase the therapeutic potential for T3 and T7, and more broadly for LPS-targeting phages.

•T3 and T7 were retargeted to bind a nanobody receptor•Nanobody binding expands T3 and T7 host range•T7 antigen display on capsid reduces EOP, which is rescued by nanobody expression•Desired evolutionary steering is guided by target receptor binding and expression

T3 and T7 were retargeted to bind a nanobody receptor

Nanobody binding expands T3 and T7 host range

T7 antigen display on capsid reduces EOP, which is rescued by nanobody expression

Desired evolutionary steering is guided by target receptor binding and expression

Bacteriology; Microbial biotechnology; Microbiology