# Novel ACE2 binding in bat merbecoviruses expands potential host range

## TL;DR

This study shows that certain bat viruses can bind to ACE2 receptors in different animals, suggesting they could potentially spread to humans via intermediate hosts.

## Contribution

The study reveals novel ACE2 binding patterns in merbecoviruses, expanding understanding of their host range and zoonotic potential.

## Key findings

- HKU5 binds exclusively to Pipistrellus abramus ACE2, while P. khulii-2011 interacts solely with Murina aurata ACE2.
- BtVs-SC2013 and HKU25 bind to ACE2 in multiple species, including mink and pangolin, indicating potential intermediate hosts.
- Carbohydrate at position 329 on ACE2 influences binding specificity, with structural and mutagenesis experiments confirming its role.

## Abstract

Coronaviruses often cross species barriers, with receptor binding dictating their host range and zoonotic potential. Merbecoviruses, such as MERS-CoV, typically utilize DPP4 as their receptor, whereas Sarbecoviruses, like SARS-CoV, rely on ACE2. This study explores the receptor usage of four merbecoviruses identified in Vespertilionidae bats: HKU5, BtVs-SC2013, HKU25, and P. khulii-2011. Our findings reveal species-specific binding to bat ACE2: HKU5 binds exclusively to Pipistrellus abramus ACE2, P. khulii-2011 interacts solely with Murina aurata ACE2, BtVs-SC2013 recognizes ACE2 from Murina aurata and Myotis myotis, and HKU25 displays the broadest binding range. Beyond bats, BtVs-SC2013 binds to mink ACE2, while HKU25 interacts with both mink and pangolin ACE2, hinting at potential intermediate hosts for cross-species transmission. We also elucidated the mechanism behind HKU5’s selective binding preference for P. abramus ACE2. Structural analysis and mutagenesis revealed that a carbohydrate attached at position 329 play a crucial role. Introducing the N-glycosylation site into P. abramus ACE2 eliminated binding, while its removal from P. pipistrellus ACE2, combined with two additional mutations, restored it. Moreover, we pinpointed key residues in mink ACE2 essential for binding the receptor-binding domain (RBD) of BtVs-SC2013 and HKU25. These findings illuminate the receptor usage and host specificity of bat merbecoviruses, enhancing our understanding of their potential for cross-species transmission and adaptation.

Coronaviruses jumping from bats to humans—sometimes via another animal—can trigger outbreaks or pandemics. To infect a host, a virus must latch onto a receptor, a molecular doorway, on its cells. We studied four bat viruses from the merbecovirus group, related to the Middle East Respiratory Syndrome (MERS) virus, to explore their ability to cross species barriers. Previously thought to bind the DPP4 receptor, we found these viruses actually target ACE2, the same receptor SARS uses. Each virus prefers ACE2 from specific bats, with two also binding to mink and pangolin ACE2—suggesting these animals could bridge the gap to humans. We discovered that sugar molecules on ACE2, especially at one key spot, act like a shield, blocking some viruses from attaching. This research reveals how viruses adapt to new hosts, offering clues about their potential to jump to humans. Understanding these receptor preferences could help predict and prevent future outbreaks.