Cloning, expression and characterisation of antigen-specific recombinant bat immunoglobulin from the black flying fox (Pteropus alecto)

Jun Jet Hen^1,2Ariel Isaacs^2,3Benjamin Liang²Tony Schountz⁴Keith Chappell^2,3,5Paul R. Young^2,3,5Naphak Modhiran^1,3,5*Daniel Watterson^2,3,5*

• ¹The University of Queensland, Brisbane, Australia
• ²School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia, Australia
• ³Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, Australia, Brisbane, Queensland, Australia, Australia
• ⁴Department of Microbiology, Immunology and Pathology, Colorado State University, Colorado, United States
• ⁵The University of Queensland Australian Institute for Bioengineering and Nanotechnology, Saint Lucia, Australia

Bats are natural reservoir of viruses that cause severe disease in livestock and humans. Recent high-profile spillover events have directed significant attention towards the relationship between zoonotic viruses and antiviral immunity inherent to bats. Studies have highlighted that bats could harbour some deadly viruses without exhibiting outward symptoms. Various hypotheses have been proposed on how bats coexist with viruses, this includes dampened inflammation and altered innate immunity. However, there is limited literature on the humoral immune response in bats due to the scarcity of bat-specific reagents. To address this knowledge gap, we generated antigen-specific chimeric bat antibodies using recombinant antibody design techniques. This strategy involves combining the paratope of well-characterised antiviral antibodies with the IgG1 constant region of the black flying fox (Pteropus alecto). Characterisation of recombinant bat antibodies have revealed that they display canonical features of mammalian IgG. Additionally, recombinant bat antibodies display a binding and neutralising profile akin to human antibody counterparts. This approach provides much needed diagnostic tools and novel reagents to accelerate research into bat immune system.