Contribution of a Novel Pertussis Toxin-Like Factor in Mediating Persistent Otitis Media Longhuan Ma 1† , Colleen Sedney 1† , Yang Su 2 , Kalyan K. Dewan 1 , Bodo Linz 1 and Eric T. Harvill 1 * 1 Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States, 2 Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States Chronic otitis media (COM) is the long-term infection and inflammation of the middle ears typically caused by upper respiratory tract pathogens that are able to ascend the Eustachian tube. Our understanding of contributing factors is limited because human otopathogens cannot naturally colonize or persist in the middle ears of mice. We recently described a natural COM in mice caused by Bordetella pseudohinzii and proposed this as an experimental system to study bacterial mechanisms of immune evasion that allow persistent infection of the middle ear. Here we describe a novel pertussis toxin (PTx)-like factor unique to B. pseudohinzii, apparently acquired horizontally, that is associated with its particularly efficient persistence and pathogenesis. The catalytic subunit of this toxin, PsxA, has conserved catalytic sites and substantial predicted structural homology to pertussis toxin catalytic subunit PtxA. Deletion of the gene predicted to encode the catalytic subunit, psxA, resulted in a significant decrease in persistence in the middle ears. The defect was not observed in mice lacking T cells, indicating that PsxA is necessary for persistence only when T cells are present. These results demonstrate the role of a novel putative toxin in the persistence of B. pseudohinzii and its generation of COM. This PsxA- mediated immune evasion strategy may similarly be utilized by human otopathogens, via other PTx-like toxins or alternative mechanisms to disrupt critical T cell functions necessary to clear bacteria from the middle ear. This work demonstrates that this experimental system can allow for the detailed study of general strategies and specific mechanisms that otopathogens use to evade host immune responses to persist in the middle ear to cause COM. Keywords: chronic otitis media (COM), Bordetella pseudohinzii, PTx-like toxin, T cell function, middle ear INTRODUCTION Otitis media (OM) is the infection and inflammation of the middle ears, and a major reason for doctor visits and antibiotic prescriptions among children (Schilder et al., 2016). Many causative agents of OM begin as colonizers of the nasopharynx and then ascend the Eustachian tube via poorly understood mechanisms. While most infections are resolved by host immune mechanisms, some result in persistent infections of the middle ear. A variety of human pathogens have been Frontiers in Cellular and Infection Microbiology | www.frontiersin.org March 2022 | Volume 12 | Article 795230 1 Edited by: Brian J. Akerley, University of Mississippi Medical Center, United States Reviewed by: Kristian Riesbeck, Lund University, Sweden Luchang Zhu, Houston Methodist Research Institute, United States *Correspondence: Eric T. Harvill harvill@uga.edu † These authors have contributed equally to this work and share first authorship Specialty section: This article was submitted to Bacteria and Host, a section of the journal Frontiers in Cellular and Infection Microbiology Received: 14 October 2021 Accepted: 17 February 2022 Published: 11 March 2022 Citation: Ma L, Sedney C, Su Y, Dewan KK, Linz B and Harvill ET (2022) Contribution of a Novel Pertussis Toxin-Like Factor in Mediating Persistent Otitis Media. Front. Cell. Infect. Microbiol. 12:795230. doi: 10.3389/fcimb.2022.795230 ORIGINAL RESEARCH published: 11 March 2022 doi: 10.3389/fcimb.2022.795230