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ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.
Sec. Bacteria and Host
Volume 14 - 2024 | doi: 10.3389/fcimb.2024.1425624
This article is part of the Research Topic Host-Bacteria Interactions in Fish Pathogens View all 7 articles

Tad pili contribute to the virulence and biofilm formation of virulent Aeromonas hydrophila

Provisionally accepted
Hasan C. Tekedar Hasan C. Tekedar 1*Fenny Patel Fenny Patel 1Jochen Blom Jochen Blom 2Matt J. Griffin Matt J. Griffin 1Geoffrey C. Waldbieser Geoffrey C. Waldbieser 3Salih Kumru Salih Kumru 4Hossam Abdelhamed Hossam Abdelhamed 1Vandana Dharan Vandana Dharan 1Larry A. Hanson Larry A. Hanson 1Mark L. Lawrence Mark L. Lawrence 1
  • 1 Mississippi State University, Starkville, United States
  • 2 University of Giessen, Giessen, Germany
  • 3 Warmwater Aquaculture Research Unit, Agricultural Research Service (USDA), Stoneville, Mississippi, United States
  • 4 Recep Tayyip Erdoğan University, Rize, Rize, Türkiye

The final, formatted version of the article will be published soon.

    Type IV pili (T4P) are versatile proteinaceous protrusions that mediate diverse bacterial processes, including adhesion, motility, and biofilm formation. Aeromonas hydrophila, a Gramnegative facultative anaerobe, causes disease in a wide range of hosts. Previously, we reported the presence of a unique Type IV class C pilus, known as tight adherence (Tad), in virulent Aeromonas hydrophila (vAh). In the present study, we sought to functionalize the role of Tad pili in the pathogenicity of A. hydrophila ML09-119. Through a comprehensive comparative genomics analysis of 170 A. hydrophila genomes, the conserved presence of the Tad operon in vAh isolates was confirmed, suggesting its potential contribution to pathogenicity. Herein, the entire Tad operon was knocked out from A. hydrophila ML09-119 to elucidate its specific role in A. hydrophila virulence. The absence of the Tad operon did not affect growth kinetics but significantly reduced virulence in catfish fingerlings, highlighting the essential role of the Tad operon during infection. Biofilm formation of A. hydrophila ML09-119 was significantly decreased in the Tad operon deletant. Absence of the Tad operon had no effect on sensitivity to other environmental stressors, including hydrogen peroxide, osmolarity, alkalinity, and temperature, however, it was more sensitive to low pH conditions. Scanning electron microscopy revealed that the Tad mutant had rougher surface structure during log phase growth than the wildtype strain, indicating the absence of Tad impacts the outer surface of vAh during cell division, of which the biological consequences are unknown. These findings highlight the role of Tad in vAh pathogenesis and biofilm formation, signifying the importance of T4P in bacterial infections.

    Keywords: A. hydrophila, Virulence, type IV pili, Tad (Tight adherence), host-pathogen interaction

    Received: 30 Apr 2024; Accepted: 01 Jul 2024.

    Copyright: © 2024 Tekedar, Patel, Blom, Griffin, Waldbieser, Kumru, Abdelhamed, Dharan, Hanson and Lawrence. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Hasan C. Tekedar, Mississippi State University, Starkville, United States

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