Infection kinetics of Tenacibaculum maritimum on the abraded skin of Japanese flounder Paralichthys olivaceus

Abstract

Tenacibaculum maritimum is the gliding bacterium that causes tenacibaculosis, an ulcerative disease in marine fish. In this study, we conducted a pathogenicity test to assess the effect of skin abrasion on the infectivity of gliding and non-gliding strains of T. maritimum, NUF1128 and NUF1129, respectively, and investigated the infection kinetics by enumeration and immunohistochemical observation of the adhered and proliferated T. maritimum on the abraded skin of Japanese flounder Paralichthys olivaceus. In the pathogenicity test, Japanese flounder whose dorsal skin was abraded with a cotton swab or blade or tip of dorsal fin was clipped with scissors were immersed for 30 min in seawater containing 106 CFU/mL of cultured NUF1128 or NUF1129 cells. As a result 100% mortality was achieved in the fish groups pretreated with blades or scissors followed by challenged with NUF1128. NUF1129 was unable to induce infection regardless of the treatments applied. The infection kinetic studies revealed that NUF1128 adhered more readily than NUF1129 to dermal connective tissues which were exposed by abrasion with blades and subsequently proliferated mainly in the dermal connective tissues and perimysium.