First report of Perkinsus marinus occurrence associated with wild Pacific oysters Crassostrea gigas from the west coast of Korea

Seung-Hyeon Kim; S D N K Bathige; Hyung-Bae Jeon; Donghyun Lee; Kwang-Sik Choi; Hyoun Joong Kim; Kyung-Il Park

doi:10.1016/j.jip.2024.108119

First report of Perkinsus marinus occurrence associated with wild Pacific oysters Crassostrea gigas from the west coast of Korea

J Invertebr Pathol. 2024 Apr 27:204:108119. doi: 10.1016/j.jip.2024.108119. Online ahead of print.

Authors

Seung-Hyeon Kim¹, S D N K Bathige², Hyung-Bae Jeon², Donghyun Lee¹, Kwang-Sik Choi³, Hyoun Joong Kim⁴, Kyung-Il Park⁵

Affiliations

¹ Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea.
² Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea; Research Institute of Fisheries in Offshore Wind Farm (RIFO), Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea.
³ Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea.
⁴ Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea; Research Institute of Fisheries in Offshore Wind Farm (RIFO), Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea. Electronic address: hjkim@kunsan.ac.kr.
⁵ Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea; Research Institute of Fisheries in Offshore Wind Farm (RIFO), Kunsan National University, 558 Daehakro, Gunsan 54150, Republic of Korea. Electronic address: kipark@kunsan.ac.kr.

PMID: 38679368
DOI: 10.1016/j.jip.2024.108119

Abstract

This study reports the occurrence of Perkinsus marinus associated with wild Pacific oyster (Crassostrea gigas) specimens collected along the west coast of Korea. Confirmation of P. marinus presence was achieved by conventional PCR using World Organization of Animal Health (WOAH)-recommended primers that specifically targeted regions of the rDNA locus (ITS1, 5.8S, and ITS2). Sequencing of 10 samples revealed two distinct sequences differing by a single base pair, indicating potential haplotype variability. One sequence closely resembled the P. marinus strain found in Maryland, USA, whereas the other exhibited divergence, indicative of species diversity in the Korean strain, as was evident from the haplotype network analysis. Further validation involved the Ray's Fluid Thioglycollate Medium (RFTM) assay, which initially yielded inconclusive results, possibly due to low infection intensity. Subsequently, RFTM and 2 M NaOH assays conducted on the isolates in the present study, cultured P. marinus cells in standard DMEM/F12 medium, and a positive P. marinus strain (ATCC 50509), revealed characteristic hypnospores of P. marinus upon Lugol's iodine staining. These comprehensive investigations underscore the conclusive confirmation of P. marinus in Korean waters and mark a significant milestone in our understanding of the distribution and characteristics of this parasite in previously unreported regions.

Keywords: Crassostrea gigas; In vitro culture; PCR; Pacific oysters; Perkinsus marinus.