Abalone Withering Syndrome Disease Dynamics: Infectious Dose and Temporal Stability in Seawater

Abstract

Withering syndrome (WS) is a chronic bacterial disease that affects numerous northeastern Pacific abalone Haliotis spp. The causative agent of WS is an obligate intracellular Rickettsiales‐like bacterium (WS‐RLO) that remains unculturable, thereby limiting our understanding of WS disease dynamics. The objectives of our study were to (1) determine the temporal stability of WS‐RLO DNA outside of its abalone host in 14°C and 18°C seawater, (2) develop a standardized protocol for exposing abalones to known concentrations of WS‐RLO DNA, and (3) calculate the dose of WS‐RLO DNA required to generate 50% infection prevalence (ID50) in the highly cultured red abalone Haliotis rufescens. The WS‐RLO stability trials were conducted in October 2016, February 2017, and June 2017. A quantitative PCR (qPCR) analysis was used to quantify bacterial DNA for 7 d in seawater collected at an abalone farm in southern California, where the pathogen is now endemic. For all trials and temperature treatments, WS‐RLO DNA was unstable in seawater for longer than 2 d. To determine an ID50, groups of uninfected juvenile red abalone were subjected to 3‐h bath exposures with four concentrations of WS‐RLO at 0, 103, 104, and 105 DNA copies/mL. Abalone feces were tested biweekly for the presence of WS‐RLO DNA, and abalone tissues were sampled 9 weeks postinfection for histological and qPCR analyses. The ID50 results indicated that our protocol was successful in generating WS‐RLO infections; a pathogen dose of 2.3 × 103 DNA copies/mL was required to generate a 50% infection prevalence in red abalone tissue. These findings are critical components of disease dynamics that will help assess WS transmission risk within and among abalone populations and facilitate appropriate management and restoration strategies for both wild and cultured abalone species in WS‐endemic areas.

Genotyping of Haliotis discus hannai and machine learning models to predict the heat resistant phenotype based on genotype

“…These datasets can be used to elucidate preliminary gene markers such as heat shock proteins (HSPs), which function in transcription and translation in abalone (Kyeong et al, 2020). Heat stress also alters energy metabolism and increases susceptibility to various pathogens, such as Vibrio parahemolyticus (Nam et al, 2016;Crosson et al, 2020), affecting the reproduction and growth of abalones (Swezey et al, 2020) as well as the metabolic rate in the digestive tract (Frederick et al, 2022). To our knowledge, no genotyping studies or datasets are available for Haliotis discus hannai other than a population assessment (Nam et al, 2021).…”

Whole genome resequencing reveals signatures of rapid selection in a virus‐affected commercial fishery

“…Marine infectious diseases are responsible for incremental and mass mortalities in a variety of wildlife groups, including keystone and habitat‐forming taxa (Clemente et al, 2014; Harvell & Lamb, 2020; Harvell et al, 2007; Martin et al, 2016; Montecino‐Latorre et al, 2016), and species supporting wild commercial fisheries (Cawthorn, 2011; Crosson et al, 2020; Lafferty et al, 2015; Marty et al, 2010). The Australian blacklip abalone ( Haliotis rubra ), a species targeted by the world’s largest wild abalone fisheries and a rapidly expanding aquaculture industry (FAO FishStat, 2021), was heavily impacted by disease between 2006 and 2010 (Mayfield et al, 2012).…”

Whole genome resequencing reveals signatures of rapid selection in a virus affected commercial fishery

“…Marine infectious diseases are responsible for incremental and mass mortalities in a variety of wildlife groups, including keystone and habitat forming taxa (Harvell et al 2007;Clemente et al2014;Martin et al 2016;Montecino-Latorre et al 2016;Harvell & Lamb 2020), and species supporting wild commercial fisheries (Marty et al 2010;Cawthorn 2011;Lafferty et al 2015;Crosson et al 2020). The Australian blacklip abalone (Haliotis rubra ), a species targeted by the world's largest wild abalone fisheries and a rapidly expanding aquaculture industry (FAO Fishstat 2021), was heavily impacted by disease between 2006 and 2010 (Mayfield et al 2012).…”