Novel diagnostic tests for the putative agent of bacterial gill disease in Pacific razor clams (Siliqua patula).

Nuclear inclusion X (NIX) is a gamma proteobacteria that infects the nuclei of gill epithelial cells in Pacific razor clams. NIX has been associated with clam die-offs in coastal Washington. A quantitative PCR (qPCR) assay was developed to detect NIX in Pacific razor clams, and assay specificity was confirmed by chromogenic in situ hybridization (CISH). Both tests were applied to evaluate NIX infections in wild Pacific razor clams collected during spring 2019. Consistent with results from earlier histopathological assessments, qPCR and CISH indicated 100% prevalence in razor clams from two Washington beaches and 0% prevalence from two Alaskan beaches.