A nested quantitative PCR assay for detection of the hard clam pathogen Mucochytrium quahogii (=QPX) in environmental samples

Progress in understanding and managing QPX disease outbreaks hard clams ( Mercenaria mercenaria ) has been limited by lack of insight into basic aspects the biology ecology opportunistic pathogen Mucochytrium quahogii (formerly or Quahog Parasite Unknown). One barrier is that while several methods have able to detect M. seawater sediment, its abundance was typically too low for reliable quantification those methods. Here we describe development validation a sensitive, -specific, nested quantitative PCR (nqPCR) assay following Minimum Information Publication Quantitative Real-Time Experiments (MIQE) guidelines. The reaches theoretical limit detection (LOD) at 3 copies per reaction with excellent efficiency, linearity, minimal sample inhibition. functionality evaluated quantifying sediment samples, which revealed broadly distributed throughout marine environment, detected 75% mean estimated 0.21 cells mg 0.55 ml bottom seawater, 0.02 surface seawater. most prevalent abundant suggesting flocculent layer sediment-water interface an important environmental reservoir where may interact clams. This will serve as valuable tool better understand dynamics offers model guide similar assays other microbes present similarly abundance.