Comparison of Perkinsus marinus, Perkinsus chesapeaki and Perkinsusolseni infections in eastern oysters (Crassostrea virginica)

摘要

Determining the infectivity and pathogenicity of Perkinsus spp. to economically important bivalves can provide valuable information to identify which Perkinsus sp. should be of concern when their geographical ranges overlap and to predict the potential impact of introduced Perkinsus species. The objectives of this study were to compare the infection of eastern oysters (Crassostrea virginica) when challenged with cultured P. marinus, P. chesapeaki or P. olseni, and to determine the associated host defense responses. A control group consisted of oysters that received saline. At the end of the study, parasite numbers as determined by the body burden assay were significantly higher in P. marinus challenged oysters than in the other groups. Parasite numbers in P. chesapeaki and P. olseni challenged oysters, and control oysters were generally low except for a few heavily infected oysters. These heavily infected oysters were likely infected with P. marinus. Detection of P. marinus by PCR in the control group indicating the oysters were likely infected with P. marinus before challenge. Mortality was highest in P. marinus challenged oysters. Little difference in the oyster host defense responses to the three Perkinsus spp. was observed. Oyster tissue lysates from all groups of oysters however inhibited the growth of P. chesapeaki and P. olseni but not the growth of P. marinus which may explain the significantly higher parasite numbers in P. marinus challenged oysters.