Seasonal occurrence of Perkinsus spp. and tissue distribution of P. olseni in clam (Soletellina acuta) from coastal waters of Wuchuan County, southern China

Seasonal occurrence of Perkinsus spp. infection in the wild clam, Soletellina acuta, along the coast of Wuchuan County, southern China was investigated over one year using conventional polymerase chain reaction (PCR) method combined with sequencing technique. The tissue distribution of P. olseni in (S. acuta) was also compared among four tissues, namely the gill, mantle, digestive gland, and siphon, using the real-time PCR method. S. acuta populations were concurrently infected by two Perkinsus spp., P. olseni and P. beihaiensis, among different sampling months. Prevalence of Perkinsus spp. infection in the clam ranges from 9.4% to 50.6% and is significantly different among seasons, and was significantly higher in the March sampling period (spring), while it was significantly lower in the June sampling period (summer). Different seasonal patterns of prevalence occur between P. olseni and P. beihaiensis infection in the clam (S. acuta). S. acuta is more prone to be infected by P. olseni than by P. beihaiensis. The results of qPCR assay demonstrated that positive rate of P. olseni in S. acuta differs significantly among the four tissues. P. olseni infected the gill and mantle tissues more preferably than the siphon tissue; however, the concentration of the parasite did not differ significantly among the four tissues.