Detection of Haplosporidium nelsoni in Oysters from China Coast

Oysters of nineteen cities from China coast were investigated in our study. The localization of Haplosporidium nelsoni-like (MSX) Plasmodia was detected by light microscopy. In Situ hybridization of infected tissue section was conducted with the H.nelsoni-specific DNA probe MSX1347. DNA was extracted from the oysters Crassostrea gigas, Crassostrea plicatula, Crassostrea rivularis, Ostrea crenulifera for PCR amplification. MSX-A´, MSX-B and Hap-F₂, Hap-R₂ were applied to amplify the MSX. PCR amplification of genomic DNA with primer pairs MSX-A´+B and HAP-F₂+R₂ yielded the expected products for 573 bp, 239 bp, respectively. These PCR products were sequenced and the similarities from C. gigas was 99% in the 16S-like rRNA region of H.nelsoni. Subsequently, MSX was identified in Crassostrea Plicatula. However, MSX was not detected in oysters, C. rivularis, O. crenulifera. Our study demonstrates H. nelsoni in oysters presents between 24 and 40 at north latitude in China. These results approved that H. nelsoni occured in China and the distribution of MSX could be relative to host and latitude.