Publication abstract

Enterocytozoon hepatopenaei sp. nov. (Microspora: Enterocytozoonidae), a parasite of the black tiger shrimp Penaeus monodon (Decapoda: Penaeidae): fine structure and phylogenetic relationships.

S. Tourtip, S. Wongtripop, K. Sritunyalucksana, G.D. Stentiford*, K.S. Bateman*, S. Sriurairatana, K. Chayaburakul, K. Chavadej, B. Withyachumnarnkul

Microsporidia are obligate intracellular, spore-forming parasites infecting many types of animals including insects, birds, fish, crustaceans and mammals. The black tiger shrimp Penaeus monodon is rarely infected by Microsporidia. Thai P. monodon farms reported infections by multiple pathogens, including viruses, bacteria and Microsporidia. The growth rate of the cultured shrimp was markedly reduced and referred to as monodon slow-growth syndrome (MSGS). Although the primary cause of MSGS has not been identified, it is unlikely to be the Microsporidia since many MSGS shrimp were free from it, at least by histology. Microsporidia-infected shrimp postlarvae were also found and studied under light and electron microscopy. The developmental stages from merogony to sporogony were completed in the cytoplasm of host hepatopancreatic cells. Nuclear fission was observed at the merogony stage in early plasmodial development stage and spores were finally formed in the same plasmodial membrane. The mature spores measuring 0.6 μm x 1 μm with monokaryon arrangement and 3-5 coils of the polar tube were found. The mature spore wall was composed of three layers of different electron density: Exospore layer (2 nm), the middle electron-lucent layer (10 nm) and the innermost thinnest endospore layer, which wrapped around sporoplasm. Specific DNA primers prepared by cloning from DNA extracts of microsporidian-infected hepatopancreatic tissue were used for polymerase chain reaction. The PCR product, at 784 bp, was observed and correlated with morphological evidence of the microsporidian infection. The sequence of this parasite 784 bp PCR product was 84% homologous to that of Enterocytozoon bieneusi. Together with a similar morphology to E. bieneusi, this new species is designated the name “Enterocytozoon hepatopenaei”.

Reference

S. Tourtip, S. Wongtripop, K. Sritunyalucksana, G.D. Stentiford*, K.S. Bateman*, S. Sriurairatana, K. Chayaburakul, K. Chavadej, B. Withyachumnarnkul (2009) Enterocytozoon hepatopenaei sp. nov. (Microspora: Enterocytozoonidae), a parasite of the black tiger shrimp Penaeus monodon (Decapoda: Penaeidae): fine structure and phylogenetic relationships. Journal of Invertebrate Pathology