Morphological and molecular characterization of Nosema pernyi, a microsporidian parasite in Antheraea pernyi.

Nosema pernyi is a lethal pathogen that causes microsporidiosis in the Chinese oak silkworm, Antheraea pernyi. In this study, we presented its morphological and some molecular characteristics. The mature spores were measured to be 4.36 × 1.49 μm. The spore wall consisted of an electron-dense exospore (EX) and electron-lucent endospore (EN) layer. The polar filament (PF) was isofilar with 10-12 coils that were frequently arranged in a single row. Investigation results indicated that N. pernyi can infect the gut wall, silk glands, and other tissues. A full-length SMART cDNA library of N. pernyi was constructed, and then 824 expressed sequence tags (ESTs) were sequenced. Ninety unigenes, out of 197 assembled unigenes, showed significant homology to known genes of Nosema ceranae, Nosema bombycis, Encephalitozoon cuniculi, and other microsporidian species. Based on the nucleotide sequence of the α- and β-tubulin genes and amino acid sequence of actin gene, phylogenetic trees analysis showed that N. pernyi was closely related to Nosema philosamiae and Nosema antheraeae. It was correctly assigned to the Nosema group.