Proteomic analysis of total spore proteins from Nosema pernyi and characterization of a novel spore wall protein, NpSWP13.

Microsporidia represent a group of eukaryotic, obligate intracellular parasites that form environmentally resistant spores. Spore wall proteins (SWPs) can mediate pathogen-host interactions for specific parasitism among different species. However, limited research has been conducted on SWPs inNosema pernyi that causes microsporidiosis in the economically-important Chinese oak silkworm, Antheraea pernyi. Here, we identified a total of 636 proteins fromN. pernyiusing LC-MS/MS, among which 8 SWPs were listed. A hydrophilic SWP13, whichhas identity with other homologous SWP13 among the Nosema genus, was identified both from nucleotide and peptide sequences. After the anti-NpSWP13 polyclonal antibody was produced, western blotting and immunohistochemicalanalysisshowedthat the protein exists inN. pernyi. Indirect immunofluorescence analysis (IFA) and immunoelectron microscopy (IEM) consistently demonstratedtheenrichment of NpSWP13 located in the endospore. Immunoprecipitation-Mass Spectrometry (IP-MS) analysis indicates NpSWP13 may interact with proteins in the midgut of silkworm. In this study, our results demonstrate thatNpSWP13 isa novel SWP subcellularly localized inN. pernyi.Our researchenhancesthe understanding of different SWPs in microsporidia and reveals possible mechanisms in specific infection among different Nosema species.