The Role of NbTMP1, a Surface Protein of Sporoplasm, in Nosema Bombycis Infection
Background: Nosema bombycis is a unicellular eukaryotic pathogen of the silkworm, Bombyx mori, and a hazard to the silkworm industry. Because of its long incubation period and horizontal and vertical transmission, it is a quarantine pathogen in sericulture. The microsporidian life cycle includes a dormant extracellular phase and intracellular proliferation phase. The proliferation period is the most active period of the microsporidian. This period lacks spore wall protection and may be the most
... and may be the most susceptible stage for control. Results: The N. bombycis protein (NBO_76g0014) was identified as a transmembrane protein and named NbTMP1. It is not homologous with proteins from other microsporidia and species. NbTMP1 has a transmembrane region of 23 amino acids at the N-terminus. Indirect immunofluorescence analysis (IFA) results suggest that NbTMP1 is secreted on the plasma membrane as the spores develop. Western blot and qRT-PCR analysis showed that NbTMP1 expressed in all development stages of N. bombycis in infected cells and in the silkworm midgut. Down-regulation of NbTMP1 expression resulted in significant inhibition of N. bombycis proliferation. Conclusions: We confirmed that NbTMP1 is a membrane protein of N. bombycis. Reduction of the transcription level of NbTMP1 significantly inhibited N. bombycis proliferation, and this protein may be a target for the selective breeding of N. bombycis resistant silkworm strains.