The role of NbTMP1, a surface protein of sporoplasm, in Nosema bombycis infection

Abstract

Background Nosema bombycis is a unicellular eukaryotic pathogen of the silkworm, Bombyx mori, and is an economic and occupational hazard in the silkworm industry. Because of its long incubation period and horizontal and vertical transmission, it is subject to quarantine measures in sericulture production. The microsporidian life-cycle includes a dormant extracellular phase and intracellular proliferation phase, with the proliferation period being the most active period. This latter period lacks spore wall protection and may be the most susceptible stage for control. Methods In order to find suitable target for the selective breeding of N. bombycis-resistant silkworm strains, we screen highly expressed membrane proteins from the transcriptome data of N. bombycis. The subcellular localization of the candidate protein was verified by Indirect immunofluorescence analysis (IFA) and immunoelectron microscopy (IEM), and its role in N. bombycis proliferation was verified by RNAi. Results The N. bombycis protein (NBO_76g0014) was identified as a transmembrane protein and named NbTMP1. It is homologous with hypothetical proteins NGRA_1734 from Nosema granulosis. 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 was expressed in all developmental stages of N. bombycis in infected cells and in the silkworm midgut. Downregulation 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.

Identification and subcellular localization analysis of membrane protein Ycf 1 in the microsporidian Nosema bombycis

“…NTT is a key strategy adopted by microsporidia to exploit host cells ( Heinz et al, 2014 ). Zheng et al (2021) reported that the membrane protein of N. bombycis NbTMP1 may get involved in the proliferation of N. bombycis .…”

Expression of anti-NbHK single-chain antibody in fusion with NSlmb enhances the resistance toNosema bombycisin Sf9-III cells

“…The produced monoclonal antibodies (mAbs) were harvested and assessed as documented previously (Huang et al ., 2018 a ). The mouse monoclonal antibody isotyping kit (Roche, Switzerland) was employed to assay the subtypes of mAb immunoglobulin G (IgG) as described by the manufacturer (Zheng et al ., 2021).…”

The gut commensal bacterium Enterococcus faecalis LX10 contributes to defending against Nosema bombycis infection in Bombyx mori

“…10,11 As an important intestinal pathogen, N. bombycis can be transmitted horizontally through per os infection as well as vertically from adults to offspring. 12 The pathogen N. bombycis is well adapted to the silkworm gut environment, where it germinates and penetrates the gut epithelium, absorbing nutrients and energy from the host and exporting cytotoxic compounds through the cell membrane. 13 This species has a sophisticated and unique mechanism for infecting host cells, involving a rigid spore wall and a coiled polar tube joined to an anchoring disc at the apical part of the spore.…”

“…As an important intestinal pathogen, N. bombycis can be transmitted horizontally through per os infection as well as vertically from adults to offspring 12 . The pathogen N. bombycis is well adapted to the silkworm gut environment, where it germinates and penetrates the gut epithelium, absorbing nutrients and energy from the host and exporting cytotoxic compounds through the cell membrane 13 .…”