Identification and subcellular localization of the chaperonin NbCCTβ in Nosema bombycis.

Nosema bombycis, the causative agent of pebrine disease, poses a significant threat to the silkworm industry due to its negative impact on silkworm health and productivity. The chaperonin-containing tailless complex polypeptide (CCT) plays a crucial role in protein folding, and its β subunit (CCTβ) is essential for the proper folding of cytoskeletal proteins, such as actin and tubulin. In this study, we cloned and expressed the NbCCTβ gene from N. bombycis and generated polyclonal anti-NbCCTβ antibodies to further assess NbCCTβ. Immunofluorescence subcellular localization studies revealed that NbCCTβ is primarily located in the cytoplasm and shows extensive co-localization with NbCCTδ and NbCCTθ during the proliferation stage of the pathogen, suggesting its involvement in key cellular processes. Moreover, NbCCTβ was found to co-localize with actin and tubulin, indicating a role in cytoskeletal assembly. Notably, NbCCTβ expression increased with infection duration, and RNA interference effectively reduced its expression, indicating its importance in N. bombycis survival and proliferation. These findings highlight NbCCTβ as a potential target for interventions aimed at mitigating pebrine disease, providing a foundation for future strategies to protect the silkworm industry.