TY - JOUR

T1 - Tissue-specific transcriptional reprogramming in the fat body is associated with long-term immune protection in Galleria mellonella after immune priming with Bacillus species

AU - Polenogova, Olga V.

AU - Rotskaya, Ulyana N.

AU - Artemchenko, Anna S.

AU - Klementeva, Tatyana N.

AU - Glupov, Viktor V.

N1 - Olga V. Polenogova, Ulyana N. Rotskaya, Anna S. Artemchenko, Tatyana N. Klementeva, Viktor V. Glupov, Tissue-specific transcriptional reprogramming in the fat body is associated with long-term immune protection in Galleria mellonella after immune priming with Bacillus species, Journal of Insect Physiology, Volume 175, 2026, 105092, ISSN 0022-1910, https://doi.org/10.1016/j.jinsphys.2026.105092. This research was funded by the Russian Science Foundation (grant No. 22-76-10051) and the Federal Fundamental Scientific Research Program for 2026-2030, project number FWGS-2026-0005, which partly supported the biochemical analysis.

PY - 2026/12

Y1 - 2026/12

N2 - Background Immune priming in insects is well-documented, but its persistence across larval development and the tissue-specific mechanisms remain poorly understood. Whether closely related bacteria differ in inducing durable memory and whether protection correlates with transcriptional reprogramming in specific organs is unclear. Methods First-instar Galleria mellonella larvae were orally primed with inactivated Bacillus thuringiensis subsp. galleriae (Bt), B. cereus (Bc), or B. subtilis (Bs) and challenged at fourth-instar with virulent Bt subsp. galleriae . Survival was recorded for 7 days, and phenoloxidase activity was measured in hemolymph 24 h post-challenge. In parallel, fourth-instar larvae received the same cells; at 12 h, transcription of 10 immune genes was analyzed in hemocytes, fat body, and midgut, and lysozyme-like activity was measured in the midgut at 24 h. Results Immune priming was species-specific: Bt conferred strong homologous protection against Bt subps. galleriae (82% survival), Bc moderate cross-protection (60%), Bs none (27%). Protection correlated specifically with Toll pathway activation and AMP induction in the fat body, whereas Bs triggered strong hemocyte responses yet failed to activate the fat body or restore PO activity. Conclusion Oral priming in G. mellonella is species-specific and organ-compartmentalized. Effective long-term protection requires transcriptional reprogramming in the fat body, whereas hemocyte-restricted activation is insufficient – revealing that immune memory is organized at the organ level rather than systemically. These findings link tissue-specific responses to protective efficacy.

AB - Background Immune priming in insects is well-documented, but its persistence across larval development and the tissue-specific mechanisms remain poorly understood. Whether closely related bacteria differ in inducing durable memory and whether protection correlates with transcriptional reprogramming in specific organs is unclear. Methods First-instar Galleria mellonella larvae were orally primed with inactivated Bacillus thuringiensis subsp. galleriae (Bt), B. cereus (Bc), or B. subtilis (Bs) and challenged at fourth-instar with virulent Bt subsp. galleriae . Survival was recorded for 7 days, and phenoloxidase activity was measured in hemolymph 24 h post-challenge. In parallel, fourth-instar larvae received the same cells; at 12 h, transcription of 10 immune genes was analyzed in hemocytes, fat body, and midgut, and lysozyme-like activity was measured in the midgut at 24 h. Results Immune priming was species-specific: Bt conferred strong homologous protection against Bt subps. galleriae (82% survival), Bc moderate cross-protection (60%), Bs none (27%). Protection correlated specifically with Toll pathway activation and AMP induction in the fat body, whereas Bs triggered strong hemocyte responses yet failed to activate the fat body or restore PO activity. Conclusion Oral priming in G. mellonella is species-specific and organ-compartmentalized. Effective long-term protection requires transcriptional reprogramming in the fat body, whereas hemocyte-restricted activation is insufficient – revealing that immune memory is organized at the organ level rather than systemically. These findings link tissue-specific responses to protective efficacy.

KW - Antimicrobial peptides

KW - Immune priming

KW - Phenoloxidase activity

KW - Specific immune memory

KW - Tissue-specific immunity

KW - Иммунный прайминг

KW - Специфическая иммунная память

KW - Фенолоксидазная активность

KW - Антимикробные пептиды

KW - Тканеспецифический иммунитет

UR - https://www.mendeley.com/catalogue/ae344d73-0474-39e6-89d1-219c3022503b/

UR - https://www.scopus.com/pages/publications/105055515005

U2 - 10.1016/j.jinsphys.2026.105092

DO - 10.1016/j.jinsphys.2026.105092

M3 - Article

C2 - 42950983

VL - 175

JO - Journal of Insect Physiology

JF - Journal of Insect Physiology

SN - 0022-1910

M1 - 105093

ER -