Plasmodium exposure alters midgut epithelial cell dynamics during the immune memory in Anopheles albimanus.

Immunological priming in insects is defined as a previous contact with non-virulent pathogens, which induces protection after a second virulent infection. The mechanism of this process is not well understood. We have observed midgut DNA synthesis (endoreplication) in Plasmodium berghei exposure mosquitoes (primed) and after the immune challenge, which could be an essential component of the priming response in the mosquito. Endoreplication requires cell cycle components re-direction to make multiple DNA copies. Therefore, it is fundamental to understand the role of cell cycle components in priming. Here, we analyzed the expression of the cyclins A, B, E, and AurkA, and the endoreplication components NOTCH and HNT in the mosquito Anopheles albimanus; after priming with non-infective Plasmodium berghei and challenged with an infective P. berghei. The overexpression of cell cycle elements occurred seven days after priming with a quick reduction 24 h after the challenge. Hnt and NOTCH overexpression occurred 24 h after priming. Antimicrobial peptide cecropin is quickly overexpressed after 24 h in primed mosquitoes, then is downregulated at day seven and overexpressed again after parasite challenge. We also found that DNA synthesis occurs in cells with different nuclear sizes, suggesting a change in midgut epithelial dynamics after Plasmodium exposure. Inhibition of DNA synthesis via cisplatin revealed that DNA synthesis is required for priming to limit Plasmodium infection. Our results indicate the importance of cell cycle components on DNA synthesis and Notch pathway during priming response in An. albimanus mosquitoes.