Genomic discovery and functional characterization of novel antimicrobial and anti-Plasmodium peptides in the malaria vector Anopheles gambiae

The innate immune system of Anopheles gambiae , the primary human malaria vector, utilizes a diverse array of factors and mechanisms to target Plasmodium parasites along with other microbes. However, the current understanding of its antimicrobial peptide (AMP) defenses is limited to only a few canonical members, thereby underestimating the true complexity of the mosquito’s immune response. To explore the breadth and functional specificity of An. gambiae AMP-mediated immunity, we conducted a comprehensive in silico genomic survey, identifying thirty-six previously uncharacterized putative AMPs. Transcriptional profiling revealed distinct developmental and tissue-specific expression patterns, ranging from strict larval specificity to enrichment in the salivary glands and Malpighian tubules. Functional characterization of synthetic peptides validated the four novel broad-spectrum AMPs, Anolarvin, Konopsin, Sialicin, and Cryptophelin. Notably, Konopsin was identified as an Immune Deficiency (IMD) pathway-regulated effector enriched in Malpighian tubules, while the larval-specific Anolarvin appeared essential for developmental homeostasis. Mechanistically, these AMPs demonstrated significant diversity, with some acting as non-lytic bacteriostatic agents and others functioning through membrane permeabilization. Crucially, the salivary gland-enriched AMPs Sialicin and Cryptophelin exhibited potent in vitro activity against Plasmodium falciparum sporozoites, reducing parasite viability by ~81% and ~75%, respectively. These findings reveal a mechanistically diverse and spatially specialized mosquito AMP-mediated immunity. The discovery of endogenous AMPs with anti-sporozoite activity provides promising new candidates for the development of malaria transmission-blocking interventions.