# The immune serine protease pathways in Anopheles gambiae

> **NIH NIH R21** · OKLAHOMA STATE UNIVERSITY STILLWATER · 2024 · $186,459

## Abstract

Phenoloxidase-catalyzed melanization and Spӓtzle-induced synthesis of antimicrobial proteins are
universal insect defense responses against pathogen or parasite infection. In mosquitoes such as
Anopheles gambiae, melanotic encapsulation is effective against certain malaria parasites.
Phenoloxidases are produced as inactive prophenoloxidases (proPOs) and, upon recognition of the
invading organism, activated by a serine protease (SP) cascade. POs generate reactive compounds to
kill pathogens. The SP system may activate proSpӓtzle to induce antimicrobial proteins that destroy
the infectious agents. Some of the clip-domain SPs known as CLIPs may participate in the cleavage
activation of TEP1, a complement-like factor vital for the mosquito anti-Plasmodium responses. Having
successfully expressed >30 Manduca and Drosophila proCLIPs in insect cells, we will use the
baculovirus system to produce 12 A. gambiae proCLIPs as wild-type and mutant proteins with FDNR
substituting their original activation sites. We plan to activate the twelve mutants using Manduca sexta
PAP3 (a FDNR-specific CLIP with >21 substrate proteins from insects) and then determine specificity
of the resulting CLIPs by multiplex substrate profiling. Highly specific and sensitive substrates will be
developed to examine the catalytic CLIPs and, in the next project, explore how melanization is linked
to TEP1 activation and how some catalytic CLIPs are regulated by A. gambiae serpins. We will test 30
possible reactions of SP  SP/SPH/PO/Spӓtzle. Based on the results, we plan to reconstitute a part of
the SP-SPH system for proPO and proSpӓtzle-1 activation. Acquired functional data are to be validated
by in vivo infection tests via collaboration with mosquito parasitologists in the future.

## Key facts

- **NIH application ID:** 10788867
- **Project number:** 1R21AI180325-01
- **Recipient organization:** OKLAHOMA STATE UNIVERSITY STILLWATER
- **Principal Investigator:** HAOBO JIANG
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $186,459
- **Award type:** 1
- **Project period:** 2023-12-07 → 2025-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10788867

## Citation

> US National Institutes of Health, RePORTER application 10788867, The immune serine protease pathways in Anopheles gambiae (1R21AI180325-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10788867. Licensed CC0.

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