A novel Kazal-type protease inhibitor from Aedes aegypti effective for NS2B-NS3 protease from the Zika virus and subtilases.

In recent years, Zika virus infections have spread geographically across various territories, including French Polynesia, the South Pacific, and South America, with a significant impact on Brazil. Severe Zika virus infections can lead to neurological complications, such as Guillain-Barré syndrome in adults. Furthermore, infection during pregnancy can result in microcephaly and other congenital brain malformations in the fetus. Aedes aegypti cohabits with humans and is the principal vector responsible for transmitting Zika virus to humans. Recent advances have elucidated the molecules involved in vector-pathogen interactions, but the role of mosquito protease inhibitors in arboviral infection remains unknown. In this work, we report the first mosquito Kazal-type inhibitor (Aakz211) from the mosquito Aedes aegypti that exhibits potent inhibitory activity against the Zika virus NS2B-NS3 protease (Ki = 42 nM). Furthermore, Aakz211 also exhibited potent inhibitory activity against subtilisin A (Ki = 4.7 nM) and proteinase K (Ki = 0.28 nM). Molecular docking analysis suggests that Aakz211 interacts with the catalytic pocket of NS2B-NS3 protease. Moreover, Aakz211 transcript levels are significantly upregulated in the Ae. aegypti ovaries 11 days post-blood meal, suggesting a functional role in mosquito reproduction. Collectively, our data demonstrates that Aakz211 could serve as a molecular scaffold for the development of novel antiviral therapeutics.