Antibody-mediated inhibition of Aedes aegypti midgut trypsins blocks sporogonic development of Plasmodium gallinaceum

Mohammed Shahabuddin, Francisco J.A. Lemos, David C. Kaslow, Marcelo Jacobs-Lorena

Research output: Contribution to journalArticlepeer-review


The peritrophic matrix (PM) that forms around a blood meal is a potential barrier for Plasmodium development in mosquitoes. Previously, we have shown that to traverse the PM, Plasmodium ookinetes secrete a prochitinase and that an inhibitor of chitinase blocks further parasite development. Here we report that it is the mosquito trypsin that activates the Plasmodium prochitinase. Trypsin was identified as the chitinase-activating enzyme by two criteria: (i) trypsin activity and activating activity comigrated on one-dimensional gels, and (ii) activating activity and penetration of the PM by Plasmodium parasites were both hindered by trypsin-specific inhibitors. Subsequently, we examined the effect of antitrypsin antibodies on the parasite life cycle. Antibodies prepared against a recombinant blackfly trypsin effectively and specifically inhibited mosquito trypsin activity. Moreover, when incorporated into an infective blood meal, the antitrypsin antibodies blocked infectivity of Aedes aegypti mosquitoes by Plasmodium gallinaceum. This block of infectivity could be reversed by exogenously provided chitinase, strongly suggesting that the antibodies act by inhibiting prochitinase activation and not on the parasite itself. This work led to the identification of a mosquito antigen, i.e., midgut trypsin, as a novel target for blocking malaria transmission.

Original languageEnglish (US)
Pages (from-to)739-743
Number of pages5
JournalInfection and immunity
Issue number3
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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