Laminin and a Plasmodium ookinete surface protein inhibit melanotic encapsulation of Sephadex beads in the hemocoel of mosquitoes

Alon Warburg*, Alex Shtern, Noa Cohen, Noa Dahan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


In refractory mosquitoes, melanotic encapsulation of Plasmodium ookinetes and oocysts is a commonly observed immune response. However, in susceptible mosquitoes, Plasmodium oocysts develop extracellularly in the body cavity without being recognized by the immune system. Like Plasmodium gallinaceum oocysts, negatively charged carboxymethyl (CM)-Sephadex beads implanted in the hemocoel of Aedes aegypti female mosquitoes were not usually melanized, but were coated with mosquito-derived laminin. Conversely, electrically neutral G-Sephadex beads were routinely melanized. Since mosquito laminin coated both CM-Sephadex beads and P. gallinaceum oocysts, we hypothesized that laminin prevents melanization of both. To test this hypothesis, we coated cyanogen-bromide-activated G-Sephadex beads with laminin, recombinant P. gallinaceum ookinete surface protein (PgS28) or bovine serum albumin (BSA). Beads were implanted into the abdominal body cavity of female Aedes aegypti and retrieved 4 days later. Uncoated controls as well as BSA-coated G-Sephadex beads were melanized in a normal manner. However, melanization of beads coated with mouse laminin, Drosophila L2-secreted proteins or PgS28 was markedly reduced. Fluorescent antibody labeling showed that PgS28-coated beads had adsorbed mosquito laminin on their surface. Thus, mosquito laminin interacting with Plasmodium surface proteins probably masks oocysts from the mosquito's immune system, thereby facilitating their development in the body cavity.

Original languageAmerican English
Pages (from-to)192-199
Number of pages8
JournalMicrobes and Infection
Issue number2
StatePublished - Feb 2007

Bibliographical note

Funding Information:
We thank C. Jaffe and Y. Shlomai for assistance in various aspects of this study. This research was supported by: The Center for the Study of Emerging Diseases (CSED), Yeshaya Horowitz Foundation. N.D. is the recipient of a fellowship from The Kuvin Center for the Study of Infectious and Tropical Diseases.


  • Aedes aegypti
  • Basement membrane
  • Laminin
  • Oocyst
  • Plasmodium


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