Plasmodium vivax: A Monoclonal Antibody Recognizes a Circumsporozoite Protein Precursor on the Sporozoite Surface

Authors

Lilia Gonzalez-Ceron, Centro de Investigacion de Paludismo, Instituto Nacional de Salud Publica
Mario H. Rodriguez, Centro de Investigacion Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Publica
Robert A. Wirtz, Department of Entomology, Walter Reed Army Institute of Research
Barbara J. Sina, University of Maryland at College Park
Olga L. Palomeque, Centro de Investigacion de Paludismo, Instituto Nacional de Salud Publica
Jose A. Nettel, Centro de Investigacion de Paludismo, Instituto Nacional de Salud Publica
Victor Tsutsumi, Departamento de Patologıa Experimental, Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional

Date of this Version

1998

Citation

EXPERIMENTAL PARASITOLOGY 90, 203–211 (1998)

Comments

U.S. Government Work

Abstract

The major surface circumsporozoite (CS) proteins are known to play a role in malaria sporozoite development and invasion of invertebrate and vertebrate host cells. Plasmodium vivax CS protein processing during mosquito midgut oocyst and salivary gland sporozoite development was studied using monoclonal antibodies which recognize different CS protein epitopes. Monoclonal antibodies which react with the CS amino acid repeat sequences by ELISA recognized a 50- kDa precursor protein in immature oocyst and additional 47- and 42- kDa proteins in older oocysts. A 42-kDa CS protein was detected after initial sporozoite invasion of mosquito salivary glands and an additional 50-kDa precursor CS protein observed later in infected salivary glands. These data confirm previous results with other Plasmodium species, in which more CS protein precursors were detected in oocysts than in salivary gland sporozoites. A monoclonal antibody (PvPCS) was characterized which reacts with an epitope found only in the 50-kDa precursor CS protein. PvPCS reacted with all P. vivax sporozoite strains tested by indirect immunofluorescent assay, homogeneously staining the sporozoite periphery with much lower intensity than that produced by anti-CS repeat antibodies. Immunoelectron microscopy using PvPCS showed that the CS protein precursor was associated with peripheral cytoplasmic vacuoles and membranes of sporoblast and budding sporozoites in development oocysts. In salivary gland sporozoites, the CS protein precursor was primarily associated with micronemes and sporozoite membranes. Our results suggest that the 50-kDa CS protein precursor is synthesized intracellularly and secreted on the membrane surface, where it is proteolytically processed to form the 42-kDa mature CS protein. These data indicate that differences in CS protein processing in oocyst and salivary gland sporozoites development may occur.