s systems, we engineered fusion constructs juxtaposing regions of the ectodomains of Pfs25 and Pfs48/45 with Grl1p, the major granule lattice protein of *Tetrahymena*, and expressed these in *E. coli.* In the current study, we show that the resulting chimera self-assembled into particles with peak diameters centering on 38 and 25 nm, respectively. Additionally, and perhaps more importantly, Grl1p increased the solubility of the recombinant antigens by more than 100-fold allowing high-yield purification of recombinant fusion constructs with no need for protein refolding. Malaria antigens retained their conformation-dependent transmission-blocking epitopes in the *E. coli*-derived particles, and Pfs25-containing G-SOMEs generated high-titer transmission blocking antibody production in test animals.

2. Materials and methods {#sec2}
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2.1. Materials {#sec2.1}
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Mouse monoclonal antibody 4B7 against Pfs25 \[[@bib20]\] was obtained through the Malaria Research and Reference Reagent Resource Center at the NIH. Monoclonal antibody 3E12 against Pfs48/45 \[[@bib31]\] was obtained from Dr. Nicholas MacDonald (Malaria Vaccine Branch, NIH). Monoclonal antibodies 1G2 and 4F7 against Pfs25 were obtained from Dr. David Narum and Dr. Patrick Duffy (Laboratory of Malaria Immunology and Vaccinology, NIH) \[[@bib25]\]. Mouse monoclonal antibody 32F81 against Pfs25 \[[@bib32]\], rat monoclonal antibodies 85RF45.1 and 85RF45.2b against Pfs48/45 \[[@bib33]\], and purified *P. falciparum* gametes and gametocytes were obtained from TropIQ Health Sciences (Nijmegen, the Netherlands).

2.2. Expression construct design {#sec2.2}
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Pfs25, Pfs48/45^10C^, and Grl1p genes were synthesized by a commercial vendor (Genscript). Coding sequences for the Pfs25 (amino acids 22--193) and Pfs48/45 10C fragments (amino acids 159--426 \[[@bib11]\]) lacking native N- and C-terminal signal peptide domains, were codon-harmonized for expression in *E. coli* as described previously \[[@bi