Cost-effective production of a vaginal protein microbicide to prevent HIV transmission

Abstract

A series of small-molecule microbicides has been developed for vaginal delivery to prevent heterosexual HIV transmission, but results from human clinical trials have been disappointing. Protein-based microbicides, such as HIV-specific monoclonal antibodies, have been considered as an alternative approach. Despite their promising safety profile and efficacy, the major drawback of such molecules is the economy of large-scale production in mammalian cells, the current system of choice. Here, we show that an alternative biomanufacturing platform is now available for one of the most promising anti-HIV antibodies (2G12). Our data show that the HIV-neutralization capability of the antibody is equal to or superior to that of the same antibody produced in CHO cells. We conclude that this protein production system may provide a means to achieve microbicide ingredient manufacture at costs that would allow product introduction and manufacture in the developing world.

Fig. 1.

Analysis of the 2G12 purification process. (A) Coomassie staining after SDS/PAGE (reducing conditions) of fractions taken during 2G12 purification by protein A chromatography. (B) Western blot (reducing conditions) of the 2G12 heavy and light chains from fractions taken during the same purification process. The presence of the heavy chain (HC), light chain (LC), and degradation products (D) are shown with arrows. An excess of light chain can be seen in the flow-through lane. Lanes are marked as follows: C, control; M, markers; L, load; F, flow-through; and W, wash. Numbers represent elution fractions 6, 7, 8–12 pooled, 13, and 14.

Fig. 2.

SDS/PAGE of selected fractions from non-protein A purification procedure. Lanes are marked as follows: M, markers; CR, transgenic maize crude extract; SpH 7.4-SpH 7.6, pool of eluted fractions at pH 7.4–7.6 from S-Sepharose FF cation exchanger; and IpH 6.5–6.0, pool of eluted fractions at pH 6.5–6.0 from IMAC.