Abstract
The production of envelope glycoproteins (Envs) for use as HIV vaccines is challenging. The yield of Envs expressed in stable Chinese Hamster Ovary (CHO) cell lines is typically 10–100 fold lower than other glycoproteins of pharmaceutical interest. Moreover, Envs produced in CHO cells are typically enriched for sialic acid containing glycans compared to virus associated Envs that possess mainly high-mannose carbohydrates. This difference alters the net charge and biophysical properties of Envs and impacts their antigenic structure. Here we employ a novel robotic cell line selection strategy to address the problems of low expression. Additionally, we employed a novel gene-edited CHO cell line (MGAT1- CHO) to address the problems of high sialic acid content, and poor antigenic structure. We demonstrate that stable cell lines expressing high levels of gp120, potentially suitable for biopharmaceutical production can be created using the MGAT1- CHO cell line. Finally, we describe a MGAT1- CHO cell line expressing A244-rgp120 that exhibits improved binding of three major families of bN-mAbs compared to Envs produced in normal CHO cells. The new strategy described has the potential to eliminate the bottleneck in HIV vaccine development that has limited the field for more than 25 years.
Highlights
The development of a safe, effective, and affordable HIV vaccine is a global public health priority
Rapid development of Chinese Hamster Ovary (CHO) cell lines for vaccine production produced by transient transfection in MGAT1- CHO exhibited enhanced binding to three major families of glycan dependent Broadly neutralizing monoclonal antibodies (bN-mAbs) (PG9, PGT128, and PGT121/10-1074) compared to rgp120s produced in normal CHO or 293 cell lines
To explore the utility of MGAT1CHO cells as a cellular substrate for biopharmaceutical manufacturing of HIV vaccines, we attempted to create a stable MGAT1- CHO cell line expressing a variant of the A244rgp120 envelope protein that was used in the RV144 HIV-1 vaccine trial [1]
Summary
The development of a safe, effective, and affordable HIV vaccine is a global public health priority. After more than 30 years of HIV research, a vaccine with these properties has yet to be described. The only clinical study to show that vaccination can prevent HIV infection is the 16,000-person RV144 trial carried out in Thailand between 2003 and 2009 [1]. This study involved immunization with a recombinant canarypox virus vector to induce cellular immunity [2,3,4] and a bivalent recombinant gp120 vaccine designed to elicit protective antibody responses [5,6,7]. The protective efficacy of this vaccination regimen was low (31.2%, P = 0.04).
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