Full-length G glycoprotein directly extracted from rabies virus with detergent and then stabilized by amphipols in liquid and freeze-dried forms.

Pathogen surface antigens are at the forefront of the viral strategy when invading host organisms. These antigens, including membrane proteins (MPs), are broadly targeted by the host immune response. Obtaining these MPs in a soluble and stable form constitutes a real challenge, regardless of the application purposes (e.g. quantification/characterization assays, diagnosis, and preventive and curative strategies). A rapid process to obtain a native-like antigen by solubilization of a full-length MP directly from a pathogen is reported herein. Rabies virus (RABV) was used as a model for this demonstration and its full-length G glycoprotein (RABV-G) was stabilized with amphipathic polymers, named amphipols (APols). The stability of RABV-G trapped in APol A8-35 (RABV-G/A8-35) was evaluated under different stress conditions (temperature, agitation, and light exposure). RABV-G/A8-35 in liquid form exhibited higher unfolding temperature (+6°C) than in detergent and was demonstrated to be antigenically stable over 1 month at 5°C and 25°C. Kinetic modeling of antigenicity data predicted antigenic stability of RABV-G/A8-35 in a solution of up to 1 year at 5°C. The RABV-G/A8-35 complex formulated in an optimized buffer composition and subsequently freeze-dried displayed long-term stability for 2-years at 5, 25, and 37°C. This study reports for the first time that a natural full-length MP extracted from a virus, complexed to APols and subsequently freeze-dried, displayed long-term antigenic stability, without requiring storage under refrigerated conditions.

Blinding Approaches for Large Clinical Trials Involving Sub-Cutaneous Administration of Biologicals - A CMC Perspective.

A well-controlled clinical trial is one of the critical steps to evaluate the efficacy and safety of novel medicaments. The use of a placebo is employed in several types of clinical trials in order to set a baseline against which the efficacy of the investigational drug is evaluated. An ideal placebo should match the final formulation as close as possible such that the patient/health care providers are unable to identify any difference. This is difficult for high concentration biologic intended for subcutaneous administration, mainly because of their color and viscosity. Currently, the challenge is overcome by using opaque labels or by unblinded pharmacists, both solutions are expensive. The present study provides an efficient alternative where a protein excipient (recombinant albumin) is used to prepare a placebo for biologicals. We have demonstrated that the use of recombinant albumin can match the color of the active when used in the right quantity. The evaluated solution is highly flexible and has the potential to match the color of different biopharmaceuticals at different concentrations/formulations.