Detection of Residual Proteins UL5 and UL29 Using a Targeted Proteomics Approach in HSV529, a Replication-Deficient HSV-2 Vaccine Candidate.

HSV529 is a replication defective human herpes simplex virus (HSV)-2 viral vaccine candidate in clinical development. An engineered cell line is required to support production of HSV529 by transgenic expression of the HSV-1 transcription factors UL5 (HELI) and UL29 (DNBI). These 2 genes have been deleted from the vaccine candidate to ensure replication deficiency, and the transgene products are thus impurities that must be monitored in the final product. Multiple reaction monitoring (MRM) is a mass spectrometry (MS) workflow that can be used to quickly develop targeted protein detection and quantitation methods. An MRM method was developed for detection of the HSV-1 proteins UL5 and UL29 based on results from nano-liquid chromatography-MS/MS protein analysis of HSV529 material. Sensitivity, specificity, and linearity of response for the MRM workflow were established using high-flow ultra-performance liquid chromatography coupled to a tandem quadrupole mass analyzer. Results show that residual UL5 and UL29 proteins can be detected in the HSV529 candidate, and that MRM analysis provides the appropriate sensitivity and specificity required for quantitation. The transition from nano-flow to ultra-performance driven chromatography was found to improve method robustness without compromising the sensitivity of the assay.

27Al and 31P NMR spectroscopy method development to quantify aluminum phosphate in adjuvanted vaccine formulations.

A novel qNMR method is described for the quantitative determination of total aluminum and phosphate in aluminum phosphate (AlPO4) adjuvanted vaccine samples using solution 27Al and 31P nuclear magnetic resonance (NMR) spectroscopy. External standard calibrations of AlPO4 solutions established excellent linearity in the range of 15-40 × 10-3 M and additional studies determined the level of detection for both nuclei. A commercialized combination vaccine product (Quadracel®), along with several individual adsorbed antigen components used in the vaccine were employed as model systems for method development. The developed method is also capable of quantitating the free phosphate (i.e. the fraction not bound to AlPO4 particles) in adjuvanted vaccines. This study is the first demonstration of a solution NMR method that is suitable for measuring total aluminum, and free and total phosphate concentrations in vaccine formulations consisting of antigen(s) adsorbed to aluminum adjuvant, in a single analytical workflow.

Tuberculosis vaccine candidate: Characterization of H4-IC31 formulation and H4 antigen conformation.

Tuberculosis (TB) is one of the leading causes of death worldwide, making the development of effective TB vaccines a global priority. A TB vaccine consisting of a recombinant fusion protein, H4, combined with a novel synthetic cationic adjuvant, IC31®, is currently being developed. The H4 fusion protein consists of two immunogenic mycobacterial antigens, Ag85 B and TB10.4, and the IC31® adjuvant is a mixture of KLK, a leucine-rich peptide (KLKL5KLK), and the oligodeoxynucleotide ODN1a, a TLR9 ligand. However, efficient and robust methods for assessing these formulated components are lacking. Here, we developed and optimized phase analysis light scattering (PALS), electrical sensing zone (ESZ), and Raman, FTIR, and CD spectroscopy methods to characterize the H4-IC31 vaccine formulation. PALS-measured conductivity and zeta potential values could differentiate between the similarly sized particles of IC31® adjuvant and the H4-IC31 vaccine candidate and could thereby serve as a control during vaccine formulation. In addition, zeta potential is indicative of the adjuvant to antigen ratio which is the key in the immunomodulatory response of the vaccine. ESZ was used as an orthogonal method to measure IC31® and H4-IC31 particle sizes. Raman, FTIR, and CD spectroscopy revealed structural changes in H4 protein and IC31® adjuvant, inducing an increase in both the ß-sheet and random coil content as a result of adsorption. Furthermore, nanoDSF showed changes in the tertiary structure of H4 protein as a result of adjuvantation to IC31®. Our findings demonstrate the applicability of biophysical methods to characterize vaccine components in the final H4-IC31 drug product without the requirement for desorption.