Stability, Enrichment, and Quantification of Total and HPV16-specific IgG Present in First-void Urine

First-void urine (FVU) samples, containing human papillomavirus (HPV)-specific IgG from female genital tract secretions, provide a non-invasive option for disease monitoring and vaccine impact assessment. This study explores the utility of FVU for IgG quantification, exploring stability and compatibility with DNA preservation methods, alongside various IgG enrichment methods. Healthy female volunteers provided FVU and serum samples. FVU was collected with or without urine conservation medium (UCM) and stored under different conditions before freezing at -80 °C. Four IgG enrichment methods were tested on FVU samples. All samples were analyzed using three total human IgG quantification assays and an in-house HPV16-specific IgG assay. Samples stored with UCM buffer had higher total and HPV16-specific IgG concentrations (p ≤ 0.01) and IgG remained stable for at least 14 days at room temperature. Among IgG enrichment methods, Amicon filtration (AM) and AM combined with Melon Gel purification (AM-MG) provided similar HPV16-IgG concentrations, correlating strongly with serum levels. Protein G magnetic beads methods were incompatible with time-resolved fluorescence-based assays. This study highlights FVU as a reliable and convenient sample for IgG quantification, demonstrating stability for at least 14 days at room temperature and compatibility with UCM DNA preservation. It emphasizes the need to select appropriate IgG enrichment methods and confirms the suitability of both AM and AM-MG methods, with a slightly better performance for AM-MG.