Title : Establishment of a high-throughput fluorescent antibody-to-membrane antigen assay to measure the humoral immune response against the varicella-zoster virus
Abstract:
Keywords:
varicella-zoster virus (VZV), fluorescent antibody-to-membrane antigen (FAMA), high content screening (HCS)
Varicella-zoster virus (VZV) is a highly contagious alpha-herpesvirus that infects more than 90% of people worldwide. Primary VZV infection results in Chickenpox (varicella), predominantly affecting children. Reactivation of latent VZV leads to shingles (herpes zoster), which mainly occurs in people aged 50 years and above, often accompanied with intense neuralgia. It is estimated that about one third of those who have had chickenpox will develop shingles. To date, there is still no specific cure for VZV-induced diseases, thus VZV infection is still prevalent and accounts for a significant disease burden worldwide.
Vaccination is among the most cost-effective ways for preventing chickenpox and shingles. Therefore, measuring the specific immunogenicity induced by the varicella vaccine is very crucial. The fluorescent antibody to membrane antigen (FAMA) test is a cell-based assay that uses VZV glycoproteins expressed on the surface of VZV-infected cells as antigens. Due to its high sensitivity and specificity, the FAMA test is regarded as the gold standard for measuring protective antibodies against VZV and serves as a reference method for evaluating other assays' performance.
However, the standard FAMA procedure is semi-quantitative, low-throughput, labor-intensive, and requires evaluation by trained technicians, which limits its widespread application. To overcome these challenges and to increase the applicability and robustness of the test, we developed a high content screening (HCS) based FAMA assay, which is quantitative, high-throughput, and overcomes the issue of subjectivity of observers in the standard FAMA test. Furthermore, we evaluated the stability of FAMA antigens under different storage conditions to find suitable conditions for stable storage of antigens from the same batch, thus reducing the lot-to-lot variation of FAMA antigens, as well as the time and labor required to prepare FAMA antigens.
