Respiratory syncytial virus (RSV) and influenza A (IAV) and B (IBV) viruses infect humans throughout their life with exceptionally high rates of re-infection. Serological assays are commonly used to diagnose and characterize host immune responses against microbial pathogens acquired by natural infection or vaccination. The current methods are mostly based on enzyme immunoassay (EIA) or other conventional methods in a single analyte format. Presently, there is a need to shift from single analytical methods to microarray format which enables the detection of antibodies against multiple targets in a rapid and cost-effective manner.

In this study, a highly sensitive single analyte EIA method was used for serological analyses in children’s sera. In addition, multiplex microarray immunoassay (MAIA) methods were developed for rapid and simultaneous detection of IgG antibodies against seven viral antigens (H1N1pdm09 vaccine ag, IAV H1N1, IAV H3N2, IBV Victoria, IBV Yamagata, RSV and adenovirus hexon protein). We found out that MAIA is well suitable for large-scale serosurveillance and vaccine immunity studies. We followed-up virus-specific immunity by MAIA in response to natural infection and vaccination in a large cohort of 0-2 year old children. Our serological findings showed a high rate of respiratory virus infections and reinfections in young children.

The applicability of MAIA in vaccine immunity studies was also analysed. We developed a specific, sensitive, sample and antigen saving assay for simultaneous detection of IgM and IgG antibodies against H1N1pdm09 vaccine ag and IBV Yamagata. MAIA showed excellent correlation with EIA and a good correlation with hemagglutination inhibition assay in measurement of vaccine-induced antibodies in sera of Pandemrix-vaccinated adults.