Objectives: Understanding the antibody response in monkeypox virus (MPXV)-infected and uninfected individuals is essential for developing next-generation MPXV vaccines. This study aimed to characterize neutralizing antibody (NAb) and antibody-dependent cellular cytotoxicity (ADCC) responses in both groups, providing insights into immune protection and vaccine design. Methods: A recombinant vaccinia Tian Tan (VTT) virus was utilized to develop high-throughput luciferase-reporter-based neutralization and ADCC assays. These assays were applied to evaluate the presence and levels of poxvirus-specific antibodies in MPXV-infected and uninfected individuals, including those vaccinated with vaccinia-based vaccines. Results: Poxvirus-specific NAbs were detected in MPXV-negative individuals with prior vaccinia vaccination. However, MSM individuals exhibited significantly lower pre-existing NAb levels than non-MSM individuals, potentially contributing to their higher susceptibility to MPXV infection. In individuals with mild MPXV infection, robust NAb and ADCC responses were observed, regardless of vaccination status. Additionally, HIV-positive individuals demonstrated comparable antibody responses following MPXV infection. Conclusions: These findings highlight the potential role of pre-existing NAbs in MPXV susceptibility and the strong immune response elicited by mild MPXV infection. Further research is needed to determine whether MPXV-specific antibodies mitigate disease progression, which could inform the development of effective MPXV vaccines.

Human respiratory syncytial virus (HRSV) is a major cause of severe lower respiratory tract infections in infants, young children, and older adults worldwide. With the approval of nirsevimab and HRSV vaccines, accurate measurement of neutralizing antibody levels has become essential for vaccine evaluation, immunization strategy design, and seroepidemiology. The plaque reduction neutralization test (PRNT) remains the gold standard, but it is slow, low-throughput, and requires high biosafety. In recent years, newer methods including focus reduction neutralization testing (FRNT), pseudovirus neutralization testing (PNT), and fluorescent/luminescent reporter virus systems (RVSs) have improved speed and throughput while maintaining high specificity. This review summarizes the principles, performance, applications, and standardization challenges of these assays, offering methodological guidance for HRSV research and prevention in China.