Antibody Escaping Mechanism by Human Metapneumovirus

Human Metapneumovirus (HMPV) is one of the leading causes of respiratory illness globally, particularly in infants, the elderly, and immunocompromised individuals. Despite advances in vaccine and therapeutic antibody development, the emergence of antibody-resistant variants poses a critical threat to treatment efficacy. A deeper understanding of the mechanisms by which HMPV escape neutralization is essential for guiding antibody design and informing clinical strategies. In this proposal, the UTMB team, led by Dr. Xuping Xie, will establish reverse genetic systems for contemporary HMPV-A2 and HMPV-B2 strains, using genomic sequences provided by the AZ team. Each virus will be engineered to express a green fluorescent reporter to facilitate rapid, high-throughput analysis. These recombinant viruses will be rescued from BSR-T7/5/HEp-2 or BSR-T7/5/LLC-MK2 cells and assessed for sensitivity to a panel of monoclonal antibodies (mAbs) on Vero cells supplied by AZ. To define antibody escape mechanisms, we will serially pass each recombinant virus in the presence of individual mAbs. Emergent escape variants will be evaluated in neutralization assays to quantify shifts in mAb potency (IC50) compared to parental strains. Whole-genome sequencing will be performed to identify mutations, particularly in the F (fusion) protein, associated with resistance. UTMB will then generate recombinant viruses encoding these F protein mutations—individually and in combination—to delineate the molecular basis of escape. Follow-up neutralization studies will determine the contribution of specific mutations to resistance phenotypes.