Search

Human metapneumovirus (hMPV) belongs to the Pneumoviridae family and is closely related to respiratory syncytial virus (RSV). The surface fusion (F) glycoprotein mediates viral fusion and is the primary target of neutralizing antibodies against hMPV. Here we report 113 hMPV-F specific monoclonal antibodies (mAbs) isolated from memory B cells of human donors. We characterize the antibodies' germline usage, epitopes, neutralization potencies, and binding specificities. We find that unlike RSV-F specific mAbs, antibody responses to hMPV F are less dominant against the apex of the antigen, and the majority of the potent neutralizing mAbs recognize epitopes on the side of hMPV F. Furthermore, neutralizing epitopes that differ from previously defined antigenic sites on RSV F are identified, and multiple binding modes of site V and II mAbs are discovered. Interestingly, mAbs that bind preferentially to the unprocessed prefusion F show poor neutralization potency. These results elucidate the immune recognition of hMPV infection and provide novel insights for future hMPV antibody and vaccine development. Here, Xiao et al. isolate a large panel of antibodies against human metapneumovirus fusion protein from human B cells, and characterize their epitopes, neutralization activities, and antigen binding specificity, providing a useful framework for understanding the immune response against hMPV. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection and related morbidity and mortality in infants. Passive immunization with an RSV‐neutralizing antibody can provide rapid protection to this vulnerable population. Proof‐of‐concept for this approach has been demonstrated by palivizumab; however, the use of this antibody is generally restricted to the highest‐risk infants due to monthly dosing requirements and its cost. To address the large unmet medical need for most infants, we are evaluating MK‐1654, a fully human RSV‐neutralizing antibody with half‐life extending mutations targeting site IV of the fusion protein. In this 2‐part, placebo‐controlled, double‐blind, first‐in‐human study, 152 healthy adults were randomized 3:1 to receive a single dose of MK‐1654 or placebo in 5 cohorts (100 or 300 mg as an intramuscular dose or 300, 1000, or 3000 mg as an intravenous dose). Safety, pharmacokinetics, antidrug antibodies, and RSV serum‐neutralizing antibody titers were evaluated through 1 year. MK‐1654 serum concentrations increased proportionally with dose and resulted in corresponding elevations in RSV serum‐neutralizing antibody titers. The antibody displayed a half‐life of 73 to 88 days and an estimated bioavailability of 69% at the 300‐mg dose. The overall safety profile of MK‐1654 was similar to placebo, and treatment‐emergent antidrug antibodies were low (2.6%) with no associated adverse events. These data support the continued development of MK‐1654 for the prevention of RSV disease in infants. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) infection is the leading cause of hospitalization and infant mortality under six months of age worldwide; therefore, the prevention of RSV infection in all infants represents a significant unmet medical need. Here we report the isolation of a potent and broadly neutralizing RSV monoclonal antibody derived from a human memory B-cell. This antibody, RB1, is equipotent on RSV A and B subtypes, potently neutralizes a diverse panel of clinical isolates in vitro and demonstrates in vivo protection. It binds to a highly conserved epitope in antigenic site IV of the RSV fusion glycoprotein. RB1 is the parental antibody to MK-1654 which is currently in clinical development for the prevention of RSV infection in infants. Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization. Here, the authors isolate a human monoclonal antibody that binds to a highly conserved epitope on the RSV fusion protein, neutralizes RSV A and B subtypes equipotently and is protective in the cotton rat model. [ABSTRACT FROM AUTHOR]