Human monoclonal antibodies protect against viral-mediated pneumococcal superinfection.

Introduction: Community-acquired pneumonia (CAP) is a global health concern, with 25% of cases attributed to (). Viral infections like influenza A virus (IAV), respiratory syncytial virus (RSV), and human metapneumovirus (hMPV) increase the risk of , leading to severe complications due to compromised host immunity.

Methods: We evaluated the efficacy of an anti-PhtD monoclonal antibody (mAb) cocktail therapy (PhtD3 + 7) in improving survival rates in three viral/bacterial coinfection models: IAV/, hMPV/, and RSV/.

Results: The PhtD3 + 7 mAb cocktail outperformed antiviral mAbs, resulting in prolonged survival. In the IAV/ model, it reduced bacterial titers in blood and lungs by 2-4 logs. In the hMPV/ model, PhtD3 + 7 provided greater protection than the hMPV-neutralizing mAb MPV467, significantly reducing bacterial titers. In the RSV/ model, PhtD3 + 7 offered slightly better protection than the antiviral mAb D25, uniquely decreasing bacterial titers in blood and lungs.

Discussion: Given the threat of antibiotic resistance, our findings highlight the potential of anti-PhtD mAb therapy as an effective option for treating viral and secondary pneumococcal coinfections.