Frank van Someren GréveKoenraad F. van der SluijsAnita M. TuipMarcus J. SchultzMenno D. de JongNicole P. JuffermansMahidol UniversityAmsterdam UMC - University of Amsterdam2019-08-232019-08-232018-09-01Journal of Medical Virology. Vol.90, No.9 (2018), 1431-143710969071014666152-s2.0-85049779290https://repository.li.mahidol.ac.th/handle/20.500.14594/45972© 2018 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. Secondary bacterial pneumonia is a frequent complication of influenza, associated with high morbidity and mortality. We hypothesized that treatment with neutralizing influenza A antibody AT10_002 protects against severe secondary pneumococcal infection in a mouse model of influenza A infection. Influenza A (H3N2) virus–infected male C57Bl6 mice were treated intravenously with either AT10_002 or a control 2 days postinfection. Seven days later, both groups were infected with Streptococcus pneumoniae and killed 18 hours later. Mice receiving AT10_002 showed less loss of bodyweight compared with controls (+1% vs −12%, P <.001), lower viral loads in bronchoalveolar lavage fluids (BALFs) (7 vs 194 RNA copies per µL; P <.001), and reduced bacterial outgrowth in lung homogenates (3.3 × 10 1 vs 2.5 × 10 5 colony-forming units per mg; P <.001). The treatment group showed lower pulmonary wet weights, lower cell counts, and lower protein levels in BALF compared with controls. Treatment with AT10_002 was associated with lower levels of tumor necrosis factor-α, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (KC), and interferon-γ in BALF and lower IL-6 and KC in lung homogenates. Treatment with anti-influenza antibody AT10_002 is associated with reduced weight loss, viral load, bacterial outgrowth, and lung injury in a murine model of secondary pneumococcal pneumonia following influenza infection.Mahidol UniversityImmunology and MicrobiologyMedicineArticleSCOPUS10.1002/jmv.25212