Life-threatening influenza pneumonitis in a child with inherited IRF9 deficiency

Hernandez, Nicholas; Melki, Isabelle; Jing, Huie; Habib, Tanwir; Huang, Susie S.Y.; Danielson, Jeffrey; Kula, Tomasz; Drutman, Scott; Belkaya, Serkan; Rattina, Vimel; Lorenzo-Diaz, Lazaro; Boulai, Anais; Rose, Yoann; Kitabayashi, Naoki; Rodero, Mathieu P.; Dumaine, Cecile; Blanche, Stéphane; Lebras, Marie-Noëlle; Leung, Man Chun; Mathew, Lisa Sara; Boisson, Bertrand; Zhang, Shen-Ying; Boisson-Dupuis, Stephanie; Giliani, Silvia; Chaussabel, Damien; Notarangelo, Luigi D.; Elledge, Stephen J.; Ciancanelli, Michael J.; Abel, Laurent; Zhang, Qian; Marr, Nico; Crow, Yanick J.; Su, Helen C.; Casanova, Jean-Laurent

Virus assays IAV and VSV infections SV40 fibroblasts were infected with influenza virus (A/California/4/2009) at a multiplicity of infection (MOI) of 0.5 (MOI = 0.5). The inoculum was absorbed onto the cells for 30 min at 25°C. Cells were washed twice with Hank's balanced salt solution and cultured at 37°C in the presence of 0.1 µg/ml TPCK-treated trypsin (Sigma-Aldrich). Virus samples were collected at the indicated times after infection. Influenza titers were determined by plaque assay on Madin-Darby canine kidney cells. Fibroblasts were infected with VSV at MOI = 3. The inoculum was absorbed onto the cells for 30 min at 25°C, washed twice with PBS, and cultured in DMEM 10% FBS at 37°C. Virus samples were collected at indicated time points. Viral titers were determined by endpoint dilution on Vero cells using the Reed and Muench calculation. Where indicated, cells were pretreated with IFN-α2b for 16 h before virus infection.