C1QA and infection: In the cohorts infected with Spn following IAV infection, the titers of Spn type 6A in the middle ear lavage samples of C1qa−/− and Bf−/− were significantly higher than wild-type mice at 24 h (P = 0.037 and P = 0.007 respectively), 48 h (P = 0.024 and P = 0.005 respectively), and 72 h (P = 0.034 and P = 0.002 respectively) post infection.