Figure 6: F-VHH-4 inhibits RSV A2 replication in mice.

Groups of six BALB/c mice were treated intranasally with 0.5 mg kg−1 of F-VHH-4, palivizumab or Ctrl-VHH 4 h before infection with 1 × 106 RSV A2 or PBS (mock). Five days after infection, the pulmonary RSV load was determined by (a) plaque assay (dashed line represents the detection limit) or (b) by quantification of the amount of lung viral RNA using RT-qPCR. Horizontal lines indicate medians. *P<0.05, **P<0.01 (Mann–Whitney U-test). (c) Five days after infection, BAL fluid was prepared and the percentage of immune cells was determined by flow cytometry. Bars represent the average percentage of the indicated cell type±s.d. (n=6) (AM, alveolar macrophages; DC, dendritic cells; Monoc, monocytes; CD4, CD4+ T cells; CD8, CD8+ T cells; Neutr, neutrophils; Eosino, eosinophils). *P<0.05, **P<0.01 (Mann–Whitney U-test).