FIGURE 5.

Prophylactic efficacy of AAV expressed nanobodies in a mouse challenge model of VN/04 (H5N1) NIBRG-14ma. (A) Total nanobody-Fc in serum was measured by ELISA in samples taken 39 days after IM injection of AAV vectors pre-challenge with VN/04(H5N1). Comparisons are shown in brackets (*p < 0.05). Mice were then infected intranasally with 10 MLD₅₀ (mouse lethal dose) of A/Vietnam/1194/2004 (H5N1) NIBRG-14ma 42 days post-AAV IM injection. Survival (B) and weight loss (C) were monitored for 13 days. (D) Residual viral load was determined as indicated by TCID₅₀/g of tissue from lung homogenates 3 days post-challenge with 10 MLD₅₀ VN/04. Each dot represents an individual mouse. Comparisons are shown in brackets (p < 0.05). (E) Representative histological lung sections from mice that received AAV encoding R1a-B6-mIgG1, R1a-B6-mIgG2a, R1a-B6, cAb1-mIgG2a, and PBS (untreated) 3 days post-infection with VN/04 NIBRG-14ma. Lungs were harvested from mice and stained with Hematoxylin and Eosin (H&E). Arrows represent thickening of the alveolar walls and lung ruptures are represented by dashed lines. Scale bar = 100 μm.