Figure 1.
Serum neutralization titers of FI-RSV-vaccinated lambs (FI-vaccinated) (n = 4) were significantly increased compared to mock-vaccinated lambs (n = 4) (*P<0.05).
Error bars = SEM.
Figure 2.
Bronchoalveolar lavage (BAL) titers of Control lambs (no vaccine and no RSV), mock-vaccinated (MockVac) lambs and FI-RSV-vaccinated lambs.
FI-RSV-vaccinated lambs had significantly less RSV load compared to mock-vaccinated lambs. Control lambs lacked RSV titers. Control n = 4; MockVac n = 4; FI-RSV n = 4. Error bars = SEM, *P<0.05. FFU = focus-forming units per ml.
Figure 3.
RSV RNA M37 levels in mock-vaccinated (MockVac), FI-RSV-vaccinated, and Control lambs as assessed by RT-qPCR.
FI-RSV-vaccinated lambs had significantly less RSV M37 RNA compared to mock-vaccinated lambs. Control lambs lacked RSV RNA RT-qPCR signal. Control n = 4; MockVac n = 4; FI-RSV n = 4. Error bars = SEM, *P<0.05.
Figure 4.
RSV antigen detected by immunohistochemistry (IHC).
Control bronchioles and alveoli (Control Br and Control Alv) lack RSV antigen while bronchioles and alveoli of FI-RSV-vaccinated lambs had significantly reduced levels of RSV antigen compared to mock-vaccinated (MockVac) lambs. Control(s) n = 4; MockVac Br n = 4; MockVac Alv n = 4; FI-RSV Br n = 4; FI-RSV Alv n = 4. Error bars = SEM, *P<0.05, **P<0.01, ***P<0.001.
Figure 5.
Histopathologic lesions of consolidation (A) and; bronchiolitis (B).
Controls lacked lesions while mock-vaccinated (MockVac) lambs had significantly increased consolidation and bronchiolitis scores compared to lambs vaccinated with FI-RSV. Control n = 4; MockVac n = 4; FI-RSV n = 4. Error bars = SEM, *P<0.05, **P<0.01.
Figure 6.
Extent of lymphocyte and plasma cell infiltrates into adventitia of bronchioles assessed by A. peribronchiolar lymphocytic (PbL) scores.
FI-RSV-vaccinated lambs had significantly increased infiltrates compared to mock-vaccinated (MockVac) lambs. Controls lacked lesions. Extent of lymphocyte and plasma cell infiltrates into adventitia of blood vessels assessed by perivascular lymphocytic (PvL) scores (B). FI-RSV-vaccinated lambs had significantly increased infiltrates compared to control lambs. Mock-vaccinated lamb PvL infiltrates were not significantly different from control lamb levels. Controls lacked lesions. Control n = 4; MockVac n = 4; FI-RSV n = 4. Error bars = SEM, *P<0.05, ***P<0.001.
Figure 7.
Lung of FI-RSV-vaccinated lamb with marked peribronchiolar lymphocytic infiltrates characterized by numerous, closely packed lymphocytes and plasma cells and a bronchiole that is slightly dilated but lacking intralumenal neutrophils (A) andLung of mock-vaccinated lamb with bronchiole containing neutrophils and relatively mild peribronchiolar lymphocytic infiltration characterized by a few lymphocytes and occasional plasma cells there are somewhat dispersed and not densely associated (B).
Lung of FI-RSV-vaccinated lamb with marked peribronchiolar lymphocytic infiltrates and only a few cells containing RSV antigen (C). Lung of mock-vaccinated lamb with increased viral antigen distribution in multifocal cells and intensity characterized by more intense staining (D). Bar = 150 µm.