Pulmonary leukocyte trafficking after anti-RSV G protein mAb 232-1F treatment compared to mAb 131-2G treatment after RSV infection^a.

a<p>RSV A2-infected mice were treated with normal immunoglobulin G (nIg) or anti-RSV G mAb 232-1F or mAb 131-2G on day 3 after infection. Bronchoalveolar lavage (BAL) samples from 4 mice per group were examined on days 3, 5, 7 and 11 after infection. Representative data from days 5 and 7 are shown.</p><p>Data are the mean total number of BAL cells expressing CD4, CD8, B220 (B cells), NK (natural killer cells), CD11b (macrophages and/or monocytes), or RB6-8C5 (neutrophils [PMN]) per lung on day 5 and 7 after infection. Standard errors of the mean are also shown.</p>b<p>Percent reduction is the change in total cell type after anti-RSV G mAb treatment relative to the total cell type after treatment with IgG.</p>c<p><i>p</i><0.05 between nIg and mAbs treated mice.</p>d<p><i>p</i><0.001 between nIg and mAbs treated mice.</p

Marked reduction in RSV-associated pulmonary inflammation after early anti-RSV G mAbs combination treatment.

<p>RSV-infected mice were treated with suboptimal doses of either anti-G mAb (130-6D, 150 µg/mouse) and normal Ig antibody control (nIg, 75 µg/mouse), anti-G mAb (131-2G, 75 µg/mouse) and normal Ig antibody control (nIg, 75 µg/mouse), normal Ig antibody control (nIg, 225 µg/mouse) alone or both anti-G mAbs in combination (75 µg 130-6D +150 µg 131-2G/mouse). BAL cells were harvested on days 3, 5, 7 and 11 p.i. Shown are total bronchoalveolar lavage (BAL) cell numbers (±SE) per ml (A), (B) interferon-γ (IFN-γ) (pg/ml ±SE) cytokine levels in cell-free BAL lavage fluid. (C) Virus titers (PFU/g of tissue; ± SE) and M gene expression (relative genome level equivalent PFUe/mL lung tissue ± SE) (D) in the lungs of RSV-infected mice were determined. Results are representative of three independent experiments with no fewer than three mice per time point. Asterisks indicate a significant difference (p<0.05) between nIg-treated mice and antibody-treated mice. ND indicates virus titers below the level of detection.</p

mAb 232-1F does not block RSV G protein induced leukocyte migration or RSV-associated pulmonary inflammation.

<p>(A) mAb 232-1F was examined for its ability to block RSV G protein induced leukocyte migration in vitro compared to mAb 232-1F and mAb 131-2G. An anti-RSV F antibody (nIg) was used a negative control. Data is expressed as percent inhibition of leukocyte chemotaxis. (B) BAL cells from antibody-treated (300 µg/mouse, nIg, mAb 232-1F and mAb 131-2G) mice were harvested on days 3, 5 and day 7 post-RSV infection. The data are expressed as the mean number of BAL cells (±SE) per ml. (C) IFN-γ cytokine production (pg/mL ±SE) in cell-free BAL fluid were determined and the virus titers were determined by immunostaining plaque assay (PFU/g of tissue; ±SE) (D). Asterisks represents statistical significance (p<0.05) as determined by comparing nIg treated and mAb treated group. Representative results from two separate experiments are shown. ND indicates virus titers below the level of detection.</p

Linear representation of anti-G monoclonal antibody regions of reactivity across the RSV G glycoprotein.

<p>The cysteine noose region in the G protein is indicated as C, while the transmembrane and cytoplasmic domains are indicated by TM and CT, respectively. mAb 131-2G recognizes an epitope proximal to the central conserved region at a.a 1–173. mAb 130-6D recognizes an epitope within the central conserved region at a.a 174–215. mAb 232-1F reacts to an epitope outside the central conserved region at a.a. 215–298.</p

Antibody inhibition of leukocyte migration by mAbs 130-6D and 131-2G.

<p>The inhibition of RSV A2 G protein – mediated leukocyte chemotaxis by anti-RSV G antibodies (130-6D and 131-2G) was determined as described in Materials and Methods. Antibody was included in the lower chamber of the chemotaxis chamber, along with purified RSV A2 G protein, at an equal concentration (1X) (22.5 µg/mL) to that of purified RSV G protein (22.5 µg/mL) up to a 50-fold concentration (50X) of mAb to purified RSV G protein. For combination mAb inhibition, 1X and 50X of each antibody were used. Each condition was assayed three times per experiment. Data is presented as an average percent inhibition of RSV A2 G protein mediated leukocyte chemotaxis ± standard deviation relative to the amount of chemotaxis induced by RSV A2 G protein alone. Asterisk indicates significant difference in inhibition (p<0.05) as determined by comparing to 131-2G (1X) or 130-6D (1X) mAb inhibition alone to combination of 131-2G and 130-6D mAbs (1X) or 130-6D (50X) mAb inhibition alone to combination of 131-2G and 130-6D mAbs (50X).</p

Pulmonary Leukocyte Trafficking after Treatment of a Combination of Anti-Respiratory Syncytial Virus (RSV) G Protein Monoclonal Antibodies (mAbs) 131-2G and 130-6D on Day 3.

a<p>RSV A2-infected mice were treated with suboptimal doses of normal immunoglobulin G (nIg) or anti-RSV G mAbs (130-6D and 131-2G) either alone or in combination on day 3 after infection. Bronchoalveolar lavage (BAL) samples from 4 mice per group were examined on day, 3, 5, 7 and 11 after infection. Representative data from days 5, 7 and 11 are shown. Data are the mean total no. of BAL cells expressing CD4, CD8, B220 (B cells), NK (natural killer cells), CD11b (macrophages and/or monocytes), or RB6-8C5 (neutrophils [PMN]) per lung on day 5, 7 and 11 after infection. Standard errors of the mean are also shown.</p>b<p>The percent reduction is the change in total cell type after anti-RSV G mAb treatment relative to the total cell type after treatment with IgG.</p>c<p><i>p</i><0.05 between nIg and mAbs treated mice.</p>d<p><i>p</i><0.001 between nIg and mAb- treated mice.</p

Decrease in Formalin-Inactivated Respiratory Syncytial Virus (FI-RSV) Enhanced Disease with RSV G Glycoprotein Peptide Immunization in BALB/c Mice

<div><p>Respiratory syncytial virus (RSV) is a high priority target for vaccine development. One concern in RSV vaccine development is that a non-live virus vaccine would predispose for enhanced disease similar to that seen with the formalin inactivated RSV (FI-RSV) vaccine. Since a mAb specific to RSV G protein can reduce pulmonary inflammation and eosinophilia seen after RSV infection of FI-RSV vaccinated mice, we hypothesized that RSV G peptides that induce antibodies with similar reactivity may limit enhanced disease after subunit or other non-live RSV vaccines. In support of this hypothesis, we show that FI-RSV vaccinated mice administered RSV G peptide vaccines had a significant reduction in enhanced disease after RSV challenge. These data support the importance of RSV G during infection to RSV disease pathogenesis and suggest that use of appropriately designed G peptide vaccines to reduce the risk of enhanced disease with non-live RSV vaccines merits further study. </p> </div

Decreased weight loss in FI-A2 and G-A2 peptide vaccinated mice after RSV challenge.

<p>Mice were i.m. vaccinated with formalin inactivated RSV A2 (FI-A2) and then s.c. vaccinated with G-A2 or control peptides. Two weeks following the final peptide boost, FI-A2 and RSV A2 G peptide (FI-A2+G-A2) and control L393 peptide (FI-A2+L393) mice were challenged with 10⁶ PFU live RSV A2 and percent body weight loss were determined. Five independent experiments were performed and combined (representative) data from two experiments are shown. * <i>p<0</i>.<i>05</i>.</p

Immunization and challenge timeline.

<p>Timeline of vaccination and challenge schedule as described in the Materials and Methods.</p

Decreased pulmonary cell inflammatory response in FI-A2 and G-A2 peptide vaccinated mice after RSV challenge.

<p>Mice were i.m. vaccinated with formalin inactivated RSV A2 (FI-A2) and then s.c. vaccinated with RSV A2 G peptide (FI-A2+G-A2) and control peptide (FI-A2 + L393). Two weeks following the final peptide boost, groups were challenged with live RSV A2 and the mean numbers of BAL cells/lung (A), total eosinophil counts in the BAL (B), IL-4 levels (pg/ml) (C) and IFN gamma (D) in the cell-free BAL supernatant, and viral message levels (relative genome equivalent PFU/ml) (E) at day 5 post-challenge (peak of cell infiltration) were determined. Representative data from five independent experiments are shown. * <i>p<0</i>.<i>05</i>.</p