RSV-specific IgG titer and RSV-IgG avidity do not correlate with disease severity.

<p>RSV-specific IgG levels in plasma of infants was determined by ELISA using virus particles. RSV-IgG avidity was assessed by supplementing NaSCN during ELISA. (A) RSV-specific IgG levels were displayed versus age. (B-C) Median RSV-specific IgG levels (± IQR) were compared between healthy and RSV-infected infants as well as between RSV patients with and without oxygen therapy. (D-E) Median (± IQR) avidity of RSV-IgG in healthy infants was compared to RSV-infected infants or between RSV patients with or without oxygen therapy. Associations were assessed by Spearman correlation test. Statistical analyses employed Mann Whitney U test. (**P<0.01).</p

RSV-specific IgG against F protein antigenic sites Ø and I not correlate with disease severity.

<p>The abundance of antibodies in human infant plasma that bind to the prefusion F protein antigenic site Ø or the postfusion F protein antigenic site I was determined by competition with site-specific monoclonal antibodies in ELISA. (A-B) Median (± IQR) IgG titer that blocks 25% binding of D25 (site Ø) were compared between healthy and RSV-infected infants as well as between RSV patients with and without oxygen therapy. (C-D) Median (± IQR) IgG titer that blocks 15% binding of 131-2A (site I) were compared between healthy and RSV-infected infants as well as between RSV patients with and without oxygen therapy. No significant differences were observed by Mann Whitney <i>U</i> test.</p

RSV-specific IgG against individual RSV glycoproteins do not correlate with disease severity.

<p>RSV glycoprotein-specific antibody levels were determined by ELISA against recombinant, soluble ectodomains. Median IgG levels (± IQR) were compared between healthy and RSV-infected infants as well as between RSV patients with and without oxygen therapy. Glycoproteins used for ELISA coating were (A-B) RSV G protein, (C-D) prefusion F protein, and (E-F) postfusion F protein. (G-H) The relative abundance of antibodies against prefusion F compared to G protein as well as pre- compared to postfusion F protein were categorized assessed by subtracting their levels. The median (± IQR) difference was compared between plasma from healthy infants and RSV patients with or without oxygen therapy. No significant differences were observed by Mann Whitney <i>U</i> test for comparison between two groups and Kruskall-Wallis for comparison between more than two groups.</p

RSV neutralization does not correlate with severity of disease.

<p>50% plaque reduction neutralization titers (PRNT) were determined against RSV-X and RSV-X-dG, the latter is lacking the G protein. (A-B) Median (± IQR) PRNT against RSV-X were compared between healthy and RSV-infected infants as well as between RSV patients with and without oxygen therapy. (C-D) Median (± IQR) PRNT against RSV-X-dG were compared between healthy and RSV-infected infants as well as between RSV patients with or without oxygen therapy. (E) The PRNT against RSV-X was divided the PRTN against RSV-X-dG, so that values below 1.0 indicate a contribution of anti-G antibodies to the neutralization. The median (± IQR) ratio was compared between plasma from healthy infants and RSV patients with or without oxygen therapy and all were significantly different from 1.0. Statistical analyses employed Mann Whitney <i>U</i> test for comparison between two groups and Kruskall-Wallis for comparison between more than two groups. (*<i>P</i><0.05, <i>**P<</i>0.01).</p

Study population.

<p>Study population.</p

Antibody properties do not correlate with disease severity parameters.

<p>Antibody properties do not correlate with disease severity parameters.</p

RSV-specific IgG against prefusion F epitope and G protein correlate with neutralization.

<p>Neutralization titers against RSV-X (PRNT) were compared to IgG levels against (A) postfusion F protein, (B) site I (131-2A competition titer), (C) prefusion F protein, (D) site Ø (D25 competition titer) and (E) G protein. Testing for correlation was performed with Spearman correlation test.</p