Flowchart of selection and follow-up of the Study Population from the Primary Target Sample.

<p>A total of 3,060 children, 9–12 months-old were elected for an epidemiological studies reported elsewhere <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049828#pone.0049828-Collaborative1" target="_blank">[14]</a> and referred as “Primary Target Sample”. The Clinical Trial design is highlighted by dashed format. The study population enrolled in the present investigation was selected from the “Primary Target Sample” according to the PRNT results and comprise 30 PV-PRNT⁺ and 10 PV-PRNT⁻ individuals on each experimental arm (17DD and 17D-213/77), reaching a total of 80 volunteers. The current Immunological Study design is highlighted by solid format.</p

Comparative analysis of the cytokine signatures of innate and adaptive immunity triggered by the YF-17DD and YF-17D-213/77 substrains upon the <i>in vitro</i> recall of whole blood leukocytes from seroconverter children (PV-PRNT⁺) with specific YF-Ag.

<p>The diagrams highlight each leukocyte subsets with distinct tags as they display low (white rectangle) or high (black rectangle = inflammatory, gray rectangle = regulatory) cytokine producers (top panel). The ascendant frequency of volunteers with high cytokine indexes of the innate and adaptive immunity was assembled for each experimental arm and is demonstrated by bar graphs (medium panel). Comparative analysis of the overall cytokine patterns of YF-17DD (lines with black or gray triangles) and YF-17D-213/77 (lines with black or gray squares) vaccinees were further compared by overlapping the ascendant cytokine curves (bottom panel). Dotted lines highlight the 25^th and 50^th percentiles used as reference for comparative analysis. *Differences were considered relevant when the frequency for a given cytokine emerged outside the 50^th percentile as compared to the reference cytokine pattern or signature.</p

Impact of serum titers of anti-YF neutralizing antibodies on the cytokine-mediated immune response triggered by the YF-17DD and YF-17D-213/77 substrains upon <i>in vitro</i> recall of whole blood leukocytes from seroconverter children (PV-PRNT⁺) with specific YF-Ag.

<p>The PRNT⁺ groups from each experimental arm were first categorized into two subgroups referred to as PV-PRNT^MEDIUM+ (2.5≤ serum titers ≤3.5 log₁₀ mIU/mL) and PV-PRNT^HIGH+ (serum titers >3.5 log₁₀ mIU/mL). The cytokine profile of the PV-PRNT^MEDIUM+ and PV-PRNT^HIGH+ subgroups were evaluated, considering relevant the percentages of a given inflammatory cytokine that emerged higher than the 50^th percentile, as indicate by an upward arrow (↑).</p

Comparative inflammatory and regulatory cytokine signatures triggered by the YF-17DD and YF-17D-213/77 substrains upon the <i>in vitro</i> recall of whole blood leukocytes from (A) seroconverter (PV-PRNT⁺) and nonseroconverter primary vaccinees (PV-PRNT⁻) as well as (B) seroconverter revaccinees (RV-PRNT⁺) with specific YF-Ag.

<p>The ascendant frequency of volunteers with high inflammatory and regulatory cytokine indexes was assembled for each experimental arm and demonstrated by bar graphs. Comparative analysis between PV-PRNT⁺, PV-PRNT⁻, and RV-PRNT⁺ within the same experimental arm was performed taking the ascendant cytokine curve of the YF-17DD (lines with black or gray triangles) or YF-17D-213/77 (lines with black or gray squares) groups as reference. #Differences were considered relevant when the percentage of a given cytokine emerged below the quartile of the reference cytokine signatures.</p