Immune response outcome of total 118 exposures for all 49 macaques receiving F(ab΄)₂ radiotracers.

<p>Immune response outcome of total 118 exposures for all 49 macaques receiving F(ab΄)₂ radiotracers.</p

Correlation between radio-HPLC and plasma binding assay.

<p>Strong correlation was observed between plasma binding assay and HPLC assay. Samples were assayed with either F(ab΄)₂-CD4R1 antibody (brown dots) or F(ab΄)₂-huOKT4A antibody (red dots). For samples assayed with F(ab΄)₂-CD4R1, the bootstrap estimate and 95% confidence interval of the Spearman rank correlation between PBA-ratio and HPLC-HM-ratio was -0.88 (-0.91, -0.84), and between PBA-ratio and HPLC-Fab’2-ratio was 0.90 (0.85, 0.93). Similar results were observed for samples assayed with F(ab΄)₂-huOKT4A.</p

Maximum intensity projection SPECT images.

<p>Rhesus macaques that developed antibody response to the radiotracer after baseline exposure were subsequently imaged while anti-tracer antibodies were present in the plasma in (A) healthy macaque imaged at 48 hours post-radiotracer injection with intact-huOKT4A labelled with ¹¹¹In and scanned using Triad88 (Trionix) camera, (B) SIV-TK infected non-progressor imaged at 4 hours post-radiotracer injection with F(ab΄)₂-huOKT4A labelled with ^99mTc and scanned using Triad88 (Trionix) camera, and (C) healthy macaque that underwent total body irradiation prior to 2^nd exposure and imaged at 4 hours post-radiotracer injection with F(ab΄)₂-CD4R1 labelled with ^99mTc and scanned using Symbia T2 (Siemens) camera. Images show increased hepatic uptake and altered biodistribution with minimal to no binding observed in secondary lymphoid organs when imaged in the presence of anti-tracer antibodies. Within each panel, images were adjusted (standardized) for injected dose and body weight. Tissue uptakes were converted to RAINBOW color scale as shown in color bar.</p

Acute Log₁₀ Viral Load.

<p>The distribution of acute log₁₀ viral load values in vaccine and placebo groups. Solid lines correspond to observed means and dashed lines correspond to means estimated using the multiple imputation approach.</p

Post-Infection Magnitude of CD8+ T-Cell Response.

<p>Magnitude of the post-infection CD8+ T-cell response measured by ICS, as quantified by the percentage of CD8+ T-cells producing IFN or IL-2 when stimulated with the vaccine-insert-matched peptide pools (Gag, Pol, and Nef) and other non-vaccine-insert peptide pools, for vaccine and placebo groups. Positive responses are indicated using closed red circles and negative responses using open blue circles. The p-values refer to tests comparing response magnitudes between the vaccine and placebo positive responders.</p

Signature Sites in Relation to T-Cell Responses.

<p>Locations of the signature sites and pre- and post-infection T-cell responses for Gag, Nef, and Pol. For each protein, the top graph represents the location of post-infection IFNγ ELISpot responses detected in 19 vaccine and 11 placebo recipients (light and medium blue columns, respectively), signature K-mers (red horizontal bars), amino acid signature sites (dashed vertical lines), and sites where an insert-mismatch was found to be associated with viral load in the vaccine group alone (dotted vertical lines; Materials S1 Section 5). The bottom graph corresponds to pre-infection IFNγ ELISpot responses detected in 27 vaccine recipients (green columns). The region covered by each responsive peptide is indicated by the box width, and the number of subjects reacting to that peptide is indicated by the box height.</p

Post-Infection Breadth of T-Cell Response.

<p>Breath of the post-infection T-cell response as measured by IFNγ ELISpot, as quantified by the number of reactive 15-mers, for the vaccine (grey) and placebo (black) groups. The distribution of breadth is shown for all proteins in aggregate; for Gag, Pol, and Nef combined; for other non-insert proteins; and for Gag, Pol, and Nef individually. The p-values refer to tests comparing breadth between vaccine and placebo groups.</p

Comparison of Pre- and Post-Infection T-Cell Responses.

<p>Pre- and post-infection T-cell responses to individual 15-mers in Gag, Pol, and Nef as measured by IFNγ ELISpot. Each row represents a different subject. Pre-infection responses were measured using vaccine-matched peptides and post-infection responses were measured using PTE-G peptides.</p

Safety and Immunogenicity of Pfs25-EPA/Alhydrogel^®, a Transmission Blocking Vaccine against <i>Plasmodium falciparum</i>: An Open Label Study in Malaria Naïve Adults

<div><p>Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. Pfs25 is a leading TBV candidate, and previous studies conducted in animals demonstrated an improvement of its functional immunogenicity after conjugation to EPA, a recombinant, detoxified ExoProtein A from <i>Pseudomonas aeruginosa</i>. In this report, we describe results of an open-label, dose-escalating Phase 1 trial to assess the safety and immunogenicity of Pfs25-EPA conjugates formulated with Alhydrogel^®. Thirty malaria-naïve healthy adults received up to four doses of the conjugate vaccine, with 8, 16, or 47 μg of conjugated Pfs25 mass, at 0, 2, 4, and 10 months. Vaccinations were generally well tolerated. The majority of solicited adverse events were mild in severity with pain at the injection site the most common complaint. Anemia was the most common laboratory abnormality, but was considered possibly related to the study in only a minority of cases. No vaccine-related serious adverse events occurred. The peak geometric mean anti-Pfs25 antibody level in the highest dose group was 88 (95% CI 53, 147) μg/mL two weeks after the 4^th vaccination, and declined to near baseline one year later. Antibody avidity increased over successive vaccinations. Transmission blocking activity demonstrated in a standard membrane feeding assay (SMFA) also increased from the second to the third dose, and correlated with antibody titer and, after the final dose, with antibody avidity. These results support the further evaluation of Pfs25-EPA/Alhydrogel^® in a malaria-endemic population.</p></div

Immunofluorescence assays with immune sera.

<p>A. Surface labeling of zygotes with sera from one volunteer (#20) collected on days 0, 314 and 356, with Pfs25 specific mouse mAbs 1G2 and 4B7. B. Recognition of parasite protein in fixed ookinetes with sera from one volunteer (#20) collected on days 0, 314 and 356, with Pfs25 specific mouse mAb 4B7. Magnification 1000X.</p