Fig. 4: Humoral immune responses to pNTC-Spike in nonhuman primates.
From: Preclinical evaluation of a candidate naked plasmid DNA vaccine against SARS-CoV-2
a An overview of immunogenicity and virus challenge study in rhesus macaques. pNTC-Spike vaccinates (N = 6) received three immunizations of 2 mg at 2 week intervals and were challenged with 1.0 × 105 TCID50 (1.2 × 108 RNA copies, 1.1 × 104 PFU) SARS-CoV-2 (strain nCoV-WAI-2020; MN985325.1) 4 weeks after the final immunization (week 8). Sham controls (N = 2) were SARS-CoV-2 immune naïve until inoculation with the same SARS-CoV-2 viral dose at week 8. b End-point titers of binding IgG antibodies specific for the SARS-CoV-2 spike ectodomain. c Neutralizing antibody titers measures as a 50% inhibition of virus infection (PRTN50) and the more stringent 90% inhibition (PRNT90). d Correlation between anti-spike IgG binding antibody titers and 50% neutralization titers (PRNT50) for the challenge strain. Bar graphs indicate the median and interquartile range. Dotted lines indicate the assay limit of quantitation. SARS-CoV-2 virion image created with BioRender.com.
