Human asymptomatic Ebola infection and strong inflammatory response Dr EM Leroy, DVM, S Baize, PhD, VE Volchkov, PhD, SP Fisher-Hoch, MD, M-C Georges-Courbot, MD, J Lansoud-Soukate, PhD, M Capron, PhD, P Debré, MD, AJ Georges, MD  The Lancet  Volume 355, Issue 9222, Pages 2210-2215 (June 2000) DOI: 10.1016/S0140-6736(00)02405-3 Copyright © 2000 Elsevier Ltd Terms and Conditions

Figure 1 Humoral responses in asymptomatic individuals A Specific IgM and IgG antibody responses to Ebola Zaire, as determined by ELISA. Each point represents one contact individual who was sampled several times. B Antibody responses analysed by western blotting for one symptomatic patient who recovered (T+), two negative endemic controls (EC), and five IgG-positive asymptomatic individuals. Identity of each band from symptomatic case was confirmed previously with antibody to Zaire hyperimmune goat serum.7 The Lancet 2000 355, 2210-2215DOI: (10.1016/S0140-6736(00)02405-3) Copyright © 2000 Elsevier Ltd Terms and Conditions

Figure 2 Reverse transcriptase PCR detection of Ebola-specific RNA A Results for seven asymptomatic individuals are shown. They were sampled between 7 and 16 days after the first exposure to a sick patient. The 420 bp product obtained from the first round of PCR (PCR 1) and the 298 bp product obtained after two steps of PCR (PCR 2) represent cDNA fragments of the Ebola-virus polymerase gene. The first-strand cDNA was synthesised by random hexamer primers (PCR1, PCR2) or primers specific for positively-stranded RNA (PCR2+) or primers specific for negative-stranded RNA (PCR2-). (+) is a positive symptomatic patient during the acute phase of the disease. (-) is a healthy negative endemic control. (M-) is PCR mix without cDNA. These controls were included in each run. Ten negative controls were tested but only one is shown in the figure. B Detection of Ebola RNA during infection. The cDNA was constructed with a primer set specific for negative-stranded RNA (PCR-) or positive-stranded RNA (PCR+). Peripheral-blood mononuclear cells were collected from two asymptomatic individuals (asymptomatic 1 and 2), 7, 9, 16, and 23 days after the first exposure to a sick patient. The Lancet 2000 355, 2210-2215DOI: (10.1016/S0140-6736(00)02405-3) Copyright © 2000 Elsevier Ltd Terms and Conditions

Figure 3 Inflammatory responses Concentrations of pro-inflammatory cytokines (IL-1β, TNF, and IL-6, expressed in ng/L) and chemokines (MCP-1, MIP-1α, and MIP-1β, in μg/L) were measured in plasma by ELISA. Individual values for the seven PCR-positive asymptomatic individuals are shown between 7 and 23 days after the first potentially infectious contact. Each asymptomatic individual is represented by a point. The Lancet 2000 355, 2210-2215DOI: (10.1016/S0140-6736(00)02405-3) Copyright © 2000 Elsevier Ltd Terms and Conditions