Figure 6

ELISA detection of LASV NP antigen and virus-specific immunoglobulins M and G in normal donors, G-1180, G-1180 contacts, and in two additional patient and contact sera (G-1177 and G-1177-A). An antigen capture ELISA designed with affinity-purified goat polyclonal antibody reagents was used to detect LASV NP in patient sera (A). LASV NP antigen was not detected in normal sera from Sierra Leone and U.S. origin, or in most G-1180 contacts. The level of LASV NP antigen [◆, blue] in G-1180 dropped significantly during the first 3 days of ribavirin administration (quantitative levels indicated), to nearly undetectable levels by day 11. Conversely, antigen levels in G-1180-A and –B did not drop over the course of three days of ribavirin treatment. G-1180-F registered a significant level of antigen but did not seek treatment. G-1177 succumbed to acute Lassa fever, with very high levels of viral antigen detected before expiry. LASV-specific IgM (B) [▲, red] and IgG (C) [●, green] were detected in a recombinant ELISA plate format, coated with NP, GP1, and GP2, or with individually coated proteins. Most Sierra Leonean sera showed significant levels of IgM, IgG, or both, whereas U.S. normals did not. IgM and IgG levels in G-1180 rose throughout the course of the illness, and remained high on day 74 post onset of infection (black arrow). For G-1180 data are also plotted with IgM (▬ NP, ■ GP1, ◆ GP2, green) and IgG (▬ NP, ■ GP1, ◆ GP2, red) responses to individual LASV proteins. The IgM and IgG responses were directed primarily against NP, with a low IgG titer to GP1detected on day 74. Data are plotted as mean ±SD, N=2.