This assay is a direct ELISA detecting Human IgG antibody specific for LASV Linked GP. Diluted samples, Calibrator, Positive Control and Negative Control are incubated in microwells coated with a mixture of recombinant LASV Linked GP antigens. Incubation allows the anti-LASV antibody present in the samples to react with the immobilized antigen mixture. After the removal of unbound serum or plasma proteins by washing, anti-human IgG antibodies, labeled with horseradish peroxidase (HRP), are added forming complexes with the bound IgG anti-LASV antibody. Following another washing step, the bound enzyme-antibody conjugate is assayed by the addition of TMB substrate. Color develops in the wells at an intensity proportional to the concentration of IgG anti-LASV antibody in the sample. Optical Density (O.D.) results are obtained by reading the absorbance at 450nm (minus 620 – 650nm reference) using an ELISA plate reader. It is recommended that the user establish a cut-off for the study population using LASV seronegative samples. It is also recommended that LF IgG positive convalescent LF samples from the study population be included in each assay as an additional reference sample.