Table 1.

Comparison of antibody responses measured with different assays following NV infection of human volunteers (n = 18)

Assay and parameterResult on study day
Pred271428–30180
Total ELISA (IgG, IgA, IgM)
    No. (%) seropositivea18 (100)18 (100)18 (100)18 (100)18 (100)18 (100)
    No. (%) with seroconversionb,c0 (0)9 (50)18 (100)18 (100)16 (89)
    Geometric mean fold riseb149412817
IgG
    No. (%) seropositivea16 (89)16 (89)18 (100)18 (100)18 (100)18 (100)
    No. (%) with seroconversionb,c0 (0)7 (39)18 (100)18 (100)14 (78)
    Geometric mean fold riseb14709718
IgA
    No. (%) seropositivea9 (50)10 (56)17 (94)18 (100)18 (100)18 (100)
    No. (%) with seroconversionb,c1 (6)15 (83)18 (100)18 (100)13 (72)
    Geometric mean fold riseb14063626024
IgM
    No. (%) seropositivea12 (11)13 (72)15 (83)1 (6)
    No. (%) with seroconversionb,c2 (11)12 (67)14 (78)0 (0)
    Geometric mean fold riseb124331
  • a Seropositive if IgG or IgA is >1.4 or >1.6 μg/ml, respectively, or ELISA reciprocal titer is >25 (total or IgM).

  • b Compared to prechallenge serum titer.

  • c Seroconversion is defined as a ≥4-fold rise in antibody levels between pre- and postchallenge samples.

  • d Pre, prechallenge.