Figure 6. Antibody response to LPAIV H7N2 in ducks (top) or in chickens (bottom).

Antibody titers were measured by ELISA (left) or HI method (right) from serum collected at the indicated time in days (d) after primary infection (H7 groups, black bars) or heterologous secondary infection (H5H7 groups, white bars) and were expressed as the reciprocal of the dilution used for measurement as indicated in the Materials and Methods section. Significant differences between groups are indicated with asterisks (*, P<0.05; **: P<0.01; ***: P<0.001).