CD40LG and infection: More than two thirds of the samples from the HEV-positive donors (85/125, 68%) were window period infections, as they were unreactive for anti-HEV IgG and anti-HEV IgM at the point of donation, whereas 25 donors (20%) were reactive for both anti-HEV IgG and anti-HEV IgM, 10 (8%) were reactive only for anti-HEV IgG antibodies, and finally the remaining 5 (4%) were reactive for anti-HEV IgM antibodies alone (Table 4A).