CD40LG and infection: The serum positive rates of Sj23HD specific IgG on days 0, 7, 10, 14, 18, 21 and 28 post-infection were 0, 10, 10, 30, 50, 80 and 100%, respectively; and the serum positive rates of Sj23HD specific IgM at the same times post-infection were 0, 10, 10, 30, 60, 90 and 100%, respectively (Table 2).