CD40LG and infection: Thus, antigens to be used in diagnostic serological assays or vaccine formulations are needed to: (i) actively induce strong immune response at the very beginning of the infection (i.e. strong IgM response during the first 10–15 days of infection); (ii) induce long-lasting immunity (i.e. strong IgG response until day 120); (iii) be antigenic in both forms of the parasite because transmission can occur through oocysts or tissue cysts.