CD40LG and cytomegalovirus infection: The onset of PI was set at the mid time between the last IgG -negative and the first IgG-positive serum sample; (ii) when only IgM antibodies were detected at first positive serology, onset of PI was set at that point; (iii) in the presence of clinical symptoms and/or biochemical alterations compatible with HCMV infection as well as specific IgM antibodies and a significant rise in IgG, the onset was set at the time of symptoms.