CD40LG and cytomegalovirus infection: In our patient, the primary CMV infection was diagnosed after excluding other possible diagnoses (e.g., negative blood cultures, no improvement after broad antibiotic treatment) and by detection of CMV-specific IgM reactivity in the context of low IgG avidity and low IgG levels in the absence of anti-CMV recgB2 IgG with broad epitope specific IgM reactivity against CMV IE1, p150, CM2, and p65 [11].