CD40LG and rubella: A panel of 239 sera was assembled that included 36 archival sera from the NML’s rubella serology proficiency panel program inventory and 203 sera that were IgM positive for a number of other viruses (chikungunya virus, dengue virus, HHV-6 [roseola], measles virus, parvovirus B19, or zika virus) or were from patients who presented with fever and rash of unknown etiology (the “non-rubella” panel) (Table 1).