Both the PPR [95] and B2542 [96] are capable of inducing immunological and neurological abnormalities in vivo that are consistent with immunodeficiency-causing lentiviruses, thus the ability of viruses to infect cells using CRD1 of CD134 alone is not in itself, debilitating to viral replication. The gene discussed is TNFRSF4; the disease is Immunodeficiency.