Similarly, mAb 4E10 recognizes an epitope in the membrane proximal region of gp41 and also binds to host antigens including cardiolipin, phospholipids, lupus erythematosus autoantigen SS-A/Ro, and cytoplasmic and nuclear antigens of HEp-2 cells, and has lupus anticoagulant reactivity [17]. The gene discussed is CALR; the disease is systemic lupus erythematosus.