Moreover, varicella zoster virus (VZV), another human alphaherpesvirus which infects keratinocytes in the host to cause chickenpox or shingles, is highly cell- associated in culture [43], and unlike other alphaherpesviruses which can spread by the extracellular route, VZV does not have a homologue of HSV1 gD for receptor binding from the outside [43]. This evidence concerns the gene PAEP and chickenpox.