In conclusion, results of our study consistently document that in two of four transplanted patient populations examined, long-term protection from HCMV infection was reached only in the presence of HCMV-specific CD4+ T-cells above the established cutoff (and always in association with HCMV-specific CD8+ T-cells), as we preliminarily observed (19). The gene discussed is CD4; the disease is cytomegalovirus infection.