Symptomatic cytomegalovirus infection in seropositive kidney recipients: reinfection with donor virus rather than reactivation of recipient virus

74 patients receiving cadaver kidney grafts were investigated prospectively for cytomegalovirus (CMV) infection. Among seropositive recipients CMV infection, especially symptomatic and disseminated infection, occurred significantly more frequently when kidneys came from seropositive than from seronegative donors. Since seropositive recipients can become infected with donor virus, the excess is probably accounted for by reinfection. This conclusion was supported by restriction enzyme typing of virus isolates from recipient pairs receiving kidneys from the same donor; proven reinfection with donor strain virus was significantly commoner than proven reactivation of recipient virus. Furthermore, symptoms occurred only in the proven reinfection group. Although the proportion of reinfections that caused symptoms was less than that seen in primary infections, prior natural infection with CMV clearly does not prevent symptomatic reinfection in seropositive recipients, a point which has profound implications for future vaccination strategies in renal allograft recipients and choice of donors.