Sequence analyses of variable cytomegalovirus genes for distinction between breast milk- and transfusion-transmitted infections in very-low-birth-weight infants.

BACKGROUND

Cytomegalovirus (CMV) transmission to very-low-birth-weight infants (VLBWIs) sometimes induces serious clinical symptoms. Although breast milk is considered a major source of transmission, transfusion-transmitted CMV (TT-CMV) infection is often suspected when CMV disease develops after transfusion. Thus, it is clinically important to distinguish between transfusion-transmitted and breast milk-transmitted CMV infections.

STUDY DESIGN AND

METHODS

Study A: The incidence of acquired CMV transmission was prospectively investigated in 65 VLBWIs. Study B: To determine the transmission routes in 18 TT-CMV-suspected VLBWIs who had been reported in our hemovigilance system, we performed polymerase chain reaction for CMV DNA in fed breast milk and/or repository blood samples related to transfused leukoreduced blood products. Furthermore, we evaluated the identity of CMV strains in patients' urine/blood samples and fed breast milk by sequence analyses of variable CMV genes UL139 and UL146.

RESULTS

Study A: Acquired CMV infection was found in 4 of 65 VLBWIs (6.2%). Study B: CMV DNA was detected in fed breast milk for 12 of 14 TT-CMV-suspected cases, for which breast milk was available. Furthermore, CMV DNA sequence-matching rates between fed breast milk and patients' urine/blood for both UL139 and UL146 genes were 100% or nearly 100% in 11 patients. In contrast, repository blood samples for 11 of 14 patients were CMV DNA negative.

CONCLUSION

CMV is principally transmitted through breast milk in VLBWIs. The risk of TT-CMV seems to be extremely low when using leukoreduced blood products. Sequence analyses of the variable CMV genes are useful for evaluating CMV transmission routes.