The nucleic acid positive rate and genotype distribution of human cytomegalovirus in human milk banks in China.

To determine the status of human cytomegalovirus (HCMV) infection in human milk in China, a total of 510 human milk samples obtained from three provinces, including 211 donor human milk samples from human milk banks and 299 milk samples obtained from the mothers of premature infants, were tested to detect HCMV DNA. Overall, 46.4% of the donated milk samples and 59.2% of the samples obtained from mothers of premature infants were positive for HCMV DNA. The concentration of HCMV DNA was approximately 103 -104 copies/ml in the HCMV-DNA-positive human milk samples. Based on the nucleotide sequence of a 299- to 305-bp fragment of the glycoprotein B (gB) gene, three HCMV genotypes (gB1, gB2 and gB3) were identified in human milk samples. Mixed infection with genotypes gB1 and gB3 was also found in four milk samples from mothers. Genotype gB1 was the predominant genotype in the HCMV-DNA-positive human milk samples, and it could be subdivided into three lineages. There were also some characteristic nucleotides and amino acids in the three HCMV genotypes, which were helpful for distinguishing the genotypes. This is the first study to clarify the HCMV infection status and genetic characteristics of human milk obtained from banks in China, which will be helpful in preventing postnatal HCMV infections and ensuring the safety of human milk banks.