[Analysis of Polymorphisms in the HCMV UL144 Gene in Clinical Isolates from Children with Asymptomatic Infection].

The purpose of this study was to examine polymorphisms in the human cytomegalovirus(HCMV)UL144gene in children with asymptomatic HCMV infection. PCR was performed to amplify the UL144 open reading frame(ORF)from urine specimens of asymptomatic HCMV-DNA positive children and both strands of the amplicon were sequenced. Sequence analysis was performed with software including BioEdit,DNAstar,Mega5.0and GeneDoc. Twenty-one of 50 clinical strains were successfully amplified and sequenced, giving a positive rate of detection of 42%.Nucleotide sequence homology ranged from 80.2%to100% and amino acid sequence homology ranged from 77.8%to 100%.The UL144 sequences were distributed among two genotypes, type A(47.61%)and type B(52.38%).The Expasy database was used to analyze the important functional motifs of the UL144 protein. These results revealed that there was a high level of conservation of post-translational modification sites including ASN, PKC, TNFR, and NCD3 G.UL144type B added a PROKAR-LIPOPROTEIN site and ZF-CTCHY site between amino acid residues 1 and 16 and between amino acid residues 30 and 96,respectively,as compared with type A.Compared to the UL144 gene from the Toledo strain, there was a high level of conservation in the CRD1 and CRD2of UL144 type A, while significantly more variability was observed in CRD1 and CRD2of UL144 type B. The transmembrane and cytoplasmic domains were highly conserved in both UL144 type A and type B. Variation in nucleotide sequences of UL144 type A and type B did not cause major changes to the predicted isoelectric point or secondary structure of the UL144 protein. The UL144 genotype of children with asymptomatic HCMV infection was divided into type A and type B, which was different from children with symptomatic HCMV infection.