Human cytomegalovirus UL144 open reading frame: sequence variability in Guangzhou congenital infected children

Abstract

Objective To investigate the polymorphism of human cytomegalovirus (HCMV) UL144 gene of the low passage clinical isolates in Guangzhou and explore the role of UL144 gene in HCMV pathogenicity. Methods The clinical isolates of HCMV were obtained from the urine sample collected from those infants with intra-uterus HCMV infection in Guangzhou. The virus genome DNA was extracted. According to the genome sequence of Toledo, primers for UL144 gene were designed and used to amplify the complete open reading frames (ORF) of the UL144 gene in our 3 different clinical isolates. These ORFs of the UL144 gene were cloned into pMD18-T vector and their sequences were confirmed by sequencing. Bioinformatics methods were used subsequently to analyze the polymorphisms of these genes in different stains. Results Three HCMV low passage clinical isolates were successfully isolated, named D2, D3 and D52. As shown by PCR, all of these three strains contained UL144 ORF region. Three complete ORFs were amplified in total and their sequences were submitted to GenBank (Accession No.: DQ180368, DQ180382 and DQ180355). In D2, D3 and D52 isolates, their UL144 ORFs consisted of 531 nucleotides. DNA sequences were quite conservative,all variability were base substitution, and the amino acid sequences were high conservative, the rate of amino acid variability was 1.1%. There were no additional or deleted sites of posttranslational modification of UL144 protein in all clinical isolates. There were some differences in the secondary structure among different isolates. The isoelectric point of UL144 protein of all clinical isolates was 8.97. Conclusions All DNA and deduced amino acid sequences of UL144 gene share great similarity among Guangzhou HCMV clinical strains regardless of their polymorphism. It implies that maybe UL144 gene plays an important role in congenital infection. Key words: UL144; Human cytomegalovirus; Clinical isolates, low passage; Gene sequence; Sequence variability; Pathopoiesis