Polymorphisms of human cytomegalovirus UL148A, UL148B, UL148C, UL148D genes in clinical strains
Objective To describe the features of HCMV UL148A, UL148B, UL148C and UL148D open reading frames (ORF) and the variable sites within the frames in clinical strains. Methods PCR was per- formed to amphfy these ORFs in 22 clinical strains. PCR amplification products were sequenced directly and ana- lyzed. Results The nueleotide diversity of UL148A, UL148B, UL148C and UL148D ORFs in studied strains is 0.5% to 8.3%, 0.5% to4.6%, 0.5% to 3.0% and 0.6% to 8.5%, respectively; the amino acid diversity of their putative proteins is 1.3% to6.3%, 1.3% to 5.0%, 1.3% to 3.9% and 1.7% to8.1%, respective- ly, compared to the Merlin strain. The modification sites of UL148A, UL148B, UL148C and UL148D predicted proteins from strains in unpassaged urine samples were conserved, except for strain U96, compared with that of the Merlin strain. By phylogenetie and statistical analysis, the UL148A and UL148D sequences of clinical strains were classified into three groups. Conclusion Compared to the UL148A, UL148B and UL148D ORFs, the UL148C ORF was relatively conserved, as well as the amino acid sequence of the UL148C putative protein. Isolates that have been passaged several times in human embryonic lung fibroblasts showed some changes of modification sites, however. A discrete linkage was found between the groups of UL148A gene and those of UL148D gene.