ABSTRACT
<p><b>OBJECTIVE</b>To study and research the transcription pattern of UL131A-128 mRNA in human cytomegalovirus (HCMV) clinical low passage strains.</p><p><b>METHODS</b>The UL131A-128 mRNAs of from different clinical strains and kinetic periods were amplified using 3' RACE and analyzed by sequencing. Meanwhile, clones containing UL131A-128 transcripts in a HCMV cDNA library of clinical strain were selected and sequenced.</p><p><b>RESULTS</b>It is successful to obtain the transcription pattern of UL131A, UL130 and UL128 gene in HCMV clinical low passage strains, the UL131A gene consisted of two exons and the coding region of UL130 gene was not interrupted by any intron in the region as reported before. However, the transcript of UL128 gene showed two patterns, one pattern consisted of the three exons, the length is 519bp, and the other one contained the three exons and the sequence of the first intron further, the length is 642bp. The quantities of UL128 transcript containing the sequence of the first intron were higher than that of transcript only containing the three exons in the studied clinical strains at all kinetic classes. It was demonstrated that the UL131A-128 mRNA were expressed with immediately early, early and late kinetics. The result of 3'RACE and HCMV cDNA library of clinical strain is conformity.</p><p><b>CONCLUSIONS</b>Our results demonstrated that the UL131A, UL130 and UL128 genes were transcribed with 3'-coterminal, although the initiation points of their mRNA may be different. The variation of the transcripts found in our study indicated complex nature of transcription of UL131A-128 genes in HCMV clinical strains.</p>