Isolation and characterization of a low-abundance splice variant from the human cytomegalovirus major immediate-early gene region.
The major immediate-early (IE) gene region of human cytomegalovirus (HCMV) encodes several proteins as a result of differential RNA splicing events. By expression vector cloning of HCMV IE mRNA, we isolated and characterized a cDNA for a novel splice variant from the major IE gene region. The RNA product is a derivative of the IE55 mRNA and contains an additional splice from nucleotides 170,635 to 170,307 in the IE2 gene region (UL122), resulting in a 1.4-kb mRNA. The predicted open reading frame codes for a 164-amino-acid protein with a calculated molecular mass of 18 kDa (IE18). Mung bean nuclease analysis and PCR were used to characterize expression of IE18 mRNA in HCMV-infected cells. While the 1.4-kb mRNA was detected in infected human fibroblasts in the presence of a protein synthesis inhibitor, it was not detectable during a normal infection. However, the 1.4-kb mRNA was readily detected in infected human monocyte-derived macrophages at IE times. These results suggest that the novel IE18 mRNA exhibits cell type-specific expression indicating differential regulation of the major IE gene region in different permissive cell types.
Kerry
J A
JA
Department of Microbiology and Immunology, Eastern Virginia Medical School, Norfolk, 23501, USA.
Sehgal
A
A
Barlow
S W
SW
Cavanaugh
V J
VJ
Fish
K
K
Nelson
J A
JA
Stenberg
R M
RM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003587:Cytomegalovirus / Q000235:genetics*; D018076:DNA, Complementary; D017874:Immediate-Early Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D012326:RNA Splicing
D018076:DNA, Complementary; C093522:IE18 protein, Human cytomegalovirus; D017874:Immediate-Early Proteins