A gene (HJ1) present in murine cytomegalovirus (MCMV) encodes an open
reading frame (ORF) whose predicted amino acid sequence shows homology
to the beta (or C-C) class of chemotactic cytokines known as chemokin
es. The region of homology is located in the carboxyl-terminal portion
of the 116-amino-acid ORF. A 0.9-kb RNA transcript corresponding to t
he HJ1 gene is expressed in MCMV-infected fibroblasts and macrophages
as a member of the late kinetic class of virally encoded transcripts.
A transcriptional start site is located between the third and fourth m
ethionine residues in the ORF, predicting a primary amino acid structu
re, starting at the fourth methionine residue, which includes a possib
le signal peptide as well as conserved cysteine residues typical for m
ammalian beta chemokines. The RNA transcript is polyadenylated, sugges
ting that it can undergo translation within the cytoplasm of an MCMV-i
nfected cell, We speculate that expression of the chemokine homolog at
late times in the MCMV replication cycle plays a role in MCMV pathoge
nesis, possibly by action as a chemotactic agonist or antagonist or by
alteration of the activation or differentiation state of a susceptibl
e cell such as a macrophage.