Chemokines and Chemokine Receptors Encoded by Cytomegaloviruses - Human Cytomegalovirus - page 222

Table 2 Cytomegalovirus chemokine receptor-like genes
CMV Species Gene GenBank accession References

HCMV UL33 NC_006273 Casarosa et al. 2003

CCMV UL33 AF480884 Davison et al. 2003

RhCMV rh56 AY186194 Hansen et al. 2003

MCMV M33 U68299 Davis-Poynter et al. 1997

RCMV R33 AF232689 Beisser et al. 1998

GpCMV GP33 AF355272 Liu and Biegalke 2001

HHV-6 U12 NC_001664 Isegawa et al. 1998

HHV-7 U12 U43400 Nanako et al. 2003

HCMV UL78 NC_006273 Michel et al. 2005

CCMV UL78 AF480884 Davison et al. 2003

RhCMV rh107 AY186194 Hansen et al. 2003

MCMV M78 U68299 Oliveira et al. 2001

RCMV R78 AF232689 Beisser et al. 1999

GpCMV GP78 Unavailable Stropes and Miller 2004

HHV-6 U51 NC_001664 Milne et al. 2000

HHV-7 U51 U43400 Tadagaki et al. 2005

HCMV US27 NC_006273 Fraile-Ramos et al. 2002

CCMV US27 AF480884 Sahagun-Ruiz et al. 2004

HCMV US28 NC_006273 Gao and Murphy 1994

CCMV US28 AF480884 Davison et al. 2003

RhCMV rh214, rh215, rh216, AY186194 Sahagun-Ruiz et al. 2004

rh218, rh220

UL33 and UL78 homologs are also present within the genomes of murine, rat
and guinea pig CMV (GpCMV), as well as on the genomes of HHV-6 and -7
(Table 2). These species lack US27- and US28-like genes. HCMV and HHV-6
species were estimated to have diverged approximately 110 My ago (Davison
2002). Since the genomic locations of UL33- and UL78-like genes are highly
conserved among all known betaherpesvirus species, it is likely that these genes
were acquired by a common ancestor of the betaherpesviruses, rather than
independently, after divergence of the different betaherpesvirus species. The
notion that the UL33 and UL78 gene families have been maintained over such
a long period of time suggests an essential role for these genes in the survival
of betaherpesviruses in vivo. The US27- and US28-like genes have only been
identified in primate CMV species. It is likely that these genes have emerged
somewhere after the branching of a common ancestor of rodents and primates,
100 My ago (Li et al. 1990). Interestingly, RhCMV possesses five consecutive
US27/US28-like genes (Penfold et al. 2003b) rather than the two genes (US27
and US28) found in CCMV (Davison et al. 2003) and HCMV (Murphy et al.
2003a). Since the sequences of US27- and US28-like genes in primate CMVs
are highly similar and consecutively positioned with their respective genomes,
it is likely that these genes have emerged from a single hijacked host GCPR
gene-by-gene multiplication.