HHV8-encoded vMIP-I Selectively Engages Chemokine Receptor CCR8

Abstract

Uncertainty regarding viral chemokine function is mirrored by an incomplete knowledge of host chemokine receptor usage by the virally encoded proteins. One such molecule is vMIP-I, a C-C type chemokine of undefined function and binding specificity, encoded by the Kaposi's sarcoma herpesvirus HHV-8. We report here that vMIP-I binds to and induces cytosolic [Ca2+] signals in human T cells selectively through CCR8, a CC chemokine receptor associated with Th2 lymphocytes. Furthermore, using a panel of 65 different human, viral, and rodent chemokines, we have established a comprehensive ligand binding “fingerprint” for CCR8. The receptor exhibits marked “high” affinity (Kd < 15 nm) only for four chemokines, three of them of viral origin: vMIP-I, vMIP-II, vMCC-I, and human I-309. A previously unreported second class of lower affinity ligands includes MCP-3 and possibly two other viral chemokines. vMIP-I and I-309 appear to act as CCR8 agonists: binding to and inducing cytosolic [Ca2+] elevation through the receptor. By contrast, vMIP-II and vMCC-I act as potent antagonists: binding without inducing signaling, and blocking the effects of I-309 and vMIP-I. These results suggest a ligand hierarchy for CCR8, identifying vMIP-I as a selective viral chemokine agonist. CCR8 may thus engage a specific subset of chemokines with the potential to regulate each other during viral infection and immune regulation. Uncertainty regarding viral chemokine function is mirrored by an incomplete knowledge of host chemokine receptor usage by the virally encoded proteins. One such molecule is vMIP-I, a C-C type chemokine of undefined function and binding specificity, encoded by the Kaposi's sarcoma herpesvirus HHV-8. We report here that vMIP-I binds to and induces cytosolic [Ca2+] signals in human T cells selectively through CCR8, a CC chemokine receptor associated with Th2 lymphocytes. Furthermore, using a panel of 65 different human, viral, and rodent chemokines, we have established a comprehensive ligand binding “fingerprint” for CCR8. The receptor exhibits marked “high” affinity (Kd < 15 nm) only for four chemokines, three of them of viral origin: vMIP-I, vMIP-II, vMCC-I, and human I-309. A previously unreported second class of lower affinity ligands includes MCP-3 and possibly two other viral chemokines. vMIP-I and I-309 appear to act as CCR8 agonists: binding to and inducing cytosolic [Ca2+] elevation through the receptor. By contrast, vMIP-II and vMCC-I act as potent antagonists: binding without inducing signaling, and blocking the effects of I-309 and vMIP-I. These results suggest a ligand hierarchy for CCR8, identifying vMIP-I as a selective viral chemokine agonist. CCR8 may thus engage a specific subset of chemokines with the potential to regulate each other during viral infection and immune regulation. It has recently been appreciated that in addition to roles in regulating leukocyte trafficking, the chemokine system is intimately linked to the biology of infectious disease (1Weiss R. Nat. Med. 1996; 2: 277-278Crossref PubMed Scopus (33) Google Scholar, 2Bacon K.B. Greaves K.B. Dairaghi D.J. Schall T.J. Thompson A. The Cytokine Handbook. 3rd Ed. Academic Press, London1998: 753-775Google Scholar, 3Baggiolini M. Nature. 1998; 392: 565-568Crossref PubMed Scopus (2388) Google Scholar). This has prompted intensive investigation of viral chemokine analogues that have been identified in herpesvirus and poxvirus genomes. Human herpesviruses including CMV and HHV-8 (Kaposi's sarcoma herpesvirus; Refs. 4Dittmer D. Kedes D. BioEssays. 1998; 20: 367-370Crossref PubMed Scopus (13) Google Scholar and 5Moore P. Boshoff C. Weiss R. Chang Y. Science. 1996; 274: 1739-1744Crossref PubMed Scopus (821) Google Scholar), as well the poxvirus Molluscum contagiosum(MCV), 1The abbreviations used are: MCV, poxvirusMolluscum contagiosum ; PBMC, peripheral blood mononuclear cell; FBS, fetal bovine serum; IL-2, interleukin 2; CMV, cytomegalovirus; ORF, open reading frame; HHV8, human herpesvirus 8.1The abbreviations used are: MCV, poxvirusMolluscum contagiosum ; PBMC, peripheral blood mononuclear cell; FBS, fetal bovine serum; IL-2, interleukin 2; CMV, cytomegalovirus; ORF, open reading frame; HHV8, human herpesvirus 8. encode versions of chemokines, chemokine receptors, and chemokine-binding proteins (6McFadden G. Lalani A. Everett H. Nash P. Xu X. Semin. Cell Dev. Biol. 1998; 9: 359-368Crossref PubMed Scopus (59) Google Scholar, 7Senkevich T.G. Bugert J.J. Sisler J.R. Koonin E.V. Darai G. Moss B. Science. 1996; 273: 813-816Crossref PubMed Scopus (276) Google Scholar). For example, HHV8 encodes three predicted CC-type chemokines (vMIP-I, vMIP-II, and vMIP-III) and one predicted chemokine receptor (ORF 74) (5Moore P. Boshoff C. Weiss R. Chang Y. Science. 1996; 274: 1739-1744Crossref PubMed Scopus (821) Google Scholar, 8Nicholas J. Ruvolo V. Burns W. Sandford G. Wan X. Ciufo D. Hendrickson S. Guo H. Hayward G. Reitz M. Nat. Med. 1997; 3: 287-292Crossref PubMed Scopus (337) Google Scholar, 9Boschoff C. Endo Y. Collins P. Takeuchi Y. Reeves J. Schweickart V. Siani M. Sasaki T. Williams T. Gray P. Moore P. Chang Y. Weiss R. Science. 1997; 278: 290-294Crossref PubMed Scopus (440) Google Scholar). Similarly, human CMV has long been known to encode a chemokine receptor, a product of the US28 ORF (10Neote K. DiGregorio D. Mak J. Horuk R. Schall T.J. Cell. 1993; 72: 415-421Abstract Full Text PDF PubMed Scopus (698) Google Scholar, 11Bodaghi B. Jones T.R. Zipeto D. Vita C. Sun L. Laurent L. Arenzana-Seisdedos F. Virelizier F. Michelson S. J. Exp. Med. 1998; 188: 855-866Crossref PubMed Scopus (259) Google Scholar). More recently clinical isolates of CMV have been shown to encode two CXC chemokines, designated vCXC-1 and vCXC-2, which are products of the UL146 and UL 147 ORFs (12Cha T. Tom E. Kemble G.W. Duke G.M. Mocarski E.S. Spaete R.R. J. Virol. 1996; 70: 78-83Crossref PubMed Google Scholar, 13Penfold M.E.T. Dairaghi D.J. Duke G.M. Saederup N. Mocarski E.S. Kemble G.W. Schall T.J. Proc. Natl Acad. Sci. U. S. A. 1999; (in press)PubMed Google Scholar). The selective advantage which these virally encoded chemokine elements confer to their pathogens is yet unclear. Although the multiple biological activities of viral chemokine elements are likely to be directly related to pathogenesis, including enhanced dissemination of viral particles (9Boschoff C. Endo Y. Collins P. Takeuchi Y. Reeves J. Schweickart V. Siani M. Sasaki T. Williams T. Gray P. Moore P. Chang Y. Weiss R. Science. 1997; 278: 290-294Crossref PubMed Scopus (440) Google Scholar, 14Saederup N. Dairaghi D.J. Schall T.J. Mocarski E.S. Proc. Natl Acad. Sci. U. S. A. 1999; (in press)Google Scholar), the molecular mechanisms underlying the actions of most of the viral chemokines are largely unknown. In two cases, viral chemokines have been shown to interact with a spectrum of host chemokine receptors, such as evidenced by the actions of HHV8-encoded vMIP-II (15Kledal T. Rosenkilde M. Coulin F. Simmons G. Johnsen A. Alouani S. Power C. Luttichau H. Gerstoft J. Clapham P. Clark-Lewis I. Wells T. Schwartz T. Science. 1997; 277: 1656-1659Crossref PubMed Scopus (425) Google Scholar) and MCV-encoded vMCC-I (a product of MCV ORF148R; Refs. 7Senkevich T.G. Bugert J.J. Sisler J.R. Koonin E.V. Darai G. Moss B. Science. 1996; 273: 813-816Crossref PubMed Scopus (276) Google Scholar and 16Damon I. Murphy P. Moss B. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6403-6407Crossref PubMed Scopus (105) Google Scholar). 2For convenience, we denote the viral CC chemokine gene product encoded by the Molluscum contagiosumvirus ORF MC148R as vMCC-I (viral, MolluscumCC chemokine-I). No standard nomenclature yet exists for the human chemokine superfamily, let alone chemokines encoded by viruses, but this designation follows the convention for designating chemokines simply as either “CXC” or “CC,” followed by a numerical designator of order of entry into publicly available gene sequence data banks. (A systematic nomenclature is under consideration and will be published by a chemokine nomenclature committee elsewhere.)2For convenience, we denote the viral CC chemokine gene product encoded by the Molluscum contagiosumvirus ORF MC148R as vMCC-I (viral, MolluscumCC chemokine-I). No standard nomenclature yet exists for the human chemokine superfamily, let alone chemokines encoded by viruses, but this designation follows the convention for designating chemokines simply as either “CXC” or “CC,” followed by a numerical designator of order of entry into publicly available gene sequence data banks. (A systematic nomenclature is under consideration and will be published by a chemokine nomenclature committee elsewhere.)These chemokines have been reported to have antagonist activities, but at least in the case of vMIP-II, this may be altered with N-terminal sequence variants (9Boschoff C. Endo Y. Collins P. Takeuchi Y. Reeves J. Schweickart V. Siani M. Sasaki T. Williams T. Gray P. Moore P. Chang Y. Weiss R. Science. 1997; 278: 290-294Crossref PubMed Scopus (440) Google Scholar, 15Kledal T. Rosenkilde M. Coulin F. Simmons G. Johnsen A. Alouani S. Power C. Luttichau H. Gerstoft J. Clapham P. Clark-Lewis I. Wells T. Schwartz T. Science. 1997; 277: 1656-1659Crossref PubMed Scopus (425) Google Scholar). Apart from the promiscuous binding patterns of vMIP-II and vMCC-I, the receptor interactions of other virally derived chemokines have not been fully characterized. As such they remain “orphan” chemokine ligands, analogous to putative chemokine receptor-like molecules for which no ligands have yet been identified. One such molecule is the HHV8-encoded vMIP-I protein (5Moore P. Boshoff C. Weiss R. Chang Y. Science. 1996; 274: 1739-1744Crossref PubMed Scopus (821) Google Scholar, 8Nicholas J. Ruvolo V. Burns W. Sandford G. Wan X. Ciufo D. Hendrickson S. Guo H. Hayward G. Reitz M. Nat. Med. 1997; 3: 287-292Crossref PubMed Scopus (337) Google Scholar), which was originally identified from genomic sequencing and subsequently reported to have some angiogenic and anti-HIV infectivity activities (5Moore P. Boshoff C. Weiss R. Chang Y. Science. 1996; 274: 1739-1744Crossref PubMed Scopus (821) Google Scholar, 9Boschoff C. Endo Y. Collins P. Takeuchi Y. Reeves J. Schweickart V. Siani M. Sasaki T. Williams T. Gray P. Moore P. Chang Y. Weiss R. Science. 1997; 278: 290-294Crossref PubMed Scopus (440) Google Scholar, 17Nicholas J. Ruvolo V. Zong J. Ciudo D. Guo H. Reitz M. Hayward G. J. Virol. 1997; 71: 1963-1974Crossref PubMed Google Scholar). In this manuscript, we have reported our investigation of the biochemical properties of vMIP-I. Specifically, we have examined the activities of vMIP-I on primary human T cells and compared these actions to those from a spectrum of other human and human virus-encoded chemokines. We have also introduced comprehensive receptor profiling, using an array of over five dozen recombinant chemokines to define comprehensively the molecular recognition properties of CCR8. In so doing, we have identified that CCR8, which is known to bind human I-309 and is associated with human Th2 cells (18Roos R. Loetscher M. Legler D. Clark-Lewis I. Baggiolini M. Moser B. J. Biol. Chem. 1997; 272: 17251-17254Abstract Full Text Full Text PDF PubMed Scopus (159) Google Scholar, 19Goya I. Gutierrez J. Varona R. Kremer L. Zaballos A. Marquez G. J. Immunol. 1998; 160: 1975-1981PubMed Google Scholar, 20Tiffany H. Lautens L. Gao J. Pease J. Locati M. Combadiere C. Modi W. Bonner T. Murphy P.M. J. Exp. Med. 1997; 186: 165-170Crossref PubMed Scopus (183) Google Scholar, 21D'Ambrosio D. Iellem A. Bonecchi R. Mazzeo D. Sozzani S. Montovani A. Sinigaglia F. J. Immunol. 1998; 161: 5111-5115PubMed Google Scholar, 22Zingoni A. Soto H. Hedrick A. Stoppacciaro A. Storlazzi C. Sinigaglia F. D'Ambrosio D. O'Garra A. Robinson D. Rocchi M. Santoni A. Zlotnik A. Napolitano M. J. Immunol. 1998; 161: 547-551PubMed Google Scholar), is also the molecular target of vMIP-I. Unlike vMIP-II, which is promiscuous in its binding profile, vMIP-I selectively engages CCR8. Moreover, whereas vMIP-II and vMCV-II are CCR8 antagonists, vMIP-I is, like I-309, a CCR8 agonist. Last, our comprehensive binding profile shows that other chemokines previously not known to bind to CCR8, such as MCP-3 and possibly two other viral chemokines, may engage the receptor at moderate to low affinities. Thus, an expanded ligand binding fingerprint for human CCR8 has been defined, and most chemokines that engage this receptor are of viral origin. These results suggest that human Th2 function may be a prime target of viruses through the actions of virally encoded chemokines. In particular, Th2 cells may be controlled through CCR8 by the actions vMIP-I, and these effects may be cross-regulated by other viral chemokines. Human peripheral blood mononuclear cells (PBMC) were obtained from buffy coats of healthy blood donors (Stanford blood bank) by density gradient on LSM (lymphocyte separation media) as described in the protocol of the manufacturer (ICN). Isolated PBMC were resuspended in RPMI 1640 medium supplemented with 10% FBS, 1% penicillin-streptomycin. PBMC were cultured (37 °C, 16 h) to allow monocytes to adhere. Nonadherent lymphocytes were transferred in suspension (initial density 106/ml), and subsequently cultured for 12–15 days (RPMI 1640 medium containing 10% FBS, 1 ng/ml human recombinant IL-2 (R&D Systems), fed weekly). In all cases, the phenotype of the cultured cells was >90% CD3-positive (T cells), CD45RO-positive (mature T cells), CD14-negative (monocytes), CD20-negative (B cells), and CD45RA-negative (immature T cells). Other T cell population markers, CD4, CD8, CD56, and HLA-DR, demonstrated donor variability. Human CCR8 NSO transfected cells (R&D Systems) were cultured in Iscove's modified Dulbecco's medium (supplemented with 5% FBS, 1% penicillin-streptomycin). Human, viral, and murine recombinant chemokines were obtained from R&D Systems. 125 I-labeled I-309 was obtained from NEN Life Science Products. The monoclonal antibodies used in flow cytometry were from R&D Systems (MAB155 (CCR1); MAB150 (CCR2); MAB330 (CXCR1); MAB331 (CXCR2); MAB160 (CXCR3); MAB173 (CXCR4)), and from the National Institutes of Health AIDS Research and Reference Reagent Program (7B11 (CCR3), and 2D7 (CCR5)). We have recently developed a technique for global profiling of chemokine receptor/chemokine ligand interactions, designated DisplaceMax™. This technology employs expanded, efficiency-maximized radioligand binding utilizing filtration protocols (23Bacon K. Schall T.J. Dairaghi D.J. J. Immunol. 1998; 160: 1894-1900PubMed Google Scholar). In these assays, DisplaceMax™ employed the simultaneous interrogation of primary T cells or CCR8 transfectants by 65 distinct purified chemokines in the ability to displace radiolabeled I-309. Briefly, for each of the 65 chemokines, 5 × 105CCR8-NSO cells or × IL-2 cultured lymphocytes were with 125 I-labeled I-309 of nm) in the of chemokine at 1 5 and bovine to were using a cell were 1 5 to was to and in a were and using were using standard Briefly, cells were in containing 1% bovine resuspended at × cells well in and with the monoclonal were three and with the The cells were on a and results have been for cells using were as described previously using an D.J. E. K. Schall T.J. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google Scholar). were with in medium °C, cells were of and resuspended with 1% FBS, was using at using a at at and were at with 5 to primary human immune cells were of by virally encoded chemokines, we established of T cells by using flow The cell of chemokine was in these cell using chemokine receptor antibodies available and by [Ca2+] in to a panel of chemokines of binding and of the cell of chemokine by specific antibodies and cell in cell from multiple donors a was of and with of other chemokine were the available panel of receptor antibodies is we the and function of all known chemokine on these cells by [Ca2+] chemokine These patterns are with the by [Ca2+] signals are in to and and and with their In the of and CCR8 were from the profile We the cells with viral chemokines, two of vMIP-II and vMCC-I, have been reported to bind to multiple chemokine their reported binding an [Ca2+] the only viral chemokine a was the HHV8-encoded vMIP-I. This that vMIP-I for likely through one or of the chemokine on T of by chemokines has been used to at a receptor (10Neote K. DiGregorio D. Mak J. Horuk R. Schall T.J. Cell. 1993; 72: 415-421Abstract Full Text PDF PubMed Scopus (698) Google Scholar). Thus, vMIP-I were for of [Ca2+] signals by the chemokines which were previously shown to the T cell in a [Ca2+] to be by of the [Ca2+] and The one was with the I-309, of was to and other chemokines that the was at the of the CCR8 receptor only and not of interactions with other chemokine or of and define the ligand binding fingerprint of a chemokine receptor, we have established an to comprehensively chemokine using a array of purified chemokines. We used this to the of vMIP-I with CCR8. radioligand binding of 125 I-labeled I-309 to CCR8 chemokine for CCR8 was known chemokines which be obtained in purified were used as at a of 125 I-labeled I-309 in binding The in that the only potent chemokine interactions for human CCR8 other human I-309 were the viral chemokines vMIP-I, vMIP-II, and Moreover, the of this was by the of a potential second class of lower affinity chemokine including MCP-3 and possibly and The binding interactions identified in the primary were examined by radioligand binding to CCR8 transfectants and of the data and The results the affinity binding affinity 15 nm) of I-309 and the viral chemokines in the order I-309 vMCC-I vMIP-I The binding results were in human lymphocytes with that were the two cell The class of potential moderate to low affinity ligands to These chemokines not previously reported to bind to and two viral chemokines, and each not The of these lower affinity interactions has not been The HHV8-encoded chemokine vMIP-II has been previously reported as either or antagonist activities on specific chemokine (9Boschoff C. Endo Y. Collins P. Takeuchi Y. Reeves J. Schweickart V. Siani M. Sasaki T. Williams T. Gray P. Moore P. Chang Y. Weiss R. Science. 1997; 278: 290-294Crossref PubMed Scopus (440) Google Scholar, 15Kledal T. Rosenkilde M. Coulin F. Simmons G. Johnsen A. Alouani S. Power C. Luttichau H. Gerstoft J. Clapham P. Clark-Lewis I. Wells T. Schwartz T. Science. 1997; 277: 1656-1659Crossref PubMed Scopus (425) Google Scholar, S. W. G. P. Wells T. Napolitano M. G. A. D'Ambrosio D. Mazzeo D. Sinigaglia F. Santoni A. E. S. A. 1998; PubMed Google Scholar), whereas vMCC-I has been previously reported as a chemokine receptor antagonist I. Murphy P. Moss B. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6403-6407Crossref PubMed Scopus (105) Google Scholar). the interactions of the affinity CCR8 ligands I-309, vMIP-I, vMIP-II, and vMCC-I, we a of using of these chemokines. vMIP-I and I-309 [Ca2+] in T vMIP-II vMCC-I a [Ca2+] In the T cells with of either vMIP-II and vMCC-I that these viral chemokines CCR8 antagonist such that the to I-309 and vMIP-I were were to this be by of I-309 or vMIP-I The suggest by vMCC-I and vMIP-II of the actions of I-309 and vMIP-I. regarding the molecular recognition of host chemokine by the HHV8-encoded chemokine vMIP-I have not previously been This the ability of vMIP-I and other viral chemokines to in human T and to define the ligand binding of vMIP-I chemokine comprehensive chemokine and binding we have shown on human T cells and chemokine receptor transfectants that vMIP-I selectively engages the chemokine receptor CCR8 with The of vMIP-I with CCR8 selective in that demonstrated only with I-309. Thus, like I-309 (18Roos R. Loetscher M. Legler D. Clark-Lewis I. Baggiolini M. Moser B. J. Biol. Chem. 1997; 272: 17251-17254Abstract Full Text Full Text PDF PubMed Scopus (159) Google Scholar, 19Goya I. Gutierrez J. Varona R. Kremer L. Zaballos A. Marquez G. J. Immunol. 1998; 160: 1975-1981PubMed Google Scholar, 20Tiffany H. Lautens L. Gao J. Pease J. Locati M. Combadiere C. Modi W. Bonner T. Murphy P.M. J. Exp. Med. 1997; 186: 165-170Crossref PubMed Scopus (183) Google Scholar), vMIP-I to be a CCR8 the only other affinity ligands, the viral chemokines vMIP-II and vMCC-I (15Kledal T. Rosenkilde M. Coulin F. Simmons G. Johnsen A. Alouani S. Power C. Luttichau H. Gerstoft J. Clapham P. Clark-Lewis I. Wells T. Schwartz T. Science. 1997; 277: 1656-1659Crossref PubMed Scopus (425) Google Scholar, 16Damon I. Murphy P. Moss B. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6403-6407Crossref PubMed Scopus (105) Google Scholar), act as of CCR8. here in the regarding the of I-309 and vMCC-I on CCR8, but not the that CCR8 also engages and as ligands G. Hedrick J. Sozzani S. W. G. Weiss M. S. A. Montovani A. Santoni A. Napolitano M. J. Immunol. 1998; PubMed Scopus Google Scholar). It be that the of those ligands was not on biochemical binding and of CCR8 and its putative ligands but on a in In that cells to to and CCR8 G. Hedrick J. Sozzani S. W. G. Weiss M. S. A. Montovani A. Santoni A. Napolitano M. J. Immunol. 1998; PubMed Scopus Google Scholar). The data here suggest the that the of function may have been or or CCR8 but are not directly a of CCR8 binding It is also that a report that binds multiple chemokine I. Murphy P. Moss B. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6403-6407Crossref PubMed Scopus (105) Google Scholar), we of vMCC-I for CCR8. In addition to some ligands as directly through CCR8, the of a comprehensive ligand binding fingerprint for this receptor that may interact also with and possibly two viral chemokines, and These interactions are to at affinity those of the affinity CCR8 ligands vMIP-I, I-309, vMIP-II, and are to this class of lower affinity interactions is of The of of CCR8 by vMIP-I are not yet but to we have or no of either I-309 or vMIP-I in T cells not This is the that these ligands [Ca2+] in T cells from multiple donors and the that the cells to in [Ca2+] signals and in One is from the of I-309 on murine T cell the human chemokine to the cells from J. F. P. J. J. J. Immunol. 1996; Google Scholar). We are vMIP-I may regulate the of T lymphocytes through CCR8 as of may be a function for a herpesvirus such as HHV8, which in It is also to that the ability of I-309 or vMIP-I to act as in may be For example, in T cells CCR8 is not in Th2 D. Iellem A. Bonecchi R. Mazzeo D. Sozzani S. Montovani A. Sinigaglia F. J. Immunol. 1998; 161: 5111-5115PubMed Google A. Soto H. Hedrick A. Stoppacciaro A. Storlazzi C. Sinigaglia F. D'Ambrosio D. O'Garra A. Robinson D. Rocchi M. Santoni A. Zlotnik A. Napolitano M. J. Immunol. 1998; 161: 547-551PubMed Google Scholar). of Th2 T cells has been reported in Kaposi's sarcoma S. W. G. P. Wells T. Napolitano M. G. A. D'Ambrosio D. Mazzeo D. Sinigaglia F. Santoni A. E. S. A. 1998; PubMed Google Scholar) has been to through an of vMIP-II, vMIP-I, on the CCR8 receptor. the in effects of vMIP-I, or other viral chemokines, may not be predicted from receptor interactions the chemokine binding fingerprint of CCR8 here regarding the on the of viral chemokines for this receptor. It is to that some advantage is to human viruses of CCR8, possibly through of in a virally In comprehensive chemokine profiling a in the recognition and of ligands for chemokine such as CCR8. The of vMIP-I as a for CCR8, and one which is cross-regulated by other viral chemokines, may into the function of viral chemokines and of Th2 cells during infection and immune regulation. We and at R&D Systems for of of the recombinant chemokines and and we for NSO We also for and chemokine for in assays, and R. Greaves for