HLA-DR and HLA-DP restricted epitopes from human cytomegalovirus glycoprotein B recognized by CD4+ T-cell clones from chronically infected individuals.
OBJECTIVE
Helper CD4(+) T cells presumably play a major role in controlling cytomegalovirus (CMV) by providing help to specific B and CD8(+) cytotoxic T cells, as well as through cytotoxicity-mediated mechanisms. Since CMV glycoprotein B (gB) is a major candidate for a subunit vaccine against CMV, we searched for gB-epitopes presented by human leukocyte antigen (HLA)-class II molecules.


METHODS
Dendritic cells obtained from CMV-seropositive donors were loaded with a recombinant gB and co-cultured with autologous CD4(+) T cells. Microcultures that specifically recognized gB were cloned by limiting dilution using autologous Epstein-Barr virus (EBV)-immortalized B cells pulsed with gB as antigen-presenting cells. To pinpoint precisely the region encoding the natural epitope recognized by a given CD4(+) clone, we assessed the recognition of recombinant Escherichia coli expressing gB-overlapping polypeptides after their processing by autologous EBV-B cells.


RESULTS
We isolated several gB-specific CD4(+) T-cell clones directed against peptides gB(190-204), gB(396-410), gB(22-36) and gB(598-617) presented by HLA-DR7, HLA-DP10 and HLA-DP2. While their precise role in controlling CMV infection remains to be established, gB-specific CD4(+) T cells are likely to act by directly targeting infected HLA-class II cells in vivo, as suggested by their recognition of EBV-B cells infected by the Towne CMV strain.


CONCLUSIONS
The characterization of such gB-epitopes presented by HLA-class II should help to understand the contribution of CD4(+) T-cell responses to CMV and may be of importance both in designing a vaccine against CMV infection and in immunomonitoring of subjects immunized with recombinant gB or with vectors encoding gB.
Discovery Department, Sanofi Pasteur, 1541 Avenue Marcel Mérieux, 69280 Marcy l’Etoile, France.
Claire
C
Ventura
Hélène
H
Bisceglia
Yves
Y
Girerd-Chambaz
Nicolas
N
Burdin
Pascal
P
Chaux
D000595:Amino Acid Sequence; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology / Q000821:virology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology / Q000821:virology; D002908:Chronic Disease; D002999:Clone Cells; D018920:Coculture Techniques; D003587:Cytomegalovirus / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D003586:Cytomegalovirus Infections / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000821:virology; D003713:Dendritic Cells / Q000276:immunology / Q000473:pathology / Q000821:virology; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D004926:Escherichia coli / Q000235:genetics; D006682:HLA-DP Antigens / Q000235:genetics / Q000276:immunology*; D015809:HLA-DR7 Antigen / Q000235:genetics / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000276:immunology; D061251:Primary Cell Culture; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000473:pathology / Q000821:virology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*
D000939:Epitopes; D006682:HLA-DP Antigens; D015809:HLA-DR7 Antigen; D009842:Oligopeptides; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus