Detection of IgA inhibiting the interaction between gp120 and soluble CD4 receptor in serum and saliva of HIV-1-infected patients.
OBJECTIVE
To evaluate the presence of IgA directed to the CD4-binding domain of gp120 and to a conserved region of gp41 (the Kennedy epitope) in serum and parotid saliva of HIV-1-seropositive patients.


METHODS
IgA were separated from IgG by anion-exchange chromatography and protein G treatment. The reactivity of IgA was tested against peptides and fusion proteins of the maltose-binding protein (MBP) and the CD4-binding site (MBP24) and MBP and the Kennedy epitope (MBP42). The capacity of serum and saliva IgA to interfere with the gp120-soluble CD4 (sCD4) interaction was examined. IgA were also purified by affinity chromatography using the MBP proteins adsorbed to a resin.


RESULTS
Peptides representing the CD4-binding domain and the Kennedy epitope were recognized by serum and saliva IgA of HIV-1-seropositive patients. Of the sera and saliva samples tested, 6/26 serum IgA and 5/25 saliva IgA inhibited the gp120-sCD4 interaction by approximately 50%. The gp120-sCD4 interaction was inhibited by MBP24 affinity-purified IgA but not by MBP42 affinity-purified IgA.


CONCLUSIONS
Immunogens capable of eliciting IgA antibodies that inhibit gp120-CD4 binding might be efficiently used in vaccine to prevent mucosal transmission of HIV-1.
Vincent
Nadine
N
Groupe Immunité des Muqueuses et Agents Pathogènes, University of Saint-Etienne, Saint-Etienne, France.
Malvoisin
Etienne
E
Pozzetto
Bruno
B
Lucht
Frédéric
F
Genin
Christian
C
D000914:Antibodies, Viral / Q000032:analysis; D015704:CD4 Antigens / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis* / Q000097:blood; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D058619:Maltose-Binding Proteins; D012463:Saliva / Q000276:immunology; D012995:Solubility
D000914:Antibodies, Viral; D015704:CD4 Antigens; D002352:Carrier Proteins; D015699:HIV Envelope Protein gp120; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D058619:Maltose-Binding Proteins