Production of a novel antigen by conjugation of HIV-1 to Brucella abortus: studies of immunogenicity, isotype analysis, T-cell dependency, and syncytia inhibition.
In the present study inactivated human immunodeficiency virus type 1 (HIV-1) was conjugated to Brucella abortus and tested for immunogenicity in normal and anti-L3T4-treated BALB/c mice. HIV-BA was more immunogenic than uncoupled HIV in normal mice, since 6-fold less virus in HIV-BA preparations elicited higher titer responses than HIV-1 alone. Furthermore, the HIV-BA antibody response reached higher levels before the HIV-1 response. Immunoblot analysis showed that most of the HIV-1 antigens were recognized by antibodies induced by either HIV-1 or HIV-BA. Isotype analysis revealed that HIV-1 induced similar levels of IgG1 and IgG2a antibodies, whereas the IgG2a responses to HIV-BA were more pronounced than the IgG1 response. These different IgG subclass patterns suggest that conjugation of HIV-1 to BA changed the immunogenic nature of HIV-1. The requirement for helper T cells was examined by immunizing mice that were depleted of CD4+ T cells by in vivo anti-L3T4 treatment. Under these conditions the IgG responses to HIV-1 were completely eliminated. Although HIV-BA antibody responses were markedly reduced in anti-L3T4-treated mice, anti-HIV-1 antibodies, mainly of the IgG2a isotype, were produced. The antibodies generated by HIV-1 and HIV-BA immunization were also tested for their ability to inhibit syncytia formed by infecting CD4 + CEM cells with gp160 vaccinia. Sera from normal mice, immunized with either HIV-1 or HIV-BA were capable of inhibiting syncytia. In contrast, following anti-L3T4 treatment, only mice immunized with HIV-BA, but not HIV-1, produced antibodies capable of inhibiting syncytia.
Laboratory on Cell Biology, U.S. Food and Drug Administration, Bethesda, MD 20892.
B
B
Golding
H
H
Golding
S
S
Preston
D
D
Hernandez
P R
PR
Beining
J
J
Manischewitz
L
L
Harvath
R
R
Blackburn
E
E
Lizzio
T
T
Hoffman
D000818:Animals; D000918:Antibody Specificity; D002003:Brucella abortus / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D015686:Gene Products, env / Q000276:immunology; D015726:Giant Cells / Q000276:immunology*; D015483:HIV Antibodies / Q000096:biosynthesis; D015488:HIV Antigens / Q000138:chemical synthesis* / Q000276:immunology; D019302:HIV Envelope Protein gp160; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007132:Immunoglobulin Isotypes / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D011498:Protein Precursors / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology*; D014765:Viral Vaccines / Q000276:immunology*
D015686:Gene Products, env; D015483:HIV Antibodies; D015488:HIV Antigens; D019302:HIV Envelope Protein gp160; D007132:Immunoglobulin Isotypes; D011498:Protein Precursors; D014614:Vaccines, Synthetic; D014765:Viral Vaccines