title: Potent neutralizing serum immunoglobulin A (IgA) in human immunodeficiency virus type 2-exposed IgG-seronegative individuals.
abstract: The mechanisms behind the resistance to human immunodeficiency virus type 2 (HIV-2) infection are still not fully understood. In the present study, we explored the HIV-2-specific humoral serum immunoglobulin A (IgA) immune response in HIV-2-exposed IgG-seronegative (EGSN) individuals. Serum samples from heterosexual EGSN individuals and their known HIV-2-infected partners, as well as controls originating from Guinea-Bissau in Africa, were studied. Antibody reactivity to native and recombinant envelope glycoproteins was investigated, and the capacity of purified serum IgA to neutralize HIV-2(SBL6669) was tested. Our results showed that 16 of 25 EGSN samples exhibited reactivity against whole HIV-2 antigen, 6 of 25 samples reacted with recombinant gp36 (rgp36), and 3 of 25 samples were positive against HIV-2 rgp105; no reactivity to native HIV-2 gp125 was detected. Purified serum IgA antibodies from both EGSN and HIV-2-positive individuals, but not that from the negative controls, exhibited neutralization of HIV-2(SBL6669). The most potent neutralization activity was exhibited by IgA purified from EGSN compared to infected individuals' IgA. The antigenic pattern of the HIV-2-positive partners showed that all serum IgA samples were reactive to whole HIV-2 antigen, and 14 of 15 reacted with rgp36. For rgp105 and gp125, 5 of 15 and 4 of 15 samples exhibited binding, respectively. The serum of the EGSN group had a higher mean IgA concentration than that of the negative controls (P < 0.05). Thus, we describe HIV-2-specific serum IgA antigen reactivity and show a more potent serum IgA-mediated HIV-2-neutralizing activity in EGSN individuals than in HIV-2-infected patients.
authors.affiliation: Research Center, South Hospital, Stockholm, Sweden.
authors.forename: Qin
authors.initials: Q
authors.lastname: Lizeng
authors.forename: Charlotta
authors.initials: C
authors.lastname: Nilsson
authors.forename: Samer
authors.initials: S
authors.lastname: Sourial
authors.forename: Sören
authors.initials: S
authors.lastname: Andersson
authors.forename: Olav
authors.initials: O
authors.lastname: Larsen
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
authors.forename: Mariethe
authors.initials: M
authors.lastname: Ehnlund
authors.forename: Ewa
authors.initials: E
authors.lastname: Björling
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D015686:Gene Products, env / Q000235:genetics / Q000276:immunology; D015488:HIV Antigens / Q000235:genetics / Q000276:immunology; D015658:HIV Infections / Q000276:immunology* / Q000821:virology; D015498:HIV-2 / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D011498:Protein Precursors / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D054299:env Gene Products, Human Immunodeficiency Virus
chemical_list: D015686:Gene Products, env; D015488:HIV Antigens; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D011498:Protein Precursors; D011994:Recombinant Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; C059763:env protein gp36, Human immunodeficiency virus; C069790:gp105 envelope protein, Human immunodeficiency virus 2; C066316:gp125 envelope protein, Human immunodeficiency virus 2