Biomedical subjects

Mariethe Ehnlund

Publications and source records attributed to Mariethe Ehnlund.

3 recordsLinked to original sources

PubMed2004

Potent neutralizing serum immunoglobulin A (IgA) in human immunodeficiency virus type 2-exposed IgG-seronegative individuals.

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.

Adolescent↗

PubMed2003

Serum immunoglobulin A (IgA)-mediated immunity in human immunodeficiency virus type 2 (HIV-2) infection.

In the present study, we sought to define the importance of serum IgA (sIgA)-mediated immunity in HIV-2 infection. Serum samples from a total of 29 HIV-2-infected patients from Guinea-Bissau (n = 20) and Portugal (n = 9) were studied. Samples from seronegative individuals were used as controls. Antibody reactivity to native and recombinant envelope glycoproteins as well as peptides representing various regions of the envelope glycoproteins was investigated. Furthermore, the capacity of purified IgA to neutralize the HIV-2(SBL6669) strain was tested. All serum samples showed IgA reactivity against whole HIV-2 antigen. Twenty-eight out of 29 IgA samples (96%) reacted with native HIV-2 gp125, 26/29 (90%) with recombinant gp105, and 29/29 (100%) with recombinant gp36. When using peptides, the most prominent IgA reactivity was seen against the peptide representing aa 644-658 of the transmembranous protein gp36, to which 72% of the sera reacted. Purified sIgA antibodies showed neutralizing effects against HIV-2(SBL6669) in 17/29 cases (59%). This work describes the HIV-2-specific sIgA antigenic response. Moreover, our findings show, for the first time, that sIgA may play a role in the in vitro neutralization of HIV-2.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Human neutralizing human immunodeficiency virus type 2-specific Fab molecules generated by phage display.

A panel of human immunodeficiency virus type 2 (HIV-2)-neutralizing, recombinant Fab fragments was generated by using the phage display technique. The combinatorial library was derived from an asymptomatic, HIV-2-seropositive individual and constructed on the surface of filamentous phage by using the pComb3 phagemid vector and then screened against native HIV-2 envelope glycoprotein (gp125). Ten of 30 Fab fragments generated displayed strong reactivity in an ELISA and were therefore selected for further study. Six of these possessed neutralizing capacity, with titres varying from 20 to 80 against the homologous HIV-2 strain, and one also had a weak neutralizing capacity against a heterologous HIV-2 isolate, K135. Sequencing of the heavy chain CDR3 regions showed that the gp125-specific Fabs represented individual clones. These reagents may be useful for studies on the conformational structures of the HIV-2 envelope antigens and their immunogenicity, which may help in vaccine design. Furthermore, the cloned Fab genes may be transformed into whole IgG for eukaryotic expression, and as such used for therapeutic and immunoprophylactic studies in HIV-2-infected macaques and, possibly, for human immunoprophylaxis against HIV-2.

Amino Acid Sequence↗