Immunoglobulin G3 from polyclonal human immunodeficiency virus (HIV) immune globulin is more potent than other subclasses in neutralizing HIV type 1
| Autor: | Nancy Eller, Hana Golding, Orit Scharf, Basil Golding, Dorothy E. Scott, Doug Frazier, Lisa R. King |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
medicine.drug_class
Immunology chemical and pharmacologic phenomena HIV Infections Monoclonal antibody Antibodies Viral Microbiology Subclass Neutralization Immunoglobulin G Immunoglobulin Fab Fragments Neutralization Tests Virology parasitic diseases Vaccines and Antiviral Agents medicine Humans biology Effector Molecular biology Polyclonal antibodies Insect Science biology.protein HIV-1 Antibody |
| Zdroj: | Journal of virology. 75(14) |
| ISSN: | 0022-538X |
| Popis: | Passive antibody prophylaxis against human immunodeficiency virus type 1 (HIV-1) has been accomplished in primates, suggesting that this strategy may prove useful in humans. While antibody specificity is crucial for neutralization, other antibody characteristics, such as subclass, have not been explored. Our objective was to compare the efficiencies of immunoglobulin G (IgG) subclasses from polyclonal human HIV immune globulin (HIVIG) in the neutralization of HIV-1 strains differing in coreceptor tropism. IgG1, IgG2, and IgG3 were enriched from HIVIG by using protein A-Sepharose. All three subclasses bound major HIV-1 proteins, as shown by Western blot assay and enzyme-linked immunosorbent assay. In HIV-1 fusion assays using X4, R5, or X4R5 envelope-expressing effector cells, IgG3 more efficiently blocked fusion. In neutralization assays with cell-free viruses using X4 (LAI, IIIB), R5 (BaL), and X4R5 (DH123), a similar hierarchy of neutralization was found: IgG3 > IgG1 > IgG2. IgG3 has a longer, more flexible hinge region than the other subclasses. To test whether this is important, IgG1 and IgG3 were digested with pepsin to generate F(ab′)2fragments or with papain to generate Fab fragments. IgG3 F(ab′)2fragments were still more efficient in neutralization than F(ab′)2of IgG1. However, Fab fragments of IgG3 and IgG1 demonstrated equivalent neutralization capacities and the IgG3 advantage was lost. These results suggest that the IgG3 hinge region confers enhanced HIV-neutralizing ability. Enrichment and stabilization of IgG3 may therefore lead to improved HIVIG preparations. The results of this study have implications for the improvement of passive immunization with polyclonal or monoclonal antibodies and suggest that HIV-1 vaccines which induce high-titer IgG3 responses could be advantageous. |
| Databáze: | OpenAIRE |
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