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Published on: March 8, 2012
Antigenic characterization of human interferon derived from amniotic membranes induced by virus
L F Reis1, J R Dos Santos, P C Ferreira
1Department de Microbiologia, Instituto de Ciencias Biologicas, UFMG, Minas Gerais, Brazil.
Abstract:
The presence of protein(s) with interferon (IFN)-like activity in culture fluid from human amniotic membranes induced by viruses has been described by different groups. However, the antigenic structure of this protein is controversial. Here we report the presence of IFN activity in supernatants of human amniotic membranes induced by Sendai virus. The major component responsible for this antiviral activity seems to be the classical IFN-beta. However, we were able to demonstrate the presence of a protein fraction with antiviral activity that does not bind to an affinity column for IFN-beta. The antiviral activity of this unbound fraction cannot be neutralized by antibodies to IFN-alpha, -beta, gamma, or by a mixture of them. We called this unbound fraction IFN-AM. We also report the development of a monoclonal antibody that does not neutralize the antiviral activity of IFN-alpha or IFN-beta but reduces the antiviral activity of a partially purified preparation of Sendai virus-induced amniotic membrane supernatant. These observations suggest that the IFN-AM (the unbound fraction that lacks reactivity with antibodies against known IFNs) contains a unique antigenic determinant that is not present, or, if so, is not located at the functional domain of IFN-alpha, -beta, or -gamma.
Insights
Researchers identified a novel interferon (IFN)-like protein, IFN-AM, in human amniotic membranes. This unique antiviral protein fraction does not react with antibodies against known interferons, suggesting a distinct antigenic structure.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- Interferon (IFN)-like antiviral activity has been detected in human amniotic membranes.
- The antigenic structure of these IFN-like proteins remains controversial.
- Virus induction of human amniotic membranes yields supernatants with antiviral properties.
Purpose of the Study:
- To characterize the IFN-like antiviral activity in human amniotic membrane supernatants induced by Sendai virus.
- To investigate the antigenic properties of the antiviral components.
- To identify novel interferon-associated proteins.
Main Methods:
- Induction of human amniotic membranes with Sendai virus.
- Assay of antiviral activity in culture supernatants.
- Affinity chromatography using IFN-beta binding columns.
- Neutralization assays with antibodies against IFN-alpha, -beta, and -gamma.
- Development and testing of a novel monoclonal antibody.
Main Results:
- Supernatants contained significant IFN activity, primarily attributed to IFN-beta.
- A distinct antiviral protein fraction (IFN-AM) was isolated that did not bind to IFN-beta affinity columns.
- IFN-AM's antiviral activity was not neutralized by antibodies to known IFNs (IFN-alpha, -beta, -gamma).
- A monoclonal antibody was developed that recognized IFN-AM, reducing its antiviral activity without affecting IFN-alpha or IFN-beta.
Conclusions:
- Human amniotic membranes produce a unique interferon-like antiviral protein, designated IFN-AM.
- IFN-AM possesses distinct antigenic determinants not found in or accessible on IFN-alpha, -beta, or -gamma.
- This discovery suggests a novel type of interferon with potential therapeutic implications.
