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-β. 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-β. The antiviral activity of this unbound fraction cannot be neutralized by antibodies to IFN-α, -β, γ, 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-α or IFN-β 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-α, -β, or -γ.
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