Culture of human amniotic cells: A system to study interferon production

This study investigated whether primary culture of human amniotic membrane cells (PCHAM) could be used as an in vitro model system for the study of interferon (IFN) production. PCHAM cells infected with Newcastle disease virus (NDV) produced the two antigenic types of IFN, previously shown in a amniotic membrane cells (HAM) system. PCHAM IFN was detected as early as 2 h after NDV infection and was composed by two antigenically distinct fractions, one neutralized with anti-HuIFNβ antibody and another that is not related to IFNβ, -α and -γ. These fractions correspond respectively to 80 and 20 per cent of the IFN produced 4 h after virus induction, 55 and 45 per cent of the IFN produced from 4 to 12 h and 67 and 33 per cent of the IFN produced 12 h after virus induction. A cDNA library, established from PCHAM with or without NDV infection, was screened for IFNα and −β using specific primers. The PCR product, amplified by IFNβ primers, was cloned, sequenced and expressed in Escherichia coli M15. The sequences of several cloned cDNAs were identical to HuIFNβ gene and the antiviral activity of the expressed protein was neutralized only by antlHuIFN-β antibody. The other IFN fraction not neutralized by polyclonal antibodies anti-IFNβ, -α and -γ is now being studied.