Recombinant plasmids were constructed to produce in E. coli the variola virus proteins homologous to the human immune interferon (IFN-gamma) receptor. The target proteins were isolated and assayed for specific suppression of IFN-gamma antiviral activity in vitro. The recombinant proteins exhibited high neutralizing activity against human IFN-gamma but not IFN-alpha. No appreciable difference in activity was found between proteins from high-virulence VAR strain India-1967 and low-virulence Garcia-1966.
To study specific properties of the human gamma-interferon (gamma-IFN) receptor-like proteins of the highly virulent and low virulent strains of variola (smallpox) virus (VAR) recombinant plasmids determining synthesis of these proteins in E. coli cells have been constructed. The recombinant viral gamma-IFN receptor-like proteins have been found to have high interferon-neutralising activity with regard to human gamma-IFN but not murine gamma-IFN and human alpha-IFN. The variola major and variola minor proteins under study do not differ in the efficiency of human gamma-IFN antiviral activity inhibition.