Human MxA protein confers resistance to double-stranded RNA viruses of two virus families.

The interferon-induced human MxA protein belongs to the dynamin superfamily of large GTPases and accumulates in the cytoplasm. MxA is a key component of the innate antiviral response and has previously been shown to inhibit several viruses with single-stranded RNA genomes of both polarities and a DNA virus. In addition, MxA also targets two double-stranded RNA viruses, Infectious bursal disease virus and a mammalian reovirus as shown in this study. Thus, the antiviral spectrum of human MxA is broader than hitherto suspected. Interestingly, virus growth was not affected in cells expressing MxA(E645R), a mutant form of MxA that showed antiviral activity against orthomyxoviruses.