Inhibition of influenza C viruses by human MxA protein

Human MxA protein was analyzed for its ability to inhibit the replication o f different influenza C viruses. Three laboratory derivatives of viral stra in C/Ann Arbor/1/50 were investigated, namely the parental wild-type virus C/AA-wt, the persistent variant C/AA-pi and the highly cytopathogenic varia nt C/AA-cyt. In addition, strain C/Paris/214/91 isolated from an influenza patient was used. Multiplication of all four viruses was suppressed in MxA- expressing Vero cells, as indicated by a decrease in viral RNA synthesis, v iral protein synthesis, virion production and induction of a cytopathic eff ect. Inhibition correlated with the level of MxA expression. Furthermore, i nhibition was independent of cell clone-specific differences in expression of virus receptors, as demonstrated by receptor reconstitution experiments. Thus, human MxA protein has antiviral activity against influenza C viruses . (C) 2000 Elsevier Science B.V. All rights reserved.