In vivo reconstitution of active Thogoto virus polymerase: assays for the compatibility with other orthomyxovirus core proteins and template RNAs

Tick-borne Thogoto virus (THOV), the prototype of a new genus in the Orthom yxoviridae family, contains six single-stranded RNA segments of negative po larity. Four of them encode gene products that correspond to the influenza virus PB1, PB2, PA and NP core proteins. Here we describe an in vivo system in which the expression of a THOV model RNA is driven by THOV core protein s synthesized from cloned cDNAs. Our results demonstrated the biological ac tivity of our cloned genes and showed that the three polymerase subunits an d the NP are required for gene expression. For comparison, we also used the in vivo reconstituted systems of the influenza A and B viruses. None of th e polymerase or NP proteins was active in a heterologous orthomyxovirus cor e, indicating a high specificity in core assembly and/or function. Interest ingly, the THOV polymerase did not recognize the influenza A virus promoter and vice versa. (C) 1998 Elsevier Science B.V. All rights reserved.