The translation of vaccinia virus messenger RNA in animal cell‐free systems

IntroductionCell-tree .,';ystemsfrom animal cells in which added viral messenger RN,*t's (mRNA's)are translated have proved useful in studies on eukaryotic protein synthesis and its control.Of the v/ruses which contain their own transcrip~ases for the synti~e:ds of viral mRNA, however, o:dy with reovirus has it been possible to synthesise in vitro sufficient intact mRNA for its translation to be stt~died in this way [1][2][3].Vaccinia is a large DNA virus which contains an RNA polymerase activity associated with the virus cores [4].The core polymerase: prepared in vitro from purified virus, ~-itl effect the synthesis of RNA having properties similar to the viral mRNA present at early times in vaccinia-infected cells [4].This RNA is a mixture of species, the sizes of which are consistent with their coding predominantly l'or individual viral proteins rather than for very.large precursor molecules as is the case with the picornavirus RNA's [5,61.Furthermore these RNA species unlike the reovirus mRNA's have poty A at their 3'-ends [7].Ttms these presumptive vaccinia mRNA's appear to resemble animal cell messengers more than do either of the other viral mRNA * Pre~nt addresses: F.