Abstract: Multichain polypeptides or proteins and processes for their production in cells of host organisms which have been transformed by recombinant DNA techniques. According to a first aspect of the present invention, there is provided a process for producing a heterologous multichain polypeptide or protein in a single host cell, which comprises transforming the host cell with DNA sequences coding for each of the polypeptide chains and expressing said polypeptide chains in said transformed host cell. According to another aspect of the present invention there is provided as a product of recombinant DNA technology an Ig heavy or light chain or fragment thereof having an intact variable domain. The invention also provides a process for increasing the level of protein expression in a transformed host cell and vectors and transformed host cells for use in the processes.

Abstract: A process for the production of a synthetic gene for an influenza haemagglutinin which comprises:(a) subjecting isolated vRNA to the action of reverse transcriptase to produce a double-stranded RNA/DNA hybrid;(b) digesting the RNA component of the hybrid;(c) treating the residual DNA component of the hybrid to produce a double-stranded DNA molecule having one "hairpin" end; and(d) treating the "hairpin" structure with a single-strand specific nuclease to produce a bimolecular double-stranded copy of the vRNA.

Abstract: A plasmid having an insertion site for a eukaryotic DNA fragment adjacent to a bacterial promoter and downstream from a prokaryotic ribosome binding site and initiator codon such that the bacterial promoter controls transcription and translation of an inserted DNA fragment is disclosed.The production and use of such plasmids is also disclosed.In general terms, one aspect of the present invention relates to a series of plasmid vectors having the basic characteristic of a Hind III insertion site adjacent to a tryptophan promoter and also a gene for tetracycline resistance. The plasmid vectors are by virtue of the structure thereof ideally suited to receive at the Hind III site an inserted eukaryotic DNA fragment the transcription and translation of which is under the control of the tryptophan promotor.