Synthesis and modification of genes through artificial splicing by directed ligation (ASDL).

An approach to the directed genetic recombination in vitro mediated by synthetic oligodeoxynucleotides and polymerase chain reaction (PCR) is devised, which allows the joining, in a predetermined chemical-enzymatic way, of a series of DNA segments to give a precisely spliced polynucleotide sequence (Artificial Splicing by Directed Ligation, ASDL). The approach can thus lead to the totally processed eukaryotic genes using genomic DNA, with no mRNA needed. This approach has been used for the synthesis of artificial genes of interleukin-1 alpha and, in combination with PCR on the mRNA-cDNA duplex as template, of interleukin-1 receptor antagonist and their analogues, as well as for the modified genes.