 His research involved Bacteriophage MS2; he was the first to establish the complete nucleotide sequence of a gene (1972) and of a viral genome (bacteriophage MS2)(1976).In 1978 Fiers and his team were the first to reveal the complete nucleotide-sequence of SV40.The development of totally new procedures and knowledge led to the ability to clone almost any gene and to replicate these efficiently into bacteria or in other heterologous hosts.