The development of recombinant DNA technology has made a marked impact
on molecular virology. The cleavage of viral DNA genomes with
restriction enzymes and the cloning of such DNA fragments in bacterial
p1asmids has led to the amplification of selected viral DNA fragments
for sequencing and gene expression. RNA virus genomes which can be
transcribed to their cDNA form were also cloned in bacterial p1asmids,
facilitating the study of RNA virus genes. With the elucidation in
recent years of the promoter sequence of various viral genes and the
expression of these genes in bacteria or yeast, the understanding of
many viral gene functions has made great progress. Cloning and
expression of viral genes in mammalian cells was made possible by the
construction of shuttle plasmid vectors which carry the origins of DNA
replication from bacteria and/or mammalian viruses. The expression of
viral genes in bacteria, yeast and eukaryotic cells gives reason to hope
that it will be possible to produce viral antigens in large quantities
for use as human or animal vaccines. The present volume attempts to
capture for the reader some of the high- lights of recombinant DNA
research in the field of animal and plant viruses.