Coronaviruses were recognized as a group of enveloped, RNA viruses in
1968 and accepted by the International Committee on the Taxonomy of
Viruses as a separate family, the Coronaviridae, in 1975. By 1978, it
had become evident that the coronavirus genomic RNA was infectious (i.
e., positive strand), and by 1983, at least the framework of the
coronavirus replication strategy had been per- ceived. Subsequently,
with the application of recombinant DNA techniques, there have been
remarkable advances in our understanding of the molecular biology of
coronaviruses, and a mass of structural data concerning coronavirus
genomes, mRNAs, and pro teins now exists. More recently, attention has
been focused on the role of essential and accessory gene products in the
coronavirus replication cyde and a molecular analysis of the
structure-function relation- ships of coronavirus proteins.
Nevertheless, there are still large gaps in our knowledge, for instance,
in areas such as the genesis of coronavirus subgenomic mRNAs or the
function of the coronavirus RNA-dependent RNA polymerase. The diseases
caused by coronaviruses have been known for much longer than the agents
themselves. Possibly the first coronavirus-related disease to be
recorded was feline infectious peritonitis, as early as 1912. The
diseases associ- ated with infectious bronchitis virus, transmissible
gastroenteritis virus, and murine hepatitis virus were all well known
before 1950.
