The typical coronavirus cold is marked by nasal discharge and malaise; cough and sore throat are generally not as prominent as in rhinovirus colds, and there is little or no fever. The illness lasts about a week and is of no real
consequence. The lower respiratory tract is not involved, but coronavirus
infection may occasionally precipitate attacks of wheezing in asthmatic children,
or exacerbate chronic bronchitis in adults.
LABORATORY DIAGNOSIS:-
Coronaviruses are difficult to grow in cultured cells and hence are rarely recovered from humans. HCV-OC43 and related strains were originally isolated in organ cultures of human embryonic trachea or nasal epithelium.
Organ culture is too intricate a technique for a diagnostic laboratory, but some
strains can be isolated directly in diploid fibroblast lines from human embryonic
lung or intestine. Foci of "granular" cells become evident after a week
and may progress fovacuolation before disintegrating; syncytia may form in some cell types. Hemadsorption and hemagglutinatism are demonstrable
with strain OC43 only.
Though rarely called for, the diagnostic method oh choice is direct demonstration
of coronavirus antigens in nasopharyngeal aspirates or nasal swabs
by EIA using appropriate monoclonal antibodies to differentiate strain 229E
from QC43. EIA is also the most convenient method of screening for antibodies
in serological surveys. Identification and characterization of enteric
coronaviruses or toro viruses will not become practicable until a more reproducible
method of culturing them is developed.