[Virological surveillance of acute respiratory tract illnesses of children in Morioka, Japan. III. Human respiratory coronavirus].

In the virological surveillance of children with acute respiratory tract illnesses, five human respiratory coronaviruses (HRCV) were recovered. Three of these strains were isolated from nasopharyngeal swabs of patients with influenza-like illness collected in Kuji City on March 29, 1979. This may suggest the association of HRCVs and influenza-like illness. The other 2 strains were yielded from nasopharyngeal swabs of patients with afebrile acute upper respiratory tract illness collected in Morioka City on March 16 and April 27, 1979. These 5 isolates exhibited typical properties of HRCV; distinctive morphology, resistant to BUDR, chloroform sensitivity, and electron microscopic features of growth in L132 cells. These isolates were identified as 229E-like HRCV by indirect immunofluorescence test, but these were considerably different to HRCV (strain 229E) in antigenicity. Reciprocal neutralization titers of antisera against HRCV (strain 229E) and each isolate were determined by 50% plaque reduction tests in monolayers of L132 cells. The neutralizing activities of anti-HRCV (strain 229E) serum against each isolate were 40- to 100-fold lower than that of homologous reaction. The remarkable differences of antigenicity among the isolates did not be observed.