Exacerbations of asthma are often associated with respiratory infection caused by rhinoviruses. To study the effects of rhinovirus infection on respiratory epithelium, a primary target for respiratory viruses, human rhinovirus (HRV)-2 and HRV-14 were infected to primary cultures of human tracheal epithelial cells. Viral infection was confirmed by showing that viral titers of supernatants and lysates from infected cells increased with time and by polymerase chain reaction. HRV-2 and HRV-14 infections upregulated the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, the major rhinovirus receptor, on epithelial cells, and they increased the production of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in supernatants. Antibodies to ICAM-1 inhibited HRV-14 infection of epithelial cells and decreased the production of cytokines after HRV-14 infection, but they did not alter HRV-2 infection-induced production of cytokines. IL-1β upregulated ICAM-1 mRNA expression and increased susceptibility to HRV-14 infection, whereas other cytokines failed to alter ICAM-1 mRNA expression. Furthermore, a neutralizing antibody to IL-1β significantly decreased viral titers of supernatants and ICAM-1 mRNA expression after HRV-14 infection, but a neutralizing antibody to TNF-α was without effect. Immunohistochemical studies revealed that both HRV-14 infection and IL-1β increased ICAM-1 expression on cultured epithelial cells. These findings imply that HRV-14 infection upregulated ICAM-1 expression on epithelial cells through increased production of IL-1β, thereby increasing susceptibility to infection. These events may be important for amplification of airway inflammation after viral infection in asthma.

To examine the effects of bafilomycin A(1), a blocker of vacuolar H(+)-ATPase, on rhinovirus (RV) infection in the airway epithelium, primary cultures of human tracheal epithelial cells were infected with RV14. Viral infection was confirmed by showing that viral RNA in the infected cells and the viral titers in the supernatants of infected cells increased with time. RV14 infection upregulated the production of cytokines and mRNA of intercellular adhesion molecule (ICAM)-1 in epithelial cells. Bafilomycin A(1) reduced the viral titers of RV14 and inhibited the production of cytokines and ICAM-1 before and after RV14 infection. Bafilomycin A(1) reduced susceptibility of epithelial cells to RV14 infection. RV14 increased activated nuclear factor-kappaB in the cells, and bafilomycin A(1) reduced the activated nuclear factor-kappaB. Bafilomycin A(1) decreased the number of acidic endosomes in the epithelial cells. These results suggest that bafilomycin A(1) may inhibit infection by RV14 by not only blocking RV RNA entry into the endosomes but also reducing ICAM-1 expression in the epithelial cells. Bafilomycin A(1) may therefore modulate airway inflammation after RV infection.

Between December 1984 and December 1986, a microplate technique was adopted for isolation of viruses from infants and children with acute respiratory infections. By using two kinds of tissue culture microplates, i.e., the HHVM plate, containing human embryonic fibroblast (HEF), HEp-2, Vero and MDCK cells, and the MK plate which contains secondary monkey kidney cells, 1,080 field viruses were isolated from 1,061 (24.9%) out of 4,254 throat swabs. Of these 1,080 isolates, 1,003 (92.9%) were recovered in the HHVM plates and the remaining 77 (7.1%) in the MK plates. With the HHVM plate, influenza A and B viruses were cultivated in MDCK, RS virus in HEp-2, parainfluenza and mumps viruses in Vero, adenoviruses in both HEF and HEp-2, polioviruses in HEF, HEp-2 and Vero, coxsackie B viruses in both HEp-2 and Vero, rhino and echo viruses in HEF, herpes simplex virus in both HEF and HEp-2, and cytomegalovirus in HEF, although MK were more sensitive than Vero to parainfluenza and coxsackie B viruses. There was no difference in the rate of isolation of viruses between the microplate and ordinary tube methods. Cross contamination in the microplates was negligible for routine work.

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