Abstract
Summary
Rhinovirus strains representative of the 55 numbered serotypes and one subtype were tested in HeLa and WI-38 cell culture tubes for inhibition by 223 and 447 μM concentrations of 2-(α-hydroxybenzyl)-benzimidazole (HBB) and 77, 115, 192, 383, and 574 μM concentrations of D - (-) − 2 - (α - hydroxybenzyl) - benzimidazole · HCl (D-HBB · HCl). Half of strains tested showed some inhibition at a 447 μM concentration of HBB and strains of all types except 1A and subtype 1B showed some degree of inhibition at a D-HBB · HCl concentration of 574 μM or less. An increasing proportion of strains were inhibited as test concentrations of the compounds were increased. Multiple strains of rhinovirus types 7 and 24 showed similar degrees of sensitivity to a 192 μM concentration of D-HBB · HCl. Comparative testing of strains of 36 types vs a 192 μM concentration of D-HBB · HCl in WI-38 and HeLa cell culture tubes gave similar but not identical results. D-HBB · HCl concentrations of 574 and 383 μM were toxic for cells. The behavior of viruses which are insensitive to HBB or D-HBB · HCl at non-toxic concentrations, but show some sensitivity at higher concentrations, is difficult to interpret because of the problem in separating virus-specific from toxic actions of the compounds. Indirect evidence for a virus-specific inhibitory effect is provided by the linear increase in the proportion of sensitive strains with increasing compound concentrations and by the growth of some rhinovirus strains in cells exposed to cytotoxic concentrations. Experiments now in progress with a more sensitive gradient plate plaque reduction technique, using D-HBB · HCl concentrations below cytotoxic levels, support this hypothesis. These results suggest that rhino-viruses as a group show a wide range of sensitivity to these compounds but that most types share to some degree the characteristic of D-HBB · HCl sensitivity.
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