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A triazinoindole, 4-( (8-amino-7-chloro-5-methyl-5H-as-triazino ( 5,6-b) indole-3-yl) amino) -2-methyl-2-butanol (SK&F 40491), is a potent inhibitor of a broad spectrum of picotmaviruses in vitro ( 1). Since its in zlitro activity extends to human rhinoviruses, it was of interest to evaluate the compound for activity against a human rhinovirus infection in experimental animals as a prelude to clinical trials. Asymptomatic infections in chimpanzees (2, 3) and gibbons (4) with human rhinoviruses have been described. The latter system was cholsen for study due to an available supply of gibbons, the relative ease of handling this species, and our background of experience in using the gibbon for human rhinovirus infections. This report describes the effect of orally and intranasally administered SK&F 40491 on the yileld of virus in nasal secretion and on antibody response following infection. Materials and Methods. Animals. Male andfemale gibbons (Hylobates Zar) , ranging in weight from 1.8 to 7.7 kg, were employed. These animals, acquired from a variety of sources, have been maintained in our laboratory for 1 to 4 yr. In this environment they are caged individually in common rooms, and have remained in overt good health.Viruses. Rhinovirus 1A/2060, obtained from G . Douglas, was passaged 3 times in WI-38 cell cultures in our laboratory. Rhinovirus 2/HGP was obtained from D. A. J. Tyrrell, and was subsequently passed 5 times in WI-26 and once in WI-38 cells.Compound formulation. SK&F 4049 1 was prepared for oral administration at 16 mg/kg in a 5 ml dose by grinding in a mortar with an aqueous solution of %.S% lactic acid and 0.5% gum tragacanth. A 2.5% suspension for intranasal use was prepared with tross-milled compound in water containing 1% carboxymethyl cellulolse (type 7 M F ) and 0.1% Tween 80 at pH 6.3. A 0.02% solution for inltranasal use was obtained in water with 10% ,ethyl alcohol and 20% polyethylene glycol-200 at pH 4.6. No additional compound could be solubilized under these conditions. Comparable formulations lacking SK&F 40491 were used for placebo.Virus titration. Virus was assayed either by cytopathic effect (CPE) in WI-3% cell cultures or by plaquing in HeLa cell manolayers; the sensitivity of the 2 methods was comparable. For CPE titration each of 2 to 4 WI-38 tube cultures with confluent monolayers was inoculated with 1 ml of serial 10-fold dilutions of virus in maintenance medium: Eagle's minimum essential medium with Earle's balanced salt solution (MEM), 5 % heated fetal calf serum (FCS), with 100 units/ml of the sodium salt of penicillin G and 100 pg/ml each of streptomycin sulfate and neomycin. The cultures were incubated at 34' on a roller drum. The tissue culture infectious dose (TCIDSO) of virus was determined on the basis of viral CPE 7 to 10 days after inoculation. For plaque assay 0.2 ml aliquots of serial 0.5 loglo virus dilutions in maintenance medium were. added to duplicate HeLa cell monolayers in 60 x 15 mm Linbro multidish "Disposo Trays." After 60 min at 2 2 O , residual medium wa...

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