Effects of some purine analogues on Tobacco mosaic virus

SUMMARY: When sprayed on the leaves of tobacco plants inoculated with tobacco mosaic virus 8-azaguanine caused a delay in the production of virus, and a delay in the development of systemic infection. From alkaline hydrolysates of the nucleic acid prepared from virus isolated from 8-azaguanine-treated plants, a compound was isolated which had the expected properties of 8-azaguanylic acid. This evidence together with analytical data showed that in tobacco mosaic virus from 14-day-old infections in 8-azaguanine-treated plants, about 3 4 % of the guanine in the virus nucleic acid was replaced by 8-azaguanine. This incorporation of 8-azaguanine appeared to reduce the infectivity of the virus. Several other purine analogues were ineffective against tobacco mosaic virus. A serological-chromatographic method is described for the estimation of small amounts of tobacco mosaic virus in crude plant, extracts. The guanine analogue, 8-azaguanine, has a marked inhibitory effect on lucerne mosaic and cucumber mosaic viruses (Matthews, 1953a).. The compound has much less effect on disease development with tobacco mosaic virus (TMV). However it is possible with this virus to make a more detailed investigation of the inhibition. The work described here shows that 8-azaguanine is incor-porated into TMV nucleic acid, and suggests that the compound acts as an inhibitor because virus particles containing it are incapable of further multiplication. A number of compounds related to 8-azaguanine were ineffec-tive. A preliminary report of some of these results has already appeare