In Vivo Uncoating of Tobacco Mosaic Virus

II. Complete Uncoating to TMV-RNA

Abstract

In vivo uncoating of tobacco mosaic virus (TMV) was studied ,and evidence for the presence of TMV-RNA completely free of coat protein was obtained. Complete uncoating of TMV takes place very early after infection in the particulate fraction, probably in the nucleus. In contrast, partial uncoating took place with most of the viruses inoculated and only a small amount of TMV was uncoated completely. The efficiency of uncoating was comparable to those viral infections measured by bioassay. Combining the results obtained and including previous findings, a two-step uncoating reaction was suggested; namely, initiation of uncoating taking place in the cytoplasm and a further uncoating in the particulate fraction.