[The specific enzyme inhibitors for potential therapeutic use]. / Specyficzne inhibitory enzymów o potencjalnym zastosowaniu terapeutycznym.

Therapy for hepatitis C virus (HCV) initially consisted on administering ribavirin - having a broad spectrum of action - and pegylated interferon, and was only effective in 40-50% of patients. Appropriate was to find effective inhibitors of viral replication e.g. by inhibition of a viral enzyme, NTPase/helicase required in the process of translation and RNA replication of the HCV. We developed methods of synthesis of many compounds belonging to different groups - derivatives of nucleosides, benzotriazole, benzimidazole, tropolone and epirubicine. Some of the derivatives inhibit HCV helicase activity at low concentrations and reduces replication of the viral RNA in subgenomic replicon system. In the process of HCV replication casein kinase CK2 plays an important role. It regulates the level of phosphorylation of HCV protein NS5A, which affects the production of infectious virions of HCV. Effective and selective inhibitors of kinase CK2 could be of use in the treatment of HCV in combination with other drugs. CK2 kinase phosphorylates approximately 300 proteins that affect the growth, differentiation, proliferation or apoptosis. Elevated CK2 kinase activity has been observed in several types of cancer and other diseases, therefore, inhibitors of this enzyme are potential therapeutic importance, particularly for anti-cancer treatment. Research carried out in collaboration with prof. Shugar led to the synthesis of one of the most selective inhibitors of this enzyme which is 4,5,6,7-tetrabromo-1H-benzotriazole, used for the study of the role of kinase CK2 in a number of metabolic processes in tumor cells.

Not as they seem.

I recount the early influences that directed me toward a career in research and then describe some efforts investigating Cowpea mosaic virus and the satellite RNA of Tobacco ringspot virus. These descriptions have a common theme of surprise, how things often can be not as they are expected to be. Finally, I examine the widely held belief that a plant transgene derived from a distant taxonomic source presents a greater risk than a transgene derived from a closely related plant and contend that this also is a situation in which things may not be as they initially seem.

Discovering viroids--a personal perspective.

During 1970 and 1971, I discovered that a devastating disease of potato plants is not caused by a virus, as had been assumed, but by a new type of subviral pathogen, the viroid. Viroids are so small--one fiftieth of the size of the smallest viruses--that many scientists initially doubted their existence. We now know that viroids cause many damaging diseases of crop plants. Fortunately, new methods that are based on the unique properties of viroids now promise effective control.

1917 avian influenza virus sequences suggest that the 1918 pandemic virus did not acquire its hemagglutinin directly from birds.

Wild waterfowl captured between 1915 and 1919 were tested for influenza A virus RNA. One bird, captured in 1917, was infected with a virus of the same hemagglutinin (HA) subtype as that of the 1918 pandemic virus. The 1917 HA is more closely related to that of modern avian viruses than it is to that of the pandemic virus, suggesting (i) that there was little drift in avian sequences over the past 85 years and (ii) that the 1918 pandemic virus did not acquire its HA directly from a bird.

From heresy to dogma in accounts of opposition to Howard Temin's DNA provirus hypothesis.

In 1964 the Wisconsin virologist Howard Temin proposed the DNA provirus hypothesis to explain the mechanism by which a cancer-producing virus containing only RNA infects and transforms cells. His hypothesis reversed the flow of genetic information, as ordained by the central dogma of molecular biology. Although there was initial opposition to his hypothesis it was widely accepted, after the discovery of reverse transcriptase in 1970. Most accounts of Temin's hypothesis after the discovery portray the hypothesis as heretical, because it challenged the central dogma. Temin himself in his Nobel Prize speech of 1975 narrates a similar story about its reception. But are these accounts warranted? I argue that members of the virology community opposed Temin's provirus hypothesis not simply because it was a counterexample to the central dogma, but more importantly because his experimental evidence for supporting it was inconclusive. Furthermore, I propose that these accounts of opposition to the DNA provirus hypothesis as heretical, written by Temin and others after the discovery of reverse transcriptase, played a significant role in establishing retrovirology as a specialized field.

The unfolding of our understanding of RNA structure: a personal reflection.

In this article, I review how our research on RNA began, how it led us to demonstrate the single-stranded nature of RNA, and the ways in which it differs from double-stranded DNA. It was based on the development of a method for the isolation of undegraded rRNA and the observation that in rRNA preparations due to their viscosity behavior resemble a flexible, contractile coil. In support of this assumption, birefringence of flow measurements showed that rRNA solutions gave moderate positive values, which disappeared upon addition of salt. This is in contrast with DNA solutions where considerable negative birefringence persists even in the presence of salt. Further studies on RNA showed a close correlation of the ionic strength dependencies of optical rotation, optical density and hydrodynamic properties. These early results indicated that rRNA and tRNA possess a significant secondary structure. I then review the basis of the hairpin model for the secondary structure of RNA and finally, summarize current understanding of the tertiary structure of RNA.