Angel S. Galabov

By Angel S. Galabov

Adenoviruses occupy a substantial place as causative agents of seasonal respiratory infections, the most characteristic and severe being epidemic keratoconjunctivitis (EKC). Moreover, adenovirus infections are very characteristic with their severe course in persons with impaired immune system. The absence of specific anti-adenovirals is the major problem, and the development of compounds effective against adenoviruses is a principal task. This chapter embraces the results of studies on search for antivirals with anti-adenovirus activity, nucleoside/nucleotide analogues and nonnucleoside compounds. Ganciclovir and cidofovir demonstrated effects against adenovirus serotypes in vitro and in animal ocular infection models. Cidofovir applied alone or in combination with cyclosporine manifested therapeutic effects on patients with EKC in a controlled clinical study. We characterized abitylguanide as anti-adenovirus agent in broad-scale investigations, including cell culture experiments, and in two double-blind trials with very beneficial results.

Part of the book: Adenoviruses

By Milka Mileva and Angel S. Galabov

Influenza is an infectious disease causing huge medical and economic losses. Influenza pathogenesis is associated with two processes in the human body: (i) lung damage due to viral replication in the columnar ciliary epithelium of bronchi and bronchioles and (ii) inflammatory burst inducing an increase in reactive oxygen species generation that causes extensive damage in cellular membranes of the small vessels. The oxidative stress in influenza virus-infected organism provokes free-radical oxidation of unsaturated lipid chains in the cell membranes. As vitamin E is a lipid-soluble substance and possesses a hydrophobic tail, it tends to accumulate within lipid membranes. There, it acts as the most important chain breaker, reacting with lipid peroxyl radicals much faster than they can react with adjacent fatty acid side chains. Among the antioxidants tested in influenza virus infections in mice, vitamin E occupies the leading position because of its efficacy in preventing oxidative damage through its free-radical scavenging activity. Although vitamin E is not possessing specific antiviral action, its antioxidant effect probably plays important role in lung and liver protection. Attention should be paid to the synergistic character of antiviral effect of the combination vitamin E and oseltamivir. Vitamin E could be recommended as a component in multitarget influenza therapy.

Part of the book: Vitamin E in Health and Disease

By Neli Vilhelmova-Ilieva, Angel S. Galabov and Milka Mileva

Tannins possess a variety of biological effects, not a small part of which is of medical significance. Tannins, isolated from plants as well as synthetically obtained, manifest activity against a large spectrum of viruses: enteroviruses (polio- and coxsackie-), caliciviruses (feline calicivirus, mouse norovirus), rotavirus, influenza virus A, rhabdo- (vesicular stomatitis virus), paramyxoviruses (Sendai and Newcastle disease viruses), human immunodeficiency virus, herpes simplex virus, and adenoviruses. A special importance merits several ellagitannins manifesting pronounced effects against herpes simplex virus type 1 and 2 and on some herpes viruses affecting domestic animals, causing diseases of economic importance. An advantage of ellagitannins as anti-herpesvirus agents is that they have a non-nucleoside structure. Their targets are virus-specific proteins, so they retain activity against acyclovir-resistant strains of HSV types 1 and 2. Besides, these tannins manifest a synergistic effect with acyclovir when combined. Some initial results on their mechanism of action were carried out. In addition, it was found that most of the tannins have antioxidant properties in experimental models in vitro as well as in experimental influenza viral infection in mice.

Part of the book: Tannins