Investigation of the Antiviral Activity of the Triterpenoid Compound, Cicloxolone Sodium

Galt, Catherine B (1989) Investigation of the Antiviral Activity of the Triterpenoid Compound, Cicloxolone Sodium. PhD thesis, University of Glasgow.

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Cicloxolone sodium (CCX) and the closely related compound Carbenoxolone sodium (CBX) have been shown to inhibit the growth of HSV 1 and HSV 2 in Flow 2002 and BHK-21 cells (Dargan and Subak-Sharpe, 1985). The anti-HSV effect is characterised by the synthesis of poor quality progeny virus particles (Dargan and Subak-Sharpe, 1986a and b). This results in an elevated particle/p. f. u. ratio in the virus yield accompanied by a small reduction in the total number of virus particles made. Based on their analysis of protein synthesis in infected cells, Dargan and Subak-Sharpe have concluded that CCX and CBX disrupt the normal functioning of host cell membrane, affecting aspects of protein synthesis, transport and post-translational processing, particularly glycosylation and sulphation. This proposed antiviral action involving cell membranes implies that the effect of CCX is of a more general nature, suggesting that the replication of several unrelated virus groups would be affected by the drug. In order to examine the effect of CCX on the replication of a range of viruses, cell lines permissive for virus growth and resistant to CCX treatment had to be identified, to allow uncoupling of cytotoxic and antiviral effects. The aims of this thesis were: 1) to determine the tolerance of a range of cell lines to CCX, 2) to determine the antiviral range of CCX and 3) to more clearly elucidate the mode of action of CCX. Twenty cell lines were studied for their sensitivity to CCX treatment. The survey revealed that cell lines differed in their tolerance to the drug and could be designated as Resistant, Intermediate or Sensitive on the basis of cell viability counts. Nine cell lines (Flow 2002, RK-13, Chang Liver, Detroit 532, HeLa, Hep2, MDBK, MDCK and BS-C-1), fell into the Resistant class, six into the Sensitive class (FG-293, XTC-2, HOOD, Re a , Re99 and PCEF), while five displayed Intermediate sensitivity (BHK-21, Flow 4000, MRC-5, Rabbit Epithelium and Rabbit Keratocytes). Although the viability of cells in the Resistant class remained high in the presence of CCX, the replication of cells was inhibited at high concentrations (200 and 300muM CCX). However, this should not contribute to any antiviral effect as all virus dose-response experiments were performed in confluent monolayers. Most importantly, the effect on the cell lines used in the virus dose-response experiments was shown to be fully reversible. Using cell lines identified as resistant to CCX treatment as hosts, a range of viruses was examined for their sensitivity to CCX and placed into three general groupings depending on their response. The first class is composed of Vesicular Stomatitis virus (VSV), Influenza A and the Herpes viruses Herpes Simplex virus 1 and 2 (HSV 1/2), Equine Herpes virus (EHV-1) and Bovine Herpes virus (BHV-1), all of which exhibit a continuous drug dose-dependant reduction in virus infectivity. The extent of the reduction varies for individual viruses from 100 fold (Influenza A) to greater than 10,000 fold (BHV-1). For Varicella Zoster virus (VZV) and Human Cytomegalovirus (HCMV) only ED50 values could be ascertained. Since these values are lower than those obtained for HSV 1/2, it would seem likely that both these herpesviruses also belong to this class. The second class contains Bunyamwera and Germiston virus, Poliovirus-1, Reovirus-3 and Adenovirus-5. Members in general, exhibit a less extensive total CCX response, infectivity being reduced by only 20-100 fold, even with 300muM CCX. All the dose-response curves reach their plateau level with concentrations between 100 and 200muM CCX. However, this second class falls into two sub-divisions: whereas both Adenovirus-5 and Reovirus-3 exhibit great sensitivity to low doses of drug and then reach their plateau values, Polio virus-1, Bunyamwera and Germiston are little affected by doses less than 50muM and only then respond to increased doses until a plateau is reached between 150-200muM CCX. The third class, presently consists of only Semliki Forest virus (SFV), whose infectious virus yields are unaffected by CCX treatment when whole cell harvests are performed. Representatives of each class were chosen for further investigation. However, VSV was the most extensively studied virus in this survey, as apart from the herpes viruses, this was most drastically affected by the drug. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Virology, Pharmacology
Date of Award: 1989
Depositing User: Enlighten Team
Unique ID: glathesis:1989-78012
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:43
Last Modified: 30 Jan 2020 15:43

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