Great reduction of human and avian type A Influenza virus multiplication by MESNA ( sodium-2 mercaptoethanesulfonate ) treatment.

7.3 Great reduction of human and avian type A Influenza virus multiplication by MESNA (sodium-2 mercaptoethanesulfonate ) treatment. G. Conti 1, P.Portincasa 1, F. Piazza (), G. Dieci 2, F. Zani () and C. Zini () 1 Department of Pathology and Laboratory Medicine, Microbiology Section 2 Department of Biochemistry and Molecular Biology Department of Pharmacy Department of Otorino-Odonto-Ophthalmology University of Parma, Gramsci 14, Parma, Italy The antiviral activity of MESNA, a thiol group compound, was evaluated in LLC-MK2 cells infected by Influenza virus. MESNA was able to inhibit viral multiplicaton in a dose-dependent fashion and virus yield, obtained both with HA and plaque assaies, were reduced at concentrations which did not suppress protein synthesis in mock-infected cells. Experiments of post-treatment performed at different times showed that addition of the drug was effective until 6 hours p.i. Removal of the compound at various times showed that the inhibition was not reversible at all times p.i. Also in this case haemagglutination assayes were carried out at 24, 48 and 72 hours of infection. Pre-treatment of uninfected LLC-MK2 cell monolayers were performed to gain informations on the possibility to render these cells resistant to viral infection. At 24,48 and 72 hours p.i. the presence of virus particles in maintenance medium without MESNA was evaluated by HA assayes . In these conditions no mature viral particles were detected at all times tested after infection.. Viral protein synthesis was studied in condition of treatment. At different interval-times monolayers of infected LLCMK2 cells were pulse-labeled with [35S]-methionine (30μCi/ml). MESNA-treatment determines a marked reduction of the normal synthesis of early and late viral proteins suggesting an action on viral transcriptase. “In vitro” assay of viral RNA dependent-RNA polymerase activity performed on purified Influenza virions showed negative results: MESNA is not able to determine an inhibition or block of the virus enzyme activity. This evidence leads us to hypothesise a possible involvement of a cellular factor (s). We are currently investigating the role / concentration level of the ratio Ox-Red glutathione, GSSG / GSH. Results obtained with human influenza virus strain, A, NWS, H1N1,were completely reproducible and comparable with those obtained with avian influenza virus strain, A, Ulster 73, H7N1. Furthermore, data obtained in MDCK cells were comparable to those, above described, obtained in LLC-MK2 cells. Corresponding Author: prof. Giorgio Conti