Comparative study of herpes simplex virus type 1 and 2 variants obtained by selective preassure exerted by carrageenans

MATEU C, ARTUSO C, LINERO F, SCOLARO L, PUJOL C, CARLUCCI M.

Salt Lake City, Utha.

Workshop; 35th Internationl Herpesvirus Workshop.; 2010

Natural carrageenans are widely known as potent and selective antiviral compounds, specially against herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), because they possess heparan-like structures that mimic the cell receptor required for virus entry. Frequent use of antivirals against HSV favors the appearance of resistant virus populations. Previous studies shown that viral variants of HSV-1 (F) obtained through several passages on Vero cells with increasing concentrations of the m/n carrageenan 1C3 (precursor of  é and ê carrageenans) extracted from the red seaweed Gigartina skottsbergii did not show neither morbidity nor mortality when C57BL/6 mice were infected via intranasal or intravaginal. New variants of HSV-2 (MS) were obtained using the same protocol with  é and ê carrageenans. To test the phenotypic stability, variants were passaged  5-10 times in Vero cells without compound. These variants exhibited properties similar to those observed for HSV-1 variants when considering: 1) cytopathic action (100% syncytial phenotype ), 2) relative resistance (ratio between IC50 for each variant and the IC50  for the parental strain) to the compounds used during the selective treatment (between 10,5 to 79) and to Acyclovir (between 2 and 10), 3) cellular disemination in vitro and 4) differential cytokine activation (the level of TNF-a, IL-6 and IFN-a were drastically diminished in animals inoculated with syncitial variants). Sequencing of tk genes obtained from variants did not reveal significative changes other than those associated to viral polymorphism. The results obtained support the idea that the strategy employed to obtain HSV variants could probably affect genomic regions that are involved in strain virulence, tropism, immune response and pathology of the host.