Herpes simplex virus: Attenuation and Cytokine modulation with Natural compounds

MATEU CG, ARTUSO MC, LINERO F, SCOLARO L, PUJOL CA, CARLUCCI MJ

Buenos Aires

Simposio; III International Clínical Virology Symposium and Advances in vaccines; 2010

Background and Aims Natural carrageenans are well known as potent and selective inhibitors of Herpes Simplex virus (HSV). They have a chemical structure similar to heparan sulfate (HS) and interfere with HSV attachment to cells by blocking the interaction with HS, which serves as a primary receptor for adsorption. In this work, we used different carrageenans (ê and é) to obtain viral variants of HSV-2 (MS). Previous studies shown that viral variants of HSV-1 (F), obteined with a related carrageenan 1C3, did not cause neither morbidity nor mortality when C57BL/6 mice were infected via intranasal or intravaginal. The aim of this study is to prove that similar characteristics can be found among viral variants of different types of HSV using the same protocol with related carrageenans. Methods For the viral selection, several passages of HSV-2 were made in Vero cells with increasing amounts of each carrageenan. Twenty two passages were made and four syncytial clones were selected: é22-9,  é22-12, ê22-12 and ê22-13. The drug susceptibility was tested against the ê and é carrageenans, heparin, aciclovir and foscarnet. Two routes of infection with the viral variants (intranasal and intravaginal) in C57BL/6 and BALB/c mice were compared . Vaginal lavages were obtained from mice intravaginally infected for cytokine determination (ELISA), and for viral quantification. The mutations responsible for the syncytial phenotype were studied using Cyclosporin and Melittin, and the TK gene was secuenced.  Results The HSV-2 (MS) variants showed a 100% syncytial phenotype on Vero cells. The variants  ê22-13 and é22-12 were resistant to ACV. These variants were also asymptomatic in C57BL/6 mice infected by intravaginal inoculation and this may be correlated to the ACV resistance. The cytokines play a protective role in mice infected with the syncytial variants . Conclusions Viral variants selected with related carrageenans were less aggressive in comparisson with the parental strain and had a different pattern of cytokines. This selection protocol may also produce alterations in the TK gene and could be used as an attenuation protocol for the production of vaccines or for other therapeutic approach.