title: An indole alkaloid from a tribal folklore inhibits immediate early event in HSV-2 infected cells with therapeutic efficacy in vaginally infected mice.
abstract: Herpes genitalis, caused by HSV-2, is an incurable genital ulcerative disease transmitted by sexual intercourse. The virus establishes life-long latency in sacral root ganglia and reported to have synergistic relationship with HIV-1 transmission. Till date no effective vaccine is available, while the existing therapy frequently yielded drug resistance, toxicity and treatment failure. Thus, there is a pressing need for non-nucleotide antiviral agent from traditional source. Based on ethnomedicinal use we have isolated a compound 7-methoxy-1-methyl-4,9-dihydro-3H-pyrido[3,4-b]indole (HM) from the traditional herb Ophiorrhiza nicobarica Balkr, and evaluated its efficacy on isolates of HSV-2 in vitro and in vivo. The cytotoxicity (CC50), effective concentrations (EC50) and the mode of action of HM was determined by MTT, plaque reduction, time-of-addition, immunofluorescence (IFA), Western blot, qRT-PCR, EMSA, supershift and co-immunoprecipitation assays; while the in vivo toxicity and efficacy was evaluated in BALB/c mice. The results revealed that HM possesses significant anti-HSV-2 activity with EC50 of 1.1-2.8 µg/ml, and selectivity index of >20. The time kinetics and IFA demonstrated that HM dose dependently inhibited 50-99% of HSV-2 infection at 1.5-5.0 µg/ml at 2-4 h post-infection. Further, HM was unable to inhibit viral attachment or penetration and had no synergistic interaction with acyclovir. Moreover, Western blot and qRT-PCR assays demonstrated that HM suppressed viral IE gene expression, while the EMSA and co-immunoprecipitation studies showed that HM interfered with the recruitment of LSD-1 by HCF-1. The in vivo studies revealed that HM at its virucidal concentration was nontoxic and reduced virus yield in the brain of HSV-2 infected mice in a concentration dependent manner, compared to vaginal tissues. Thus, our results suggest that HM can serve as a prototype to develop non-nucleotide antiviral lead targeting the viral IE transcription for the management of HSV-2 infections.
authors.affiliation: ICMR Virus Unit, ID and BG Hospital, Beliaghata, Kolkata, India.
authors.forename: Paromita
authors.initials: P
authors.lastname: Bag
authors.forename: Durbadal
authors.initials: D
authors.lastname: Ojha
authors.forename: Hemanta
authors.initials: H
authors.lastname: Mukherjee
authors.forename: Umesh Chandra
authors.initials: UC
authors.lastname: Halder
authors.forename: Supriya
authors.initials: S
authors.lastname: Mondal
authors.forename: Nidhi S
authors.initials: NS
authors.lastname: Chandra
authors.forename: Suman
authors.initials: S
authors.lastname: Nandi
authors.forename: Ashoke
authors.initials: A
authors.lastname: Sharon
authors.forename: Mamta Chawla
authors.initials: MC
authors.lastname: Sarkar
authors.forename: Sekhar
authors.initials: S
authors.lastname: Chakrabarti
authors.forename: Debprasad
authors.initials: D
authors.lastname: Chattopadhyay
mesh_terms: D000212:Acyclovir / Q000494:pharmacology; D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D002522:Chlorocebus aethiops; D005260:Female; D006558:Herpes Genitalis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018258:Herpesvirus 2, Human; D006801:Humans; D026121:Indole Alkaloids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D014709:Vero Cells
chemical_list: D000998:Antiviral Agents; D026121:Indole Alkaloids; D010936:Plant Extracts; D000212:Acyclovir