Indian Journal of Virology

Host exhibits a variety of responses to pathogens. Susceptible hosts develop symptoms of infection, while resistance is elicited by interaction between incompatible hosts and viral genes. Both types of responses involve coordinated challenge against host genes, which can induce broad-spectrum defense pathways in resistant hosts. RNAi Interference - a double stranded RNA instigated silencing machinery is used to combat against pathogenic intruders for inhibiting infection. However in several instances, an inhibitor of RNAi system is produced by viral genome to overcome the silencing programme. Here we found that RNA viruses in animals, which normally reside in the cytosol of the infected cells also remotely, disrupt transcriptional gene silencing and condensed chromatin. A major reduction of histone methylation and their subsequent accumulation along with heterochromatin specific proteins on the repetitive sequence of the infected cells was found. These results suggest that RNA virus might play a crucial role in chromatin remodeling. Similarly, baculovirus infection on silkworm was not completely protected by the RNAi machinery. Earlier studies and our findings revealed that degradation of single gene product is not sufficient for protection against viral infection. Currently we are looking answer of this question “whether transcripts of genomic DNA or product of any specific viral gene acts as antidote for RNAi machinery”.