Investigation of the host cellular requirements of two positive strand RNA viruses, by microarray, phospho-proteome array and by siRNA screening identified differential expression of host genes during hepatitis C virus viral entry. Also my studies suggest that NS4B regulates a newly identified oncogenic pathway. For hepatitis E virus, I looked for the cellular effects conferred by the capsid protein ORF2, and the results showed that ORF2 induced activation of CHOP did not lead to apoptosis which might be due to the up regulation of anti-apoptotic chaperones like Hsp72.