Managing director and CEO of IT major Infosys Mr Vishal Sikka has resigned and board has accepted his resignation with immediate effect.UB Pravin Rao will be interim managing director and CEO.Shares of the company plunged over 7 per cent after the announcement.Dr Sikka, 50, has cited “personal” attacks on him as one of the reasons for his sudden decision to resign, saying they were “amplified” by people who should have supported him.