SHANGHAI (Reuters) – Two of China’s largest bitcoin exchanges said their trading accounts at certain domestic banks would be closed down by the lenders next week, the latest blow to the virtual currency. Unlike conventional money, bitcoin is generated by computers and is not backed by any central bank or government, or by physical assets. Huobi.com said in a statement posted on its website that Industrial and Commercial Bank of China Ltd would close its accounts by April 18. However, it added accounts at other banks were currently unaffected. …