 The net profit of Indias largest private lender, HDFC Bank Ltd, grew by nearly a fifth, it said on Saturday, driven by higher interest income and lower costs. HDFC Banks net profit for the quarter ending June rose to 66.58 billion rupees 889.11 million, up from 55.68 billion rupees a year earlier, the company said in a regulatory filing. Net interest income grew about 18, while operating costs fell by nearly 3, the bank said. 