UPDATE 1-Vertex posts wider-than-expected loss

(Adds outlook, revenue, expense details, share price)

NEW YORK, July 31 (Reuters) - Vertex Pharmaceuticals Inc reported a smaller, but wider-than-expected, second-quarter net loss on Thursday on higher collaboration revenue and lower costs associated with its experimental hepatitis C drug.

The biotechnology company said it expects a larger full-year loss than it had previously forecast and its shares fell more than 4 percent in extended trading.

It posted a net loss of $91.3 million, or 66 cents per share, compared with a loss of $117.8 million, or 91 cents per share, a year ago.

Analysts on average expected a loss of 59 cents per share, according to Reuters Estimates.

Revenue for the quarter jumped 82 percent to $69.4 million as Vertex received a $45 million milestone payment from Johnson & Johnson (JNJ.N) for beginning pivotal late-stage clinical trials of its telaprevir hepatitis C treatment.

The highly anticipated drug is expected to show that it can cut the onerous current 48-week standard treatment time for the serious liver disease in half.

Research and development costs for the quarter fell to $127.1 million from $136.2 million due to expensive telaprevir trials that were underway in the year-ago quarter.

Cambridge, Massachusetts-based Vertex said it now expects a full-year net loss of $450 million to $470 million, including about $60 million in stock-based compensation and restructuring expense, up from its prior forecast for a net loss of $380 million to $410 million.

The larger anticipated loss is based on expectations of increased telaprevir development costs, including production of a commercial supply, as well as development costs associated with an experimental cystic fibrosis treatment.

Vertex (VRTX.O) shares fell to $33 in after-hours trading from a Nasdaq close at $34.50, giving back the entire day's gain. (Reporting by Bill Berkrot, editing by Leslie Gevirtz and Carol Bishopric)