After more than four months of debate that roiled the scientific community, one of two controversial papers on a laboratory-engineered form of the bird-flu virus was published on Wednesday in the journal Nature. Last December the National Institutes of Health prevented the virologist Yoshihiro Kawaoka, of the University of Wisconsin at Madison, from publishing the work because the agency feared the paper contained the recipe for a pandemic; that decision was reversed in March. “I have read it, and I can assure you that the results do not enable the construction of a deadly biological weapon,” Vincent R. Racaniello, a virologist at Columbia University, wrote on his blog. The paper does show that a mutation stabilizing a viral protein is a key to easier airborne transmission among mammals, and it gives disease detectives a marker to watch for. The second paper on the topic, by the virologist Ron Fouchier of the Erasmus Medical Center, in the Netherlands, is set to be published soon in the journal Science.