After an epic debate over whether to release research detailing how scientists created H5N1 in the lab, Nature finally published one of the two controversial papers on Wednesday.

You might not have noticed, but the influenza world has been in a bit of an uproar since late last year, when news leaked out that two teams of researchers had purposefully tweaked H5N1 bird flu in the lab to potentially make it more transmissible among human beings. (H5N1 spreads like wildfire among birds and usually kills them but the virus only rarely seems to jump to human beings, though when it does the infections are often fatal.)

The two scientists Yoshihiro Kawaoka of the University of WisconsinMadison and TIME 100 honoree Ron Fouchier of Erasmus University in the Netherlands had submitted their research toNature andScience, respectively, with the expectation of swift publication. In December, the National Science Advisory Board for Biosecurity (NSABB) did something unprecedented: they ruled that the two papers should be censored if published, that they should be scrubbed of the complete methods and viral mutations that the researchers studied, in order to head off the risk that terror groups could use the information to craft a deadly bioweapon.

(PHOTOS: The Bird Flu Outbreaks in 2008)

That led to intense fighting within the scientific community. Some researchers wanted the papers published in full, both because they believed the work could help arm us against a future flu pandemic, and because they worried about the chill of government censorship on science. Other scientists were against publication and even the experiments themselves, believing that nothing gleaned from the work could be important enough to offset the risk of creating a potentially deadly flu virus.

In the end, Fouchier explained that his man-made flu virus wasnt the merciless killer that early media reports had made it out to be Kawaokas man-made virus was always believed to be less dangerous and in March the NSABB took a look at revised papers submitted by the two research teams and voted to recommend that they be published.

On Wednesday, Nature finally published Kawaokas research. (Were still waiting for the Fouchier paper, though the Dutch scientist was recently granted an export license for his work, so it should appear soon.) The sobering takeaway: avian H5N1 flu viruses in nature may be only one mutation away from spreading effectively between mammals, likely including human beings. If that happens and if H5N1 retains its apparently sky-high mortality rate we could be in for serious trouble.

For all the controversy, the research itself is actually quite fascinating. Kawaoka and his team mutated H5N1s hemagglutinin (HA) gene the H in H5N1 which produces the protein the virus needs to attach itself to host cells. They produced millions of genes, mimicking the effect of random mutation in nature, and found one version of H5N1 hemagglutinin that seems particularly effective at invading human cells.

(MORE: Dangers of Man-Made Bird Flu Are Exaggerated, Its Creators Say)

The genes for that protein contained four new mutations, three of which altered the shape of the gene, while the fourth one changed the pH level at which the protein attaches to the cell and injects the viruss genetic material inside. (Its a bit reminiscent of Alien, if the virus is the face-hugger and this poor guys face is the cell.)The team combined the mutated HA gene with seven other genes flu viruses have eight genes in all from the highly transmissible if not highly deadly H1N1 strain, which caused the 2009 flu pandemic. The result was an H1N1 virus with mutant H5N1 hemagglutinin proteins on the outside.

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H5N1 Paper Published: Deadly, Transmissible Bird Flu Closer than Thought?