HIV breakthrough: How do antiretroviral treatments work?

A Mississippi baby girl born with HIV has reportedly been cured. But how?

Researchers are still trying to make sense of the success, but early intervention and heavy medication appear to be key. 

Here's what happened: born with HIV, the baby had something called a retrovirus. A retrovirus is kind of like a computer virus — it gets into your body's hard drive, its DNA, and starts producing, essentially, a corrupt code that replicates quickly, spreading diseases such as AIDS like wildfire.

Doctors often respond to a retrovirus with antiretroviral therapy, a method similar to antibiotics in that it pounds the patient's system with virus-fighting medication. Antiretroviral therapy is defined by the World Health Organization as a barrage of at least three heavy HIV-fighting drugs. The treatment is not expensive and is often used to combat HIV — but never has it seen this kind of success.

In fact, by administering a powerful drug cocktail to an hours-old infant, the deadly cancer-cell-creating virus seems to have been stopped in its tracks. 

More on GlobalPost: The global state of AIDS/HIV (INFOGRAPHIC)

Dr. Hannah Gay, who treated the Mississippi baby, told the Guardian it is the first known "functional cure" of a child with HIV. A functional cure means that the patient tests negative for the virus although technically there is still the possibility some infinitesimal amount remains in the system, reported the Guardian. That chance is very slim, according to Dr. Deborah Persaud, who lead the follow-up research on the Mississippi case. 

The drugs came into play after the Mississippi baby's mother tested positive for the virus while in labor, meaning she had no prenatal treatment, according to Science. The 31-hour-old infant was rushed over to Dr. Gay of the University of Mississippi medical center, who proceeded to administer intense HIV-fighting medication without even waiting for the baby's HIV test results to come back, said Reuters.

The baby, it was later found, indeed had a "robust infection," reported Science. 

Standard HIV-fighting treatment continued for a while, but then, about 23 months later, the little girl was found clear of the virus during a check-up, even though she had been completely taken off HIV-fighting medication five months earlier, according to the Foundation for AIDS Research (amfAR).

That was potentially a huge deal — and Dr. Gay knew it. She quickly put out lines to the research community for help with further testing.

Dr. Persaud, who responded to the call, said her team's "comprehensive tests have confirmed beyond doubt that both mother and child were HIV positive when the child was born, and today no signs of HIV infection in the child can be detected by the most sensitive means available,"said amfAR, a non-profit organization that helped fund Persaud's work. 

Doctors say additional testing needs to be done to see how applicable such treatment actually is. They also want more information about the child — maybe the little girl had a crazy-strong immune system, for example — before saying how likely the results can be replicated. 

Britain's cancer-fighting Terrence Higgins Trust Foundation called the news "interesting" but cautioned that the case needs further study, according to the Guardian. Nevertheless, the institute said "for those babies born with the [HIV] virus, this may be significant."

The child, whose name has not been released due to privacy concerns, needs no additional treatment at this time, said Reuters. She is now two-and-a-half years old.