“Treating an exposure is easier than treating an infection. The end of AIDS is likely still many years away.”
by Mark J. Siedner
A 24-hour news-cycle virus was released from its vial at the annual HIV conference in Atlanta last week with word that a child infected with the HIV virus that causes AIDS had been cured. The news spread quickly through media outlets around the world.
Colleagues in Uganda, where I work as an HIV clinician and researcher, asked me a barrage of questions soon after reading about it in local newspapers: “Is there a new cure for HIV?” “Can babies be cured of HIV?” “Is this finally the end of AIDS?”
At the conference, the news of the case preceded the actual presentation of the results. The excitement surrounding this potentially game-changing breakthrough filled the main hall to capacity with more than 4,000 people who dedicate their lives to the disease. What we heard from the researchers who presented the case on March 4 was that a baby girl, born in Mississippi to a woman with HIV, was found with HIV in her blood shortly after birth. Care providers quickly started the infant on a full set of three HIV medicines (typically, only one or two are used in exposed babies to prevent infection).
The medicines were continued for 18 months, after which mother and child went missing from care. When they returned after almost five months without medicines, no evidence of active HIV infection was found in the child. The medical team performed an exhaustive array of tests to try to confirm the prior presence of HIV and its subsequent eradication, and to rule out rare forms of resistance to HIV infection.
Skeptics in the conference audience got the chance to ask a handful of questions and were given a handful of answers. Then the discussion ended, the room cleared—and the news cycle moved on.
But the word “cure” and the hope it brings have remained in the minds of many, leading to countless questions from many of the more than 30 million people infected with HIV world-wide, as well as friends, families and care providers. For now, their questions are mostly unanswered.
To understand what the word “cure” means for HIV, it is helpful to review how people become infected and why a cure has been so hard to develop. People can be exposed to HIV when they have contact with infectious bodily fluids, which can include blood products during donations (an incredibly rare event with today’s blood-screening techniques), sexual intercourse or, in the case of newborns, in utero, during birth or breast-feeding.
But exposure to HIV does not necessarily mean infection. Only a small proportion of sexual encounters between couples where one person has HIV result in transmission of the virus, and we have known for more than a decade that antiviral medicines, when given within days of exposure, can prevent infection from taking hold. This is because for infection to occur, the virus must invade immune cells and incorporate itself into the DNA, where it can remain dormant for decades.
The medicines used to treat HIV are excellent at suppressing HIV-virus replication and preventing destruction of immune cells, but the medicines are unable to eradicate the dormant, or sleeping, copies in immune cells. This is why the drugs have afforded health and life to millions of people around the world, but also why those infected must continuously take medicines to keep the virus under control.
There has been one prior cure of an HIV-infected adult, which involved a bone-marrow transplant, a procedure that is too risky and expensive to be a common cure. Today, dozens of researchers and millions of dollars in funding support a mission to locate, activate and kill cells infected by dormant virus without harming patients. Then a durable HIV cure will have been achieved. In this mission, researchers remain years from their target.
In the case of the Mississippi baby, we know she was exposed to HIV, had HIV in her blood, and that at least some cells in her blood were found with sleeping virus—though we will likely never know if those cells were from the child or maternal cells that had been transmitted during pregnancy or birth. Was the baby infected with HIV and, thus, cured?
To many of the researchers at the conference, the answer is “no.” It seems more likely that her treatment prevented her, after exposure to HIV, from being infected. The reason we give medicines to both pregnant women and their newborns is precisely to prevent HIV exposures in children from becoming established infections, an intervention that can decrease the rate of transmission from about 30% to less than 1% in optimal conditions.
So what does this mean for patients with HIV? For the hundreds of pregnant women in the U.S. and Europe, and many thousands elsewhere who are diagnosed with HIV infection at the time of delivery, it offers hope for further decreasing the likelihood of passing the virus to their children. It also offers more data to support the notion that very early treatment after HIV exposure can prevent establishment of infection in some populations. We look to future studies to corroborate these hypotheses and improve our ability to prevent HIV transmission.
But for the more than 30 million adults and children currently infected—and for the vast majority of the hundreds of thousands who are newly infected annually—last week’s news represents neither a path toward a cure nor support for discontinuing antiviral medicines. Those of us in the field of HIV care and research remain steadfast in working toward a cure, a vaccine, better-tolerated therapies, and better access to care and reproductive-health services for those infected and at risk. Now we will also be accountable for explaining the relevance of the “baby cured” news to HIV-infected individuals, likely with a careful attention to the words we choose.
Dr. Siedner is a postdoctoral fellow in the division of infectious diseases at Massachusetts General Hospital and Harvard Medical School.
Article source: The Wall Street Journal