Children born to HIV-positive mothers can contract the virus at any one of several points between pregnancy and the postpartum period, including during pregnancy, childbirth or while breastfeeding. Although there are numerous ways to prevent the spread of the virus in these situations, mother-to-child HIV transmission still occurs in a significant number of cases. According to findings presented to the Conference on Retroviruses and Opportunistic Infections in early 2013, researchers from a multi-university team appear to have discovered a way to halt the actions of HIV in the days immediately after childbirth, and thereby do away with the need for ongoing HIV treatment.
Virus Can’t Hide
Inside the human bloodstream, HIV causes most of its damage by attacking immune system cells called CD4 T-cells, which the body needs as part of its early response mechanism for detecting dangerous microorganisms. After attacking these cells, copies of HIV enter them and start reproducing. This process has two effects. First, it seriously reduces the body’s ability to keep enough CD4 T-cells in circulation to maintain normal immune system function. At the same time, it produces a significant increase in the number of HIV copies found in the bloodstream. Because new HIV copies attack more CD4 T-cells and create new avenues for virus reproduction, the effects of HIV infection steadily magnify until the immune system collapses and the individual develops acquired immune deficiency syndrome, or AIDS.
In adults, doctors counteract the effects of HIV with medications commonly known as antiretroviral drugs. These medications disrupt several phases of HIV’s reproductive cycle, and thereby seriously reduce the virus’s ability to reproduce and spread to more CD4 T-cells. As a rule, antiretroviral therapy does not kill off HIV; instead, the virus goes dormant and “hides” inside a certain number of cells. If therapy is discontinued, these dormant pockets of infection will return to activity and continue their progressively damaging spread inside the body.
Standard Treatment in Newborns
When working with newborn children who have high chances of contracting HIV from their mothers, doctors don’t wait until the children test positive for HIV infection. Instead, they give at-risk newborns preventive or prophylactic doses of antiretroviral drugs for about six weeks after childbirth and keep the treated children under observation. If, at some later date, infants treated with prophylactic doses of antiretroviral medication test positive for HIV, their doctors will start them on heavier, regular antiretroviral doses (known as therapeutic doses) designed to keep HIV reproduction in check.
An Advance in Treatment
As part of what is now a two-year study-in-progress, researchers from Johns Hopkins Children’s Center, the University of Massachusetts Medical School and the University of Mississippi gave unusually heavy, therapeutic doses of antiretroviral medication to a newborn who contracted HIV from her mother during delivery. These doses were administered during the child’s first 30 hours of life. Over the next month, the researchers measured the levels of HIV circulating in the child’s system; these levels dropped steadily until, after 29 days, they fell below the measurable threshold used in standard testing procedures. For the next year and a half, the child continued to receive therapeutic antiretroviral therapy. After this time period, the research team discontinued treatment for 10 months. When they re-tested the child after the 10-month interval, they found that her HIV levels were still undetectable.
The researchers believe that early use of heavy antiretroviral therapy prevented HIV from entering the dormant stage that typically gives the virus the opportunity to hide and reemerge when antiretroviral medications are discontinued. They believe that they have discovered a “functional cure” for HIV infection. This term describes a nearly complete eradication of a virus or other infectious microorganism; a functional cure differs from a “sterilizing cure,” which wipes out every trace of an infectious invader. In the annals of medicine, doctors have recorded only one case of a sterilizing cure for HIV infection, and the process involved in that case is generally considered too complicated and expensive for practical, real-world use. On the other hand, the functional cure described in 2013 presents a low-cost alternative that may prove useful in millions of cases throughout the world.