Scientists solve mystery of how antibodies stop HIV reinfection

Scientists have deciphered the mechanism behind an alternative to lifelong antiretroviral therapies for people with AIDS, and in the process, have solved a long-standing mystery about how antibodies can halt HIV reinfection in people.

Recent studies have shown that early initiation of antiretroviral therapies (ART) can lead to sustained post-treatment control of the virus in the blood, raising hopes of long-term HIV-1 remission.

However, ART involves a cocktail of drugs that only reduces, but does not eliminate, the viral load in the body while preventing further transmission. Consequently, AIDS patients have to endure lifelong treatment with ART to prevent a reignition of the infection. However, a 2017 study involving macaques and published in Nature Magazine found that chances of infection reignition was significantly reduced within those patients who were given early immunisation with HIV antibodies. This is called bNAb therapy.

However, scientists did not necessarily understand the mechanisms underlying the control elicited by bNAb therapy. If the infection was not treated, it led to a progression of the disease.

To study how early immunisation with bNAb antibodies helps control HIV, researchers led by Professor Narendra Dixit of the Department of Chemical Engineering, Indian Institute of Science (IISc) built a mathematical model of the HIV infection.

Their model confirms that the long-lasting reduction of viral load is switched on by interventions like ART or bNAb therapy. Furthermore, it also predicts that early bNAb therapy enhances the stimulation of the host’s immune cells and therefore helps in mounting a better defense against the virus as compared to ART.

The researchers say that their model is the first quantitative description of the HIV dynamics under bNAb therapy and that it unravels the mechanism underlying the response described in the 2017 primate study.

“Since a prolonged ART treatment regime compromises the quality of life of the patient, the study adds to the evidence that bNAb therapy may be a promising alternative to ART as researchers seek to find a functional cure for the disease,” IISc said.

Acquired Immune Deficiency Syndrome (AIDS) is a chronic, life-threatening condition that has claimed 40 million lives so far, since it was first reported in 1981. It is caused by the Human Immunodeficiency Virus (HIV) which is known for its ability to evade the host’s immune system. There is no known cure or vaccine for AIDS.