New research boosts search for cure for HIV/AIDS
Fresh data from several small trials presented at an AIDS conference on July 3 provides encouraging news in the quest for a cure for HIV, scientists said.
Giving an update in an eagerly-followed trial, researchers said an HIV-positive infant in Mississippi who was put on a course of antiretroviral drugs within a few days of birth had remained free of the AIDS virus 15 months after treatment was stopped.
In Boston, two HIV-positive men who were given bone-marrow transplants for cancer also had no detectable virus 15 weeks and seven weeks respectively after stopping AIDS drugs, a separate team reported.
Both research projects are at an early stage and should not be taken as a sign that a cure for the human immunodeficiency virus (HIV) is around the corner, researchers cautioned at a world forum of AIDS scientists in Kuala Lumpur, Malaysia.
Even so, they said it strengthens the motivation for pursuing the once-unthinkable goal of eradicating HIV or repressing it without daily drugs — a condition referred to as a “functional cure” or “functional remission”.
“I don’t actually want to use the cure word in this situation,” said Timothy Henrich, from the Brigham and Women’s Hospital in Boston, Massachusetts, of the bone-marrow study he is co-leading. “But what I can say is that if these patients are able to stay without detectable HIV for at least a year, maybe a year and a half, after we stop treatment, then the chances of the virus coming back are very small,” he told an AFP correspondent in Paris.
Introduced in 1996, the famous cocktail of antiretroviral drugs is a lifeline to millions with HIV. But if the drugs are stopped, the virus rebounds from “reservoirs” among old cells in the blood stream and body tissue. It then renews its attack on CD4 cells, part of the immune system’s heavy weaponry. Deborah Persaud, heading the so-called Mississippi Child investigation, said early treatment of newborns appears to offer the best hope of attacking the virus before it gets established in these reservoirs.
“Therapy in the first few days of life really curtailed the reservoir formation to the point that (it) was not established in this child and allowed treatment cessation without having the virus rebound,” Persaud, an associate professor of pediatrics at Johns Hopkins Children’s Center in Baltimore, Maryland, said by phone.
An estimated 34 million people are infected with HIV worldwide, and about 1.8 million die each year. The virus was first identified in 1981, and until the advent of antiretrovirals was essentially a death sentence, progressively destroying the immune system until the patient succumbed to pneumonia or another opportunistic disease. Three years ago, Nobel-winning French researcher Francoise Barre-Sinoussi launched a campaign for a cure — a hope bolstered by the case of a Berlin man whose HIV-count dropped to undetectable levels after a bone-marrow transplant for leukaemia.
In his case, the transplanted cells had a genetic variant, called CCR5 delta-32, which thwarts HIV’s attempts to latch on to the cell’s surface and then penetrate it.
The two Boston patients did not have this mutation in their transplants. But they were kept on antiretrovirals until the donor cells were fully established in their bodies, and this may have helped, suggested Henrich. In two other studies presented at the International AIDS Society (IAS) conference, French researchers said patients who began treatment as soon as possible after diagnosis had the best chance of shrinking the viral reservoir and reviving their immune system.
This backs new treatment guidelines published by the UN World Health Organization and strengthens hopes for a drug-free life for HIV patients, the French National Agency for Research on AIDS (ANRS) said.
“Given the large decrease in reservoirs in these two studies, it is possible that functional remission, i.e. prolonged control of the infection without treatment, may in time be achieved in patients treated early,” ANRS chief Jean-Francois Delfraissy said.
The four-day IAS meeting concluding on July 3 is held every two years.
What is bone marrow?
Bone marrow is the soft spongy tissue that lies within the hollow interior of long bones. In adults, marrow in large bones produces new blood cells. Bone marrow forms around 4% of total body weight (around 2.6 kg in a healthy adult).
Types of bone marrow
There are two types of bone marrow:
Red marrow that is responsible for producing red blood cells, white blood cells and platelets
Yellow marrow consisting mainly of fat cells
There are a number of blood vessels and capillaries traversing through the marrow making it a very vascular organ.
At birth and in early childhood most of the marrow is red. As a person ages more and more of it is converted to the yellow type. About half of adult bone marrow is red.
Functions of bone marrow
Red blood cells (erythrocytes) carry oxygen to the tissues.
Platelets or thrombocytes (derived from megakaryocytes) help prevent bleeding and aid in clotting of blood.
Granulocytes (neutrophils, basophils and eosinophils) and macrophages (collectively known as myeloid cells) fight infections from bacteria, fungi, and other parasites. They also remove dead cells and remodel tissue and bones.
B-lymphocytes produce antibodies, while T-lymphocytes can directly kill or isolate invading cells.
RBC live for around 170 days and rest are shorter lived and need to be replenished continuously. An average human requires approximately one hundred billion new hematopoietic cells each day. This is performed by the Hematopoietic Stem Cells (HSCs).
Bone marrow and stem cells
Around the central bore of the bone or the central sinus lie the Mesenchymal stem cells. These cells have the capacity to form various cells of the body including