HIV drug may destroy hidden HIV

Main Category: HIV / AIDS
Article Date: 15 Feb 2004 - 0:00 PDT


A drug developed in the USA could pick off cells that harbour HIV. Reservoirs of the virus can remain in some types of human cell, this has been one of the major problems in treating HIV.

According to doctors at the University of Texas Southwestern Medical Centre (center), they have found a toxin which targets these cells directly.

A short course of treatment could purge these infected cells, say the doctors (their laboratory tests suggest this).

They are not sure whether this treatment would work in actual patients or whether the long-term outcomes would improve.

One thing is for certain, keeping the number of these cells (that harbour HIV) would most definitely help the patients keep the virus under control for longer.

When patients are treated using anti-retroviral therapy (successfully) and tests do not find any sign of HIV in the blood, it finds the hiding places where drugs do not destroy it (and become active later on).

T-cells are the target in this treatment (more specifically - memory helper T cells).

These cells are the ones that have the information about infections. The immune system can then respond if the same virus (bacterium) appears again. They also harbour HIV.

Scientists used an immunotoxin which is designed to attack this type of cell. Their work is published in the journal called 'Proceedings of the National Academy of Sciences'.

It is an antibody. It is designed to lock onto this type of T cell. It is coupled with a toxin molecule (derived from ricin).

24 HIV patients whose blood seemed to have no sign of the virus and extracted T cells from them. When treated with the immunotoxin the number of the key cell type believed to act as a reservoir for the virus went down significantly.

'Our results suggest this immunotoxin should be tested for ability to purge one of the critical latent viral reservoirs in patients.' said the researchers.

The researchers have asked other HIV research teams to help them conduct a bigger trial (on the immunotoxin).

Some UK scientists are saying that for the treatment to be fully successful the immunotoxin would have to gain entry to the lymph nodes. This is quite difficult.

About 95% of these cells are found outside the peripheral blood system. We can't say whether something that works in the laboratory would work in humans.

Some worried that the effect of this treatment might be to make the body more vulnerable to infection by destroying its immune system 'memory.

Other wondered about the dangers of using ricin. They suggested that maybe we should carry out further tests on primates rather than humans.

• Additional
• References
• Citations