An antibiotic will help fight HIV

Antibiotic helps the immune system to see HIV

Kirill Stasevich, Science and Life (nkj.ru )

HIV affects immune cells, however, the immune system could well detect infected cells and destroy them along with the virus. But the virus, firstly, is able to penetrate into the cellular genome and hide there, and secondly, it has a special protein, because of which the immune system simply cannot detect infected cells.

Immunity detects infection by fragments of viral proteins that appear on the surface of an infected cell. All the proteins that are inside the cell have their own service life. They periodically fail and are disposed of. Some of the fragments of the split proteins are exposed on the outer cell membrane – the immune system sees pieces of normal cellular proteins and does not touch the cell. But viral proteins are also periodically disposed of (although this in itself does not prevent the virus from multiplying in any way). Fragments of viral proteins are also sent to the surface – and now, when the immune system detects them, it will understand that the cell is infected and will try to destroy it.

But protein fragments don't stick out on the membrane by themselves. They have a special holder – the so-called proteins of the main histocompatibility complex. These are extremely important molecules, they are present in almost all cells of our body. Thanks to them, the immune system can distinguish our cells from others, healthy cells from sick ones.

And now HIV has the Nef protein, which suppresses the synthesis of histocompatibility complex proteins, the holding proteins. If there are no such proteins, then there is no one to put viral molecules on public display. The immune system simply will not understand that the cell is infected. So, it would be good to somehow disable or spoil the viral protein Nef itself.

Researchers from the University of Michigan write in PNAS that substances called plecomacrolides, antibiotics from the group of macrolides, could turn off Nef. They inhibit the growth of bacteria, and they should not act on viruses. But in this case, strictly speaking, they do not directly harm the virus itself – they only make it visible to the immune system.

Generally speaking, plecomacrolides are quite toxic not only for bacteria, but also for our cells, and as a medicine they are used with great caution. However, the authors of the work found out that one of them, concanamycin A, acts in such concentrations when it does not harm the cell itself yet. That is, you can pick up such an amount of antibiotic that the viral protein Nef will no longer work, and the cell will not feel any damage yet. In experiments, immune cells actually began to see – and destroy – their colleagues infected with the virus after the affected cells were treated with concanamycin A. Now it remains to wait for how effectively the antibiotic will manifest itself in clinical trials.

This is not the first time an antibiotic has helped the immune system fight the virus. Two years ago we wrote about how some antibiotics stimulate the activity of antiviral genes in cells, helping to fight against viral infection.

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