The key, it turned out, was the killer T-cells, also known as CD8 cells.

Instead of looking for the virus itself, killer T-cells look for cells that are infected with a virus.

Over the last 15 years, scientists have steadily built a case that killer T-cells can hold the AIDS virus in check.

Lymphocytes are much more common in the lymphatic system, and include natural killer T-cells.

Normally, such white blood cells, known as killer T-cells, cruise through the body, on surveillance for cells that are infected or malignant.

The killer T-cells recognize these cells because they have abnormal proteins on their surfaces.

It also stimulates the activity of a type of immune cell, the killer T-cell, when the body is attacked by a pathogen.

The mice possess almost no killer T-cells to fight infections, however, and must be housed in sterile boxes.

In most people, virus levels rise and then fall, beaten down mostly by a white blood cell called a killer T-cell.

The vaccinated animals became infected, but their killer T-cells managed to keep the virus in check, and they never got sick.