A new disease model showed HIV spreads through the body in a similar way to a virus infecting a computer.

The findings showed that HIV can spread through the bloodstream or directly between cells, University College London reported. This is similar to how some computer worms move through the Internet and local networks to infect a large number of computers.

A team of researchers worked to create a model for this type of "hybrid spreading," which could predict how quickly the infection will progress into AIDS. They took samples from 17 patients who were infected with HIV and found this type of spreading was the most logical explanation for the way the virus moved through the body. The findings also highlight the benefits of early treatment for HIV.

 HIV infects CD4+ T-cells, which are crucial for the immune system and preventing disease. As these cells are depleted by the virus the immune system loses its ability to function. Current World Health Organization guidelines suggest only starting treatment when T-cell counts fall below a certain level, but these new findings suggest the treatment should  begin immediately after diagnosis.

"The number of HIV cells in the bloodstream is always relatively low, and our model shows that HIV spread through the bloodstream alone would not be enough to cause AIDS," said co-senior author Professor Benny Chain of UCL Infection & Immunity. "It is likely that when HIV gains a foothold somewhere with a high T-cell population, such as the gut, it uses a cell-to-cell transfer mechanism to efficiently spread directly between them. As such, if HIV has already spread to an area rich in T-cells by the time treatment begins, preventing its spread through the bloodstream will not stop AIDS. Our model suggests that completely blocking cell-to-cell transfer would prevent progression to AIDS, highlighting the need to develop new treatments."

The findings were published in a recent edition of the journal PLOS Computational Biology.