A new HIV strain that is so aggressive that it can become full-blown AIDS in just three years was discovered by a team of international researchers in Cuba.

Researchers at KU Leuven's Laboratory for Clinical and Epidemiological Virology described how the HIV strain spreads in the body of the host. In common HIV infection, the virus enters the human cells through anchor points called CCR5 before it switches to the anchor point CXCR4. This process usually takes 10 years until the virus switches to full-blown AIDS.

But based on the observation in infected patients in Cuba, the HIV strain was found to switch in just three years, much faster than the usual progression because it directly attacks the CXCR4 upon initial contact.

The international researchers led by professor Anne-Mieke Vandamme examined the blood samples of 73 newly infected patients; 73 percent of them were already AIDS-positive. They compared these samples to those collected from 22 patients diagnosed with AIDS who underwent regular progression.

The researchers observed that the blood samples of those infected with the aggressive form of HIV strain had unusually high doses of the virus and the molecule RANTES that binds the CCR5 to protect the cell from the virus. The high concentration of RANTES implied that the CCR5 was no longer available and that the strain had started targeting the CXCR4.

Based on the speed of the progression, infected patients would be AIDS-positive in three years without even realizing that they are critically ill.

The HIV strain in Cuba is considered unique at this point although scientists are aware that the virus can mutate.

"The only thing now is that in Cuba, it is associated with rapid progression [of the disease]. It's something that hasn't been seen before that clearly," Hector Bolivar, a physician and infectious disease specialist at the University of Miami Miller School of Medicine, told the Miami Herald. He wasn't part of the study.

The study was published in the journal EBioMedicine.