 This is the VOA Special English Technology Report. A team of scientists in the United States has created a new kind of mouse that has an immune system similar to that of humans. The scientists hope their research with these mice will speed up development of a vaccine to prevent human immunodeficiency virus, or HIV. Scientists from the Reagan Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard are carrying out the new research. Earlier research has shown that certain individuals with HIV have immune systems that do better at controlling the AIDS virus. These individuals are commonly known as elite controllers. They often live longer with the virus and have fewer problems early on. Todd Allen is one of the lead authors of the new study, which was published in Science Translational Medicine. He says some people are able to control HIV very well. By using the new experimental mice, the researchers hope to learn what it is about the immune systems of these elite controllers that causes them to deal with the HIV virus better than others. The humanized mice were created using stem cells and tissue from human donors. Some of the tissue was taken from the liver and thymus. The thymus is a large gland at the bottom of the throat. It trains T lymphocytes or T cells to attack unwelcome microbes. In that way, it protects the body from infection. When the scientist infected the so-called humanized mice with the HIV virus, the T cell reaction in the mice was exactly the same as that of humans. Earlier research using rhesus monkeys helped scientists understand how the virus attacks cells. These monkeys were seen as good replacements for humans because they could easily be infected with the primate version of HIV, known as FIV. But genetic differences in the two versions of the virus and the immune systems suggested that monkeys were not the best candidates for HIV research. Todd Allen says the experiments with the new humanized mouse did a better job of showing what happens in the human body with the AIDS virus. He says the experimental mouse permits researchers to test the discoveries they have made about individuals infected with HIV. Todd Allen and the other researchers hope further studies with the humanized mouse will lead to an HIV vaccine. For VOA Special English, I'm Carolyn Presuti.