A new human-mouse hybrid is the first mammalian model that can develop the human AIDS virus.
The scientists in Texas who developed the "humanized" animal are paving the way to a new generation of AIDS research that could significantly accelerate the quest for an AIDS vaccine and other therapies, scientists say.
"(The time it takes for) vaccine research may collapse from decades to years or even years to months," said Michael Allerton, who develops HIV policy for the Kaiser Permanente medical group.
AIDS is notoriously difficult to study because only humans contract the disease. Research into HIV has largely been limited to humans and macaque monkeys, which develop a similar form of the disease. But a mouse engineered to have a human immune system shows how the human infection spreads, and provides a model for testing treatments.
The mice could reveal a number of secrets about HIV, including "the cells that it encounters first, how it reaches them, how the cells communicate with other cells, and how the virus migrates to the lymph nodes and multiplies once it gets there," said Rowena Johnston, vice president of research for the Foundation for AIDS Research.
For more than a decade, scientists have worked on the difficult task of transplanting parts of the human immune system into mice.
"You and I have human immune cells in the entire body, meaning your blood, your liver, your lungs, your kidney, your spleen and your gut especially," said J. Victor Garcia, leader of the research and professor of medicine at the University of Texas Southwestern Medical Center.
The first mouse-human hybrids, he said, had human immune cells only in specific organs or regions of the mouse. In research described in the March 27 online edition of the Journal of Experimental Methods, Garcia and his colleagues describe how they've given the rodents more complete human immune systems.
First, they genetically engineered the mice to be born without immune systems. They then inserted human stem cells into the mice, which created bone marrow. Then they added bits of human liver and thymus from fetuses to goose the bone marrow into producing immune-system T cells.
The scientists inserted drops of purified AIDS virus into the rectums of the hybrid mice, mimicking a common method of human transmission. Six of seven mice became infected.
There is one big caveat: Mice aren't humans, even if they have human immune systems, and the animals can't exactly replicate what happens in infected humans.
But scientists still say the hybrid mouse is a big advance. Among other things, HIV-infected mice could help scientists study microbicides designed to prevent transmission of the AIDS virus. The mice could also help scientists examine the usefulness of drugs that might prevent transmission or stop infection after exposure, Garcia said.
He also said he'll make the mouse freely available to other scientists.
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Testing the First AIDS Vaccine
