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(CNN)Nearly everyone carries one version or another of the herpes virus. A recent study suggests that the new gene-editing technology known as CRISPR/Cas9 may be able to eliminate this ever-present virus -- or at least suppress it.
"At this point, there is no cure for the herpes virus infection. Once infected, you're infected for life," said Robert Jan Lebbink, co-author of the study and a molecular biologist at University Medical Center in Utrecht, Netherlands.
The virus develops a latent stage, in which it lies dormant in an infected cell without reproducing. Because our immune systems cannot recognize latent infections, we cannot clear them from our bodies.
Previously, similar experiments have been reported only by scientists in China. Engineering human genes in the embryo stage opens up the possibility of correcting their defective parts that cause inherited diseases. The new trait is passed on to subsequent generations. But the practice is controversial, since many fear it could be used for unethical purposes such as creating "designer babies" with specific enhanced abilities or traits.
A DNA double helix is seen in an undated artist's illustration released by the National Human Genome Research Institute. For the first time, U.S. scientists have successfully edited genes of human embryos.
Oregon scientists led by Kazakhstan-born Shoukhrat Mitalipov successfully repeated the experiment on scores of embryos created with sperm donated for scientific purposes by men with inherited disease mutations. The editing was done very close to the moment of fertilization of the egg in order to make sure the changes would be repeated in all subsequent cells of the embryo.
Scientists have been experimenting with gene editing for a long time, but the availability of the technique called CRISPR rapidly advanced the precision, flexibility and efficiency of cutting and replacing parts of the molecule chains that comprise genes. Citing ethical concerns, the U.S. Congress made it illegal to turn genetically-edited embryos into babies. Many other countries do not have such regulations.
Scientists in US Successfully Edit Human Embryo's Genes
The report from the National Academy of Sciences (NAS) and the National Academy of Medicine said scientific advances make gene editing in human reproductive cells "a realistic possibility that deserves serious consideration.” The statement signals a softening in approach over the use of the technology known as CRISPR-Cas9, which has opened up new frontiers in genetic medicine because of its ability to modify genes quickly and efficiently. In December 2015, scientists and ethicists at an international meeting held at the NAS in Washington said it would be "irresponsible" to use gene editing technology in human embryos for therapeutic purposes, such as to correct genetic diseases, until safety and efficacy issues are resolved.
The latest NAS report now says clinical trials for genome editing of the human germline could be permitted, "but only for serious conditions under stringent oversight." CRISPR-Cas9 works as a type of molecular scissors that can selectively trim away unwanted parts of the genome, and replace it with new stretches of DNA. Genome editing is already being planned for use in clinical trials of people to correct diseases caused by a single gene mutation, such as sickle cell disease. But these therapies affect only the patient.
The concern is over the use of the technology in human reproductive cells or early embryos because the changes would be passed along to offspring. Research using the powerful technique is plowing ahead even as researchers from the University of California and the Broad Institute battle for control over the CRISPR patent. Although gene editing of human reproductive cells to correct inherited diseases "must be approached with caution, caution does not mean prohibition," the committee said in a statement.
Scientists Soften on DNA Editing of Human Eggs, Sperm, Embryos: Report
"What we've finally shown is that we can do it. It's not just on the chalkboard," said Dr. Matthew Porteus, senior author of the study published in the journal Nature. With the study, and unpublished findings from his lab, Porteus believes his team has amassed enough proof to start planning the first human clinical trial using the powerful CRISPR-Cas9 gene editing system to correct the genetic mutation that causes sickle cell disease. "We think we have a complete data set to present to the FDA (Food and Drug Administration) to say we've done all pre-clinical experiments to show this is ready for a clinical trial," Porteus told Reuters by phone. CRISPR-Cas9 has quickly become the preferred method of gene editing in research labs because of its ease of use compared with older techniques. CRISPR works as a type of molecular scissors that can selectively trim away unwanted parts of the genome, and replace it with new stretches of DNA.
Research using the powerful technique is plowing ahead even as researchers from the University of California and the Broad Institute battle for control over the CRISPR patent. Oral arguments in the case are expected on Dec. 6 at the U.S. Patent and Trademark Office in Alexandria, Va. In sickle cell disease, the body makes mutant, sickle-shaped hemoglobin, the protein in red blood cells that carries oxygen to the body's tissues. It is caused by a single mutation in a gene that makes a hemoglobin protein. In a study published last month in Science Translational Medicine, a team from the University of California, Berkeley, and colleagues used the CRISPR gene editing tool to snip out the diseased gene and deliver a new stretch of DNA to correct the mutation in human stem cells. In that study, some 25 percent of blood-forming cells were corrected.
In the Stanford study, Porteus and colleagues took a different approach. They used CRISPR to snip the gene, but they used a harmless virus to introduce the repair mechanism into cells. After a series of tests in healthy cells, the team tested the gene editing system in blood-forming cells from four patients with sickle cell disease. They showed they could correct the mutation in 30 to 50 percent of these diseased cells. Sixteen weeks after they injected the cells into young mice, the team found the cells were still thriving in the bone marrow. Porteus said the findings were very encouraging because prior studies have shown that if you can correct mutations in 10 percent of cells, that should create enough to cure the disease. Stanford is now scaling up its laboratory processes to support human trials.
The process will involve using chemotherapy to wipe out a patient's blood system but not their immune system, as is done in a stem cell transplant. Then, the team would inject the patient's own corrected stem cells, which the researchers hope would engraft into the bone marrow and produce healthy blood cells. Porteus has equity interest in CRISPR Therapeutics of Cambridge, Massachusetts, but he said the sickle cell work has been independent of it. The university has built a cell manufacturing plant for this purpose. "We hope to develop the entire process here at Stanford," he said. Porteus said the team plans to make an initial submission to the FDA in the next few months to map out the clinical trial, and hopes to treat the first patient in 2018.
Stanford Uses CRISPR to Correct Sickle Cell, Human Trials Planned
New gene editing tools let scientists alter the DNA of living cells - from plants, animals, even humans - more precisely than ever before. Think of it as a biological cut-and-paste program. A look at the science.
What is gene editing?
While scientists have long been able to find defective genes, fixing them has been so cumbersome that it's slowed development of genetic therapies. There are several gene editing methods, but a tool called CRISPR-Cas9 has sparked a boom in research as laboratories worldwide adopted it over the past five years because it's faster, cheaper, simple to use with minimal training and allows manipulation of multiple genes at the same time.
How it works
Pieces of RNA are engineered to be a guide that homes in on the targeted stretch of genetic material. The Cas9 is an enzyme that acts like molecular scissors to snip that spot. That allows scientists to delete, repair, or replace a particular gene.
Medical research
The fresh attention comes from research involving human embryos. In laboratory experiments, a team lead by Oregon researchers used CRISPR to successfully repair a heart-damaging gene in human embryos, marking a step toward one day being able to prevent inherited diseases from being passed on to the next generation. But there's wide agreement that more research is needed before ever testing the technique in pregnancy.
Professor Wendy Harwood poses for a photograph in a plant breeding incubator room with barley plants that have undergone gene editing at the John Innes Centre in Norwich, Britain.
The biggest everyday use of CRISPR so far is to engineer animals with human-like disorders for basic research, such as learning how genes cause disease or influence development and what therapies might help. But promising research, in labs and animals so far, also suggests gene editing might lead to treatments for such diseases as sickle cell, cancer, maybe Huntington's _ by altering cells and returning them to the body. Another project aims to one day grow transplantable human organs inside pigs.
The biggest hurdle
The milestone, published this week in the journal Nature, was confirmed last week by Oregon Health and Science University (OHSU), which collaborated with the Salk Institute and Korea's Institute for Basic Science to use a technique known as CRISPR-Cas9 to correct a genetic mutation for a heart condition. Until now, published studies using the technique had been done in China with mixed results.
CRISPR-Cas9 works as a type of molecular scissors that can selectively trim away unwanted parts of the genome, and replace it with new stretches of DNA. "We have demonstrated the possibility to correct mutations in a human embryo in a safe way and with a certain degree of efficiency," said Juan Carlos Izpisua Belmonte, a professor in Salk's Gene Expression Laboratory and a co-author of the study.
Juan Carlos Izpisua Belmonte, professor at Salk Institute's Gene Expression Laboratory and Jun Wu, Salk staff scientists
To increase the success rate, his team introduced the genome editing components along with sperm from a male with the targeted gene defect during the in vitro fertilization process. They found that the embryo used the available healthy copy of the gene to repair the mutated part. The Salk/OHSU team also found that its gene correction did not cause any detectable mutations in other parts of the genome - a major concern for gene editing.
Still, the technology was not 100 percent successful - it increased the number of repaired embryos from 50 percent, which would have occurred naturally, to 74 percent. The embryos, tested in the laboratory, were allowed to develop for only a few days. "There is still much to be done to establish the safety of the methods, therefore they should not be adopted clinically," Robin Lovell-Badge, a professor at London's Francis Crick Institute who was not involved in the study, said in a statement.
'Utmost Caution'
