Complete Human Cytomegalovirus Cloned

By Colleen Owens

Research may lead to new antivirals and vaccines For the first time, Welsh researchers have generated a clone of the human cytomegalovirus (HCMV) that contains the complete genome of a HCMV strain. Researchers added a green fluorescent label to a cloned HCMV; in this image, infected cells glow green. “Previously, if you took a virus from a patient and grew it in the lab, it would mutate,” Richard Stanton, PhD, told Pharmaceutical Formulation & Quality. “It was therefore no longer representative of virus found in patients, and that was a major problem for HCMV research. Now we can grow a complete copy of the virus in the lab that represents virus found in patients, without risk of it mutating.” Dr. Stanton is a lecturer in the department of infection, immunity, and biochemistry at Cardiff University School of Medicine in Wales. This “wild-type” virus is critical to HCMV research, according to Eddie C.Y. Wang, PhD, also in the department of infection, immunity, and biochemistry at Cardiff University School of Medicine. “We can now explore more physiologically how a complete virus interacts with us,” he told PFQ. This knowledge will help researchers develop treatments for the life-threatening diseases associated with HCMV infection, said Dr. Wang, who was not involved in the research. Easily Manipulated The cloned virus is easily manipulated, Dr. Stanton said. By adding new genes or removing genes, researchers can create customized virus for vaccine development. “In addition, the ability to remove HCMV genes and explore their function means we can investigate which HCMV genes are most important to it,” Dr. Wang said. “In this way, we can identify the best targets for treatments.” “Now we can grow a complete copy of the virus in the lab that represents virus found in patients, without risk of it mutating.” —Richard Stanton, PhD, Cardiff University School of Medicine Cloning the virus should accelerate HCMV research, Dr. Wang said. “Previously, it would take six months to remove one of the genes in HCMV to investigate its function during a viral life cycle—now this takes a few weeks. Considering that HCMV is the biggest known human virus, with about 170 genes, you can see how much this will accelerate our knowledge of the virus.” HCMV is the primary infectious cause of congenital malformations, Dr. Stanton said. In addition, it is a major cause of colitis, retinitis, pneumonitis, and hepatitis in transplant patients and patients with AIDS, resulting in long hospital stays and increasing cost of care. The National Center for Biotechnology Information, an international database that provides reference standards for biomedical and genomic information, has designated this genome sequence as the international HCMV reference. The cloned virus has been distributed to research laboratories worldwide, and the World Health Organization is testing it as part of a study to develop an international diagnostic standard that will compare clinical isolates.