Harmless Virus May Kill Cancer Cells

A common virus may have the potential to become a powerful cancer fighter.

Laboratory tests showed that the virus, known as adeno-associated virus type 2 (AAV2), kills many types of cancer cells without harming healthy cells.

"We believe that AAV2 recognizes that the cancer cells are abnormal and destroys them. This suggests that AAV2 has great potential to be developed as an anticancer agent," says researcher Craig Meyers, PhD, professor of microbiology and immunology at Penn State College of Medicine, in a news release.

Meyers presented the results this week at the 24th annual meeting of the American Society for Virology held at Penn State in University Park.

Read Web MD's "Curry May Curb Breast Cancer's Spread"
Read Web MD's "Novel Drug Stops Cancer Growth"

Virus May Lead to New Cancer Treatments

AAV2 is considered a harmless virus and infects the majority of the population. The virus normally resides in epithelial cells, which form the outermost layer of tissues.

For unknown reasons, people who carry the virus are less likely to develop human papillomavirus (HPV), some strains of which are associated with cervical cancer.

Researchers say AAV2 usually requires a second, helper virus, such as HPV, to become activated. When it finds a helper virus, AAV2 replicates and causes infected cells to die.

In the study, researchers examined the effects of AAV2 on normal human epithelial cells and cells infected with HPV or cancer.

In one test, researchers combined cells infected with both HPV and AAV2 and found that after six days all HPV-infected cells had died.

Similar tests showed that the AAV2 virus killed four different types of cancer cells (cervical, breast, prostate, and squamous cells) within six days of treatment without affecting healthy cells. It did so without the presence of a second, helper virus.

"One of the most compelling findings is that AAV2 appears to have no pathologic effects on healthy cells," says Meyers. "So many cancer therapies are as poisonous to healthy cells as they are to cancer cells. A therapy that is able to distinguish between healthy and cancer cells could be less difficult to endure for those with cancer."

Researchers say future studies are needed to determine exactly how AAV2 causes cancer cell death and how the virus might be developed to more aggressively target and treat cancers.

Read Web MD's "Newly Diagnosed with Cancer? Start Here"
Read Web MD's "How Much Do You Know about Cancer?"

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: 24th Annual meeting of the American Society for Virology, University Park, Pa., June 18-22, 2005. News release, Penn State University.