Mice given a relatively new cancer drug can survive an otherwise lethal dose of vaccinia virus, a relative of smallpox virus, report scientists supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. The findings, say the investigators, suggest that Gleevec or similar drugs might be useful in preventing adverse side effects of smallpox vaccine. The classic smallpox vaccine is made from live, weakened vaccinia virus and is not recommended for people with compromised immunity, except in emergency situations where they may have been exposed to smallpox virus.
This study helps illuminate the cellular machinery used by poxviruses to exit infected cells, and also provides new support for the concept of treating viral infections by targeting specific host cell molecules rather than the viruses themselves, says NIAID director Anthony S. Fauci, MD.
The senior author of the paper, published online last week in the journal Nature Medicine, is Daniel Kalman, PhD, of Emory University School of Medicine in Atlanta.
Like all viruses, poxviruses co-opt various cellular molecules and processes to enter a cell, replicate and then spread to uninfected cells. Using lab-grown cells, Kalman and his colleagues identified specific cell proteins vaccinia uses to detach from an infected cell and move toward an uninfected cell. The proteins, members of the Abl-family (pronounced able) of tyrosine kinases, are well known to cancer investigators because mutation of one family member, Abl, causes a rare form of cancer known as chronic myelogenous leukemia (CML). Gleevec inhibits Abl-family tyrosine kinases and has proved very useful in treating CML.
To learn whether Gleevec could prevent or lessen vaccinias ability to spread in a living organism, the researchers treated mice with either saline solution or with Gleevec at a dose equivalent to that given to humans being treated for CML. Next, they exposed the mice to ordinarily lethal amounts of vaccinia. All of the Gleevec-treated mice survived, while 70 percent of the untreated mice died.
This finding, if confirmed in additional animal model studies, suggests that Gleevec might play a role in addressing a public health emergency in the event of a smallpox outbreak, Kalman says. Specifically, Gleevec might be useful as a preventive against adverse effects of smallpox vaccine, enabling clinicians to use the vaccine even in people who otherwise could not take it. Given for a short period, Gleevec theoretically could hamper the cell-to-cell spread of virus and allow the bodys immune system to mount a successful defense, he explains. Experiments to test whether Gleevec might work against smallpox virus as well as against vaccinia virus are now being planned, Kalman says. The approach of fighting disease by targeting drugs to cellular molecules rather than to disease agents themselves may be applicable to a wide variety of pathogenic microorganisms, he says.
Routine vaccinations for smallpox ended in this country in the early 1970s, and the World Health Organization declared smallpox eradicated in 1980. Nevertheless, concern remains that smallpox virus could be unleashed through an act of bioterror. For this reason, scientists are working to better understand the mechanisms of smallpox disease and to develop new and improved smallpox treatments and vaccines.
Reference: PM Reeves et al. Disabling poxvirus pathogenesis by inhibition of Abl-family tyrosine kinasas. Nature Medicine DOI: 10.1038/nm1265 (2005).
Source: National Institutes of Health
CDC Urges Vigilance: New Recommendations for Monitoring and Testing H5N1 Exposures
July 11th 2025With avian influenza A(H5N1) infections surfacing in both animals and humans, the CDC has issued updated guidance calling for aggressive monitoring and targeted testing to contain the virus and protect public health.
A Helping Hand: Innovative Approaches to Expanding Hand Hygiene Programs in Acute Care Settings
July 9th 2025Who knew candy, UV lights, and a college kid in scrubs could double hand hygiene adherence? A Pennsylvania hospital’s creative shake-up of its infection prevention program shows that sometimes it takes more than soap to get hands clean—and keep them that way.
Broadening the Path: Diverse Educational Routes Into Infection Prevention Careers
July 4th 2025Once dominated by nurses, infection prevention now welcomes professionals from public health, lab science, and respiratory therapy—each bringing unique expertise that strengthens patient safety and IPC programs.
How Contaminated Is Your Stretcher? The Hidden Risks on Hospital Wheels
July 3rd 2025Despite routine disinfection, hospital surfaces, such as stretchers, remain reservoirs for harmful microbes, according to several recent studies. From high-touch areas to damaged mattresses and the effectiveness of antimicrobial coatings, researchers continue to uncover persistent risks in environmental hygiene, highlighting the critical need for innovative, continuous disinfection strategies in health care settings.