Study notes benefits of 2-dose varicella vaccination
Two doses of a combined measles-mumps-rubella-varicella vaccine (MMRV) were more efficacious at preventing moderate to severe varicella infection (chickenpox) than one dose of monovalent varicella vaccine and markedly more effective against varicella of any severity, according to a study today in The Lancet.
In 2005 and 2006 researchers administered vaccine to 5,285 children aged 12 to 22 months in 10 European countries where varicella was endemic; the children were followed for an average of 3 years.
They randomized the children into one of three groups: (1) those who received two doses of MMRV, (2) those who received one dose of the measles-mumps-rubella (MMR) vaccine and then MMR plus the monovalent varicella vaccine at dose two, and (3) those who received two MMR doses, to serve as the control group. All vaccines were made by GlaxoSmithKline, which funded the study.
The investigators found the efficacy of two-dose MMRV against all varicella to be 94.9% and against moderate to severe varicella to be 99.5%. In comparison, the efficacy of one-dose varicella vaccine against all varicella was 65.4% and against moderate to severe varicella, 90.7%.
A commentary in the same issue by Australian immunization expert Kristine Macartney, MBBS, MD, said the study showed that varicella vaccine should be administered in two doses and noted the benefits of combining varicella vaccine with the MMR vaccine.
Jan 29 Lancet study abstract
Jan 29 Lancet commentary
Researchers discover phage that attacks anthrax bacterium
An international team of researchers has discovered a new giant virus called a phage that infects Bacillus anthracis, the bacterium that causes anthrax, according to a new study in PLoS One.
The phage was isolated from samples collected from carcasses of zebras that died of anthrax in Etosha National Park in Namibia. The finding, which the team dubbed Tsamsa phage, is a giant siphovirus that sports a long, flexible tail trailing out of a circular head and a very large genome. Its dimensions place it among the largest known bacteriophages, according to a University of California, Davis (UC-Davis) news release.
The team found that the virus was a voracious predator of B anthracis, said Holly Ganz, PhD, of UC-Davis's Genome Center and first author of the study. They discovered in addition that it also infects some closely related bacteria, including strains of B cereus, which can cause foodborne disease.
Through gene sequencing the researchers identified the gene for lysin, an enzyme the phage uses to kill bacterial cells. They noted that the gene has potential for use as an antibiotic or disinfecting agent.
"With growing concerns about antibiotic resistance and superbugs, people are coming back to look at phages," said Ganz. One advantage of phages is that their specificity may allow them to target only pathogenic bacteria while not harming beneficial bacteria, the release said.
Jan 27 PLoS One study
Jan 27 UC-Davis press release
DARPA awards university $15 million to probe bio, chemical threats
The Defense Advanced Research Projects Agency (DARPA) of the Department of Defense has awarded the University of Colorado Boulder $14.6 million to develop new technology to rapidly determine how drugs and biological or chemical agents affect human cells.
The project will be conducted by an interdisciplinary team led by William Old, PhD, assistant professor of chemistry and biochemistry.
"Traditionally it takes decades to figure out how drugs affect an organism's biology," Old said in a university press release. "Our goal is to rapidly speed up the process, identifying how these compounds work in weeks. This could lower the barriers to developing effective drugs that have minimal side effects."
Old's team is developing new microfluidic devices to control and manipulate individual cell components to obtain subcellular resolution that will provide new insights into the functions of individual organelles and proteins within cells.
To help prevent mortality during potential terrorist attacks, DARPA wants to better understand the biochemical mechanisms at work during cellular exposures to biological or chemical agents, according to the release. But Old said the project is also expected to lead to new broad-scale techniques to analyze cellular processes for wider application.
Jan 28 University of Colorado Boulder news release