NEWS SCAN: Cost of select-agent research, drug-resistant Salmonella, botulism mechanism, avian flu in Mongolia, rotavirus vaccine safety

May 11, 2010

'Select agent' regulations may have boosted cost of research
Restrictions enacted in 2001 and 2002 on "select agents" such as anthrax and Ebola virus did not stifle research on those pathogens but did make it more costly, according to an analysis in Proceedings of the National Academy of Sciences (PNAS). A team led by Elizabeth A. Casman of Carnegie Mellon University studied the effects of the USA Patriot Act of 2001 and the Bioterrorism Preparedness Act of 2002 on anthrax and Ebola research. They determined that the average number of Bacillus anthracis research papers per million dollars of US funding before 2002 was 17, but after 2002 it dropped to just 3. For Ebola research the number dropped from 14 before 2002 to 6 after 2002. For a control pathogen not classified as a select agent, Klebsiella pneumoniae, the number dropped from 26 to 17. The team acknowledges that the funding can't be matched to specific research papers, but they write that the figures "clearly indicate that the efficiency of select agent research fell sharply after passage of the laws," perhaps by two- to fivefold. On the other hand, such measures as the number of papers published per year, the number of authors, and the influx rate of new authors indicated an overall stimulus to select-agent research, they report. "Contrary to expectation, research did not become centralized around a few gatekeeper institutions," they add.
May 10 PNAS abstract

Study finds drug-resistant Salmonella in supermarket chicken
To explore if drug-resistant Salmonella strains found on supermarket chicken play a role in human infections, Pennsylvania researchers obtained samples from raw chicken during 2006 and 2007 and compared them to Salmonella isolates from human infections that were in the US Center for Disease Control and Prevention's PulseNet database. Of 378 chicken samples, 22% (84) contained Salmonella. Twenty-six of those were resistant to at least three antimicrobials, and 18 were resistant to ceftiofur, an antibiotic used in poultry production. Of 28 Salmonella serovar Typhimurium isolates, 20 were resistant to at least three antimicrobials, including 12 that were resistant to ceftiofur. One of the ceftiofur-resistant Salmonella Typhimurium isolates had a pattern that was indistinguishable from a human isolate in PulseNet. Both carried the same resistance gene. The authors concluded that the findings show that chicken meat can be a source of multidrug-resistant Salmonella in humans. In a posting on the Effect Measure public health blog today, the pseudonymous author Revere noted that the findings were interesting, though the sample size was small. The author also noted that supermarkets are one possible way drug-resistant Salmonella can circulate from commercial farms to the larger community.
May 5 Foodborne Pathog Dis abstract
May 11 Effect Measure post

Study uncovers key mechanism in foodborne botulism
Japanese researchers writing in the Journal of Cell Biology report that they have discovered how botulinum toxin crosses from the gastrointestinal tract into the blood in foodborne botulism cases. They write that the nontoxic components of botulinum toxin, including hemagglutinin (HA), protect the toxin from the acid and enzymes found in the digestive tract. The team determined that HA binds epithelial cadherin, thereby blocking it from mediating cell-to-cell adhesion and disrupting the epithelial barrier. They also found that this mechanism is species-specific in that botulinum toxin HA binds human, bovine, and mouse epithelial cadherin, but not the cadherin found in rats or chickens.
May 10 J Cell Biology report abstract
May 10 Rockefeller University press release

Avian flu strikes waterfowl near Mongolian lake
Veterinary officials from Mongolia yesterday reported the deaths of 26 waterfowl from a highly pathogenic H5 virus, according to their report to the World Organization for Animal Health (OIE). The birds, whooper swans and greylag geese, died near Ganga Lake in Sukhbaatar province, in eastern Mongolia not far from the border with China. The source of the virus isn't known. Mongolia's last H5N1 avian influenza outbreak occurred last August when the virus struck 171 wild birds in Arkhangai province, in the northern part of the country.
May 10 OIE report

Vaccine-safety groups urge FDA to suspend use of Rotateq
Two organizations concerned about vaccine safety, the National Vaccine Information Center (NVIC) and the Coalition for Vaccine Safety (CVS), have called on the Food and Drug Administration (FDA) to suspend the use of Merck's rotavirus vaccine, Rotateq, in view of the discovery that it contained traces of DNA from a pig virus. Merck reported its finding on May 6, making Rotateq the second US-licensed rotavirus vaccine found to contain DNA from porcine circovirus (PCV). The viral DNA was previously found in GlaxoSmithKline's Rotarix, and the FDA said on Mar 22 that the vaccine didn't appear to pose any risks but recommended that its use be suspended until scientists could study the findings. The FDA's vaccine advisory committee discussed the findings concerning both vaccines May 7 but did not call for suspending the use of Rotateq, with most members saying the benefits of the vaccine outweighed the risks. In a statement yesterday, the NVIC, a nonprofit group that advocates reform of the US vaccine safety system, called on the FDA to recommend suspending the use of Rotateq until Merck can guarantee it is free from PCV and other "adventitious agents." The CVS, an alliance of groups seeking to improve vaccine safety, echoed this call, noting that Hong Kong authorities ordered a halt to the use of Rotateq after the PCV finding. The FDA has said that neither subtype of PCV has been known to cause illness in humans, although PCV2, which was found in the Rotateq vaccine, can cause illness in pigs.
May 10 NVIC statement
May 10 CVS statement

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