In Science this week, a group of Chinese researchers report on the use of reverse genetics to gain insights into how H5N1 avian flu can spread to, and between, mammals. In the past, avian flu viruses have crossed species barriers by reassorting with mammal-infective viruses in intermediate livestock hosts. The team created 127 reassortant viruses between a duck isolate of H5N1 and a highly transmissible human H1N1 virus. They tested the viruses' virulence in mice and transmissibility to guinea pigs, which both have avian and mammalian types of airway receptors, and found that some reassortments were transmissible by airborne droplet, although they were not lethal. The findings indicate that avian H5N1 subtype viruses have the "potential to acquire mammalian transmissibility by reassortment," the researchers write.
Also in Science, researchers from the University of Oxford publish data giving clues about how one type of long, non-coding RNA, or lncRNA, is regulated. The investigators found that an lncRNA they had identified in Arabidopsis is regulated through its interaction with an R-loop, a triple-stranded nucleic acid structure formed by an RNA/DNA hybrid and a displaced single-stranded DNA. Based on the findings, the team concludes that differential stabilization of R-loops could be a "general mechanism influencing gene expression in many organisms."