Stvb-i, a Rice Gene Conferring Durable Resistance to Rice stripe virus, Protects Plant Growth From Heat Stress
FRONTIERS IN PLANT SCIENCE
Authors: Hayano-Saito, Yuriko; Hayashi, Keiko
Disease resistance is affected by temperature. A rice gene, Stvb-i, is known to have conferred sustained resistance to Rice stripe virus (RSV) despite global warming. Stvb-i protects plants from growth stunting caused by RSV. The underlying resistance mechanism is unclear. Here, Stvb-i showed stable RSV resistance for 20 years in laboratory experiments. This gene encodes a protein distinct from well-studied plant disease-resistance proteins. It has a domain homologous to the histidine kinase/heat-shock protein 90-like ATPase superfamily. Rice has three paralogous genes including Stvb-i. The genes are expressed mainly in meristematic tissues. In the initial period after viral inoculation, RSV multiplication enhanced Stvb-i, whereas Stvb-i suppressed RSV multiplication. Stvb-i silencing inhibited plant growth regardless of viral infection, and silencing of the other paralogous gene that located closely to Stvb-i caused morphological abnormalities. The results suggested that the Stvb-i and its paralogs are related to plant development; especially, Stvb-i supports meristem growth, resulting in plant growth stabilizing. Growth stunting in the Stvb-i-silenced plants was more severe under repetitive heat stress, suggesting that Stvb-i contributed to the attenuation of heat damage in plant development. The symptoms of RSV infection (chlorosis, wilting, stunting, fewer tillers, and defective panicles) were similar to those of heat damage, suggesting that RSV multiplication induces heat-like stress in meristematic cells. Our findings suggest that the mechanism of meristem growth protection conferred by Stvb-i allows plants to withstand both heat stress and RSV multiplication. The suppression of RSV multiplication by the Stvb-i function in meristems results in durable resistance.
Burden and Cost of Hospitalization for Respiratory Syncytial Virus in Young Children, Singapore
EMERGING INFECTIOUS DISEASES
Authors: Tam, Clarence C.; Yeo, Kee Thai; Tee, Nancy; Lin, Raymond; Mak, Tze Minn; Thoon, Koh Cheng; Jit, Mark; Yung, Chee Fu
Respiratory syncytial virus (RSV) is the most common cause of pediatric acute lower respiratory tract infection worldwide. Detailed data on the health and economic burden of RSV disease are lacking from tropical settings with year-round RSV transmission. We developed a statistical and economic model to estimate the annual incidence and healthcare cost of medically attended RSV disease among young children in Singapore, using Monte Carlo simulation to account for uncertainty in model parameters. RSV accounted for 708 hospitalizations in children <6 months of age (33.5/1,000 child-years) and 1,096 in children 6-29 months of age (13.2/1,000 child-years). The cost of hospitalization was SGD 5.7 million (US $4.3 million) at 2014 prices; patients bore 60% of the cost. RSV-associated disease burden in tropical settings in Asia is high and comparable to other settings. Further work incorporating efficacy data from ongoing vaccine trials will help to determine the potential cost-effectiveness of different vaccination strategies.