Precision Tracing of Household Dengue Spread Using Inter- and Intra-Host Viral Variation Data, Kamphaeng Phet, Thailand.

Dengue control approaches are best informed by granular spatial epidemiology of these viruses, yet reconstruction of inter- and intra-household transmissions is limited when analyzing case count, serologic, or genomic consensus sequence data. To determine viral spread on a finer spatial scale, we extended phylogenomic discrete trait analyses to reconstructions of house-to-house transmissions within a prospective cluster study in Kamphaeng Phet, Thailand. For additional resolution and transmission confirmation, we mapped dengue intra-host single nucleotide variants on the taxa of these time-scaled phylogenies. This approach confirmed 19 household transmissions and revealed that dengue disperses an average of 70 m per day between households in these communities. We describe an evolutionary biology framework for the resolution of dengue transmissions that cannot be differentiated based on epidemiologic and consensus genome data alone. This framework can be used as a public health tool to inform control approaches and enable precise tracing of dengue transmissions.

Chemical composition and enzymatic degradability of xylem and nonxylem walls isolated from alfalfa internodes.

During plant maturation, degradability of alfalfa (Medicago sativa L.) stems declines due to accumulation of highly lignified xylary tissue. Xylem and nonxylem tissues dissected from lower alfalfa internodes were analyzed for cell wall constituents and degradability. Cell walls comprised 740 mg g(-1) of xylem and 533 mg g(-1) of nonxylem tissues. Xylem tissues contributed about 60% of the cell wall mass in internodes. Xylem walls contained 28% lignin, 4% pectin, 29% hemicellulose, and 39% cellulose as compared to 15% lignin, 25% pectin, 30% hemicellulose, and 30% cellulose in nonxylem walls. Fungal enzymes hydrolyzed 22 and 73% of the structural carbohydrates in xylem and nonxylem walls, respectively. In both cell wall fractions, the release of xylose was 56-90% lower than that of other sugars, indicating that lignin preferentially restricted xylan degradation in secondary walls and xyloglucan degradation in primary walls. Elucidation of lignin-xylose interactions may reveal strategies for improving fiber degradability of alfalfa.