G1-like PB2 gene improves virus replication and competitive advantage of H9N2 virus.

H9N2 subtype avian influenza virus has dramatically evolved and undergone extensive reassortment since its emergence in early 1990s in China. The genotype S (G57), emerging in 2007 with the substitution of F98-like PB2 and M gene by G1-like ones, has become the overwhelming predominant genotype for the past 11 years since 2010. Here, we found that virus with G1-like PB2 were more efficient in protein expression and in infectious virus production than that with F98-like PB2 gene. By coinfected MDCK cells with the reassortant virus, more survival opportunity for viruses with G1-like PB2 than that of F/98-like was observed. Besides, in animal experiments, we found that the G1-like PB2 increases virus infectivity, replication, and virus shedding of H9N2 in chickens. Our results suggested that the substitution of G1-like PB2 play important role in promoting the fitness of genotype S H9N2 virus in China.

Ulcerative colitis alleviation of colon-specific delivered rhamnolipid/fullerene nanocomposites via dual modulation in oxidative stress and intestinal microbiome.

As a typical inflammatory bowel disease (IBD), ulcerative colitis (UC) has become prevalent worldwide in recent years. Though several materials have been proved to be effective in reducing intestinal oxidative stress to alleviate UC symptoms, dependence on high doses of exogenous drugs amplifies their safety risk for patients. To address this challenge, an oral therapy based on colon-targeting delivery of low-dose rhamnolipid (RL)/fullerene (C60) nanocomposites has been reported. With high biocompatibility being verified, RL/C60 largely mitigated the inflammation of mice with colitis shortly after its oral administration. Not only this, but also the intestinal microbiome of diseased mice was remarkably restored to the near-healthy level by our composites. Specifically, RL/C60 significantly promoted the colonization of intestinal probiotics and suppressed the biofilm formation of pathogenic bacteria, which is beneficial for reshaping the intestinal barrier. A close relationship of cytokines and oxidoreductases levels with gut flora further revealed that a change in RL/C60-induced intestinal microecology effectively improved the organismal immune system, which can be considered important for long-time recovery from UC.

The Packaging Regions of G1-Like PB2 Gene Contribute to Improving the Survival Advantage of Genotype S H9N2 Virus in China.

The genotype S (G57) H9N2 virus, which first emerged in 2007 with the substitution of the G1-like PB2 gene for F98-like ones, has become the predominant genotype in the past 10 years. However, whether this substitution plays a role in the fitness of genotype S H9N2 viruses remains unknown. Comparison of the PB2 genes of F98-like and G1-like viruses revealed a close homology in amino acid sequences but great variations at nucleotide levels. We then determined if the packaging region, a unique sequence in each segment utilized for the assembly of the vRNA into virions, played a role in the fitness of the S genotype. The chimeric H9N2 virus with PB2 segments of the G1-like packaging regions significantly increased viral protein levels and polymerase activity. Substituting the packaging regions in the two terminals of F98-like PB2 with the sequence of G1-like further improved its competitive advantage. Substitution of the packaging regions of F98-like PB2 with those of G1-like sequences increased the infectivity of the chimeric virus in the lungs and brains of chicken at 3 days post infection (dpi) and extended the lengths of virus shedding time. Our study suggests that the packaging regions of the G1-like PB2 gene contribute to improve the survival advantage of the genotype S H9N2 virus in China.