Two Plant Bacteria, S. meliloti and Ca. Liberibacter asiaticus, Share Functional znuABC Homologues That Encode for a High Affinity Zinc Uptake System

The Znu system, encoded for by znuABC, can be found in multiple genera of bacteria and has been shown to be responsible for the import of zinc under low zinc conditions. Although this high-affinity uptake system is known to be important for both growth and/or pathogenesis in bacteria, it has not been functionally characterized in a plant-associated bacterium. A single homologue of this system has been identified in the plant endosymbiont, Sinorhizobium meliloti, while two homologous systems were found in the destructive citrus pathogen, Candidatus Liberibacter asiaticus. To understand the role of these protein homologues, a complementation assay was devised allowing the individual genes that comprise the system to be assayed independently for their ability to reinstate a partially-inactivated Znu system. Results from the assays have demonstrated that although all of the genes from S. meliloti were able to restore activity, only one of the two Ca. Liberibacter asiaticus encoded gene clusters contained genes that were able to functionally complement the system. Additional analysis of the gene clusters reveals that distinct modes of regulation may also exist between the Ca. Liberibacter asiaticus and S. meliloti import systems despite the intracellular-plant niche common to both of these bacteria

Non-invasive assessment of changes in liver fibrosis via liver stiffness measurement in patients with chronic hepatitis B: impact of antiviral treatment on fibrosis regression

BACKGROUND: Liver stiffness measurement (LSM) can assess liver fibrosis in patients with chronic hepatitis B (CHB). We evaluated whether LSM can be used to assess changes in liver fibrosis during antiviral treatment using nucleos(t)ide analogs in patients with CHB. METHODS: We recruited 41 patients with CHB who had significant liver fibrosis, normal or slightly elevated serum alanine aminotransferase (ALT) levels (≤2 × upper limit of normal), and detectable serum hepatitis B virus DNA before antiviral treatment. Patients in Group 1 (n = 23) and Group 2 (n = 18) underwent follow-up LSM after antiviral treatment for 1 and 2 years, respectively. RESULTS: The mean age, ALT and LSM value of all patients (34 men and 7 women) before antiviral treatment were 46.6 ± 9.5 years, 40.6 ± 17.2 IU/L and 12.9 ± 8.6 kPa, respectively. Hepatitis B e antigen (HBeAg) was detected in 31 patients (75.6%). Fibrosis stage was F2 in 12 (29.3%), F3 in 6 (14.6%) and F4 in 23 (56.1%) patients. After antiviral treatment, LSM values and DNA positivity decreased significantly as compared to baseline (P = 0.018 and P < 0.001 in Group 1; P = 0.017 and P < 0.001 in Group 2, respectively), whereas ALT levels were unchanged (P = 0.063 in Group 1; P = 0.082 in Group 2). CONCLUSIONS: Our preliminary data suggest that LSM can be used to assess liver fibrosis regression after antiviral treatment using nucleos(t)ide analogs in patients with CHB.ope