The Rob protein, isolated on the basis of its ability to bind to the right arm of the Escherichia coli origin of chromosomal replication, is about 50% identical in amino acid sequence to SoxS and MarA, the direct regulators of the superoxide (soxRS) and multiple antibiotic resistance (mar) regulons, respectively. Having previously demonstrated that SoxS (as a MalE-SoxS fusion protein) and MarA are essentially identical in their abilities to activate in vitro transcription of genes of the sox-mar regulons, we investigated the properties of Rob as a transcriptional activator. We found that Rob (i) activates the transcription of zwf, fpr, fumC, micF, nfo, and sodA, (ii) requires a 21-bp soxbox-marbox-robbox sequence to activate zwf transcription, (iii) protects the soxbox/marbox/robbox from attack by DNase I, (iv) is ambidextrous, i.e., requires the C-terminal domain of the ␣ subunit of RNA polymerase for activation of zwf but not fumC or micF, (v) bends zwf and fumC DNA, and (vi) binds zwf and fumC DNA as a monomer. Since these transcription activation properties of Rob are virtually identical to those of MalE-SoxS and MarA, it appears as if the E. coli genome encodes three genes with the same functional capacity. However, in contrast to SoxS and MarA, whose syntheses are induced by specific environmental stimuli and elicit a clear defense response, Rob is expressed constitutively and its normal function is unknown.

Chronic hepatitis B virus (HBV) infection is a serious public health burden, and current therapies cannot achieve satisfactory cure rate. There are high unmet medical needs of novel therapeutic agents with differentiated mechanism of action (MOA) from the current standard of care. RG7834, a compound from the dihydroquinolizinone (DHQ) chemical series, is a first-in-class highly selective and orally bioavailable HBV inhibitor which can reduce both viral antigens and viral DNA with a novel mechanism of action. Here we report the discovery of RG7834 from a phenotypic screening and the structure–activity relationship (SAR) of the DHQ chemical series. RG7834 can selectively inhibit HBV but not other DNA or RNA viruses in a virus panel screening. Both in vitro and in vivo profiles of RG7834 are described herein, and the data support further development of this compound as a chronic HBV therapy.

Hepatitis B e antigen (HBeAg) is an important immunomodulator for promoting host immune tolerance during chronic hepatitis B (CHB) infection. In patients with CHB, HBeAg loss and seroconversion represent partial immune control of CHB infection and are regarded as valuable endpoints. However, the current approved treatments have only a limited efficacy in achieving HBeAg seroconversion in HBeAg‐positive patients. Hepatitis B virus (HBV) core protein has been recognized as an attractive antiviral target, and two classes of core protein allosteric modulator (CpAM) have been discovered: the phenylpropenamides (PPAs) and the heteroaryldihydropyrimidines (HAPs). However, their differentiation and potential therapeutic benefit beyond HBV DNA inhibition remain to be seen. Here, we show that in contrast to PPA series compound AT‐130, a HAP CpAM, HAP_R01, reduced HBeAg levels in multiple in vitro and in vivo HBV experimental models. Mechanistically, we found that HAP_R01 treatment caused the misassembly of capsids formed by purified HBeAg in vitro. In addition, HAP_R01 directly reduces HBeAg levels by inducing intracellular precore protein misassembly and aggregation. Using a HAP_R01‐resistant mutant, we found that HAP_R01‐mediated HBeAg and core protein reductions were mediated through the same mechanism. Furthermore, HAP_R01 treatment substantially reduced serum HBeAg levels in an HBV mouse model. Conclusion: Unlike PPA series compound AT‐130, HAP_R01 not only inhibits HBV DNA levels but also directly reduces HBeAg through induction of its misassembly. HAP_R01, as well as other similar CpAMs, has the potential to achieve higher anti‐HBeAg seroconversion rates than currently approved therapies for patients with CHB. Our findings also provide guidance for dose selection when designing clinical trials with molecules from HAP series.

Ziresovir (RO-0529, AK0529) is reported here for the first time as a promising respiratory syncytial virus (RSV) fusion (F) protein inhibitor that currently is in phase 2 clinical trials. This article describes the process of RO-0529 as a potent, selective, and orally bioavailable RSV F protein inhibitor and highlights the in vitro and in vivo anti-RSV activities and pharmacokinetics in animal species. RO-0529 demonstrates single-digit nM EC50 potency against laboratory strains, as well as clinical isolates of RSV in cellular assays, and more than one log viral load reduction in BALB/c mouse model of RSV viral infection. RO-0529 was proven to be a specific RSV F protein inhibitor by identification of drug resistant mutations of D486N, D489V, and D489Y in RSV F protein and the inhibition of RSV F protein-induced cell–cell fusion in cellular assays.

BackgroundGut microbiota is closely related to age. Studies from Europe and the U.S. identified featured microbiota in different age groups for the elderly. Asian studies mainly focused on people living in longevity areas. Featured microbiota for the elderly people of different age groups, especially in the centenarian in the general population, has not been well investigated in China.MethodWe conducted a comparative study by including 198 subjects of three age groups (65–70, 90–99, and 100+ years) in East China. Information regarding age, sex, height, weight, waist circumference, hip circumference, food preference, smoking status and alcohol consumption were collected by using a structured questionnaire. Fecal samples for each participant were collected as well. 16S rRNA gene sequencing were employed to analyze the gut microbiota composition. Logistic regression with LASSO feature selection was used to identify featured taxa in different age groups and to assess their potential interactions with other factors such as lifestyle.ResultThe gut microbiota of the 90–99 year and 100+ year age groups showed more diversity, robustness, and richness compared with the 65–70 year age group. PCoA analysis showed a clear separation between the 65–70 and 100+ year age groups. At the species level, Bacteroides fragilis, Parabacteroides merdae, Ruminococcus gnavus, Coprococcus and Clostridium perfringens increased, but Bacteroides vulgatus, Ruminococcus sp.5139BFAA and Clostridium sp.AT5 decreased in the 90–99 year age group. The age differences in gut microbiota were similar across the strata of smoking, alcohol consumption status and food preference.ConclusionOur study demonstrated age differences in many aspects of gut microbiota, such as overall diversity, microbiota structure, and relative abundance of key taxa. Moreover, the gut microbiota of centenarian was significantly different from those of younger age groups of the elderly.