Methods: Each 24-well plate of Vero cells infected with all four DENV serotypes, singly, was subjected to treatments with various doses of AR-12. Following 48 h of incubation, inhibitory efficacies of AR-12 against the different DENV serotypes were evaluated by conducting a virus yield reduction assay whereby DENV RNA copy numbers present in the collected supernatant were quantified using qRT-PCR. The underlying mechanism(s) possibly involved in the compound's inhibitory activities were then investigated by performing molecular docking on several potential target human and DENV protein domains.
Results: The qRT-PCR data demonstrated that DENV-3 was most potently inhibited by AR-12, followed by DENV-1, DENV-2 and DENV-4. Our molecular docking findings suggested that AR-12 possibly exerted its inhibitory effects by interfering with the chaperone activities of heat shock proteins.
Conclusions: These results serve as vital information for the design of future studies involving in vitro mechanistic studies and animal models, aiming to decipher the potential of AR-12 as a potential therapeutic option for DENV infection.
AIM: The objective of this study was to determine the pathogenicity of Salmonella enterica subspecies enterica serovar Enteritidis (SE) phage type (PT) 1 in one-day-old specific pathogen-free (SPF) chicks.
METHODS: Seventy, one-day-old SPF chicks, were divided into SE group (30 chicks), mortality group (10 chicks), both orally inoculated (1.0 ml) with SE PT1 (1 × 108 colony-forming unit per 1.0 ml), and one control group (30 chicks). The chicks were sacrificed at 6 and 12 hours, and days 1, 2, 3, 5, 7, 10, 14, and 21 post-inoculation (pi). Samples were collected for bacterial isolation, histological examination, and ultrastructural examination.
RESULTS: Starting from day 2 pi, the body weight in the SE group significantly (p < 0.05) decreased. The SE isolation percentages from the liver, spleen, mid-intestinal content, cecal content, cecal tonsil, blood, and cloacal swab were 0.73, 0.77, 0.33, 0.33, 0.36, 0.40, and 0.30, respectively. The isolation percentage in the liver was significantly (p < 0.05) higher than the blood and cloacal swab. The villi heights and crypt depths in the SE group were significantly (p < 0.05) greater and smaller, respectively. Ultrastructurally, erosion and necrosis were observed in the microvilli of the cecal tonsil. The bacteria were engulfed by macrophages at the interepithelial clefts of the M-like M cells.
CONCLUSION: It was concluded that the inoculation of SE PT 1 in one-day-old chicks caused a systemic infection with diarrhea, a decrease in the body weight and villi height in the duodenum, jejunum, and ileum, and high bacterial loading in the liver with mild gross and histological lesions of organs, erosion, and necrosis of microvilli and low mortality. The bacteria entered the body system from the intestinal tract through the interepithelial clefts of the M-like M cells of the cecal tonsil.
RESULTS: A PCR of the gtrIC cluster showed that serotype 1c isolates from different geographical origins were genetically conserved. An analysis of sequences flanking the gtrIC cluster revealed remnants of a prophage genome, in particular integrase and tRNA(Pro) genes. Meanwhile, Southern blot analyses on serotype 1c, 1a and 1b strains indicated that all the tested serotype 1c strains may have had a common origin that has since remained distinct from the closely related 1a and 1b serotypes. The identification of prophage genes upstream of the gtrIC cluster is consistent with the notion of bacteriophage-mediated integration of the gtrIC cluster into a pre-existing serotype.
CONCLUSIONS: This is the first study to show that serotype 1c isolates from different geographical origins share an identical pattern of genetic arrangement, suggesting that serotype 1c strains may have originated from a single parental strain. Analysis of the sequence around the gtrIC cluster revealed a new site for the integration of the serotype converting phages of S. flexneri. Understanding the origin of new pathogenic serotypes and the molecular basis of serotype conversion in S. flexneri would provide information for developing cross-reactive Shigella vaccines.