A case report on rare hepatitis B viral subgenotype from a tertiary care center in Chennai

Hepatitis B virus (HBV) is a global health concern with 350 million chronic carriers. With respect to HBV India is classified as an intermediate endemic country. The disease progression may be due to many viral factors including HBV viral load, HBe antigen, genotype, mutations in polymerase gene, and X gene. In this case, the individual was a treatment naïve chronic HBV carrier. The reverse transcriptase gene and X gene were sequenced and mutations were analyzed. The individual had D3 subgenotype. rt80I was identified in reverse transcriptase and A102V in HBx protein. Identification of genotype and mutations in reverse transcriptase/X gene may help in predicting and improving the clinical outcomes.

Adenovirus Vectors Expressing Eight Multiplex Guide RNAs of CRISPR/Cas9 Efficiently Disrupted Diverse Hepatitis B Virus Gene Derived from Heterogeneous Patient

Hepatitis B virus (HBV) chronically infects more than 240 million people worldwide, causing chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Genome editing using CRISPR/Cas9 could provide new therapies because it can directly disrupt HBV genomes. However, because HBV genome sequences are highly diverse, the identical target sequence of guide RNA (gRNA), 20 nucleotides in length, is not necessarily present intact in the target HBV DNA in heterogeneous patients. Consequently, possible genome-editing drugs would be effective only for limited numbers of patients. Here, we show that an adenovirus vector (AdV) bearing eight multiplex gRNA expression units could be constructed in one step and amplified to a level sufficient for in vivo study with lack of deletion. Using this AdV, HBV X gene integrated in HepG2 cell chromosome derived from a heterogeneous patient was cleaved at multiple sites and disrupted. Indeed, four targets out of eight could not be cleaved due to sequence mismatches, but the remaining four targets were cleaved, producing irreversible deletions. Accordingly, the diverse X gene was disrupted at more than 90% efficiency. AdV containing eight multiplex gRNA units not only offers multiple knockouts of genes, but could also solve the problems of heterogeneous targets and escape mutants in genome-editing therapy.

Genetic Characterization of the Tetracycline-Resistance Gene tet(X) Carried by Two Epilithonimonas Strains Isolated from Farmed Diseased Rainbow Trout, Oncorhynchus mykiss in Chile

The main objective of this study was to characterize the tet(X) genes, which encode a monooxygenase that catalyzes the degradation of tetracycline antibiotics, carried by the resistant strains FP105 and FP233-J200, using whole-genome sequencing analysis. The isolates were recovered from fin lesion and kidney samples of diseased rainbow trout Oncorhynchus mykiss, during two Flavobacteriosis outbreaks occurring in freshwater farms located in Southern Chile. The strains were identified as Epilithonimonas spp. by using biochemical tests and by genome comparison analysis using the PATRIC bioinformatics platform and exhibited a minimum inhibitory concentration (MIC) of oxytetracycline of 128 µg/mL. The tet(X) genes were located on small contigs of the FP105 and FP233-J200 genomes. The sequences obtained for the tet(X) genes and their genetic environment were compared with the genomes available in the GenBank database of strains of the Chryseobacterium clade belonging to the Flavobacterium family, isolated from fish and carrying the tet(X) gene. The Tet(X) proteins synthesized by the Chilean Epilithonimonas strains showed a high amino acid similarity (range from 84% to 100%), with the available sequences found in strains belonging to the genus Chryseobacterium and Flavobacterium isolated from fish. An identical neighborhood of tet(X) genes from both Chilean strains was observed. The genetic environment of tet(X) observed in the two strains of Epilithonimonas studied was characterized by the upstream location of a sequence encoding a hypothetical protein and a downstream located alpha/beta hydrolase-encoding gene, similar to the observed in some of the tet(X) genes carried by Chryseobacterium and Flavobacterium strains isolated from fish, but the produced proteins exhibited a low amino acid identity (25–27%) when compared to these synthesized by the Chilean strains. This study reports for the first time the carriage of the tet(X) gene by the Epilithonimonas genus and their detection in fish pathogenic bacteria isolated from farmed salmonids in Chile, thus limiting the use of therapies based on oxytetracycline, the antimicrobial most widely used in Chilean freshwater salmonid farming. This results suggest that pathogenic strains of the Chryseobacterium clade occurring in Chilean salmonid farms may serve as important reservoirs of tet(X) genes.

Biochar influence on antibiotic resistance genes abundance in the manure derived composts

Composting chicken droppings with the addition of biochar and an antibiotic led to a decrease in the concentration of oxytetracycline on the 28th day and an increase in the amount of the resistant tet(X) gene.

Impact of parental origin of X-chromosome on clinical and biochemical profile in Turner syndrome

ObjectivesTo evaluate if the parental origin of X-chromosome has an impact on the phenotype and biochemical profile in Turner syndrome (TS). Result of the previous studies have been equivocal and could be attributable to the multicentric study design with different experts examining heterogeneous TS population of various ethnic background.MethodsA cross-sectional single center study from Northern India. Fifty nine diagnosed subjects of TS and their parents participated in the study. Parental origin of intact X-chromosome was determined using 12 highly polymorphic short tandem repeats (STR) on X-chromosome. For the evaluation of parent-of-origin effects, typical phenotypic traits including congenital malformations, anthropometry, body composition by dual energy X-ray absorptiometry (DXA) and biochemical profile were compared. Clinical stigmata of TS in all subjects were examined by a single expert.ResultsThe intact X-chromosome was of maternal origin (Xm) in 49.1% subjects while 50.9% had paternal origin (Xp). Skeletal anomalies were more common in Xm group, out of which prevalence of short neck and short fourth metatarsal reached statistical significance (p=0.04 and 0.01 respectively). A strong correlation was observed between subject’s baseline height standard deviation score (Ht SDS) and paternal height (r=0.593, p<0.001), maternal height (r=0.564, p<0.001) and mid-parental height (MPH) (r=0.372, p=0.047) in Xp group. This effect was not seen in Xm subjects whose baseline Ht SDS showed no significant correlation with maternal height, paternal height or MPH. No differences were detected between the groups with regard to biochemical profile or body composition.ConclusionsWe speculate that the differences in skeletal anomalies and height correlations between Xm and Xp groups could be due to the modifying effect of epigenetic signature on short stature homeobox (SHOX) gene of Xm. SHOX gene is not modified on Xp thereby explaining the paucity of skeletal changes and height correlations in Xp subjects.