Genomic characterization of endemic diarrheagenic Escherichia coli and Escherichia albertii from infants with diarrhea in Vietnam.

BACKGROUND: Diarrheagenic Escherichia coli (DEC) is a group of bacterial pathogens that causes life-threatening diarrhea in children in developing countries. However, there is limited information on the characteristics of DEC isolated from patients in these countries. A detailed genomic analysis of 61 DEC-like isolates from infants with diarrhea was performed to clarify and share the characteristics of DEC prevalent in Vietnam. PRINCIPAL FINDINGS: DEC was classified into 57 strains, including 33 enteroaggregative E. coli (EAEC) (54.1%), 20 enteropathogenic E. coli (EPEC) (32.8%), two enteroinvasive E. coli (EIEC) (3.3%), one enterotoxigenic E. coli (ETEC), and one ETEC/EIEC hybrid (1.6% each), and surprisingly into four Escherichia albertii strains (6.6%). Furthermore, several epidemic DEC clones showed an uncommon combination of pathotypes and serotypes, such as EAEC Og130:Hg27, EAEC OgGp9:Hg18, EAEC OgX13:H27, EPEC OgGp7:Hg16, and E. albertii EAOg1:HgUT. Genomic analysis also revealed the presence of various genes and mutations associated with antibiotic resistance in many isolates. Strains that demonstrate potential resistance to ciprofloxacin and ceftriaxone, drugs recommended for treating childhood diarrhea, accounted for 65.6% and 41%, respectively. SIGNIFICANCE: Our finding indicate that the routine use of these antibiotics has selected resistant DECs, resulting in a situation where these drugs do not provide in therapeutic effects for some patients. Bridging this gap requires continuous investigations and information sharing regarding the type and distribution of endemic DEC and E. albertii and their antibiotic resistance in different countries.

Genetic diversity of environmental Vibrio cholerae O1 strains isolated in Northern Vietnam.

Cholera epidemics have been recorded periodically in Vietnam during the seventh cholera pandemic. Since cholera is a water-borne disease, systematic monitoring of environmental waters for Vibrio cholerae presence is important for predicting and preventing cholera epidemics. We conducted monitoring, isolation, and genetic characterization of V. cholerae strains in Nam Dinh province of Northern Vietnam from Jul 2013 to Feb 2015. In this study, four V. cholerae O1 strains were detected and isolated from 110 analyzed water samples (3.6%); however, none of them carried the cholera toxin gene, ctxA, in their genomes. Whole genome sequencing and phylogenetic analysis revealed that the four O1 isolates were separated into two independent clusters, and one of them diverged from a common ancestor with pandemic strains. The analysis of pathogenicity islands (CTX prophage, VPI-I, VPI-II, VSP-I, and VSP-II) indicated that one strain (VNND_2014Jun_6SS) harbored an unknown prophage-like sequence with high homology to vibriophage KSF-1 phi and VCY phi, identified from Bangladesh and the USA, respectively, while the other three strains carried tcpA gene with a distinct sequence demonstrating a separate clonal lineage. These results suggest that the aquatic environment can harbor highly divergent V. cholera strains and serve as a reservoir for multiple V. cholerae virulence-associated genes which may be exchanged via mobile genetic elements. Therefore, continuous monitoring and genetic characterization of V. cholerae strains in the environment should contribute to the early detection of the sources of infection and prevention of cholera outbreaks as well as to understanding the natural ecology and evolution of V. cholerae.

Overexpression of the IbOr gene from sweet potato (Ipomea batatas 'Hoang Long') in maize increases total carotenoid and ß-carotene contents.

Nutritional quality of most maize varieties is very low due to the lack of lysine and tryptophan and extremely low provitamin A carotenoids including ß-carotene, α-carotene, and ß-cryptoxanthin. In this study, we report the successful overexpression of the IbOr gene in H145 and H95 inbred maize lines under the control of maize seed-specific promoter globulin 1 (Glo1) for the purpose of improving ß-carotene in maize. The results showed that the total carotenoid and ß-carotene content of all analyzed transgenic maize plants were significantly higher than those of wild-type lines. For H145-IbOr transgenic maize, in the best line (H145-IbOr.10), the total carotenoid and ß-carotene contents were increased up to 10.36- and 15.11-fold, respectively, compared to the wild type (H145-WT). In the case of H95-IbOr transgenic plants, 5.58-fold increase in total carotenoid and 7.63-fold increase in ß-carotene were achieved in the H95-IbOr.6 line compared to nontransgenic plants (H95-WT). In all the transgenic plants derived from the wild-type maize line with less carotenoid content (H145-WT), the content of both total carotenoid and ß-carotene was higher than in transgenic plants derived from the wild-type maize line having more carotenoid content (H95-WT). Our research is the first in successful overexpression of IbOr gene in maize.