BackgroundThe dominant viral etiologies responsible for acute respiratory infections (ARIs) are poorly understood, particularly among hospitalized children in resource-limited tropical countries where morbidity and mortality caused by ARIs are highest. Improved etiological insight is needed to improve clinical management and prevention.ObjectivesWe conducted a three-year prospective descriptive study of severe respiratory illness among children from 2 months to 13 years of age within the largest referral hospital for infectious diseases in southern Vietnam.MethodsMolecular detection for 15 viral species and subtypes was performed on three types of respiratory specimens (nose, throat swabs and nasopharyngeal aspirates) using a multiplex RT-PCR kit (Seeplex™ RV detection, Seegene) and additional monoplex real-time RT-PCRs.ResultsA total of 309 children were enrolled from November 2004 to January 2008. Viruses were identified in 72% (222/309) of cases, including respiratory syncytial virus (24%), influenza virus A and B (17%), human bocavirus (16%), enterovirus (9%), human coronavirus (8%), human metapneumovirus (7%), parainfluenza virus 1–3 (6%), adenovirus (5%), and human rhinovirus A (4%). Co-infections with multiple viruses were detected in 20% (62/309) of patients. When combined, diagnostic yields in nose and throat swabs were similar to nasopharyngeal aspirates.ConclusionSimilar to other parts in the world, RSV and influenza were the predominant viral pathogens detected in Vietnamese hospitalized children. Combined nasal and throat swabs are the specimens of choice for sensitive molecular detection of a broad panel of viral agents. Further research is required to better understand the clinical significance of single versus multiple viral coinfections and to address the role of bacterial (co-)infections involved in severe respiratory illness.

Highlights Multiple serotypes of enterovirus A cause hand, foot and mouth disease in southern Vietnam. Clinical characteristics differed slightly between the different pathogen groups. CV-A6 and CV-A10 emerged in Vietnam in 2013–2015. An unexpected dominance of EV-A71 was found among both inpatients and outpatients.

Background: Hepatitis B virus (HBV) infection is a major public health problem globally. HBV genotypes and subgenotypes influence disease transmission, progression, and treatment outcome. A study was conducted among treatment naive chronic HBV patients in southern Vietnam to determine the genotypes and subgenotypes of HBV. Methods: A prospective, exploratory study was conducted among treatment naïve chronic HBV patients attending at the Hospital for Tropical Diseases, in Ho Chi Minh City, Vietnam during 2012, 2014 and 2016. HBV DNA positive samples (systematically selected 2% of all treatment naïve chronic patients during 2012 and 2014, and 8% of all treatment naïve chronic patients during 2016) were subjected to whole genome sequencing (WGS) either by Sanger or Illumina sequencing. WGS was used to define genotype, sub-genotype, recombination, and the prevalence of drug resistance and virulence-associated mutations. Results: One hundred thirty five treatment naïve chronic HBV patients including 18 from 2012, 24 from 2014, and 93 from 2016 were enrolled. Of 135 sequenced viruses, 72.6% and 27.4% were genotypes B and C respectively. Among genotype B isolates, 87.8% and 12.2% were subgenotypes B4 and B2 respectively. A G1896A mutation in the precore gene was present in 30.6% of genotype B isolates. The genotype C isolates were all subgenotype C1 and 78.4% (29/37) of them had at least one basal core promoter (BCP) mutation. A1762T and G1764 T mutations and a double mutation (A1762T and G1764 T) in the BCP region were significantly more frequent in genotype C1 isolates (p < 0.001). Conclusion: HBV genotype B including subgenotype B4 is predominant in southern Vietnam. However, one fourth of the chronic HBV infections were caused by subgenotype C1.

In an earlier study, biocatalytic carbon oxyfunctionalization with water serving as oxygen donor, e.g., the bioconversion of quinaldine to 4-hydroxyquinaldine, was successfully achieved using resting cells of recombinant Pseudomonas putida, containing the molybdenum-enzyme quinaldine 4-oxidase, in a two-liquid phase (2LP) system (Ütkür et al. J Ind Microbiol Biotechnol 38:1067-1077, 2011). In the study reported here, key parameters determining process performance were investigated and an efficient and easy method for product recovery was established. The performance of the whole-cell biocatalyst was shown not to be limited by the availability of the inducer benzoate (also serving as growth substrate) during the growth of recombinant P. putida cells. Furthermore, catalyst performance during 2LP biotransformations was not limited by the availability of glucose, the energy source to maintain metabolic activity in resting cells, and molecular oxygen, a possible final electron acceptor during quinaldine oxidation. The product and the organic solvent (1-dodecanol) were identified as the most critical factors affecting biocatalyst performance, to a large extent on the enzyme level (inhibition), whereas substrate effects were negligible. However, none of the 13 alternative solvents tested surpassed 1-dodecanol in terms of toxicity, substrate/product solubility, and partitioning. The use of supercritical carbon dioxide for phase separation and an easy and efficient liquid-liquid extraction step enabled 4-hydroxyquinaldine to be isolated at a purity of >99.9% with recoveries of 57 and 84%, respectively. This study constitutes the first proof of concept on an integrated process for the oxyfunctionalization of toxic substrates with a water-incorporating hydroxylase.

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