| 1. |
- Sang, Shaowei, et al.
(author)
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The epidemiological characteristics of dengue in high-risk areas of China, 2013-2016
- 2021
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In: PLoS Neglected Tropical Diseases. - : Public Library of Science. - 1935-2727 .- 1935-2735. ; 15:12
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Journal article (peer-reviewed)abstract
- Introduction: Dengue has become a more serious human health concern in China, with increased incidence and expanded outbreak regions. The knowledge of the cross-sectional and longitudinal epidemiological characteristics and the evolutionary dynamics of dengue in high-risk areas of China is limited.Methods: Records of dengue cases from 2013 to 2016 were obtained from the China Notifiable Disease Surveillance System. Full envelope gene sequences of dengue viruses detected from the high-risk areas of China were collected. Maximum Likelihood tree and haplotype network analyses were conducted to explore the phylogenetic relationship of viruses from high-risk areas of China.Results: A total of 56,520 cases was reported in China from 2013 to 2016. During this time, Yunnan, Guangdong and Fujian provinces were the high-risk areas. Imported cases occurred almost year-round, and were mainly introduced from Southeast Asia. The first indigenous case usually occurred in June to August, and the last one occurred before December in Yunnan and Fujian provinces but in December in Guangdong Province. Seven genotypes of DENV 1-3 were detected in the high-risk areas, with DENV 1-I the main genotype and DENV 2-Cosmopolitan the secondary one. The Maximum Likelihood trees show that almost all the indigenous viruses separated into different clusters. DENV 1-I viruses were found to be clustered in Guangdong Province, but not in Fujian and Yunnan, from 2013 to 2015. The ancestors of the Guangdong viruses in the cluster in 2013 and 2014 were most closely related to strains from Thailand or Singapore, and the Guangdong virus in 2015 was most closely related to the Guangdong virus of 2014. Based on closest phylogenetic relationships, viruses from Myanmar possibly initiated further indigenous cases in Yunnan, those from Indonesia in Fujian, while viruses from Thailand, Malaysia, Singapore and Indonesia were predominant in Guangdong Province.Conclusions: Dengue is still an imported disease in China, although some genotypes continued to circulate in successive years. Viral phylogenies based on the envelope gene suggested periodic introductions of dengue strains into China, primarily from Southeast Asia, with occasional sustained, multi-year transmission in some regions of China.Author summary: Dengue is the most prevalent and rapidly spreading mosquito-borne viral disease globally. Because of the multiple introductions, dengue outbreaks occurred in epidemic seasons in Southern China, supported by suitable weather conditions. Surveillance data from 2013 to 2016 in China showed that Guangdong, Yunnan and Fujian provinces were the high-risk areas, with dengue outbreaks occurring almost every year. However, knowledge has been lacking of the epidemiological characteristics and the evolution pattern of dengue virus in these high-risk areas. This study shows a variety of epidemiological characteristics and sources of imported cases among the high-risk areas in China, with likely origins primarily from countries in Southeast Asia. Seven genotypes of the DENV 1-3 variety co-circulated with DENV1-I, the main genotype, and DENV 2-Cosmopolitan, the secondary. Genetic relationships among viral strains suggest that the indigenous viruses in the high-risk areas arose from imported viruses and sometimes persisted between years into the next epidemic season, especially in Guangdong Province. Population movement has played a vital role in dengue epidemics in China. This information may be useful in dengue control, especially during epidemic seasons and in the development of an early warning system within the region, in collaboration with bordering countries.
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| 2. |
- Sang, Shaowei, et al.
(author)
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The evolutionary dynamics of DENV 4 genotype I over a 60-year period
- 2019
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In: PLoS Neglected Tropical Diseases. - : Public Library of Science. - 1935-2727 .- 1935-2735. ; 13:7
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Journal article (peer-reviewed)abstract
- Dengue virus serotype 4 (DENV 4) has had a relatively low prevalence worldwide for decades; however, likely due to data paucity, no study has investigated the epidemiology and evolutionary dynamics of DENV 4 genotype I (DENV 4-I). This study aims to understand the diversity, epidemiology and dynamics of DENV 4-I. We collected 404 full length DENV4-1 envelope (E) gene sequences from 14 countries using two sources: Yunnan Province in China (15 strains during 2013-2016) and GenBank (489 strains up to 2018-01-11). Conducting phylogenetic and phylogeographical analyses, we estimated the virus spread, population dynamics, and selection pressures using different statistical analysis methods (substitution saturation, likelihood mapping, Bayesian coalescent inference, and maximum likelihood estimation). Our results show that during the last 60 years (1956-2016), DENV 4-I was present in mainland and maritime Southeast Asia, the Indian subcontinent, the southern provinces of China, parts of Brazil and Australia. The recent spread of DENV 4-I likely originated in the Philippines and later spread to Thailand. From Thailand, it spread to adjacent countries and eventually the Indian subcontinent. Apparently diverging around years 1957, 1963, 1976 and 1990, the different Clades (Clade I-V) were defined. The mean overall evolution rate of DENV 4-I was 9.74 (95% HPD: 8.68-10.82) x 10(-4) nucleotide substitutions/site/year. The most recent common ancestor for DENV 4-I traces back to 1956. While the demographic history of DENV 4-I fluctuated, peaks appeared around 1982 and 2006. While purifying selection dominated the majority of E-gene evolution of DENV 4-I, positive selection characterized Clade III (Vietnam). DENV 4-I evolved in situ in Southeast Asia and the Indian subcontinent. Thailand and Indian acted as the main and secondary virus distribution hubs globally and regionally. Our phylogenetic analysis highlights the need for strengthened regional cooperation on surveillance and sharing of sample sequences to improve global dengue control and cross-border transmission prevention efforts. Author summary Dengue virus (DENV) can be classified into four serotypes, DENV 1, 2, 3 and 4. Although DENV 4 is the first dengue serotype to diverge in phylogenetic analyses of the genus Flavivirus, this serotype occurs at a low prevalence worldwide and spreads the least rapidly. Similar to other serotypes, DENV 4 can also cause severe dengue (SD) disease manifestations, such as dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). To date, no study has investigated the epidemiology and dynamics of DENV 4 genotype I comprehensively. In this study, we seek to address this gap. Our study shows that the distribution of DENV 4-I is mainly restricted to Southeast Asia and the Indian subcontinent. The most recent spread of DENV 4-I likely originated from Southeast Asia-initially circulating in the Philippines, then Thailand and later on the Indian subcontinent. Viruses evolved in situ in Southeast Asia and the Indian subcontinent, respectively. Although DENV 4-I occasionally spread elsewhere, this genotype did not become widely established. The overall evolution rate of DENV 4-I was comparable with that of DENV 2-4. The nucleotide sequences indicates that the demographic history of DENV 4-I fluctuated with peaks apparent during parts of the 1980s and 2000s. Although a weak positive selection existed in Clade III -predominately in Vietnam, purifying selection dominated the E-gene evolution of DENV 4-I.
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| 3. |
- Liu, Qiyong P., et al.
(author)
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Bacterial glycosidases for the production of universal red blood cells
- 2007
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In: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1546-1696 .- 1087-0156. ; 25:4, s. 454-464
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Journal article (peer-reviewed)abstract
- Enzymatic removal of blood group ABO antigens to develop universal red blood cells ( RBCs) was a pioneering vision originally proposed more than 25 years ago. Although the feasibility of this approach was demonstrated in clinical trials for group B RBCs, a major obstacle in translating this technology to clinical practice has been the lack of efficient glycosidase enzymes. Here we report two bacterial glycosidase gene families that provide enzymes capable of efficient removal of A and B antigens at neutral pH with low consumption of recombinant enzymes. The crystal structure of a member of the alpha-N-acetylgalactosaminidase family reveals an unusual catalytic mechanism involving NAD(+). The enzymatic conversion processes we describe hold promise for achieving the goal of producing universal RBCs, which would improve the blood supply while enhancing the safety of clinical transfusions.
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| 4. |
- Liu, Qiyong P, et al.
(author)
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Identification of a GH110 subfamily of alpha 1,3-galactosidases - Novel enzymes for removal of the alpha 3Gal xenotransplantation antigen
- 2008
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In: Journal of Biological Chemistry. - 1083-351X. ; 283:13, s. 8545-8554
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Journal article (peer-reviewed)abstract
- In search of alpha-galactosidases with improved kinetic properties for removal of the immunodominant alpha 1,3-linked galactose residues of blood group B antigens, we recently identified a novel prokaryotic family of alpha-galactosidases (CAZy GH110) with highly restricted substrate specificity and neutral pH optimum (Liu, Q. P., Sulzenbacher, G., Yuan, H., Bennett, E. P., Pietz, G., Saunders, K., Spence, J., Nudelman, E., Levery, S. B., White, T., Neveu, J. M., Lane, W. S., Bourne, Y., Olsson, M. L., Henrissat, B., and Clausen, H. (2007) Nat. Biotechnol. 25, 454-464). One member of this family from Bacteroides fragilis had exquisite substrate specificity for the branched blood group B structure Gal alpha 1-3(Fuc alpha 1-2) Gal, whereas linear oligosaccharides terminated by alpha 1,3-linked galactose such as the immunodominant xenotransplantation epitope Gal alpha 1-3Gal beta 1-4GlcNAc did not serve as substrates. Here we demonstrate the existence of two distinct subfamilies of GH110 in B. fragilis and thetaiotaomicron strains. Members of one subfamily have exclusive specificity for the branched blood group B structures, whereas members of a newly identified subfamily represent linkage specific alpha 1,3-galactosidases that act equally well on both branched blood group B and linear alpha 1,3Gal structures. We determined by one-dimensional H-1 NMR spectroscopy that GH110 enzymes function with an inverting mechanism, which is in striking contrast to all other known alpha-galactosidases that use a retaining mechanism. The novel GH110 subfamily offers enzymes with highly improved performance in enzymatic removal of the immunodominant alpha 3Gal xenotransplantation epitope.
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