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Rotavirus (RV) is the most common cause of severe childhood diarrhea worldwide. Since 2006, the WHO has approved the use of two vaccines against Rotavirus (RotaTeq and Rotarix), which has contributed to a significant reduction in morbidity and mortality from this disease in children under 5 years of age. Beside of that, the presence of vaccines could also cause selective pressure among circulating RV strains. Diarrhea samples were a part of the study of the project “Evaluation of rotavirus vaccine effectiveness in Vietnam” and some diarrhea samples were randomly selected from 2010 - 2015 and were stored in our laboratory. Rotavirus antigen in diarrhea samples was detected using the Premier Rotaclone kit. G and P genotypes were determined by RT-PCR using type specific primers. The nucleotide sequencewas determined by next generation sequencing and phylogenetic analysis was performed by the neighbor-joining method. 375/1715 (21.9%) samples detected G3 strain include equine-like G3 (eG3) and human G3 (hG3). The prevalence of G3 strains decreased from 2016 to 2021. All eleven gene segments were typed among 34 samples and substantial diversity among the circulating strains was observed. The circulating G3 strains were also phylogenetically diverse and related to strains from several different countries, different origins such as human (20 samples), pig (1 sample), cat (3 samples) and equine (10 samples). Comparing with the vaccine strains, the antigenic epitopes present on VP7 ofG3 in Vietnam differed considerably, especially the K238N. With the genetic characteristics of the G3 strain, it could contribute to the vaccine effectiveness in Vietnam.

Rotavirus (RV), Norovirus (NV), Sapovirus (SaV) and Astrovirus (Ast) are the leading causes of gastroenteritis and mortality in children worldwide. RV vaccines help to reduce the burden of diarrhea while the importance of other viruses is increasing. Therefore, we conducted a cross-sectional descriptive study to determine prevalence of these viruses in hospitalized children under 5 years old in Nam Dinh province with approximately 80% of RV vaccine coverage. We randomly selected 579 (25%) among diarrheal samples collected in 4 district hospitals from Dec. 2017 to Nov. 2019. An ELISA kit was employed to detect RV and the multiplex real-time RT-PCR with specific primers to detect NV, SaV and Ast. These viruses were found among 64.3% of hospitalized children, of which NV and RV were present in 28.5% and 21.4%, respectively, while SaV and Ast were detected in 3.3% and 2.6%, respectively. Co-infections accounted for 8.5%, mainly among RV and 3 other viruses. There is a significant difference in RV and NV positive rates between vaccinated and unvaccinated groups (p < 0.001 and p = 0.008, respectively). This study contributed to the understanding of the potential impact of rotavirus vaccine on other diarheal pathogens and emphasize the need for further epidemiological studies when the nationwide RV vaccination in Vietnam is implementing.

We conducted nucleotide and amino acid sequence alignment and phylogenetic analysis of porcine circovirus ORF2 (Cap protein) from 17 PCV2-positive clinical samples from nine different northern Vietnamese provinces (Mar 2018-Nov 2020), four local vaccines, and 77 reference strains. We identified one PCV2a (1/17 = 5.9%), five PCV2b (5/17 = 29.9%), and 11 PCV2d (11/17 = 64.7%) isolates, while only PCV2d was detected in 2020. Timeline analysis indicated an increasing predominance of PCV2d nationwide (2018-2020). With strong nodal support (98% for nucleotides and 74% for amino acids), the phylogenetic tree topology revealed a distinct PCV2h clade including recombinant/intermediate strains and local vaccines. The Cap protein sequences from 11 PCV2d field strains had the 2d-genotype-typical motif

Vietnam is undergoing a forest transition stage with an overall increase in forest cover since the 1990s; however, deforestation and forest degradation of natural forests still occur in several areas, especially in the Central region of the country. In order to better manage and protect natural forests, predicting deforestation probability and understanding its associated factors are necessary. In the present study, we focused on the two mountainous districts (Nam Dong and A Luoi) in Central Vietnam as a case study. We used Landsat satellite images for identifying changes of natural forests over the period of 1989–2020. The logistic regression model showed a good performance in prediction of deforestation (testing AUC = 0.874) in the study area. Our data showed that deforestation probability of natural forests in the study area in the period of 1989–2020 could be influenced by 11 socio-economic and topographical factors. In particular, forest areas with low elevation, gentle slopes, nearby rivers and residential areas have a high deforestation probability. Production forest, forest areas not included in payment for environmental service (PFES) schemes, forest with no ownership and forest areas managed by private owners may also have a high deforestation probability. The total area of very high level of deforestation probability in A Luoi (8,988 ha) and Nam Dong (5,304 ha) districts occupied about 11.4% of natural forests in the study area. Our study suggests that protection activities should be focused on high deforestation probability-prone forest areas.

Porcine epidemic diarrhea (PED) is known as a serious disease infecting all ages of pigs, with a mortality rate of up to 100% in piglets. The spike protein (S) of porcine epidemic diarrhea virus (PEDV), in particular, the S1-CTD (C-terminal domain), which contains the conservative neutralizing epitopes CO­26K equivalent (COE) (aa 499–638), exhibits a high degree of genetic and antigenic diversity. We obtained 26 Vietnamese PEDV-S1-CTD sequences (630 bp) from samples collected from seven northern provinces from June 2018 to January 2019 and analyzed them with 35 sequences from previous studies, representing the G1a and 1b, G2a and 2b, and recombinant (G1c) genotypes, and PEDV vaccines. The majority (73.1%) of strains (19/26) belonged to the subgroup G2b. With strong nodal support (98%), seven strains were clustered into an independent, “distinct subgenogroup” (named dis-subG), separate from both G1a and G1b and other G2a, 2b, and 1c (recombinant strains). When compared with the prototype CV777 strain (AF353511), sequence analysis revealed distinct changes of 513T>S, 520G>D, 527V>(I/L/M), 591L>F, 669A>(S/P), 691V>I in the COE and S1D regions of the S1-CTD protein that were only identified in these Vietnamese strains. This cluster is a new antigenic variant subgroup and further studies are required to investigate its anigenicity. The results in this study revealed the continuous evolution in the S1 region of the Vietnamese PEDV strains, which emphasizes the need for frequent updates of the vaccines for effective protection.

International audience; Abstract Two strains, designated as Marseille-P2918 T and Marseille-P3646 T , were isolated from a 14-week-old Senegalese girl using culturomics: Urmitella timonensis strain Marseille-P2918 T (= CSUR P2918, = DSM 103634) and Marasmitruncus massiliensis strain Marseille-P3646 T (= CSUR P3646, = CCUG72353). Both strains were rod-shaped, anaerobic, spore forming motile bacteria. The 16S rRNA gene sequences of strains Marseille-P2918 T (LT598554) and Marseille-P3646 T (LT725660) shared 93.25% and 94.34% identity with Tissierella praeacuta ATCC 25539 T and Anaerotruncus colihominis CIP 107754 T , their respective phylogenetically closest species with standing in nomenclature. Therefore, strain Marseille-P2918 T is classified within the family Tissierellaceae and order Tissierellales whereas strain Marseille-P3646 T is classified within the family Oscillospiraceae and order Eubacteriales . The genome of strain Marseille-P2918 T had a size of 2.13 Mb with a GC content of 50.52% and includes six scaffolds and six contigs, and that of strain Marseille-P3646 T was 3.76 Mbp long consisting of five contigs with a 50.04% GC content. The genomes of both strains presented a high percentage of genes encoding enzymes involved in genetic information and processing, suggesting a high growth rate and adaptability. These new taxa are extensively described and characterised in this paper, using the concept of taxono-genomic description.

Trade facilitation plays a key role in international trade and trade supply chains, which is also an important issue of the world in general and Vietnam in particular. The new WTO Trade Facilitation Agreement (TFA) is a significant step forward for the international trading regime, representing new hope for the relevance of the WTO Keywords

A clinical trial of measles and rubella combined vaccine (MR: MRVAC) produced by POLYVAC was conducted in Vietnam in 2016. A total of 756 subjects were enrolled, and 504 were allocated to MRVAC and 252 to control MR vaccine groups. Paired sera were obtained in 733, and the number of subjects was 403 aged 1 - 2 years, 164 aged 2 - 18 years, and 166 aged 18 - 45 years. Antibodies against measles and rubella viruses were evaluated by EIA. Most subjects had been immunized with a single dose of Expanded Programme on Immunization (EPI) measles vaccine at 9 months of age. Only 41 of 403 subjects aged 1 - 2 years were negative for measles antibody before vaccination, and all became seroconverted. A serological response of more than a 2-fold increase against measles was noted in 214 (47%, 95% CI; 42.4% - 51.6%) of 458 initially seropositive individuals immunized with MRVAC and 65 (28%, 95% CI; 22.3% - 33.8%) of 234 in the control group, and geometric mean titer (GMT) after vaccination was 25.49-5.60 in MRVAC and 25.03-5.24 in control group. Seroconversion against rubella virus after immunization with MRVAC was noted in 267 (98.5%, 95% CI; 97.1% - 100%) of 271 initially seronegative subjects, similar to that after immunization with control group. GMT after immunization with MRVAC was 24.88-5.11 significantly lower than that after immunization with control vaccine (25.59-5.80). Most subject ≥ 2 years of age had rubella antibody because of MR vaccination campaign and no significant serological response was observed in initially seronegatives. MRVAC was highly immunogenic and safe vaccine and the domestic production of MR vaccine would contribute to realizing the goal of eliminating measles and rubella.

Forward osmotic (FO) membrane is a new process for producing fresh water from salt water. The study of draw solute is essential in the development and application of FO technology; draw solution should be good at drawing water and easy at recovery. In this paper, three complex draw solutes such as ammonium iron (II) sulfate, ammonium iron (III) sulfate and ammonium iron (III) citrate with different concentrations were studied. The physical properties such as pH, conductivity and total dissolved solids (TDS) have simultaneously been investigated. The pH of most ammonium complexes was decreased whereas TDS increased with increasing of draw solution concentrations. We found that high water flux of these iron complexes was reported in the range of 8.88–11.24 LMH which was higher than the ammonium bicarbonate draw solution. In addition, more than 90% iron complexes draw solutions were recovered by NF-90 membrane, which plays an important role in the FO process to produce fresh water. This study provides direct evidence for the ability of permeate water from feed solution to draw solution, which shows the potential applications of iron complexes in FO process to produce fresh water from sea-, brackish or river water.

application/pdf, 学位記番号：論工第1628号, 主査：古田 雅一

The ubiquitous skin colonist Staphylococcus epidermidis elicits a CD8 + T cell response pre-emptively, in the absence of an infection 1 . However, the scope and purpose of this anti-commensal immune program are not well defined, limiting our ability to harness it therapeutically. Here, we show that this colonist also induces a potent, durable, and specific antibody response that is conserved in humans and non-human primates. A series of S. epidermidis cell-wall mutants revealed that the cell surface protein Aap is a predominant target. By colonizing mice with a strain of S. epidermidis in which the parallel β-helix domain of Aap is replaced by tetanus toxin fragment C, we elicit a potent neutralizing antibody response that protects mice against a lethal challenge. A similar strain of S. epidermidis expressing an Aap-SpyCatcher chimera can be conjugated with recombinant immunogens; the resulting labeled commensal elicits high titers of antibody under conditions of physiologic colonization, including a robust IgA response in the nasal mucosa. Thus, immunity to a common skin colonist involves a coordinated T and B cell response, the latter of which can be redirected against pathogens as a novel form of topical vaccination.