Insight into heavy metal chemical fractions in ash collected from municipal and industrial waste incinerators in northern Vietnam.

This investigation involved the collection of fly ash and bottom ash specimens from seven waste incinerators situated in the northern provinces of Vietnam, aimed at assessing the composition and distribution patterns of five chemical fractions of heavy metals (Pb, Cr, As, Cd Cu, and Zn) present in incinerator waste ash. The outcomes reveal that fly ash exhibited a relatively elevated concentration of industrial waste metals (25-66%) such as As, Cd, and Pb primarily in exchangeable (F1) and carbonate fractions (F2), which are mobile forms susceptible to environmental dissolution and consequential bioaccumulation posing health risks to humans. The predominant states of the metals Cr, Cu, and Zn were identified as residual, Fe-Mn oxide, and carbonate, respectively, with their relative proportions showing minimal variation. Conversely, heavy metals were predominantly present in residual residue and Fe-Mn bound form (F3) in bottom ash derived from both residential and commercial waste incineration operations. The non-carcinogenic hazard indices (HI) associated with the examined metals, ranked for both adults and children, were as follows: Pb > Cr > As > Cd > Cu > Zn. Notably, the HI values for Pb, Cr, and As exceeded the permissible threshold (HI > 1) for children. However, the risk of As, Cd, and Pb-related cancer via exposure pathways remained within acceptable limits for both age groups. Conversely, the probability of carcinogenic effects attributable to Cr surpassed the permissible threshold (>10-4), indicating significant health concerns associated with heavy metals in waste incinerators for humans, particularly children.

Assessing the effect of COVID 19 lockdowns on the composition of organic compounds and potential source of PM2.5 in Hanoi, Vietnam.

The ambient air quality during COVID-19 lockdowns has been improved in many cities in the world. This study is to assess the changes in persistent organic pollutants in PM2.5 during the COVID-19 lockdown in Hanoi. Individual organic species in PM2.5 ((e.g., polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and organochlorine pesticides (OCPs)) were measured in an urban residential area in Hanoi from before the March 10th to April 22nd, 2020, including before the partial lockdown (BL) and the partial lockdown (PL) phases. During the PL phase, the concentration of Σ14PAHs and Σ28PCBs was reduced by 38 and 52% compared with the BL period, respectively. The diagnostic ratio method implied that the sources of PAHs within the PL phase had a less effect on traffic and industrial activities than in the BL phase. The characteristic ratio method indicated that PCBs were mixed by commercial product and combustion process in both the BL and the PL periods, however, the source of PCBs in the BL phase was influenced by municipal waste incineration more than those in the PL phase. The decreasing concentration of Σ20OCPs during the partial lockdown was attributed to the restriction of human activities during the quarantine period. The results suggested that the source of OCPs was probably derived from the usage of pesticides in current and, historical degradation or the transportation of pesticides from the soil to the atmosphere.

RNA therapeutics for ß-thalassemia.

ß-thalassemia is an autosomal recessive disease, caused by one or more mutations in the ß-globin gene that reduces or abolishes ß-globin chain synthesis causing an imbalance in the ratio of α- and ß-globin chain. Therefore, the ability to target mutations will provide a good result in the treatment of ß-thalassemia. RNA therapeutics represents a promising class of drugs inclusive antisense oligonucleotides (ASO), small interfering RNA (siRNA), microRNA (miRNA) and APTAMER have investigated in clinical trials for treatment of human diseases as ß-thalassemia; Especially, ASO therapeutics can completely treat ß-thalassemia patients by the way of making ASO infiltrating through erythrocyte progenitor cells, migrating to the nucleus and hybridizing with abnormal splicing sites to suppress an abnormal splicing pattern of ß-globin pre-mRNA. As a result, the exactly splicing process is restored to increase the expression of ß-globin which increases the amount of mature hemoglobin of red blood cells of ß-thalassemia patients. Furthermore, current study demonstrates that RNA-based therapeutics get lots of good results for ß-thalassemia patients. Then, this chapter focuses on current advances of RNA-based therapeutics and addresses current challenges with their development and application for treatment of ß-thalassemia patients.

RNA therapeutics history and future perspectives.

Ribonucleic acid (RNA) therapeutics have significantly used RNA-based drugs to the prevention and treatment of diseases as effective messenger RNA-based vaccines in response to the COVID-19 pandemic. The RNA therapeutics with five classes including antisense oligonucleotide, small interfering RNA, microRNA, APTAMER and messenger RNAs are being quickly developed to treat various human diseases as neurological disease, cardiovascular disease, genetic and rare disease, cancer disease, coronavirus disease… which cannot be treated by other conventional drugs as small molecule-based drugs and antibodies. Therefore, the discovery of these RNA therapeutics created a new avenue for treatment of various human diseases. This chapter demonstrates the history of important discoveries in RNA biology and their impact on key developments in RNA therapeutics as well as the advantages of RNA therapeutics; RNA therapeutics describes the action mechanisms and examples of RNA-based drugs approved for treatment of various disease; and RNA therapeutics discusses delivery methods for RNA therapeutics to target organs and cells. In conclusion, this chapter is designed to offer an updated important development and advance of RNA therapeutics for the prevention and treatment of various human diseases.

Five undescribed aryltetralin lignans with cytotoxic activities from the fruits of Cleistanthus eberhardtii.

Five undescribed lignans, cleiseberharnins A-D (1-4), cleiseberharside A (5) were isolated from the fruits of Cleistanthus eberhartii (Phyllanthaceae), together with six known aryltetralin lignans, cleistantoxin (6), picroburseranin (7), neocleistantoxin (8), 7-hydroxypicropolygamain (9), cleisindoside D (10), and cleisindoside A (11). Their structures and relative configurations were established by analysis of HRESIMS and NMR data, and quantum chemical calculations of JH,H coupling constants. The absolute configurations of 1-5 were determined by analysis of their experimental CD spectra and comparison with calculated electronic circular dichroism (ECD) spectra. All compounds (1-11) were evaluated for their cytotoxicity against KB, MCF-7, HepG-2, and Lu-1 human cancer cell lines. Among the tested compounds, compounds 6 and 7 showed strong activity against KB, MCF7, HepG2 and Lu-1 cell lines with IC50 values in the range of 0.02-0.62 µM. Compound 1 showed activity against three cancer cell lines KB, HepG2, and Lu-1 with IC50 values of 6.98, 7.61 and 11.75 µM, respectively. Compound 2 exhibited a selective inhibition with moderate cytotoxicity against Lu-1 with IC50 value of 15.30 µM. Compounds 4, 5 and 9 showed moderate activity against the three cancer cell lines with IC50 values in the range of 8.73-19.70 µM.

Multimodal analysis of methylomics and fragmentomics in plasma cell-free DNA for multi-cancer early detection and localization.

Despite their promise, circulating tumor DNA (ctDNA)-based assays for multi-cancer early detection face challenges in test performance, due mostly to the limited abundance of ctDNA and its inherent variability. To address these challenges, published assays to date demanded a very high-depth sequencing, resulting in an elevated price of test. Herein, we developed a multimodal assay called SPOT-MAS (screening for the presence of tumor by methylation and size) to simultaneously profile methylomics, fragmentomics, copy number, and end motifs in a single workflow using targeted and shallow genome-wide sequencing (~0.55×) of cell-free DNA. We applied SPOT-MAS to 738 non-metastatic patients with breast, colorectal, gastric, lung, and liver cancer, and 1550 healthy controls. We then employed machine learning to extract multiple cancer and tissue-specific signatures for detecting and locating cancer. SPOT-MAS successfully detected the five cancer types with a sensitivity of 72.4% at 97.0% specificity. The sensitivities for detecting early-stage cancers were 73.9% and 62.3% for stages I and II, respectively, increasing to 88.3% for non-metastatic stage IIIA. For tumor-of-origin, our assay achieved an accuracy of 0.7. Our study demonstrates comparable performance to other ctDNA-based assays while requiring significantly lower sequencing depth, making it economically feasible for population-wide screening.

Microplastics and trace metals in river sediment: Prevalence and correlation with multiple factors.

Microplastics (MPs), which are ubiquitous, are no longer novel emerging pollutants, yet our knowledge of them is insufficient. This study investigates the prevalence of MPs and trace metals in sediment belonging to Ma River, Vietnam, and their interaction with various parameters, including nutrients such as total carbon (TC), total nitrogen (TN), and total phosphorus (TP), grain sizes, and MPs in surface water. The study revealed that the abundance of MPs in sediment (MPs/S) is relatively high (i.e., 1328.3 ± 1925.5 items.kg-1 dry weight), while the concentration of MPs in surface water (MPs/W) was relatively low (i.e., 57.3 ± 55.8 items.m-3) compared to other areas. Notably, the study found that arsenic and cadmium concentrations exceeded baseline levels, indicating their anthropogenic origin. To interpret the relationship between MPs/S, metals, and the aforementioned parameters, principal component analysis and Pearson correlation analyses were employed. The results demonstrated a significant correlation between metals and nutrients, as well as small grain sizes such as clay and silt. It was observed that the majority of metals displayed co-occurrence with one another but showed weak associations with the levels of MPs present in both water and sediment. Additionally, a weak correlation was observed between MPs/W and MPs/S. In conclusion, these findings suggest that the distribution and behavior of MPs and trace metals in aquatic systems are influenced by multiple factors, including nutrient levels, grain size, and other chemical and physical characteristics of the environment. While certain metals may have natural sources, others may result from human activities such as mining, industrial discharge, and wastewater treatment plants. As a result, understanding the sources and aspects of metal contamination are critical for determining their relationship with MPs and developing effective strategies for mitigating their impact on aquatic ecosystems.

Multimodal analysis of genome-wide methylation, copy number aberrations, and end motif signatures enhances detection of early-stage breast cancer.

Introduction: Breast cancer causes the most cancer-related death in women and is the costliest cancer in the US regarding medical service and prescription drug expenses. Breast cancer screening is recommended by health authorities in the US, but current screening efforts are often compromised by high false positive rates. Liquid biopsy based on circulating tumor DNA (ctDNA) has emerged as a potential approach to screen for cancer. However, the detection of breast cancer, particularly in early stages, is challenging due to the low amount of ctDNA and heterogeneity of molecular subtypes. Methods: Here, we employed a multimodal approach, namely Screen for the Presence of Tumor by DNA Methylation and Size (SPOT-MAS), to simultaneously analyze multiple signatures of cell free DNA (cfDNA) in plasma samples of 239 nonmetastatic breast cancer patients and 278 healthy subjects. Results: We identified distinct profiles of genome-wide methylation changes (GWM), copy number alterations (CNA), and 4-nucleotide oligomer (4-mer) end motifs (EM) in cfDNA of breast cancer patients. We further used all three signatures to construct a multi-featured machine learning model and showed that the combination model outperformed base models built from individual features, achieving an AUC of 0.91 (95% CI: 0.87-0.95), a sensitivity of 65% at 96% specificity. Discussion: Our findings showed that a multimodal liquid biopsy assay based on analysis of cfDNA methylation, CNA and EM could enhance the accuracy for the detection of early- stage breast cancer.

Clinical validation of a ctDNA-Based Assay for Multi-Cancer Detection: An Interim Report from a Vietnamese Longitudinal Prospective Cohort Study of 2795 Participants.

The SPOT-MAS assay "Screening for the Presence Of Tumor by Methylation And Size" detects the five most common cancers in Vietnam by evaluating circulating tumor DNA in the blood. Here, we validated its performance in a prospective multi-center clinical trial, K-DETEK. Our analysis of 2795 participants from 14 sites across Vietnam demonstrates its ability to detect cancers in asymptomatic individuals with a positive predictive value of 60%, with 83.3% accuracy in detecting tumor location. We present a case report to support further using SPOT-MAS as a complementary method to achieve early cancer detection and provide the opportunity for early treatment.

Distribution characteristics and ecological risks of heavy metals in bottom ash, fly ash, and particulate matter released from municipal solid waste incinerators in northern Vietnam.

Residue concentrations of heavy metals, including As, Cd, Cr, Cu, Ni, Pb, and Zn, were determined in bottom ash, fly ash, and particulate matter (PM10) samples collected from five municipal incinerators in northern Vietnam to assess their occurrence, distribution characteristics, and potential risks. Concentrations and profiles of heavy metals are presented, showing the dominance of Zn in all types of samples. Highly volatile elements (Cd, Pb, and Zn) were found at elevated proportions in PM10 but not fly ash. The large difference in the heavy metal profiles could be explained by the variation of input raw materials, the absence of an appropriate cycle for the material feeding process, and post-combustion technology applied. Mass balance of heavy metals in the bottom ash, fly ash, and PM10 varied significantly between the investigated incinerators, largely due to the difference in incineration technology and air pollution control system. Emission factors and annual emissions were also estimated, indicating the highest value and amount in bottom ash, followed by PM10 and fly ash. Our results are among the first studies reporting contents and emissions of toxic elements in incinerated solid wastes in Vietnam.

Dietary supplementation with Pediococcus pentosaceus enhances the innate immune response in and promotes growth of Litopenaeus vannamei shrimp.

To reach the sustainable development goals on health management in Litopenaeus vannamei shrimp culture, Pediococcus pentosaceus AB01 was supplemented in shrimp diet. In this study, the control diet and three experimental diets containing P. pentosaceus AB01 (108 , 109 , 1010 CFU/g) were separately introduced to L. vannamei for a 28 days feeding trial. After the feeding trial, percent weight gain, feeding efficiency, and feed conversion ratio (FCR) were significantly elevated in L. vannamei administered with P. pentosaceus AB01 at 109 and 1010 colony-forming unit (CFU)/g. Protease, amylase, and trypsin were found at higher levels in the probiotic-supplied groups. The feeding of shrimps with P. pentosaceus AB01 significantly increased innate immune response and levels of related biochemical parameters in the haemolymph. After the white spot syndrome virus (WSSV) challenge, supplementation of P. pentosaceus AB01 had significant positive effects (p < .05) on survival rate, compared to that of the control diet. The higher resistance of L. vannamei to WSSV might have been due to alterations in the gut microbiome composition and upregulation of the Toll-Like Receptor (TLR) signalling pathway. Hence, P. pentosaceus AB01 may be a promising alternative feed to promote growth rate, modulate microbiota composition, and enhance immunity in L. vannamei shrimp.

The Combined Use of Pediococcus pentosaceus and Fructooligosaccharide Improves Growth Performance, Immune Response, and Resistance of Whiteleg Shrimp Litopenaeus vannamei Against Vibrio parahaemolyticus.

In this study, we evaluated the effect of probiotic bacteria Pediococcus pentosaceus supplemented at different inclusion levels in a control diet [basal diet containing 0.5% fructooligosaccharide (FOS)] on the growth performance, feed conversion ratio, immune response, and the disease resistance of whiteleg shrimp Litopenaeus vannamei juveniles against Vibrio parahaemolyticus. A control diet with 0.5% FOS but without P. pentosaceus supplementation (Control) was prepared. In addition, three other test diets were also formulated: control diet supplemented with P. pentosaceus at (i) 1 × 106 cfu g-1 diet (P1), (ii) 1 × 107 cfu g-1 diet (P2), or (iii) 1 × 108 cfu g-1 diet (P3). After a 60-day feeding trial, the experimental shrimps were challenged with V. parahaemolyticus. The results showed that dietary supplementation of P. pentosaceus significantly improved the growth performance and immune responses of L. vannamei juveniles. The juveniles that were fed with a P2 or P3 diet recorded the maximum increase in the final body weight, final length, weight gain, and survival rate. The total hemocyte counts, phenoloxidase, and lysozyme activity of shrimp fed with either of these two diets were significantly enhanced. The results also showed that juveniles fed with a P2 or P3 diet exhibited significantly lower mortality when challenged with V. parahaemolyticus. Overall results suggested that a combination of P. pentosaceus at the inclusion level of 1 × 107 cfu g-1 diet (P2) and 0.5% FOS could be considered as a potential synbiotic formulation for improving the growth, health, and robustness of L. vannamei.

Impact of Covid-19 partial lockdown on PM2.5, SO2, NO2, O3, and trace elements in PM2.5 in Hanoi, Vietnam.

Covid-19 lockdowns have improved the ambient air quality across the world via reduced air pollutant levels. This article aims to investigate the effect of the partial lockdown on the main ambient air pollutants and their elemental concentrations bound to PM2.5 in Hanoi. In addition to the PM2.5 samples collected at three urban sites in Hanoi, the daily PM2.5, NO2, O3, and SO2 levels were collected from the automatic ambient air quality monitoring station at Nguyen Van Cu street to analyze the pollution level before (March 10th-March 31st) and during the partial lockdown (April 1st-April 22nd) with "current" data obtained in 2020 and "historical" data obtained in 2014, 2016, and 2017. The results showed that NO2, PM2.5, O3, and SO2 concentrations obtained from the automatic ambient air quality monitoring station were reduced by 75.8, 55.9, 21.4, and 60.7%, respectively, compared with historical data. Besides, the concentration of PM2.5 at sampling sites declined by 41.8% during the partial lockdown. Furthermore, there was a drastic negative relationship between the boundary layer height (BLH) and the daily mean PM2.5 in Hanoi. The concentrations of Cd, Se, As, Sr, Ba, Cu, Mn, Pb, K, Zn, Ca, Al, and Mg during the partial lockdown were lower than those before the partial lockdown. The results of enrichment factor (EF) values and principal component analysis (PCA) concluded that trace elements in PM2.5 before the partial lockdown were more affected by industrial activities than those during the partial lockdown.

Determination of Pharmaceutical Residues by UPLC-MS/MS Method: Validation and Application on Surface Water and Hospital Wastewater.

In this study, an analytical method for the simultaneous determination of 7 major pharmaceutical residues in Vietnam, namely, carbamazepine, ciprofloxacin, ofloxacin, ketoprofen, paracetamol, sulfamethoxazole, and trimethoprim, in surface water and hospital wastewater has been developed. The method includes enrichment and clean-up steps by solid phase extraction using mix-mode cation exchange, followed by identification and quantification using an ultrahigh-performance liquid chromatography and tandem mass spectrometry and employing electrospray ionization (UPLC-ESI-MS/MS). Seven target compounds were separated on the reversed phase column and detected in multiple reaction monitoring (MRM) mode within 6 minutes. The present study also optimized the operating parameters of the mass spectrometer to achieve the highest analytical signals for all target compounds. All characteristic parameters of the analytical method were investigated, including linearity range, limit of detection, limit of quantification, precision, and accuracy. The important parameter in UPLC-ESI-MS/MS, matrix effect, was assessed and implemented via preextraction and postextraction spiking experiments. The overall recoveries of all target compounds were in the ranges from 55% to 109% and 56 % to 115% for surface water and hospital wastewater, respectively. Detection limits for surface water and hospital wastewater were 0.005-0.015 µg L-1 and 0.014-0.123 µg L-1, respectively. The sensitivity of the developed method was allowed for determination of target compounds at trace level in environmental water samples. The in-house validation of the developed method was performed by spiking experiment in both the surface water and hospital wastewater matrix. The method was then applied to analyze several surface water and hospital wastewater samples taken from West Lake and some hospitals in Vietnam, where the level of these pharmaceutical product residues was still missed. Sulfamethoxazole was present at a high detection frequency in both surface water (33% of analyzed samples) and hospital wastewater (81% of analyzed samples) samples.

Deep modifications of the microbiome of rice roots infected by the parasitic nematode Meloidogyne graminicola in highly infested fields in Vietnam.

Meloidogyne graminicola, also known as the rice root-knot nematode, is one of the most damaging plant-parasitic nematode, especially on rice. This obligate soilborne parasite induces the formation of galls that disturb the root morphology and physiology. Its impact on the root microbiome is still not well described. Here, we conducted a survey in Northern Vietnam where we collected infected (with galls) and non-infected root tips from the same plants in three naturally infested fields. Using a metabarcoding approach, we discovered that M. graminicola infection caused modifications of the root bacterial community composition and network structure. Interestingly, we observed in infected roots a higher diversity and species richness (+24% observed ESVs) as well as a denser and more complex co-occurrence network (+44% nodes and +136% links). We identified enriched taxa that include several hubs, which could serve as potential indicators or biocontrol agents of the nematode infection. Moreover, the community of infected roots is more specific suggesting changes in the functional capabilities to survive in the gall environment. We thus describe the signature of the gall microbiome (the 'gallobiome') with shifting abundances and enrichments that lead to a strong restructuration of the root microbiome.

Emission of Unintentionally Produced Persistent Organic Pollutants from Some Industrial Processes in Northern Vietnam.

Concentrations of PCDD/Fs, dioxin-like PCBs (dl-PCBs), PeCB and HCB were determined in flue gas, fly ash and bottom ash samples collected from brick production, steel production, and zinc production plants, an industrial waste incinerator and a medical waste incinerator in northern Vietnam to understand the contamination levels, accumulation patterns and extent of emission. Total TEQs concentrations of PCDD/Fs and dl-PCBs in flue gas and ash samples from these industrial plants ranged from 0.304 to 50.55 pg/Nm3 and 1.43 to 440 pg/g, respectively. PeCB and HCB residues in flue gas samples ranged from 0.839 to 46.59 ng/Nm3 and 1.16 to 60.5 ng/Nm3, respectively. The emission factors of 4.8-740 ngTEQs/tonne for PCDD/Fs and dl-PCBs, 67.12-240.7 µg/ton for PeCB and 11.64-889.3 µg/ton for HCB were obtained in flue gas samples. This is among the first reports on the emission factor of PCDD/Fs, dl-PCBs, PeCB, HCB in brick production, zinc production and waste incineration in Vietnam.

Polychlorobenzenes and polychlorinated biphenyls in ash and soil from several industrial areas in North Vietnam: residue concentrations, profiles and risk assessment.

Polychlorinated benzenes (PCBzs) including penta- and hexachlorobenzene can be unintentionally formed from thermal processes in different industrial activities, and very little information is available on the contamination and emission characteristics of these new persistent organic pollutants from industries in Vietnam. In this study, contamination of PCBzs (including penta- and hexachlorobenzene, named PeCBz and HCB, respectively) and PCBs (including CB-28, 52, 101, 153, 138, 180) in fly ash, bottom ash and soil from combustion processes of waste incineration, metallurgy (steel making and zinc production) and cement production from several provinces in the Northern Vietnam, including Hai Duong, Hanoi, Bac Ninh, Hai Phong and Thai Nguyen, was preliminary investigated. The PCBzs concentrations in fly ash, bottom ash and soil ranged from 2.7 to 100 ng g(-1), from 2.7 to 159 ng g(-1) and from 0.28 to 33.9 ng g(-1), respectively. Relatively high residues of PeCBz in fly ash and bottom ash from municipal waste incinerators in some provinces from the Northern Vietnam were encountered. Total PCBs concentrations ranged from 18.0 to 8260 ng g(-1), from 1.0 to 10600 ng g(-1) and from 14.5 to 130 ng g(-1) for the fly ash, bottom ash and soil, respectively. Daily intakes of PeCBz, HCB and PCBs through soil ingestion and dermal exposure estimated for children ranged 0.33-9.93 (mean 3.14), 0.39-21.1 (mean 4.9) and 6.09-1530 ng/kg bw/day (mean 346), respectively; and these intakes were about 4.7-5.4 times higher than those estimated for adult. The intakes of PeCBz and HCB were relatively low, while those for PCBs exceeded WHO TDI for some samples.

Survey-based cancer mortality in the Lao PDR, 2007-08.

BACKGROUND: The Lao PDR is a landlocked country with 5,920,000 inhabitants for which very few epidemiological studies on cancer have been performed. The aim of the present study was to examine cancer mortality in 2007-2008. METHODS: A descriptive cancer epidemiology protocol was designed with a data collection form and guideline for both demographics and list of all deaths from all 757 local Health Centers of 17 provinces/ cities. Five indicators, name, age, sex, date of death and the cause of death (ICD-10), were collected for each case. The age-specific cancer mortality rate and ASRs per 100,000 were estimated. RESULTS: There were 448 cancer cases reported from Health Centers within 7 of 17 provinces/cities. Number of person-years was 654,459 for the two-year period. Cancer mortality rates of all sites (ASR) were 116.7 and 97.2 per 100,000 in males and females, respectively. The five most common cancers causing mortality per 100,000 were liver (52.2), followed by colorectal (19.0), lung (17.3), stomach (6.9), and leukemia-lymphoma (7.2) in males and liver (28.4); followed by colorectal (19.0), lung (14.0), cervical uteri (9.2) and stomach (7.1) in females. CONCLUSIONS: Liver and colorectal cancers were the first and second most common, respectively, in both males and female.

Transcriptional response in the peripheral blood of patients infected with Salmonella enterica serovar Typhi.

We used microarrays and transcriptional profiling of peripheral blood to investigate the host response of 29 individuals who contracted typhoid fever in the Mekong Delta region of Vietnam. Samples were taken over a nine month period encompassing acute disease, convalescence, and recovery. We found that typhoid fever induced a distinct and highly reproducible signature in the peripheral blood that changed during treatment and convalescence, returning in the majority of cases to the "normal" profile as measured in healthy uninfected controls. Unexpectedly, there was a strong, distinct signature of convalescence present at day 9 after infection that remained virtually unchanged one month after acute infection and in some cases persisted as long as nine months despite a complete clinical recovery in all patients. Patients who retain the convalescent signature may be genetically or temporarily incapable of developing an effective immune response and may be more susceptible to reinfection, relapse, or the establishment of a carrier state.

Toll-like receptor 4 (TLR4) and typhoid fever in Vietnam.

Understanding the host genetic susceptibility to typhoid fever may provide a better understanding of pathogenesis and help in the development of new therapeutics and vaccines. Here we determine the genetic variation within the human TLR4 gene encoding the principal receptor for bacterial endotoxin recognition in typhoid fever patients. It is possible that genetic variants of TLR4 could detrimentally affect the innate immune response against S. typhi infection. Mutation detection and genotyping of TLR4 was performed on DNA from 414 Vietnamese typhoid fever patients and 372 population controls. dHPLC detected a total of 10 polymorphisms within the upstream and exonic regions of TLR4, of which 7 are novel. Two SNPs, T4025A and C4215G, were more frequent in typhoid cases than in controls however due to their low allele frequencies they showed borderline significance (T4025A: OR 1.9, 95%CI 0.9-4.3, P 0.07 and C4215G: OR 6.7, 95%CI 0.8-307, P 0.04). Six missense mutations were identified, with 5/6 positioned in the ectoplasmic domain. Four missense mutations and one promoter SNP (A-271G) were only present in typhoid cases, albeit at low allele frequencies. Here we determined the extent of genetic variation within TLR4 in a Vietnamese population and suggest that TLR4 may be involved in defense against typhoid fever in this population.