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• PD-1/PD-L1 signalling involves T-cell exhaustion in patients with chronic hepatitis B virus (HBV) infection. • Increased expression of PD-1 is considered to be associated with infectious diseases. • PD-1.9 and PD-1.9 are associated with HBV-associated liver disease outcomes. • Increased sPD-1 levels are associated with HBV-related liver inflammation and fibrosis. Programmed cell death-1 (PD-1) variants and circulating level of soluble PD-1 are associated with susceptibility to malignant and infectious disease. This study aimed to examine the association of PD-1.5 and PD-1.9 variants, and plasma sPD-1 level with hepatitis B virus (HBV) infection and disease progression. The study cohort consisted of adults infected with HBV (n =513) – stratified by clinical course, including chronic hepatitis B (CHB, n =173), liver cirrhosis (LC, n =134) and hepatocellular carcinoma (HCC, n =206) – and matched healthy controls (HC, n =196). The PD-1.5 (rs2227981 C/T) and PD-1.9 (rs2227982 C/T) genetic variants were genotyped by Sanger sequencing, and plasma sPD-1 levels were quantified by enzyme immunoassay. Plasma sPD-1 levels were significantly higher among patients infected with HBV. The highest plasma sPD-1 levels were observed in patients with CHB, followed by patients with LC and HCC. In addition, the plasma sPD-1 levels correlated positively with liver inflammation [aspartate transaminase (AST): rho=0.57, P <0.0001; alanine aminotransferase: rho=0.57, P <0.0001], and were positively correlated with liver fibrosis [AST to platelet ratio index score: rho=0.53, P <0.0001). The PD-1.9 TT genotype was less common in patients with CHB compared with patients with LC, HCC, and HCC+LC in both codominant and recessive models (P <0.01), and was found to be a risk factor for HCC predisposition {HCC vs non-HCC: odds ratio (OR) 2.0 [95% confidence interval (CI) 1.13–3.7], P adj =0.017}. The PD-1.5 CT genotype was associated with reduced risk of acquiring HCC [OR 0.6 (95% CI 0.4–0.9), P adj =0.031]. sPD-1 level was associated with liver inflammation and progression of liver fibrosis, and the PD-1.5 and PD-1.9 variants were associated with HBV infection and progression of liver disease. [ABSTRACT FROM AUTHOR]

• Secondary infections prevail in North Vietnamese adults with few cases of severe disease. • Dengue virus serotypes DENV1 and DENV2 are predominant with higher viremia in primary infection than secondary infection. • Adult secondary dengue infection is distinguished by IgM:IgG ratio cut off <0.7. • Platelet loss correlates with dengue-specific IgG and IgM levels but does not necessarily lead to longer hospital stay or worsening illness. • Platelet autoantibodies in acute dengue infection and autoimmune complications in post-dengue warrant further investigation. The morbidity in dengue fever is dependent on the dengue virus (DENV) serotypes, the patient age, predisposing immunogenic markers and the frequency of primary and secondary infections. This study aims to distinguish acute primary from secondary dengue infections of Vietnamese adults and to assess the association of viremia and anti-dengue immunoglobulin levels with clinical outcomes. Viral RNA, dengue serotypes and levels of anti-dengue IgM and IgG of hospitalized adult cases were determined in EDTA-plasma samples prospectively collected during three consecutive years of dengue infection in Hanoi. Patients admitted to hospital within 7 days of their 1st reported fever were included. Primary infections were anti-dengue IgG enzyme-linked immunosorbent assay (ELISA) negative on both day of hospital entry (day 0) and day two or three of hospitalization (day 2 or 3) with a positive anti-dengue IgM on either day 0 or day 2 or 3 hospitalization. The secondary infections were anti-dengue IgG ELISA positive on both day 0 and day 2 or 3 with positive anti-dengue IgM ELISA on either day 0 or day 2 or 3. The hospitalized dengue fever cases between October 2016 and March 2019 were predominantly secondary infections (74%, 68% and 77%, respectively) with DENV-1 (60% and 65%) and DENV-2 (22% and 26%) serotypes determined in the latter two years. The viremia in primary infection was significantly higher than that in secondary infection (P < 0.01) and positively correlated with the days of hospital stay. In secondary infections, platelet counts were lower than in primary infections (P = 0.04) and IgG levels in secondary infection negatively correlated with platelet counts (Spearman's r = −0.22, P < 0.01). Our results indicate high rates of secondary infection with DENV1 and DENV2 serotypes. Anti-dengue immunoglobulins negatively correlate with hospital stay and platelet counts with few warning signs or severe disease. Further investigations of specific antibodies in adults which predict auto-inflammatory activity after the recovery from dengue infection are warranted. [ABSTRACT FROM AUTHOR]

• Variations in natural killer cell receptors affect the risk of hepatitis B virus (HBV) and clinical outcomes. • Variation in KIR2DS4 is associated with a risk to chronic HBV. • Combinations of killer-cell immunoglobulin-like receptor (KIR) and human leukocyte antigen (HLA) ligands protect from chronic HBV and liver cirrhosis. • Activating KIR protects HBV patients from hepatocellular carcinoma. Genes of host immunity play an important role in disease pathogenesis and are determinants of clinical courses of infections, including hepatitis B virus (HBV). Killer-cell immunoglobulin-like receptor (KIR), expressed on the surface of natural killer cells (NK), regulate NK cell cytotoxicity by interacting with human leukocyte antigen (HLA) class I molecules and are candidates for influencing the course of HBV. This study evaluated whether variations in KIR gene content and HLA-C ligands are associated with HBV and with the development of liver cirrhosis and hepatocellular carcinoma. A Vietnamese study cohort (HBV n = 511; controls n = 140) was genotyped using multiplex sequence-specific polymerase chain reaction (PCR-SSP) followed by melting curve analysis. The presence of the functional allelic group of KIR2DS4 was associated with an increased risk of chronic HBV (OR = 1.86, pcorr = 0.02), while KIR2DL2+HLA-C1 (OR = 0.62, pcorr = 0.04) and KIR2DL3+HLA-C1 (OR = 0.48, pcorr = 0.04) were associated with a decreased risk. The pair KIR2DL3+HLA-C1 was associated with liver cirrhosis (OR = 0.40, pcorr = 0.01). The presence of five or more activating KIR variants was associated with hepatocellular carcinoma (OR = 0.53, pcorr = 0.04). KIR gene content variation and combinations KIR-HLA influence the outcome of HBV infection. [ABSTRACT FROM AUTHOR]

• Neopterin levels and Kyn/Trp ratios were significantly increased in dengue virus (DENV) patients and subsequently decreased after recovery. • Neopterin concentrations strongly correlated with Kyn/Trp ratios. • Neopterin levels and Kyn/Trp ratios could be used as indicators of the response to supportive care in DENV infection. During dengue fever, a pronounced gamma-interferon immune response produces neopterin and promotes tryptophan degradation by the enzyme indoleamine-2,3-dioxygenase 1 (IDO-1). Activated IDO-1 is indicated by an increased kynurenine to tryptophan ratio (Kyn/Trp) in patients. Plasma levels of neopterin, kynurenine, and tryptophan were measured in 72 hospitalized dengue virus (DENV) patients and 100 healthy individuals. Plasma levels of neopterin, kynurenine, and tryptophan were also measured prospectively in a second cohort of 13 DENV patients; on the day of hospitalization, on day 2–3 at discharge, and 7–10 days after discharge. DENV RNA positivity was determined by qualitative and quantitative methodologies. DENV RNA-positive patients presented significantly higher levels of neopterin (mean 36.5 nmol/l) and Kyn/Trp ratios (mean 102 μmol/mmol) compared to DENV RNA-negative individuals. A significant correlation between neopterin levels and Kyn/Trp ratios was observed in both DENV RNA-positive (Spearman's rho = 0.37, p < 0.01) and DENV RNA-negative (Spearman's rho = 0.89, p < 0.001) patients. Kyn/Trp ratios were negatively correlated with platelet counts (Spearman's rho = −0.43, p < 0.01) and positively correlated with liver enzymes: AST (Spearman's rho = 0.68, p < 0.01) and ALT (Spearman's rho = 0.51, p < 0.05). In addition, the follow-up data presented a significant decrease in neopterin levels and Kyn/Trp ratios within 10 days after hospital entry. Neopterin levels and Kyn/Trp ratios were significantly increased in DENV patients and subsequently decreased after recovery. [ABSTRACT FROM AUTHOR]

Highlights • The NTCP S267F variant is associated with a lower risk of chronic HBV infection. • First study on NTCP S267F variant on concomitant HDV infection in Vietnamese population. • The NTCP S267F is correlated with a reduced risk on clinical progression of liver cirrhosis and liver cancer. Abstract Objectives To determine potential associations of the rs2296651 variant (c.800C > T, S267F) of NTCP with HBV and HBV plus concomitant HDV infection as well as with the progression of related liver diseases. Methods The S267F variant was genotyped by DNA sequencing in 620 HBV-infected patients and 214 healthy controls (HCs). Among the patients, 450 individuals were tested for HDV by a nested PCR assay. Logistic regression was applied to examine the association. Results The S267F variant was found more frequently among HCs (16%) compared to HBV-infected (6%) and HBV-HDV co-infected patients (3%) (HBV patients vs HC: OR = 0.32, P = 0.00002 and HDV patients vs. HC: OR = 0.17, P = 0.018). The frequency of S267F variant was inversely correlated with CHB, LC or HCC patients compared with HCs (OR = 0.31, P = 0.001; OR = 0.32, P = 0.013; OR = 0.34, P = 0.002, respectively). S267F variant was also associated with decreased risk of the development of advanced liver cirrhosis (LC) and hepatocellular carcinoma (HCC) (Child B and C vs. Child A, OR = 0.26, adjusted P = 0.016; BCLC B,C,D vs. BCLC A, OR = 0.038, P = 0.045, respectively). In addition, patients with the genotype CT had lower levels of AST, ALT, total and direct bilirubin as well as higher platelet counts, indicating an association with a more favorable clinical outcome. Conclusion The NTCP S267F variant of the SLC10A1 gene exhibits protective effects against HBV and HDV infection and is associated with a reduced risk of developing to advanced stages of LC and HCC. [ABSTRACT FROM AUTHOR]

Introduction For the identification of bacterial pathogens, blood culture is still the gold standard diagnostic method. However, several disadvantages apply to blood cultures, such as time and rather large volumes of blood sample required. We have previously established an optimised multiplex real-time PCR method in order to diagnose bloodstream infections. Material and methods In the present study, we evaluated the diagnostic performance of this optimised multiplex RT-PCR in blood samples collected from 110 septicaemia patients enrolled at the 108 Military Central Hospital, Hanoi, Vietnam. Results Positive results were obtained by blood culture, the Light Cylcler-based SeptiFast ® assay and our multiplex RT-PCR in 35 (32%), 31 (28%), and 31 (28%) samples, respectively. Combined use of the three methods confirmed 50 (45.5%) positive cases of bloodstream infection, a rate significantly higher compared to the exclusive use of one of the three methods ( P = 0.052, 0.012 and 0.012, respectively). The sensitivity, specificity and area under the curve (AUC) of our assay were higher compared to that of the SeptiFast ® assay (77.4%, 86.1% and 0.8 vs. 67.7%, 82.3% and 0.73, respectively). Combined use of blood culture and multiplex RT-PCR assay showed a superior diagnostic performance, as the sensitivity, specificity, and AUC reached 83.3%, 100%, and 0.95, respectively. The concordance between blood culture and the multiplex RT-PCR assay was highest for Klebsiella pneumonia (100%), followed by Streptococcus spp. (77.8%), Escherichia coli (66.7%), Staphylococcus spp. (50%) and Salmonella spp. (50%). In addition, the use of the newly established multiplex RT-PCR assay increased the spectrum of identifiable agents ( Acintobacter baumannii, 1/32; Proteus mirabilis, 1/32). Conclusion The combination of culture and the multiplex RT-PCR assay provided an excellent diagnostic accomplishment and significantly supported the identification of causative pathogens in clinical samples obtained from septic patients. [ABSTRACT FROM AUTHOR]