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Low-speed and heavy-duty gears will generate a lot of heat during meshing transmission, which will cause thermal deformation of the gears and affect the transmission performance of the gear system. It is of great significance to explore the influence of temperature effects on the nonlinear dynamics of the gear system. Taking the spur gear system as the research object, considering the nonlinear factors such as time-varying meshing stiffness, tooth backlash and comprehensive error, and introducing the influence of temperature change, the nonlinear dynamic model of the gear system is established, using 4~5th order Runge -Kutta algorithm performs simulation calculation on the model, combined with bifurcation diagram, maximum Lyapunov exponent diagram, phase diagram and Poincare section diagram, etc., to analyze the influence of temperature changes and time-varying stiffness coefficients on the motion characteristics of the gear system. The results show that the influence of temperature change on the gear system is related to the value of the time-varying stiffness coefficient. The larger the value, the more obvious the influence of temperature change; the system will show different dynamic response with the change of the time-varying stiffness coefficient, including four states of single-period motion, multiple-period motion, bifurcation and chaotic motion. The relevant conclusions can provide references for the design of gear systems under special working conditions.

The mechanism of occult hepatitis B infection (OBI) has not yet been fully clarified. Our previous research found that novel OBI-related mutation within S protein, E2G, could cause the hepatitis B surface antigen (HBsAg) secretion impairment, which resulted in intracellular accumulation in OBI of genotype B. Here, to further explore the role of E2 site mutations in the occurrence of OBI, we analyzed these site mutations among 119 OBI strains identified from blood donors. Meanwhile, 109 wild-type HBV strains (HBsAg positive/HBV DNA positive) were used as control group. Furthermore, to verify the E2 site mutations, two conservative 1.3-fold full-gene expression vectors of HBV genotype B and C (pHBV1.3B and pHBV1.3C) were constructed. Then, the E2 mutant plasmids on the basis of pHBV1.3B or pHBV1.3C were constructed and transfected into HepG2 cells, respectively. The extracellular and intracellular HBsAg were analyzed by electrochemical luminescence and cellular immunohistochemistry. The structural characteristics of S proteins with or without E2 mutations were analyzed using relevant bioinformatics software. E2 mutations (E2G/A/V/D) existed in 21.8% (26/119) of OBIs, while no E2 mutations were found in the control group. E2G/A/V/D mutations could strongly affect extracellular and intracellular level of HBsAg (p < 0.05). Notably, unlike E2G in genotype B that could cause HBsAg intracellular accumulation and secretion decrease (p < 0.05), E2G in genotype C could lead to a very significant HBsAg decrease both extracellularly (0.46% vs. pHBV1.3C) and intracellularly (11.2% vs. pHBV1.3C) (p < 0.05). Meanwhile, for E2G/A mutations, the relative intracellular HBsAg (110.7–338.3% vs. extracellular) and its fluorescence intensity (1.5–2.4-fold vs. with genotype-matched pHBV1.3B/C) were significantly higher (p < 0.05). Furthermore, N-terminal signal peptides, with a typical cleavage site for peptidase at positions 27 and 28, were exclusively detected in S proteins with secretion-defective mutants (E2G/A). Our findings suggest that: (1) E2G/A/V/D mutations were confirmed to significantly influence the detection of HBsAg, (2) the underlying mechanism of OBI caused by E2G mutation is quite different between genotype B and genotype C, and (3) E2G/A could produce a N-terminal truncated S protein, which might attribute to the HBsAg secretion impairment in the OBIs.

In recent years, Hepatitis C virus 6a was not only the predominant subtype in Guangdong but also has the potential of increasing in non-Guangdong in China over time. To understand the virus evolution and transmission mode, the representative HCV 6a specimens in Guangdong province were chosen for deep sequencing and performed evolutionary analysis with all the 6a whole genome reference sequences. Our results showed that less than 5% of the genome was found to be under positive selection. The protein with the highest proportion of sites under positive selection was E1 and E2; A positive association between positive selection sites and the presence of CD8 epitopes was found in non-Guangdong genomes (χ2 = 9.168, P − 4s/s/y. E2 has the fastest evolutionary rate (9.40×10− 3s/s/y), followed by E1, NS3 and NS5A. Spatio-temporal evolutionary analysis showed that Vietnam and other Southeast Asian countries were the origins of global HCV6a. Further, there were two important transmission modes which were all originated from Vietnam and other Southeast Asian countries in Guangdong. One (Group B) indicated that HCV6a was then transmitted to Hong Kong, and then to Guangdong and cross-dissemination between these two places; Another (Group C) revealed that HCV6a was directly disseminate to Guangdong and formed a regional epidemic. Our study firstly revealed the transmission mode of HCV6a by whole genome sequence, indicating that the impact of selective constraints in Guangdong and non-Guangdong, it can be helpful to plan for future prevention and management of HCV6a infection in Guangdong, China.

We performed an evolutionary analysis using whole genome sequence isolates of hepatitis C virus (HCV) 6a from Guangdong Province and reference sequences from various countries. Less than 5% of the HCV genome was found to be under positive selection. The E1 and E2 proteins had the highest proportion of positively selected sites both within and outside of CD8 T cell epitopes in all of the strains. Regions corresponding to CD8 T cell epitopes were under negative selection except in the isolates from Guangdong. Furthermore, we found evidence of three introductions of the virus into Guangdong from Vietnam and other Southeast Asian countries. Thus, this study provides information about the transmission of HCV 6a by comparison of full-length sequences, indicating the impact of selective constraints in Guangdong and across China. Supplementary Information The online version contains supplementary material available at 10.1007/s00705-021-05358-7.

The epidemiology of hepatitis C virus varies widely across geographical regions and ethnic groups. Our previous study showed that 6 strains isolated from Baisha County, Hainan Island, China, were all new genotype 6 (gt6) subtypes which differed significantly from subtypes of other regions. In the current study, we conducted a comprehensive epidemiological survey of HCV in the Li ethnic group, native to Baisha County. Anti-HCV antibodies were detected by 2 independent ELISAs in all participants, and positive results confirmed by the recombinant immunoblot assay (RIBA) and HCV RNA viral loads were measured. Univariate chi-square test and multivariable logistic regression analyses were used to determine the risk factors for HCV infection and spontaneous clearance rates. Indeterminate RIBA results were excluded or included in analyses; consequently, findings were expressed as a range. Direct sequencing of partial regions within NS5B and E1 was employed for genotyping. Among 1682 participants, 117 to 153 were anti-HCV positive (7.0%-9.1%), with 42.7%-52.6% confirmed to have cleared infection. Anti-HCV positivity was associated with older age (≥60 years) (OR = 0.02, 95% CI 0.01-0.05, P < 0.01) and surgery (OR = 2.75, 95% CI 1.36-5.57, P < 0.01), with no significant difference found between the HCV infection group and the HCV spontaneous clearance group. The gt6 subtype distribution characteristics of Baisha County were unique, complex and diverse. The sequences did not cluster with known gt6 subtypes but formed 4 Baisha community-specific groups. HCV infection in members of the Li minority ethnic group is characterized by high prevalence rates in the elderly, high spontaneous clearance rates and broad gt6 diversity.

To systematically characterize the prevalence and evolution of human T-cell lymphotropic virus (HTLV) infection among voluntary blood donors (BDs) in Guangdong province, China. A three-year survey for HTLV epidemiology among BDs was performed in Guangdong during 2016–2018. Anti-HTLV-1/2 was screened by ELISA and ECLIA, and subsequently confirmed by western blot (WB) and nucleic acid testing (NAT). The prevalence of HTLV in donors from different cities was calculated. The identified HTLV-positive cases were phylogenetically genotyped and analyzed in a Bayesian phylogenetic framework. Among 3,262,271 BDs, 59 were confirmed positive for HTLV-1 (1.81 per 100,000) and no HTLV-2 infection was found. The prevalence of HTLV-1 varied significantly among 21 cities in Guangdong province, China. The highest prevalence was found in donors from Shanwei (13.94 per 100,000), which is a coastal city in eastern Guangdong. Viral genomic sequences genotyped from 55 HTLV-1 carriers showed that 39 were transcontinental subtype and 16 were Japanese subtype. Specially, 13 out of 39 transcontinental subtype sequences were characterized with L55P mutation and 21 out of 55 sequences were characterized with L19F mutation in viral gp46 protein. The L55P mutation seemed be specific to eastern Asia since it only presented in the sequences from Japan, mainland China, and Taiwan. Phylogenetic analysis of gp46 gene shows that HTLV-1a may have been introduced to Guangdong through four different introduction events and formed major transmission clusters: clades I(13,602 years ago), II(16, 010 years ago), III(15,639 years ago) and IV(16,517 years ago). In general, Guangdong is considered to be a low-prevalence region for HTLV-1 infection, but the prevalence is significantly higher in Shanwei city. Transcontinental and Japanese subtype lineages dominate the prevalence in Guangdong. In terms of blood safety, HTLV antibody screening for first-time blood donors can effectively reduce the risk of HTLV transmission., Author summary Human T-cell lymphotropic virus type 1 distributed all over the world. Since 1988, serological screening has been included in routine blood screening in certain developed countries and regions such as American countries and some parts of Western Europe and East Asia. However, data from some highly populated countries such as China are still not available. We performed a 3-year large-scale blood screening survey to systematically characterize the prevalence of HTLV infection among blood donors in Guangdong province in south China during 2016–2018. In general, Guangdong was considered to be a low-prevalence region for HTLV-1 infection, but the prevalence is significantly higher in Shanwei, a coastal city of eastern Guangdong. Transcontinental and Japanese subtype lineages dominate the prevalence in Guangdong. Moreover, similar molecular characteristics of prevalent HTLV-1 sequences in Mainland China, Taiwan and Japan suggested a same origin of these viruses.

Additional file 1: Table S1. Repeatedly reactive donations (n=63) by confirmatory test

Background So far, the prevalence of human T-lymphotropic virus (HTLV) type 1 and 2 in some highly populated countries such as China is still unknown. In this study, a multi-center nationwide serological survey was designed and performed, to reveal the seroprevalence of HTLV infection among Chinese blood donors. Results Among 8,411,469 blood donors from 155 blood establishments, 435 were finally confirmed as HTLV carriers. The prevalence of HTLV infection in China varied in different provinces: Fujian had the highest prevalence of 36.240/100,000 (95% CI 31.990–41.050) and eleven provinces did not find HTLV-seropositive donors in the three years. no HTLV-2 infection was found. The overall prevalence of HTLV-1 in China decreased from 2016 to 2018. Female was identified as an independent risk factor of HTLV infection in China. Besides, seroconversion was observed in two of seven seroindeterminate donors 85 and 250 days after their last donation, respectively. Conclusions The seroprevalence of HTLV infection in most areas of China among blood donors is quite low, but it varies significantly in different geographic areas. Screening anti-HTLV-1/2 antibody and follow-up of serointederminate donors are essential to ensure blood safety especially in areas where we have found HTLV infected donors.

Background Natural killer (NK) cells are critical components in innate immune response to viral infection. Killer cell immunoglobulin-like receptors (KIRs) are involved in regulating the balance of activation or inhibitory function of NK cells. However, the association of KIRs with the spontaneous clearance of hepatitis C virus (HCV) remains unclear in the Chinese population. Study design and methods A total of 407 HCV-seropositive voluntary blood donors were recruited, including 203 with spontaneous viral clearance and 204 with chronic infection. The presence of KIR genes was detected individually by polymerase chain reaction with sequence-specific primers. Data of HLA and interleukin-28B (IL28B) genotypes were extracted from our previous study. Results Our results showed that KIR2DL2, 2DS2, 2DL2/2DL3, and 2DL5A-/2DL5B+ were more frequent in subjects with HCV clearance than those with chronic infection (odds ratio [OR], 1.640, p = 0.034; OR, 1.664, p = 0.032; OR, 1.636, p = 0.040; and OR, 2.601, p = 0.012, respectively). Multivariate logistic regression analysis showed that KIR2DL5A-/2DL5B+ associated with HCV clearance (OR, 2.448, p = 0.027), independent of sex, IL28B, and other KIRs. In contrast, KIR2DL3/2DL3 (OR, 0.610, p = 0.034) as well as 2DL3/2DL3+HLA-C1 or C1C1 (OR, 0.580, p = 0.017; and OR, 0.639, p = 0.025, respectively) was found associated with chronic HCV infection. The presence of the homozygous KIR2DL3 with or without its HLA ligand increased the OR of developing chronic HCV infection in the context of IL28B. Conclusions In this study we identified KIR2DL5A-/2DL5B+ associated with HCV spontaneous clearance, while KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1, or C1C1 associated with chronic infection. Our study highlighted the fact that the roles of KIR and KIR-HLA contributed to the control of HCV infection by innate immune responses.

The causative factors of occult hepatitis B infection are complicated and not yet been fully elucidated. Mutations in hepatitis B virus (HBV) S gene are one of the factors may contributing to occult infection. In this study, 89 blood donors with genotype B occult HBV infection were investigated. Fifty-seven hepatitis B surface antigen (HBsAg)-positive/HBV DNA-positive blood donors served as control group for comparison. Occult HBV-related mutations with a high incidence (P < .05) in the S gene were identified. To further verify these occult infection-related mutations, a conservative full-gene expression vector of HBV B genotype (pHBV1.3B) was constructed. Then, the mutant plasmids on the basis of pHBV1.3B were constructed and transfected into HepG2 cells. Extracellular as well as intracellular HBsAg was analysed by electrochemical luminescence and cellular immunohistochemistry. Ten occult infection-related mutations (E2G, Q101R, K122R, M133T, D144E, G145R, V168A, S174N, L175S and I226S) were significantly more frequent in the occult infection group (P < .05). Five of the ten mutations (E2G, D144E, G145R, V168A and S174N) strongly decreased extracellular HBsAg level (P < .05) in the transfection system. Notably, the E2G mutation had the most significant impact on the ratio of extracellular HBsAg (3.8% vs pHBV1.3B) and intracellular HBsAg (239.3% vs pHBV1.3B) (P < .05), and the fluorescence density of E2G mutant HBsAg was significantly higher than that of pHBV1.3B (P < .0001). Hence, ten mutations were associated with genotype B occult HBV infection; E2G and V168A were novel mutations which we confirmed significantly affect HBsAg detection. E2G might cause HBsAg secretion impairment that results in intracellular accumulation and a decrease in HBsAg secretion.

Specific human leukocyte antigen (HLA) class I and class II alleles have been associated with spontaneous clearance or persistent infection of hepatitis C virus (HCV), which seemed to be restricted by the host's ethnicity and viral genotype. Recently we reported a high prevalence and spontaneous clearance rate of HCV in a cohort of Chinese Li ethnicity who were infected with new variants of HCV genotype 6. In this study, we found that the distribution of HLA class I and class II alleles in HCV infected individuals of Chinese Li ethnicity (n = 143) was distinct from that of Chinese Han ethnicity which was reported in our previous study. HLA-DRB1*11:01 and DQB1*03:01 were more prevalent in Chinese Li subjects who cleared HCV spontaneously than those who were chronically infected (P = .036 and P = .024, respectively), which were consistent with our previous report regarding the Chinese Han population. Multivariate logistic regression analysis showed that DQB1*03:01 (odds ratio = 3.899, P = .017), but not DRB1*11:01, associated with HCV spontaneous clearance, independent of age, sex, and IFNL3 genotype. Because DQB1*03:01 and DRB1*11:01 were tightly linked because of linkage disequilibrium, our results clearly supported the associations of these two alleles with HCV spontaneous clearance in Chinese Li as well as Han ethnicity.

The distribution of hepatitis C virus (HCV) genotypes/subtypes varies among different populations. Here, we investigated HCV infection and its genotype distribution in injection drug users (IDUs) in Guangdong Province of China. A total of 318 IDUs from two prisons were recruited. The genotypes/subtypes of HCV in IDUs were determined by phylogenetic analysis using E1 and/or NS5B gene sequences. Our previous data on blood donors (BDs) with no history of drug use were used as control population data for comparison. Our results showed that the prevalence of HCV 3b (20.9% vs. 3.6%, P = 3.4E-9) and 6a (57.0% vs. 39.8%, P = 1.2E-5) was higher in IDUs than in BDs. In contrast, the prevalence of HCV 1b (43.4% vs. 5.6%, P = 9.8E-23) in BDs was higher than in IDUs. Phylogeographic analysis indicated that HCV 3b migrated from Yunnan to Guangdong Province and became endemic, with further transmission to other regions of China. The trend of HCV 3b dissemination in China in IDUs requires further attention, and a strategy for prevention and therapy is needed.

This study was carried out to determine the incidence of hepatitis B virus (HBV) infection in the young generation born after mandatory implementation of hepatitis B vaccination since 1992. Repeat blood donors born between 1992 and 1997 were enrolled, who gave blood at least twice during the past 3 years. Donors were tested for HBV infection markers of HBsAg, anti-HBc, anti-HBs and viral DNA by immunoassays (EIAs) and nucleic acid tests (NAT). A total of 14 937 pre-donation screening qualified young repeat donors aged 18-23 years were tested with 9 (0.06%) being HBsAg by EIA and 10 (1:1494) HBV DNA positive by Ultrio NAT (10.4 IU/mL), respectively. HBV DNA was further detected in 1:192 (9/1732) anti-HBc+ repeat donors with Ultrio Plus NAT (3.4 IU/mL). Most cases were identified as occult HBV infection (OBI). Of 14 937 repeat donors, 20.9% were anti-HBc+ positive, while approximately 50% of 12 024 repeat donors were anti-HBs negative or had levels

Natural killer (NK) cells are critical components in innate immune response to viral infection. Killer cell immunoglobulin-like receptors (KIRs) are involved in regulating the balance of activation or inhibitory function of NK cells. However, the association of KIRs with the spontaneous clearance of hepatitis C virus (HCV) remains unclear in the Chinese population.A total of 407 HCV-seropositive voluntary blood donors were recruited, including 203 with spontaneous viral clearance and 204 with chronic infection. The presence of KIR genes was detected individually by polymerase chain reaction with sequence-specific primers. Data of HLA and interleukin-28B (IL28B) genotypes were extracted from our previous study.Our results showed that KIR2DL2, 2DS2, 2DL2/2DL3, and 2DL5A-/2DL5B+ were more frequent in subjects with HCV clearance than those with chronic infection (odds ratio [OR], 1.640, p = 0.034; OR, 1.664, p = 0.032; OR, 1.636, p = 0.040; and OR, 2.601, p = 0.012, respectively). Multivariate logistic regression analysis showed that KIR2DL5A-/2DL5B+ associated with HCV clearance (OR, 2.448, p = 0.027), independent of sex, IL28B, and other KIRs. In contrast, KIR2DL3/2DL3 (OR, 0.610, p = 0.034) as well as 2DL3/2DL3+HLA-C1 or C1C1 (OR, 0.580, p = 0.017; and OR, 0.639, p = 0.025, respectively) was found associated with chronic HCV infection. The presence of the homozygous KIR2DL3 with or without its HLA ligand increased the OR of developing chronic HCV infection in the context of IL28B.In this study we identified KIR2DL5A-/2DL5B+ associated with HCV spontaneous clearance, while KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1, or C1C1 associated with chronic infection. Our study highlighted the fact that the roles of KIR and KIR-HLA contributed to the control of HCV infection by innate immune responses.

In 2014, an outbreak of dengue virus (DENV) infection led to 45 171 clinical cases diagnosed in Guangdong province, Southern China. However, the potential risk of blood donors asymptomatically infected with DENV has not been evaluated . In the current study we detected anti-DENV IgG antibody and RNA in volunteer Chinese blood donors. We found that anti-DENV IgG antibody was positively detected in 3.4% (51/1500) and two donors were detected as being DENV RNA positive out of 3000 blood samples. We concluded that the presence of potential DENV in blood donors might be potential risk for blood safety. Therefore, screening for DENV infection should be considered in blood donations during a period of dengue outbreak in high epidemic area of China.

Spontaneous clearance of hepatitis C virus (HCV) occurs in 10–40% of the infections. Specific human leukocyte antigen (HLA) alleles have been identified in associating with HCV clearance. However, data on the association of HLA with the spontaneous clearance of HCV are scarce in the Chinese population. In the current study we studied the HLA class I and class II genes in 231 Chinese voluntary blood donors who had cleared HCV infection spontaneously compared to 429 subjects with chronic HCV infections. We also studied their IL28B SNP (rs8099917) genotype, since a number of investigators have found a strong association of IL28B with spontaneous or treatment induced HCV clearance. We found that HLA-A*02:01 and DQB1*05:02 distributed differently between the two groups after Bonferroni correction (odds ratio [OR] = 1.839, Pc = 0.024 and OR = 0.547, Pc = 0.016, respectively). Multivariate logistic regression analysis suggested that A*02:01 and DRB1*11:01 (OR = 1.798, P = 0.008 and OR = 1.921, P = 0.005, respectively) were associated with HCV spontaneous clearance, independent of age, gender and IL28B polymorphism. We concluded that in the Chinese population, HLA-A*02:01 and DRB1*11:01 might be associated with the host capacity to clear HCV independent of IL28B, which suggesting that the innate and adaptive immune responses both play an important role in the control of HCV.

Understanding the biology of spontaneous clearance of hepatitis C virus (HCV) infection could lead to improved strategies to prevent the sequelae associated with chronic HCV infection. Chronic infections with hepatitis virus are very common in China, but the factors associated with spontaneous clearance of HCV have not been adequately studied. We evaluated the spontaneous clearance of HCV among 1918 drug users and 1526 HCV-seropositive blood donors in Guangzhou, China. Among participants who were co-infected with hepatitis B virus (HBV), 41.38% of drug users and 39.47% of blood donors had cleared their HCV infection without antiviral therapy compared to 9.41% of drug users and 16.73% of blood donors who were mono-infected with a single virus (P

Numerous eclogite-amphibolite blocks have been found along the Mayanling fault in the northern Dabie complex. Most of the eclogites are strongly retrograded and contain garnet, rutile and the amphibole-plagioclase symplectite. The occurrence of these eclogites may have something to do with the inverted movement of the Mayanling thrust fault.

Object To explore the effects of neutron-irradiation exposure on TRAIL/DR5 pathway in rat brain regions. Methods Fast neutron-irradiation was employed as the irradiated model. The expression changes of TRAIL and DR5 in cerebral cortex, hippocampus, cerebellum and corpus striatum were detected after 1, 7 and 14 d post-irradiation by RT-PCR, ELISA and western blotting. Cleaved caspase-8 was examined by western blotting. Results In protein expression level, TRAIL was increased in the four regions to different extents after 7 d and then recovered after 14 d; DR5 was detected to be up-regulated in cerebral cortex, hippocampus and corpus striatum but down-regulated in cerebellum after 14 d post-irradiation. No significant changes of TRAIL and DR5 were observed in RNA level by RT-PCR. The cleaved caspase-8 was up-expressed the greatest after 1 d in cerebral cortex, hippocampus and cerebellum but continually up-regulated in corpus striatum from 1 to 14 d after irradiation treatment. Conclusion TRAIL was induced in rat brain at early stage while the expression changes of DR5 were delayed by neutron-irradiation and vary in different brain regions. Moreover, caspase-8 was not activated in accord with the changes of TRAIL and DR5 in some brain regions. These indicate that the activation of TRAIL/DR5 pathway plays a role in irradiation-induced injury, which is regulated in a region-specific and time-dependent manner.