[Selection of statistical methods for estimating the association between exposure factors and rare outcomes based on cohort studies].

Odds ratio (OR) and relative risk (RR) are the most commonly used statistical indicators for the estimation of the association between exposure and outcome. In the cohort study with rare outcomes, the estimated OR approximately equals RR, but RR seems more interpretable. The study aims to explore the difference between OR and RR estimated by different multivariate analyses to provide reference for the selection of more appropriate multivariate regression methods and reporting indicators for estimating the association between exposure and rare outcome in cohort studies. This case study used the data from China birth cohort study. Modes of conception and congenital disabilities were regarded as exposure and outcome, respectively. Maternal age, family history of congenital disabilities with clear evidence were included as covariates. Logistic regression, log-binomial regression, and Poisson regression were used to estimate the OR and RR, respectively. Then, OR, RR, and their 95%CI estimated by three regression models were compared. The OR estimated by logistic regression was approximately equal to the RR estimated by log-binomial regression or Poisson regression. However, the RR estimated by log-binomial regression or Poisson regression was closer to 1.00, with a narrower 95%CI. Log-binomial regression or Poisson regression might have non convergence or over dispersion problems. It is recommended to report the RR obtained by log-binomial regression or Poisson regression in the cohort study with rare outcomes if applicable.

Molecular, biochemical and enzymatic characterization of photorespiratory 2-phosphoglycolate phosphatase (PGLP1) in rice.

Phosphoglycolate phosphatase (PGLP, EC3.1.3.18) is a key enzyme in photorespiration. However, genes encoding the rice photorespiratory PGLP have not yet been identified or characterized. Here, PGLP for photorespiration in rice was identified and its enzymatic properties were investigated. In order to define the function of PGLP homologs, rice PGLP mutants were constructed using CRISPR/Cas9, the transcriptional expressions were analyzed by RT-qPCR, and subcellular localizations were detected via rice protoplast transient expression analysis. Based on sequence alignment, proteins encoded by genes OsPGLP1, OsPGLP2, and OsPGLP3 in the rice genome were predicted to have PGLP activity. Subsequent experimentation showed that OsPGLP1 and OsPGLP3 are chloroplast proteins, while OsPGLP2 is localized in the cytoplasm. In rice leaves, levels of PGLP1 transcript were substantially higher than those of PGLP2 and PGLP3, whereas in roots, levels of PGLP2 transcript were higher than those of PGLP1 and PGLP3. There was no detectable PGLP activity in leaves of the OsPGLP1 mutant, which was non-viable in ambient air condition (400 ppm CO2 ) and high CO2 (4000 ppm) was unable to restore normal growth. In contrast, mutations of PGLP2 or PGLP3 did not result in visible phenotypes and the leaf PGLP activities were also unaffected It is suggested that PGLP1, encoded by Os04g0490800, is responsible for photorespiration. Furthermore, PGLP1 is a dimer with an apparent molecular mass of ca.65 kDa, and its Km is 272 µM, with a higher broad optimum pH (7.5 to 10.0) for PGLP activity than that in other higher plants.

[Development of case report form based on clinical data interchange standards consortium on special diseases to promote the ecology construction of real-world data in China].

Real world data (RWD) refers to the data generated in routine clinical practices, daily life, and real work environment and has been widely used in clinical or public health research. Still, issues related to the quality of RWD, such as incompleteness, inconsistency, and inaccuracy, would affect the validity of real-world research. To overcome the challenges due to the lack of standardization of real world source data, case report form based on clinical data interchange standards consortium (CDISC-CRF) on certain diseases was developed to promote the ecology construction of RWD based on the data standards set by the CDISC which has been widely used. Firstly, we described how to apply data standards to make up the gap between RWD and real world evidence. Then, the process was designed to build RWD ecology based on CDISC-CRF, in which the development technology of CDISC-CRF form is mainly introduced. Finally, the application prospect and significance of building real-world data based on disease-specific CDISC-CRF are described. It is believed that the present paper can provide a new idea for promoting the ecology construction of RWD in China.

[Establishment of reference interval of vitamin A for Chinese children and adolescents based on expectation-maximization algorithm].

Objective: To establish the reference interval of vitamin A for Chinese children and adolescents by indirect approach. Method: The serum retinol samples from 28 provinces, autonomous regions and municipalities in China between January 2016 and June 2019 were examined by high performance liquid chromatography in third-party clinical laboratory institutions. Using a cross-sectional study, descriptive statistics of serum vitamin A levels in children and adolescents aged 0-18 years were carried out in population, region and season. The distribution parameters of vitamin A levels were calculated iteratively by the expectation-maximization (EM) algorithm, and the reference interval was established. Results: A total of 1 096 597 cases were included in the analysis, including 631 017 males and 465 580 females, with a median age of 3(1, 6) years. Before the age of 4 years, the median serum vitamin A level increased with age [median level and its quartiles was 0.15 (0.11, 0.18) mg/L for neonates, 0.23 (0.18, 0.29) mg/L for infants aged below 1 year, and 0.27 (0.20, 0.34) mg/L for kids aged 1-<4 years]. The median serum vitamin A level was stable at the age of 4-8 years (median level ranged from 0.27 to 0.29 mg/L). Afterwards, the median serum vitamin A level reached 0.30 mg/L at the age of 9 years, and then an increasing trend with age was observed till 18 years. The median serum vitamin A level was higher in south area (male:0.33 mg/L; female:0.34 mg/L), compared with other areas (0.24-0.30 mg/L). The variation of the median serum vitamin A level among seasons was within 0.03 mg/L. Based on EM algorithm using indirect approach, the reference intervals of vitamin A for Chinese children and adolescents were as follows: newborn, 0.27-0.47 mg/L; infants aged below 1 year, 0.36-0.56 mg/L; children aged 1-<7 years, 0.35-0.54 mg/L; children aged 7-<16 years, 0.46-0.60 mg/L; and teenagers aged over 16 years, 0.38-0.59 mg/L. Conclusion: The EM algorithm can provide a basis for the establishment of vitamin A reference interval for Chinese children and adolescents, and the established reference interval needs to be further verified by direct method.

[Statistical reporting requirements for medical journals: Amplifications and explanations].

Our study aimed to amplify and explain the items of statistical reporting requirements proposed by medical journals, and to improve the statistical reporting quality of medical articles. Statistical reporting requirements were obtained from the reporting standards published by the International Committee of Medical Journal Editors (ICMJE), the Enhancing the QUAlity and Transparency of Health Research (EQUATOR) network, and the editorial board of Chinese Medical Journal, etc. The items involved in statistical reporting requirements were summarized as issues of study design, statistical analysis, and interpretation of results. Each item was amplified based on cases of original articles. It is noticeable that the statistical reporting requirements of English medical journals generally referring to guidance documents, including "Recommendations for the conduct, reporting, editing, and publication of scholarly work in medical journals" proposed by the ICMJE, or the statements for different study types published by the EQUATOR network, where the statistical reporting of medical articles had been detailed specified. The statistical reporting requirements of Chinese medical journals, however, were usually stated by the editorial boards. Although the formats and contents of statistical analysis had been regulated, the requirements of Chinese medical journals were to some extent insufficient and should be enhanced in accordance with the international standards. In conclusion, the amplification and explanation of statistical reporting requirements were expected to help investigators understand the requirements for statistical reporting in medical researches, so as to effectively improve the quality of medical articles.

[Characteristics of sleep apnea events in non-snoring children].

Objective: To investigate the characteristics of sleep-related respiratory events in normal children and to provide normal polysomnographic parameters for diagnosing sleep-disordered breathing in children. Methods: Normal subjects between 3 and 14 years old were enrolled from 1 July 2014 to 31 December 2015 and the subjects received overnight polysomnography at the sleep center of our hospital. They were children of our hospital employees or were recruited from the communities who did not have sleep and respiratory disorders. The children were divided into preschool group (3-5 years) and school-age group (6-14 years). Apnea index (AI), obstructive apnea index (OAI), central apnea index (CAI), and mixed apnea index (MAI) were compared between the two groups. Data for continuous variables that showed normal distribution were expressed as x ±s. M(P25, P75) were used when data were not normally distributed. Continuous variables that showed normal distribution were compared by using an independent-sample t-test. Wilcoxon-test was performed when data exhibited non-normal distribution. Differences in categorical data were tested with Chi-square test. Pearson correlation test was applied for the correlation analysis. P<0.05 was considered statistically significant. Results: A total of 115 normal children took part in the study including 40 in preschool group and 75 in school-age group. Children in both groups had a few sleep apnea events, most of which were central apneas, accounting for 80% and 70% of the total respiratory events respectively. Central apnea index in preschool children were significantly higher than that of school-age children (P<0.001), with median of 0.6 times/h and 0.1 times/h, respectively. Median OAI of both groups were 0.0 times/h without significant difference (P=0.748). Obstructive apnea events occurred mainly in the supine position in both groups. Conclusions: Normal children may have a few apnea events in sleep that were predominantly central apnea. CAI of preschool children is significantly higher than that of school-age children. Obstructive sleep apnea is rare in normal children, and sleep apnea occurs mainly in the supine position.

The oxalyl-CoA synthetase-regulated oxalate and its distinct effects on resistance to bacterial blight and aluminium toxicity in rice.

Oxalic acid is widely distributed in biological systems and known to play functional roles in plants. The gene AAE3 was recently identified to encode an oxalyl-CoA synthetase (OCS) in Arabidopsis that catalyses the conversion of oxalate and CoA into oxalyl-CoA. It will be particularly important to characterise the homologous gene in rice since rice is not only a monocotyledonous model plant, but also a staple food crop. Various enzymatic and biological methods have been used to characterise the homologous gene. We first defined that AAE3 in the rice genome (OsAAE3) also encodes an OCS enzyme. Its Km for oxalate is 1.73 ± 0.12 mm, and Vm is 6824.9 ± 410.29 U·min-1 ·mg protein-1 . Chemical modification and site-directed mutagenesis analyses identified thiols as the active site residues for rice OCS catalysis, suggesting that the enzyme might be regulated by redox state. Subcellular localisation assay showed that the enzyme is located in the cytosol and predominantly distributed in leaf epidermal cells. As expected, oxalate levels increased when OCS was suppressed in RNAi transgenic plants. More interestingly, OCS-suppressed plants were more susceptible to bacterial blight but more resistant to Al toxicity. The results demonstrate that the OsAAE3-encoded protein also acts as an OCS in rice, and may play different roles in coping with stresses. These molecular, enzymatic and functional data provide first-hand information to further clarify the function and mechanism of OCS in rice plants.

[The validity and reliability of simplified Chinese version of the pediatric sleep questionnaire for screening children with obstructive sleep apnea syndrome in Beijing].

Objective: To evaluate the validity and reliability of the simplified Chinese version of pediatric sleep questionnaire (PSQ) used in screening obstructive sleep apnea syndrome (OSAS) of children in Beijing. Methods: Children with snoring who presented to the Sleep Center of Beijing Children's Hospital between August 2014 and July 2015 and healthy children were included in the study. All children underwent PSG and then were divided into OSAS group and control group based on the PSG and their guardians were asked to complete the simplified Chinese version of PSQ that was formed by both translation from PSQ and retroversion to PSQ. Structure validity evaluation included confirmatory factor analysis which used Amos structural equation model and exploratory factor analysis which used principal component analysis. Predictive validity were measured with Logistic regression model. Internal reliability and test-retest reliability were evaluated by Cronbach 's alpha coefficient and intra-class correlation coefficient (ICC), respectively. The screening efficiency was evaluated by the receiver operating characteristic curve (ROC). Results: The study included 235 children aged 3-16 years old, 145 children of them with the age of (5.8±2.1) in OSAS group and 90 children with the age of (7.7±3.3) in control group. Confirmatory factor analysis indicated most items belonging to individual factors with load coefficient ≥ 0.5. Predictive validity analysis revealed 13 items positively related to the diagnosis of OSAS (all OR>1, all P<0.05). Cronbach's alpha coefficients were respectively 0.703 (overall reliability), 0.767 (breathing factor), 0.849 (sleepiness factor) and 0.689 (behavior factor). The test-retest ICC reliability was 0.986 (PSQ), 0.991 (breathing factor), 0.727 (sleepiness factor), and 0.870 (behavior factor) with P<0.05. In receiver operating characteristic curve, the area under curve of simplified Chinese version PSQ score was 0.922 with P<0.05 and the cutoff value of PSQ score was 7 in 22 items with the sensitivity of 0.776, specificity of 0.867, positive predictive value of 0.868 and negative prediction value of 0.774. Conclusions: The simplified Chinese version of PSQ is suitable to the screen of OSAS for the children in Beijing area with good reliability and validity. It also has acceptable sensitivity and specificity for screening children with OSAS when the cutoff score is 7 points.

[The application of Hoffmann method in the establishment of children's reference intervals of erythrocyte count].

OBJECTIVE: To verify the reliability and feasibility of Hoffmann method in establishing pediatric reference intervals (RI) of erythrocyte count. METHODS: Three hundreds and ninty-two thousands of hospital-based data for erythrocyte count of children aged in 1 to 17, measured by the Sysmex Xs-800i, was collected from Beijing Children's Hospital during January to December 2014. Outliers were removed using the Dixon method, then Hoffmann method was conducted to establish the gender and age stratified pediatric RIs of erythrocyte count. The erythrocyte count of 2 217 healthy children, recruited from Beijing Children's Hospital and Liaocheng Children's Hospital in Shandong province, was conducted as normal reference to verify the reliability of Hoffmann method in establishing RIs and to compare with existing RIs. RESULTS: In 4 subgroups as following, male aging 1 to 12 years, male aging 13 to 17 years, female aging 1 to 12 years, female aging 13 to 17 years, the RIs of erythrocyte count established using Hoffmann method were (4.1-5.4)×10(12)/L, (4.4-5.7)×10(12)/L, (4.0-5.3)×10(12)/L, (4.0-5.3)×10(12)/L, respectively. The verification results in 2 217 healthy children showed that the proportions of out of range in four subgroups were 6.17%, 8.81%, 6.22%, 7.78%, respectively. CONCLUSION: Hoffmann method produce reliable RIs according with the actual situation in healthy children, which is also convenient and is worth popularizing in clinical practice.

[Cross-sectional study of family drug stockpile and children medication in China].

OBJECTIVE: To investigate the current situation of family medicine stockpile and children medication in China, analyze the existing problems and provide the rationalized suggestions. METHODS: The questionnaire was designed and convenient sampling survey was performed in 20 children hospitals in China. Descriptive analysis was conducted on the survey results. RESULTS: A total of 13 940 completed questionnaires were returned, 98.33% of the families had medicine stockpile, the top three types of the medicine for children were cold medicine(73.95%), oral paregoric/febrifuge(48.01%)and external used drugs for skin disease(wound)(41.10%). The medicine was bought according to physician's prescription and guide(71.18%). Drug poisoning occurred in children of 238 families(1.71%), overdose use was the first cause(44.96%). 22.33% of the parents didn't read the specification carefully before medicine use. The non-appropriate medication for children were mainly the use of adult medicine(32.70%), untimely medication(30.90%), non-rational or unneeded use of febrifuge(26.35%). CONCLUSIONS: In China, the families mainly store common medicine for their children. The parents bought medicine mainly according to physician' s prescription and paid attention to the safety and efficiency of the medicine, but non-appropriate use of medicine was still common. It is necessary to improve the rational use of medicine for children through expert counsel and guidance.

Episodic sucrose intake during food restriction increases synaptic abundance of AMPA receptors in nucleus accumbens and augments intake of sucrose following restoration of ad libitum feeding.

Weight-loss dieting often leads to loss of control, rebound weight gain, and is a risk factor for binge pathology. Based on findings that food restriction (FR) upregulates sucrose-induced trafficking of glutamatergic AMPA receptors to the nucleus accumbens (NAc) postsynaptic density (PSD), this study was an initial test of the hypothesis that episodic "breakthrough" intake of forbidden food during dieting interacts with upregulated mechanisms of synaptic plasticity to increase reward-driven feeding. Ad libitum (AL) fed and FR subjects consumed a limited amount of 10% sucrose, or had access to water, every other day for 10 occasions. Beginning three weeks after return of FR rats to AL feeding, when 24-h chow intake and rate of body weight gain had normalized, subjects with a history of sucrose intake during FR consumed more sucrose during a four week intermittent access protocol than the two AL groups and the group that had access to water during FR. In an experiment that substituted noncontingent administration of d-amphetamine for sucrose, FR subjects displayed an enhanced locomotor response during active FR but a blunted response, relative to AL subjects, during recovery from FR. This result suggests that the enduring increase in sucrose consumption is unlikely to be explained by residual enhancing effects of FR on dopamine signaling. In a biochemical experiment which paralleled the sucrose behavioral experiment, rats with a history of sucrose intake during FR displayed increased abundance of pSer845-GluA1, GluA2, and GluA3 in the NAc PSD relative to rats with a history of FR without sucrose access and rats that had been AL throughout, whether they had a history of episodic sucrose intake or not. A history of FR, with or without a history of sucrose intake, was associated with increased abundance of GluA1. A terminal 15-min bout of sucrose intake produced a further increase in pSer845-GluA1 and GluA2 in subjects with a history of sucrose intake during FR. Generally, neither a history of sucrose intake nor a terminal bout of sucrose intake affected AMPA receptor abundance in the NAc PSD of AL subjects. Together, these results are consistent with the hypothesis, but the functional contribution of increased synaptic incorporation of AMPA receptors remains to be established.

Mapping p53 mutations in low-grade glioma: a voxel-based neuroimaging analysis.

BACKGROUND AND PURPOSE: Brain tumor location has proved to be a prognostic factor that may be associated with features of neoplastic origin. Mutation of p53 is an atypical genetic change that occurs during tumorigenesis. Thus, a potential correlation may exist between tumor location and p53 status. The purpose of the current study was to identify anatomic characteristics of mutant p53 expression by using quantitative neuroimaging analyses. MATERIALS AND METHODS: Preoperative MR images from 182 patients with histologically confirmed low-grade gliomas were retrospectively analyzed. All tumors were manually marked and registered to the standard space. Using a voxel-based lesion-symptom mapping analysis, we located brain regions associated with a high occurrence of p53 mutation and corrected them by using a permutation test. The acquired clusters were further included as a factor in survival analyses. RESULTS: Statistical analysis demonstrated that the left medial temporal lobe and right anterior temporal lobe were specifically associated with high expression of mutant p53. Kaplan-Meier curves showed that tumors located in these regions were associated with significantly worse progression-free survival compared with tumors occurring elsewhere. CONCLUSIONS: Our voxel-level imaging analysis provides new evidence that genetic changes during cancer may have anatomic specificity. Additionally, the current study suggests that tumor location identified on structural MR images could potentially be used for customized presurgical outcome prediction.

Biodegradation of nicotine by newly isolated Pseudomonas sp. CS3 and its metabolites.

AIMS: Isolation and characterization of nicotine-degrading bacteria with advantages suitable for the treatment of nicotine-contaminated water and soil and detection of their metabolites. METHODS AND RESULTS: A novel nicotine-degrading bacterial strain was isolated from tobacco field soil. Based on morphological and physiochemical properties and sequence of 16S rDNA, the isolate was identified as Pseudomonas sp., designated as CS3. The optimal culture conditions of strain CS3 for nicotine degradation were 30°C and pH 7·0. However, the strain showed broad pH adaptability with high nicotine-degrading activity between pH 6·0 and 10·0. Strain CS3 could decompose nicotine nearly completely within 24 h in liquid culture (1000 mg L(-1) nicotine) or within 72 h in soil (1000-2500 mg kg(-1) nicotine) and could endure up to 4000 mg L(-1) nicotine in liquid media and 5000 mg kg(-1) nicotine in soil. Degradation tests in flask revealed that the strain had excellent stability and high degradation activity during the repetitive degradation processes. Additionally, three intermediates, 3-(3,4-dihydro-2H-pyrrol-5-yl) pyridine, 1-methyl-5-(3-pyridyl) pyrrolidine-2-ol and cotinine, were identified by GC/MS and NMR analyses. CONCLUSIONS: The isolate CS3 showed outstanding nicotine-degrading characteristics such as high degradation efficiency, strong substrate endurance, broad pH adaptability, and stability and persistence in repetitive degradation processes and may serve as an excellent candidate for applications in the bioaugmentation process to treat nicotine-contaminated water and soil. Also, detection of nicotine metabolites suggests that strain CS3 might decompose nicotine via a unique nicotine-degradation pathway. SIGNIFICANCE AND IMPACT OF THE STUDY: The advantage of applying the isolated strain lies in broad pH adaptability and stability and persistence in repetitive use, the properties previously less focused in other nicotine-degrading micro-organisms. The strain might decompose nicotine via a nicotine-degradation pathway different from those of other nicotine-utilizing Pseudomonas bacteria reported earlier, another highlight in this study.

Immunocapture UPPCR combined with DGGE for rapid detection of Shigella species.

AIMS: To develop an immunocapture universal primer PCR (iUPPCR) combined with denaturing gradient gel electrophoresis (DGGE) and evaluate it as a method permitting rapid detection of Shigella species and their serotypes. METHODS AND RESULTS: This method amplifying the conserved regions of bacterial 16S rRNA genes of different species or serotypes of Shigella dysentery bacilli captured and enriched by polyvalent antibodies can detect and distinguish causative pathogens rapidly. Four serotypes from three Shigella species including Shigella dysenteriae serotype 1, Shigella boydii serotype 1, Shigella flexneri serotypes 1a and 3a were examined. CONCLUSION: Our approach could be adopted for not only axenic bacterial population but also mixed communities and achieve rapid detection of various bacteria from the same genus or species in one sample. SIGNIFICANCE AND IMPACT OF THE STUDY: The iUPPCR-DGGE method was shown to be more convenient than serotype-specific-antibody-based method of iUPPCR for Shigella species detection and it could be also applied to the quick detection for other kinds of pathogens with many serotypes.

Analysis of complement-bound hepatitis B virus complexes by an immuno-capture polymerase chain reaction method.

Hepatitis B Virus (HBV) can be present in the circulating blood either as a free virus or as a virion-immunoglobulin (Ig) complex with or without complement. However, information regarding the complement-bound HBV circulating immune complexes (CIC) in HBV-infected patients is currently not available. In the present study, we have combined immuno-capture and polymerase chain reaction (PCR) and developed a quick method of high specificity for the detection of complement-bound HBV CIC. We found that the frequency of HBV-factor B was associated with clinical types of hepatitis B (HB) but not with that of HBV-C1q. Moreover, increased frequency at P < 0.05 were found for HBV/C1q-CIC in the group with normal total bilirubin (TBIL) and for HBV/factor B-CIC in the group with positive hepatitis B e antigen (HBeAg). These findings suggest that the immuno-capture PCR (iPCR) for the detection of HBV-bound CIC is a valuable method for analysis of the composition of the immune complexes and for the understanding of host immune response and immune pathogenesis in HBV-infected individuals. In summary, iPCR is a valuable method for analysis of the composition of the immune complexes, which may provide new and valuable insights into HBV pathogenesis.

Analysis of hepatitis B virus-immunoglobulin isotype complexes by a novel immuno-capture polymerase chain reaction method.

Hepatitis B virus (HBV) can be present in the circulating blood either as free virus or as a virion-immunoglobulin (Ig) complex. Presently, it remains unclear what specific role each Ig plays in the clearance of HBV. In this study, a novel method that combined immuno-capture and polymerase chain reaction (PCR) amplification was used for detecting and distinguishing different HBV-Ig complexes. Three isotypes of Ig (IgM, IgG and IgA) bound to HBV were detected in the four clinically defined stages of HBV infection in 108 patients. The results showed that all the three isotypes of Ig could bind to HBV, and the patterns of HBV-Ig complexes varied according to disease categories. Interestingly, the frequency of HBV DNA-Ig complexes in hepatitis B e antigen (HBeAg)-positive patients was significantly lower than that in HBeAg-negative patients. All the data suggest that the three isotypes of HBV DNA-Ig circulating immune complex (CIC) may have different biological meanings. In summary, HBV bound to an antibody is a common feature of hepatitis B, and immuno-capture PCR is a valuable method for the analysis of the composition of the immune complexes. The detection of HBV-Ig complexes may provide new and valuable insights into HBV pathogenesis.

Analysis of complement-bound HCV complexes using a novel immuno-capture RT-PCR method.

Recently, more and more evidence has supported the hypothesis that liver cell injury was immune-mediated in patients with hepatitis C virus (HCV) infection, and that circulating immune complexes (CICs) might play a role in the pathogenesis of chronic hepatitis C (HC). In the present study, we have combined immuno-capture and reverse transcriptase-polymerase chain reaction (RT-PCR), and developed a quick method of high specificity for the detection of complement-bound HCV-CIC. We found that there were higher frequencies of HCV-C1q CIC than that of HCV-factor B, and there was a deviation of complement from immunoglobulin (Ig) in HCV-CIC. These findings suggest that immuno-capture RT-PCR (iRT-PCR) for the detection of HCV-bound CIC is a valuable method for the analysis of the composition of the immune complexes, and for the understanding of host immune response and immune pathogenesis in HCV-infected individuals.

Analysis of HCV-immunoglobulin isotype complexes provide new insights into antibody response to HCV.

Hepatitis C virus (HCV) is known for its ability to establish persistent infection and cause chronic hepatitis in most infected individuals. The antibody response to HCV in HCV-circulating immune complexes (CIC) is unknown. In the present study, we have characterized distinct changes in patterns of HCV-immunoglobulin (Ig) constituents with disease category, viral mutation and clinical markers. The number of samples positive for single HCV-Ig, HCV-IgG and HCV-IgA, HCV-IgM and HCV-IgA, HCV-IgM and HCV-IgG, HCV-IgM, HCV-IgG and HCV-IgA in 47 samples tested were 8 (17%), 1 (2.1%), 9 (19.1%), 4 (8.5%) and 17 (36.2%), respectively. The occurrence of HCV-IgM and HCV-IgA in combination of two isotypes of HCV-Ig became predominant. These results show that defective IgG in HCV-CIC may contribute to long-term viremia. Further analysis indicated that the frequency of HCV RNA/IgA-CIC in the abnormal aspartic aminotransferase (AST) group was significantly higher than that of the normal AST group, and HCV RNA/IgA-CIC frequency in the abnormal alanine aminotransferase (ALT) group was slightly higher than that in the normal ALT group. IgA complexes may reflect the damage degree of liver function during the course of HCV infection. We also found that there were more mutations in supernatant than in other constituents from single-strand conformation polymorphism (SSCP) analysis. Our results suggest that Ig-complexed virions and free virions may have different biological consequences, with the latter being elusive to immunological elimination. The findings in this study may provide some new insights into antibody response to HCV.