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OBJECTIVE@#To analyze the efficacy of Biejiajian Pill (BJJP) on intestinal microbiota in patients with hepatitis B cirrhosis/liver fibrosis, and explore its relationship with liver fibrosis.@*METHODS@#This was a prospective, randomized double-blind controlled trial. Using the stratified block randomization method, 35 patients with hepatitis B liver cirrhosis/liver fibrosis were randomly assigned (1:1) to receive entecavir (0.5 mg/d) combined with BJJP (3 g/time, 3 times a day) or placebo (simulator as control, SC group, simulator 3 g/time, 3 times a day) for 48 weeks. Blood and stool samples were collected from patients at baseline and week 48 of treatment, respectively. Liver and renal functions as well as hematological indices were detected. Fecal samples were analyzed by 16S rDNA V3-V4 high-throughput sequencing, and intestinal microbiota changes in both groups before and after treatment were compared, and their correlations with liver fibrosis were analyzed.@*RESULTS@#Compared with the SC group, there was no significant difference in liver function, renal function and hematology indices in the BJJP group, however, the improvement rate of liver fibrosis was higher in the BJJP group (94.4% vs. 64.7%, P=0.041). Principal coordinate analysis (PCoA) based on weighted Unifrac distance showed significant differences in intestinal microbiota community diversity before and after BJJP treatment (P<0.01 and P=0.003), respectively. After 48 weeks' treatment, the abundance levels of beneficial bacteria (Bifidobacteria, Lactobacillus, Faecalibacterium and Blautia) increased, whereas the abundance levels of potential pathogenic bacteria, including Escherichia coli, Bacteroides, Ruminococcus, Parabacteroides and Prevotella decreased, among which Ruminococcus and Parabacteroides were significantly positively correlated with degree of liver fibrosis (r=0.34, P=0.04; r=0.38, P=0.02), respectively. The microbiota in the SC group did not change significantly throughout the whole process of treatment.@*CONCLUSION@#BJJP had a certain regulatory effect on intestinal microbiota of patients with hepatitis B cirrhosis/liver fibrosis (ChiCTR1800016801).
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Humanos , Microbioma Gastrointestinal , Estudios Prospectivos , Cirrosis Hepática/tratamiento farmacológico , Hepatitis B/tratamiento farmacológicoRESUMEN
Background@#Cytokines play an important role in occurrence and recovery of hepatitis B virus (HBV) infection. The aim of this study was to investigate the changes of cytokines concentration and its correlation to alanine aminotransferase (ALT), HBV deoxyribonucleic acid (HBV-DNA), hepatitis B envelope antigen (HBeAg), and HBV surface antigen (HBsAg) in the development of chronic hepatitis B (CHB).@*Methods@#Thirteen healthy individuals (HI), 30 chronic HBV-infected patients in immune tolerant (IT) phase, and 55 CHB patients were enrolled between August 2015 and May 2017. The peripheral blood samples were collected from all individuals. The levels of interferon (IFN)-α2, interleukin (IL)-10, transforming growth factor (TGF)-β1, HBV-DNA, HBsAg, and HBeAg and liver function were measured. The quantitative determinations of cytokines levels, including IFN-α2, IL-10, and TGF-β1 were performed using Luminex multiplex technology. The correlation of cytokines to ALT, HBV-DNA, HBsAg, and HBeAg was analyzed by linear regression analysis.@*Results@#IFN-α2 levels were similar between HI and IT groups (15.35 [5.70, 67.65] pg/ml vs. 15.24 [4.07, 30.73] pg/ml, Z = -0.610, P = 0.542), while it elevated significantly in CHB group (35.29 [15.94, 70.15] pg/ml vs. 15.24 [4.07, 30.73] pg/ml; Z = -2.522, P = 0.012). Compared with HI group (3.73 [2.98, 11.92] pg/ml), IL-10 concentrations in IT group (5.02 [2.98, 10.11] pg/ml), and CHB group (7.48 [3.10, 18.00] pg/ml) slightly increased (χ = 2.015, P = 0.365), and there was no significant difference between IT and CHB group (Z = -1.419, P = 0.156). The TGF-β1 levels among HI (3.59 ± 0.20 pg/ml), IT (3.62 ± 0.55 pg/ml), and CHB groups (3.64 ± 0.30 pg/ml) were similar (χ = 2.739, P = 0.254). In all chronic HBV-infected patients (including patients in IT and CHB groups), the elevation of IFN-α2 level was significantly associated with ALT level (β= 0.389, t = 2.423, P = 0.018), and was also negatively correlated to HBV-DNA load (β = -0.358, t = -2.308, P = 0.024), HBsAg (β = -0.359, t = -2.288, P = 0.025), and HBeAg contents (β = -0.355, t = -2.258, P = 0.027). However, when both ALT level and cytokines were included as independent variable, HBV-DNA load, HBsAg, and HBeAg contents were only correlated to ALT level (β = -0.459, t = -4.225, P = 0.000; β = -0.616, t = -6.334, P = 0.000; and β = -0.290, t = -2.433, P = 0.018; respectively).@*Conclusions@#IFN-α2 elevation was associated with ALT level in patients with chronic HBV infection. However, in CHB patients, only ALT level was correlated to HBV-DNA, HBsAg and HBeAg contents.
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Adulto , Femenino , Humanos , Masculino , Adulto Joven , Alanina Transaminasa , Sangre , Antígenos de Superficie , Estudios de Casos y Controles , Citocinas , Sangre , ADN Viral , Hepatitis B , Antígenos de Superficie de la Hepatitis B , Antígenos e de la Hepatitis B , Virus de la Hepatitis B , Hepatitis B Crónica , Sangre , Alergia e InmunologíaRESUMEN
<p><b>BACKGROUND</b>Plasmacytoid dendritic cells (pDCs) and cytokines play an important role in occurrence and recovery of hepatitis B virus (HBV) infection. The aim of this study was to explore the frequency and function of pDC and serum cytokine network profiles in patients with acute or chronic HBV infection.</p><p><b>METHODS</b>The healthy individuals (HI group), hepatitis B envelope antigen (HBeAg)-positive chronic HBV patients in immune tolerance (IT) phase (IT group), HBeAg-positive chronic HBV patients (CHB group), and acute HBV patients (AHB group) were enrolled in this study. The frequency of cluster of differentiation antigen 86 (CD86) + pDC and the counts of CD86 molecular expressed on surface of pDC were tested by flow cytometer. The quantitative determinations of cytokines, including Fms-like tyrosine kinase 3 ligand (Flt-3L), interferon (IFN)-α2, IFN-γ, interleukin (IL)-17A, IL-6, IL-10, transforming growth factor (TGF)-β1 and TGF-β2, were performed using Luminex multiplex technology.</p><p><b>RESULTS</b>In this study, there were 13 patients in HI group, 30 in IT group, 50 in CHB group, and 32 in AHB group. Compared with HI group, HBV infected group (including all patients in IT, CHB and AHB groups) had significantly higher counts of CD86 molecular expressed on the surface of pDC (4596.5 ± 896.5 vs. 7097.7 ± 3124.6; P < 0.001). The counts of CD86 molecular expressed on the surface of pDC in CHB group (7739.2 ± 4125.4) was significantly higher than that of IT group (6393.4 ± 1653.6, P = 0.043). Compared with IT group, the profile of cytokines of Flt-3L, IFN-γ, and IL-17A was decreased, IFN-α2 was significantly increased (P = 0.012) in CHB group. The contents of IL-10, TGF-β1, and TGF-β2 in AHB group were significantly increased compared with IT and CHB groups (all P < 0.05).</p><p><b>CONCLUSIONS</b>This study demonstrated that the function of pDC was unaffected in HBV infection. The enhanced function of pDC and IFN-α2 might involve triggering the immune response from IT to hepatitis active phase in HBV infection. Acute patients mainly presented as down-regulation of the immune response by enhanced IL-10 and TGF-β.</p>
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<p><b>BACKGROUND</b>Hepatitis B is an immune response-mediated disease. The aim of this study was to explore the differences of ratios of T-helper (Th) 2 cells to Th1 cells and cytokine levels in acute hepatitis B (AHB) patients and chronic hepatitis B virus (HBV)-infected patients in immune-tolerance and immune-active phases.</p><p><b>METHODS</b>Thirty chronic HBV-infected patients in the immune-tolerant phase (IT group) and 50 chronic hepatitis B patients in the immune-active (clearance) phase (IC group), 32 AHB patients (AHB group), and 13 healthy individuals (HI group) were enrolled in the study. Th cell proportions in peripheral blood, cytokine levels in plasma, and serum levels of HBV DNA, hepatitis B surface antigen, and hepatitis B e antigen were detected.</p><p><b>RESULTS</b>The Th1 cell percentage and Th2/Th1 ratio in the HBV infection group (including IT, IC, and AHB groups) were significantly different from those in HI group (24.10% ± 8.66% and 1.72 ± 0.61 vs. 15.16% ± 4.34% and 2.40 ± 0.74, respectively; all P < 0.001). However, there were no differences in the Th1 cell percentages and Th2/Th1 ratios among the IT, IC, and AHB groups. In HBV infection group, the median levels of Flt3 ligand (Flt3L), interferon (IFN)-γ, and interleukin (IL)-17A were significantly lower than those in HI group (29.26 pg/ml, 33.72 pg/ml, and 12.27 pg/ml vs. 108.54 pg/ml, 66.48 pg/ml, and 35.96 pg/ml, respectively; all P < 0.05). IFN-α2, IL-10, and transforming growth factor (TGF)-β2 median levels in hepatitis group (including patients in AHB and IC groups) were significantly higher than those in IT group (40.14 pg/ml, 13.58 pg/ml, and 557.41 pg/ml vs. 16.74 pg/ml, 6.80 pg/ml, and 419.01 pg/ml, respectively; all P < 0.05), while patients in hepatitis group had significant lower Flt3L level than IT patients (30.77 vs. 59.96 pg/ml, P = 0.021). Compared with IC group, patients in AHB group had significant higher median levels of IL-10, TGF-β1, and TGF-β2 (22.77 pg/ml, 10,447.00 pg/ml, and 782.28 pg/ml vs. 8.66 pg/ml, 3755.50 pg/ml, and 482.87 pg/ml, respectively; all P < 0.05).</p><p><b>CONCLUSIONS</b>Compared with chronic HBV-infected patients in immune-tolerance phase, chronic HBV-infected patients in immune-active phase and AHB patients had similar Th2/Th1 ratios, significantly higher levels of IFN-α2, IL-10, and TGF-β. AHB patients had significantly higher IL-10 and TGF-β levels than chronic HBV-infected patients in immune-active phase.</p>
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<p><b>OBJECTIVE</b>The aim of this study was to explore the frequency of mDC and pDC and expression of surface markers of the neonates and to discuss the effect of different status of HBV infection of mother on biological characteristics of DC.</p><p><b>METHODS</b>Umbilicus cord blood in neonates of HBeAg positive HBV infected mother, HBeAg negative HBV infected mother, and normal mother were collected respectively; peripheral blood of healthy adults were selected as control group. Flow cytometry was employed to detect frequency of the mDC and its expression of CD86, frequency of pDC and its expression of CD80, CD83, CD86, and FlowJo software was used to compare these indicators among the groups.</p><p><b>RESULTS</b>Compared with control group, the frequency of mDC of cord blood (0.29 +/- 0.16 vs 0.81 +/- 0.17), CD86 positive rate of mDC (10.72 +/- 10.01 vs 32.13 +/- 7.46), the frequency of pDC (0.15 +/- 0.07 vs 0.30 +/- 0.07), and CD86/CD83 positive rate of pDC (31.61 +/- 12.81 vs 74.96 +/- 9.78; 42.66 +/- 20.83 vs 82.00 +/- 6.94) were lower (t = -7.86, P = 0.00; t = -5.36, P = 0.00; t = -5.43, P = 0.00; t = -8.49. P = 0.00; t = -4.90, P = 0.00).</p><p><b>CONCLUSIONS</b>The frequency of mDC and pDC in umbilical cord blood was lower than the peripheral blood of healthy adult, which was the possible mechanism of newborns easier to chronicity after the infection of hepatitis B virus. A significant correlation was found between different status of HBV infection and costimulatory molecule CD86 positive rate of mDC, but not for the frequency of mDC and pDC, and the expression of pDC molecules.</p>
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Adulto , Femenino , Humanos , Recién Nacido , Embarazo , Antígeno B7-2 , Células Dendríticas , Alergia e Inmunología , Sangre Fetal , Alergia e Inmunología , Hepatitis B Crónica , Alergia e Inmunología , Complicaciones Infecciosas del Embarazo , Alergia e InmunologíaRESUMEN
<p><b>OBJECTIVE</b>To elucidate the change in frequencies and functions of myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) before and after interferon-alpha therapy for chronic hepatitis B (CHB) patients, and its correlation with virological and biochemical data.</p><p><b>METHODS</b>Thirty patients with HBeAg-positive CHB who underwent IFN-alpha therapy were examined. Frequencies and expression of CD86 of mDC and pDC of peripheral blood were measured at baseline and treatment week (TW) 12 by flow cytometry. According to biochemical and virological parameters, the 30 patients were divided into ALT normalized group, ALT non-normalized group and virological responder group, virological non-responder group respectively. Statistical analysis of DC changes among different groups at baseline and TW12 was proceeded.</p><p><b>RESULTS</b>(1) In the ALT normalized group, the pDC frequency at TW12 (0.25 +/- 0.14%) was higher than that at baseline (0.18 +/- 0.09%) (P = 0.023); in the ALT non-normalized group, the mDC frequency (0.58 +/- 0.34%) and its surface CD86 expression (61.80 +/- 22.52%) decreased significantly as compared with baseline (0.88 +/- 0.51%, 79.92 +/- 25.94%, respectively), (P = 0.025, P = 0.036, respectively). (2) In the virological responder group, the CD86 expression on pDC at TW12 (46.86 +/- 12.22%) was higher than that at baseline (29.42 +/- 15.16%) (P = 0.002); in the virological non-responder group, the mDC frequency (0.51 +/- 0.22%) and its surface CD86 expression (59.63 +/- 22.94% ) decreased significantly as compared with baseline (0.94 +/- 0.58%, 80.11 +/- 29.34%, respectively), (P = 0.006; P = 0.049, respectively).</p><p><b>CONCLUSION</b>In IFN-alpha therapy for CHB patients, the increments of pDC frequency and function were related to biochemical and viral response, and decreases of mDC frequency and function were related to non-biochemical and non-viral response.</p>
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Adulto , Femenino , Humanos , Masculino , Alanina Transaminasa , Sangre , Antígeno B7-2 , Células Dendríticas , Fisiología , Hepatitis B Crónica , Quimioterapia , Alergia e Inmunología , Virología , Interferón-alfa , Usos Terapéuticos , Resultado del TratamientoRESUMEN
<p><b>OBJECTIVE</b>The aim of this study is to explore the cytotoxic effect of CD8+ T subsets in peripheral blood with chronic hepatitis B subjects who are at immune tolerance phase and immune clearance phase (before and after three months' treatment with interferon-alpha), further to investigate their impact in the pathogenesis of chronic hepatitis B and antiviral therapy.</p><p><b>METHODS</b>The subjects of chronic hepatitis B, including 20 subjects of immune tolerance phase and 20 subjects of immune clearance phase, are enrolled in the study. And we use flow cytometry to detect Lysosome-associated membrane protein-1 (LAMP-1, CD107a) and Granzyme B (GrB) expression of CD8(high) and CD8(low) T cells in peripheral blood with chronic hepatitis B subjects.</p><p><b>RESULTS</b>(1) At immune clearance phase, the CD8+ T subsets expressing GrB and CD107a are higher than counterpart of immune tolerance phase. (2) At immune tolerance phase and immune clearance phase in HBV infection, the CD8(low) T cells expressing GrB and CD107a are higher than that of CD8(high) T cells. (3) After three months' treatment with interferon-a, except for GrB+ CD107a+ CD8(high) T cells, CD8(high) T cells expressing GrB and CD107a present a tendency of ascensus at the same time with that of CD8(low) T cells a tendency of descensus except for GrB(-)CD107a+ CD8(low) T cells. (4) The CD8+ T cell expressing GrB and CD107a, correlate positively with HBV DNA load at immune tolerance phase, but correlated negatively at immune clearance phase.</p><p><b>CONCLUSIONS</b>(1) GrB and CD107a molecule expressed by different CD8+ T cell subsets play an important role in disease evolution and antivirus therapy of chronic hepatitis B, the cytotoxic effect of CD8(high) T cell subset became more and more stronger during the treatment of IFN-alpha, and the cytotoxic effect of CD8(low) T cell subset couldn't be neglected before antivirus therapy. (2) To some degree, the correlation between HBV-DNA load and the expression of GrB and CD107a at different CD8+ T cell subsets, could hint the relationship between virus and immune response.</p>
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Femenino , Humanos , Masculino , Alanina Transaminasa , Sangre , Linfocitos T CD8-positivos , Alergia e Inmunología , Citotoxicidad Inmunológica , Granzimas , Hepatitis B Crónica , Alergia e Inmunología , Proteína 1 de la Membrana Asociada a los LisosomasRESUMEN
<p><b>OBJECTIVE</b>To investigate the level of CD4+ CD25+ Foxp3+ regulatory T cells and observe relation between expression of Foxp3 and CD127 in peripheral blood of chronic HBV infection.</p><p><b>METHODS</b>CD4+ CD25+ Foxp3+ and CD4+ CD25+ CD127low Treg in peripheral blood from 34 patients of immune tolerance stage, 26 patients of immune clearance stage and 31 patients of non-active status were quantitatively analyzed by flow cytometry.</p><p><b>RESULTS</b>Immune tolerance group presented a higher fraction of CD4+ CD25+ Foxp3+ and CD4+ CD25+ CD127low Treg than non-active group in chronic HBV infection (Z = -2.693, P = 0.007 and t = 3.251, P = 0.002), and HBV positive group also presented a higher fraction than non-active group (t = 2.266, P = 0.026 and t = 3.208, P = 0.002), But ALT normal group is similar to ALT abnormal group (P > 0.05). In this study, the relation between expression of CD127low and Foxp3+ from CD4+ CD25+ regulatory T cells was observed, and CD4+ CD25+ CD127low Treg presented a higher fraction than CD4+ CD25+ Foxp3+ Treg.</p><p><b>CONCLUSION</b>Peripheral Treg in HBV active replication group is higher than HBV negative group of chronic HBV infection. Expression of CD127low is consistent with Foxp3+ in CD4+ CD25+ regulatory T cells, but the former is significantly higher than the latter.</p>
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Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Factores de Transcripción Forkhead , Sangre , Genética , Alergia e Inmunología , Virus de la Hepatitis B , Alergia e Inmunología , Hepatitis B Crónica , Genética , Alergia e Inmunología , Virología , Subunidad alfa del Receptor de Interleucina-2 , Sangre , Alergia e Inmunología , Subunidad alfa del Receptor de Interleucina-7 , Sangre , Genética , Alergia e Inmunología , Linfocitos T Reguladores , Alergia e InmunologíaRESUMEN
<p><b>OBJECTIVE</b>Analyzing the relationships between peripheral blood CD4+ CD25hi regulatory T (Treg) cells and peripheral blood immune status or plasma HIV-lviral load in HIV-infected individuals,so as to determine whether Treg were related to the progression of HIV-infected disease.</p><p><b>METHODS</b>116 HIV-infected patients in different stages and 21 healthy control individuals were included in this study. The CD4+ and CD8+ T cell counts were determined by a standard 4-color flow cytometry technique. The Treg cells were examined with 3-color immune staining flow cytometry. The plasma HIV-1 viral load was detected by real time PCR.</p><p><b>RESULTS</b>The frequencies of Treg cells decreased in HIV-infected individuals with high CD4+ T cell counts( > 300/microl) compared with normal controls. With the progression of disease the frequencies of Treg cells were raised gradually, until were increased in HIV-infected individuals with low levels of CD4+ T cell counts ( < 100/microl). In addition, the frequencies of Treg cells were inversely related to CD4+ T cell counts and CD4+ /CD8+ ratio, data showed a statistically significant (respectively, r = -0.564, P < 0.001; r = -0.377, P < 0.001). Furthermore, the proportions of Treg cells were closely related to plasma HIV-1 RNA viral load (r = 0.514, P < 0.001).</p><p><b>CONCLUSION</b>CD4 CD25hi Treg cells should be a kind of important cells participating the immunopathogenesis of AIDS. It may play different roles in different stages of HIV-infected disease. The exact mechanism of Treg cells in the progression of the HIV-infected disease needs to be investigate further.</p>
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Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios de Casos y Controles , Células Cultivadas , Progresión de la Enfermedad , Infecciones por VIH , Alergia e Inmunología , Patología , Virología , VIH-1 , Genética , Alergia e Inmunología , Subunidad alfa del Receptor de Interleucina-2 , Alergia e Inmunología , Linfocitos T Reguladores , Alergia e Inmunología , Carga ViralRESUMEN
<p><b>OBJECTIVE</b>A hepatitis B immunogenic complex therapeutic vaccine, yeast-derived recombinant HBsAg combined with human anti-HBs immunoglobulin (YIC), was evaluated for safety and immune response in phase I clinical trial.</p><p><b>METHODS</b>The subtypes IgG1, IgG2, IgG3 and IgG4 of serum anti-HBs collected from 20 immunized subjects were analyzed by ELISA. The lymphocyte proliferation assay was carried out in five subjects and was analyzed by 3H-thymidine incorporation. The assays for IFNgamma, IL-2, IL-4, IL-6, IL-10 and TNFalpha were measured using Human Cytometric Bead Array Kit with FACSCalibur.</p><p><b>RESULTS</b>The results showed that the subtypes of anti-HBs antibodies induced by 30, 60 and 90 microg YIC-immunized groups among all of the adult volunteers (20/20) were IgG1 and IgG3. The level of IgG1 was higher than that of IgG3 in each volunteer but the strength was different from each other. The rHBsAg-stimulated lymphocyte proliferation induced by three injections of 90 microg of YIC showed that the stimulation index was more than 2.0 in four out of the five individuals (4/5), ranging from 2.70 to 4.75. PHA-stimulated lymphocyte proliferation was not related to rHBsAg-stimulated lymphocyte proliferation. In the 60 microg YIC-immunized group there was no significant difference between the levels of IFNgamma, IL-2, IL-4, IL-6 and IL-10 at day 0 and day 42. At day 71, in comparison to day 0, the level of IFNgamma was higher in all eight subjects studied (P = 0.015) and the level of IL-2 was also increased in seven out of eight subjects (P = 0.002). In contrast, the levels of IL-4, IL-6, IL-10 and TNFalpha showed no significant difference in all the subjects (P-values: 0.298, 0.976, 0.202 and 0.996).</p><p><b>CONCLUSION</b>Our results indicate that this hepatitis B immunogenic complex therapeutic vaccine (YIC) can induce a potent anti-HBs response.</p>
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Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Hepatitis B , Alergia e Inmunología , Terapéutica , Anticuerpos contra la Hepatitis B , Alergia e Inmunología , Antígenos de Superficie de la Hepatitis B , Alergia e Inmunología , Vacunas contra Hepatitis B , Alergia e Inmunología , Usos Terapéuticos , Inmunoglobulina G , Alergia e Inmunología , Proteínas Recombinantes , Alergia e Inmunología , Usos Terapéuticos , Vacunación , Vacunas Sintéticas , Alergia e Inmunología , Usos TerapéuticosRESUMEN
<p><b>BACKGROUND</b>The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) includes sequences encoding the putative protein X4 (ORF8, ORF7a), consisting of 122 amino acids. The deduced sequence contains a probable cleaved signal peptide sequence and a C-terminal transmembrane helix, indicating that protein X4 is likely to be a type I membrane protein. This study was conducted to demonstrate whether the protein X4 was expressed and its essential function in the process of SARS-CoV infection.</p><p><b>METHODS</b>The prokaryotic and eukaryotic protein X4-expressing plasmids were constructed. Recombinant soluble protein X4 was purified from E. coli using ion exchange chromatography, and the preparation was injected into chicken for rising specific polyclonal antibodies. The expression of protein X4 in SARS-CoV-infected Vero E6 cells and lung tissues from patients with SARS was performed using immunofluorescence assay and immunohistochemistry technique. The preliminary function of protein X4 was evaluated by treatment with and over-expression of protein X4 in cell lines. Western blot was employed to evaluate the expression of protein X4 in SARS-CoV particles.</p><p><b>RESULTS</b>We expressed and purified soluble recombinant protein X4 from E.coli, and generated specific antibodies against protein X4. Western blot proved that the protein X4 was not assembled in the SARS-CoV particles. Indirect immunofluorescence assays revealed that the expression of protein X4 was detected at 8 hours after infection in SARS-CoV-infected Vero E6 cells. It was also detected in the lung tissues from patients with SARS. Treatment with and overexpression of protein X4 inhibited the growth of Balb/c 3T3 cells as determined by cell counting and MTT assays.</p><p><b>CONCLUSION</b>The results provide the evidence of protein X4 expression following SARS-CoV infection, and may facilitate further investigation of the immunopathological mechanism of SARS.</p>