Evaluating the scope of human leukocyte antigen polymorphisms influencing hepatitis B virus-related liver cancer and cirrhosis through multi-clustering analysis

Hepatitis B virus remains a major cause of cirrhosis and hepatocellular carcinoma,with genetic polymorphisms and mutations influencing immune responses and disease progression.Nguyen et al present novel findings on specific human leukocyte antigen(HLA)alleles,including rs2856718 of HLA-DQ and rs3077 and rs9277535 of HLA-DP,which may predispose individuals to cirrhosis and liver cancer,based on multi-clustering analysis.Here,we discuss the feasibility of this approach and identify key areas for further investigation,aiming to offer insights for advancing clinical practice and research in liver disease and related cancers.

Hepatitis C virus-related mixed cryoglobulinemia: Is genetics to blame?

Mixed cryoglobulinemia(MC)is the extrahepatic manifestation most strictly correlated with hepatitis C virus(HCV)infection;it is a benign autoimmune and lymphoproliferative disorder that evolves to lymphoma in5%-10%of cases.MC is reputed to be a multistep and multifactorial process whose pathogenicity is still poorly understood.It is still unknown why only some chronically infected HCV patients develop MC and only some of these exhibit systemic symptoms(MC syndrome).Several studies have investigated the pathogenetic basis of MC and the most recent ones suggest that the virus is able to trigger such a disorder only in the presence of genetic factors that are still unknown.Here,we try to clarify the complex relationship between HCVrelated MC and the host’s genetic background.The data that we report are heterogeneous and sometimes even conflicting.Therefore,large,multicenter studies are clearly needed.The identification of a characteristic genetic signature of cryoglobulinemic patients would be an important step toward a personalized approach in their clinical care.The new wide-ranging genomics technologies will hopefully help to resolve these complex issues.

Autoimmune hepatitis and primary sclerosing cholangitis after direct-acting antiviral treatment for hepatitis C virus:A case report

BACKGROUND Chronic hepatitis C virus(HCV)infection is a major global health concern that leads to liver fibrosis,cirrhosis,and cancer.Regimens containing direct-acting antivirals(DAAs)have become the mainstay of HCV treatment,achieving a high sustained virological response(SVR)with minimal adverse events.CASE SUMMARY A 74-year-old woman with chronic HCV infection was treated with the DAAs ledipasvir,and sofosbuvir for 12 wk and achieved SVR.Twenty-four weeks after treatment completion,the liver enzyme and serum IgG levels increased,and antinuclear antibody became positive without HCV viremia,suggesting the development of autoimmune hepatitis(AIH).After liver biopsy indicated AIH,a definite AIH diagnosis was made and prednisolone was initiated.The treatment was effective,and the liver enzyme and serum IgG levels normalized.However,multiple strictures of the intrahepatic and extrahepatic bile ducts with dilatation of the peripheral bile ducts appeared on magnetic resonance cholangiopancreatography after 3 years of achieving SVR,which were consistent with primary sclerosing cholangitis.CONCLUSION The potential risk of developing autoimmune liver diseases after DAA treatment should be considered.

Shear-wave elastography to predict hepatocellular carcinoma after hepatitis C virus eradication:A systematic review and meta-analysis

BACKGROUND Direct-acting antiviral agents(DAAs)are highly effective treatment for chronic hepatitis C(CHC)with a significant rate of sustained virologic response(SVR).The achievement of SVR is crucial to prevent additional liver damage and slow down fibrosis progression.The assessment of fibrosis degree can be performed with transient elastography,magnetic resonance elastography or shear-wave elastography(SWE).Liver elastography could function as a predictor for hepato-cellular carcinoma(HCC)in CHC patients treated with DAAs.AIM To explore the predictive value of SWE for HCC development after complete clearance of hepatitis C virus(HCV).METHODS A comprehensive literature search of clinical studies was performed to identify the ability of SWE to predict HCC occurrence after HCV clearance.In accordance with the study protocol,a qualitative and quantitative analysis of the evidence was planned.RESULTS At baseline and after 12 wk of follow-up,a trend was shown towards greater liver stiffness(LS)in those who go on to develop HCC compared to those who do not[baseline LS standardized mean difference(SMD):1.15,95%confidence interval(95%CI):020-2.50;LS SMD after 12 wk:0.83,95%CI:0.33-1.98].The absence of a statistically significant difference between the mean LS in those who developed HCC or not may be related to the inability to correct for confounding factors and the absence of raw source data.There was a statist-ically significant LS SMD at 24 wk of follow-up between patients who developed HCC vs not(0.64;95%CI:0.04-1.24).CONCLUSION SWE could be a promising tool for prediction of HCC occurrence in patients treated with DAAs.Further studies with larger cohorts and standardized timing of elastographic evaluation are needed to confirm these data.

Liver biopsy in the post-hepatitis C virus era in Japan

In Japan,liver biopsies were previously crucial in evaluating the severity of hepatitis caused by the hepatitis C virus(HCV)and diagnosing HCV-related hepatocellular carcinoma(HCC).However,due to the development of effective antiviral treatments and advanced imaging,the necessity for biopsies has significantly decreased.This change has resulted in fewer chances for diagnosing liver disease,causing many general pathologists to feel less confident in making liver biopsy diagnoses.This article provides a comprehensive overview of the challenges and potential solutions related to liver biopsies in Japan.First,it highlights the importance of considering steatotic liver diseases as independent conditions that can coexist with other liver diseases due to their increasing prevalence.Second,it emphasizes the need to avoid hasty assumptions of HCC in nodular lesions,because clinically diagnosable HCCs are not targets for biopsy.Third,the importance of diagnosing hepatic immune-related adverse events caused by immune checkpoint inhibitors is increasing due to the anticipated widespread use of these drugs.In conclusion,pathologists should be attuned to the changing landscape of liver diseases and approach liver biopsies with care and attention to detail.

Ensemble for evaluating diagnostic efficacy of non-invasive indices in predicting liver fibrosis in untreated hepatitis C virus population

BACKGROUND Hepatitis C virus(HCV)infection progresses through various phases,starting with inflammation and ending with hepatocellular carcinoma.There are several invasive and non-invasive methods to diagnose chronic HCV infection.The invasive methods have their benefits but are linked to morbidity and complications.Thus,it is important to analyze the potential of non-invasive methods as an alternative.Shear wave elastography(SWE)is a non-invasive imaging tool widely validated in clinical and research studies as a surrogate marker of liver fibrosis.Liver fibrosis determination by invasive liver biopsy and non-invasive SWE agree closely in clinical studies and therefore both are gold standards.AIM To analyzed the diagnostic efficacy of non-invasive indices[serum fibronectin,aspartate aminotransferase to platelet ratio index(APRI),alanine aminotransferase ratio(AAR),and fibrosis-4(FIB-4)]in relation to SWE.We have used an Artificial Intelligence method to predict the severity of liver fibrosis and uncover the complex relationship between non-invasive indices and fibrosis severity.METHODS We have conducted a hospital-based study considering 100 untreated patients detected as HCV positive using a quantitative Real-Time Polymerase Chain Reaction assay.We performed statistical and probabilistic analyses to determine the relationship between non-invasive indices and the severity of fibrosis.We also used standard diagnostic methods to measure the diagnostic accuracy for all the subjects.RESULTS The results of our study showed that fibronectin is a highly accurate diagnostic tool for predicting fibrosis stages(mild,moderate,and severe).This was based on its sensitivity(100%,92.2%,96.2%),specificity(96%,100%,98.6%),Youden’s index(0.960,0.922,0.948),area under receiver operating characteristic curve(0.999,0.993,0.922),and Likelihood test(LR+>10 and LR-<0.1).Additionally,our Bayesian Network analysis revealed that fibronectin(>200),AAR(>1),APRI(>3),and FIB-4(>4)were all strongly associated with patients who had severe fibrosis,with a 100% probability.CONCLUSION We have found a strong correlation between fibronectin and liver fibrosis progression in HCV patients.Additionally,we observed that the severity of liver fibrosis increases with an increase in the non-invasive indices that we investigated.

Genetic diversity of the hepatitis C virus: Impact and issues inthe antiviral therapy

The hepatitis C Virus (HCV) presents a high degree of genetic variability which is explained by the combination of a lack of proof reading by the RNA dependant RNA polymerase and a high level of viral replication. The re- sulting genetic polymorphism defines a classification in clades, genotypes, subtypes, isolates and quasispecies. This diversity is known to reflect the range of responses to Interferon therapy. The genotype is one of the pre- dictive parameters currently used to define the antiviral treatment strategy and the chance of therapeutic suc- cess. Studies have also reported the potential impact of the viral genetic polymorphism in the outcome of antivi- ral therapy in patients infected by the same HCV geno- type. Both structural and non structural genomic regions of HCV have been suggested to be involved in the Inter- feron pathway and the resistance to antiviral therapy. In this review, we first detail the viral basis of HCV diversity. Then, the HCV genetic regions that may be implicated in resistance to therapy are described, with a focus on the structural region encoded by the E2 gene and the non- structural genes NS3, NS5A and NS5B. Both mechanisms of the Interferon resistance and of the new antiviral drugs are described in this review.

Vitamin D deficiency and hepatitis viruses-associated liver diseases:a literature review

The secosteroid hormone vitamin D has, in addition to its effects in bone metabolism also functions in the modulation of immune responses against infectious agents and in inhibiting tumorigenesis. Thus, deficiency of vitamin D is associated with several malignancies, but also with a plethora of infectious diseases. Among other communicable diseases, vitamin D deficiency is involved in the pathogenesis of chronic liver diseases caused by hepatitis B and C viruses(HBV, HCV) and high prevalence of vitamin D deficiency with serum levels below 20 mg/mL in patients with HBV and HCV infection are found worldwide. Several studies have assessed the effects of vitamin D supplementation on the sustained virological response(SVR) to interferon(IFN) plus ribavirin(RBV) therapy in HBV and HCV infection. In these studies, inconsistent results were reported. This review addresses general aspects of vitamin D deficiency and, in particular, the significance of vitamin D hypovitaminosis in the outcome of HBVand HCV-related chronic liver diseases. Furthermore,current literature was reviewed in order to understand the effects of vitamin D supplementation in combination with IFN-based therapy on the virological response in HBV and HCV infected patients.

Complex interactions between microRNAs and hepatitis B/C viruses

MicroRNAs(miRNAs) are a class of small noncoding RNAs that post-transcriptionally regulate the expression of many target genes via mRNA degradation or translation inhibition. Many studies have shown that miRNAs are involved in the modulation of gene expression and replication of hepatitis B virus(HBV) and hepatitis C virus(HCV) and play a pivotal role in host-virus interactions. Increasing evidence also demonstrates that viral infection leads to alteration of the miRNA expression profile in hepatic tissues or circulation. The deregulated miRNAs participate in hepatocellular carcinoma(HCC)initiation and progression by functioning as oncogenes or tumor suppressor genes by targeting various genes involved in cancer-related signaling pathways. The distinct expression pattern of miRNAs may be a useful marker for the diagnosis and prognosis of virus-related diseases considering the limitation of currently used biomarkers. Moreover, the role of deregulated miRNA in host-virus interactions and HCC development suggested that miRNAs may serve as therapeutic targets or astools. In this review, we summarize the recent findings about the deregulation and the role of miRNAs during HBV/HCV infection and HCC development, and we discuss the possible mechanism of action of miRNAs in the pathogenesis of virus-related diseases. Furthermore, we discuss the potential of using miRNAs as markers for diagnosis and prognosis as well as therapeutic targets and drugs.

Human hepatitis viruses-associated cutaneous and systemic vasculitis

Human hepatitis viruses(HHVs)include hepatitis A virus,hepatitis B virus(HBV),hepatitis C virus(HCV),hepatitis delta virus,and hepatitis E virus and can cause liver inflammation in their common human host.Usually,HHV is rapidly cleared by the immune system,following acute HHV invasion.The morbidities associated with hepatitis A virus and hepatitis E virus infection occur shortly after their intrusion,in the acute stage.Nevertheless,the viral infectious process can persist for a long period of time,especially in HBV and HCV infection,leading to chronic hepatitis and further progressing to hepatic cirrhosis and liver cancer.HHV infection brings about complications in other organs,and both acute and chronic hepatitis have been associated with clinical presentations outside the liver.Vascular involvement with cutaneous and systemic vasculitis is a well-known extrahepatic presentation;moreover,there is growing evidence for a possible causal relationship between viral pathogens and vasculitis.Except for hepatitis delta virus,other HHVs have participated in the etiopathogenesis of cutaneous and systemic vasculitis via different mechanisms,including direct viral invasion of vascular endothelial cells,immune complex-mediated vessel wall damage,and autoimmune responses with stimulation of autoreactive B-cells and impaired regulatory T-cells.Cryoglobulinemic vasculitis and polyarteritis nodosa are recognized for their association with chronic HHV infection.Although therapeutic guidelines for HHV-associated vasculitis have not yet been established,antiviral therapy should be initiated in HBV and HCV-related systemic vasculitis in addition to the use of corticosteroids.Plasma exchange and/or combined cyclophosphamide and corticosteroid therapy can be considered in patients with severe life-threatening vasculitis manifestations.

Low-density lipoprotein receptor genetic polymorphism in chronic hepatitis C virus Egyptian patients affects treatment response

AIM: To correlate a genetic polymorphism of the low-density lipoprotein(LDL) receptor with antiviral responses in Egyptian chronic hepatitis C virus(HCV) patients.METHODS: Our study included 657 HCV-infected patients with genotype 4 who received interferonbased combination therapy. Patients were divided into two groups based on their response to therapy: 356 were responders, and 301 were non-responders. Patients were compared to 160 healthy controls. All patients and controls underwent a thorough physical examination, measurement of body mass index(BMI) and the following laboratory tests: serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, total bilirubin, direct bilirubin, prothrombin time, prothrombin concentration, INR, complete blood count, serum creatinine, fasting blood sugar, HCV antibody, and hepatitis B surface antigen. All HCV patients were further subjected to the following laboratory tests: HCV-RNA using quantitative polymerase chain reaction(PCR), antinuclear antibodies, thyroid-stimulating hormone, an LDL receptor(LDLR) genotype study of LDLR exon8 c.1171G>A and exon-10 c.1413G>A using real-time PCR-based assays, abdominal ultrasonography, ultrasonographic-guided liver biopsy, and histopathological examination of liver biopsies. Correlations of LDL receptor polymorphisms with HAI, METAVIR score, presence of steatosis, and BMI were performed in all cases.RESULTS: There were no statistically significant differences in response rates between the different types of interferon used or LDLR exon10 c.1413G>A. However, there was a significant difference in the frequency of the LDL receptor exon8 c.1171G>A genotype between cases(AA: 25.9%, GA: 22.2%, GG: 51.9%) and controls(AA: 3.8%, GA: 53.1% and GG: 43.1%)(P < 0.001). There was a statistically significant difference in the frequency of the LDLR exon 8C:1171 G>A polymorphism between responders(AA: 3.6%, GA: 15.2%, GG: 81.2%) and nonresponders(AA: 52.2%, GA: 30.6%, GG: 17.2%)(P < 0.001). The G allele of LDL receptor exon8 c.1171G>A predominated in cases and controls over the A allele, and a statistically significant association with response to interferon was observed. The frequency of the LDLR exon8 c.1171G>A allele in non-responders was: A: 67.4% and G: 32.6 vs A: 11.2% and G: 88.8% in responders(P < 0.001). Therefore, carriers of the A allele exhibited a 16.4 times greater risk for nonresponse. There was a significant association between LDL receptors exon8 c.1171G>A and HAI(P < 0.011). There was a significant association between LDL receptors exon8 c.1171G>A and BMI. The mean BMI level was highest in patients carrying the AA genotype(28.7 ± 4.7 kg/m2) followed by the GA genotype(28.1 ± 4.8 kg/m2). The lowest BMI was the GG genotype(26.6 ± 4.3 kg/m2)(P < 0.001). The only significant associations were found between LDL receptors exon8 c.1171G>A and METAVIR score or steatosis(P < 0.001).CONCLUSION: LDL receptor gene polymorphisms play a role in the treatment response of HCV and the modulation of disease progression in Egyptiansinfected with chronic HCV.

Exploitation of host clock gene machinery by hepatitis viruses B and C

Many aspects of cellular physiology display circadian(approximately 24-h)rhythms.Dysfunction of the circadian clock molecular circuitry is associated with human health derangements,including neurodegeneration,increased risk of cancer,cardiovascular diseases and the metabolic syndrome.Viruses triggering hepatitis depend tightly on the host cell synthesis machinery for their own replication,survival and spreading.Recent evidences support a link between the circadian clock circuitry and viruses’biological cycle within host cells.Currently,in vitro models for chronobiological studies of cells infected with viruses need to be implemented.The establishment of such in vitro models would be helpful to better understand the link between the clock gene machinery and viral replication/viral persistence in order to develop specifically targeted therapeutic regimens.Here we review the recent literature dealing with the interplay between hepatitis B and C viruses and clock genes.

Hepatic flares in chronic hepatitis C: Spontaneous exacerbation vs hepatotropic viruses superinfection

The hepatitis C virus(HCV)causes an acute infection that is frequently asymptomatic,but a spontaneous eradication of HCV infection occurs only in one-third of patients.The remaining two-thirds develop a chronic infection that,in most cases,shows an indolent course and a slow progression to the more advanced stagesof the illness.Nearly a quarter of cases with chronic hepatitis C(CHC)develop liver cirrhosis with or without hepatocellular carcinoma.The indolent course of the illness may be troubled by the occurrence of a hepatic flare,i.e.,a spontaneous acute exacerbation of CHC due to changes in the immune response,immunosuppression and subsequent restoration,and is characterized by an increase in serum aminotransferase values,a frequent deterioration in liver fibrosis and necroinflammation but also a high frequency of sustained viral response to pegylated interferon plus ribavirin treatment.A substantial increase in serum aminotransferase values during the clinical course of CHC may also be a consequence of a superinfection by other hepatotropic viruses,namely hepatitis B virus(HBV),HBV plus hepatitis D virus,hepatitis E virus,cytomegalovirus,particularly in geographical areas with high endemicity levels.The etiology of a hepatic flare in patients with CHC should always be defined to optimize follow-up procedures and clinical and therapeutic decisions.

Hepatitis C virus genotype 6:Virology,epidemiology,genetic variation and clinical implication

Hepatitis C virus (HCV) is a serious public health problem affecting 170 million carriers worldwide. It is a leading cause of chronic hepatitis, cirrhosis, and liver cancer and is the primary cause for liver transplantation worldwide. HCV genotype 6 (HCV-6) is restricted to South China, South-East Asia, and it is also occasionally found in migrant patients from endemic countries. HCV-6 has considerable genetic diversity with 23 subtypes (a to w). Although direct sequencing followed by phylogenetic analysis is the gold standard for HCV-6 genotyping and subtyping, there are also now rapid genotyping tests available such as the reverse hybridization line probe assay (INNO-LiPA II; Innogenetics, Zwijnaarde, Belgium). HCV-6 patients present with similar clinical manifestations as patients infected with other genotypes. Based on current evidence, the optimal treatment duration of HCV-6 with pegylated interferon/ribavirin should be 48 wk, although a shortened treatment duration of 24 wk could be sufficient in patients with low pretreatment viral load who achieve rapid virological response. In addition, the development of direct-acting antiviral agents is ongoing, and they give high response rate when combined with standard therapy. Herein, we review the epidemiology, classification, diagnosis and treatment as it pertain to HCV-6.

Hepatitis B and C viruses are not risks for pancreatic adenocarcinoma

AIM: To investigate whether hepatitis B virus (HBV) and hepatitis C virus (HCV) increase risk of pancreatic ductal adenocarcinoma (PDAC).

Interleukin-12 as a Genetic Adjuvant Enhances Hepatitis C Virus NS3 DNA Vaccine Immunogenicity

Hepatitis C virus (HCV) chronic infection is a worldwide health problem, and numerous efforts have been invested to develop novel vaccines. An efficient vaccine requires broad immune response induction against viral proteins. To achieve this goal, we constructed a DNA vaccine expressing nonstructural 3 (NS3) gene (pcDNA3.1-HCV-NS3) and assessed the immune response in C57BL/6 mice. In this study, the NS3 gene was amplified with a nested-reverse transcriptase-polymerase chain reaction (RT-PCR) method using sera of HCV-infected patients with genotype 1a. The resulting NS3 gene was subcloned into a pcDNA3.1 eukaryotic expression vector, and gene expression was detected by western blot. The resultant DNA vaccine was co-administered with interleukin-12 (IL-12) as an adjuvant to female C57BL/6 mice. After the final immunizations, lymphocyte proliferation, cytotoxicity, and cytokine levels were assessed to measure immune responses. Our data suggest that co-administration of HCV NS3 DNA vaccine with IL-12 induces production of significant levels of both IL-4 and interferon (IFN)-γ (p<0.05). Cytotoxicity and lymphocyte proliferation responses of vaccinated mice were significantly increased compared to control (p<0.05). Collectively, our results demonstrated that co-administration of HCV NS3 and IL-12 displayed strong immunogenicity in a murine model.

Insights for hepatitis C virus related hepatocellular carcinoma genetic biomarkers: Early diagnosis and therapeutic intervention

The current review explores the role of emerging molecular contributing factors in liver carcinogenesis on top of hepatitis C virus(HCV). Here we will try to discuss the role genetic and epigenetic factors in pathogenesis of hepatocellular carcinoma. Understanding the role of these factors will help in discovering the mystery of liver carcinogenesis on top of chronic HCV infection. Moreover, use of the studied molecular factors will provide the hepatologists with tailored diagnostic promising biomarkers and flatten the way for establishment of emerging molecular treatment based on exploring the molecular subscription of this aggressive liver cancer.

Predictive potential of IL-28B genetic testing for interferon based hepatitis C virus therapy in Pakistan: Current scenario and future perspective

In Pakistan which ranked second in terms of hepatitis C virus(HCV) infection, it is highly needed to have an established diagnostic test for antiviral therapy responseprediction. Interleukin 28B(IL-28B) genetic testing is widely used throughout the world for interferon based therapy prediction for HCV patients and is quite helpful not only for health care workers but also for the patients. There is a strong relationship between single nucleotide polymorphisms at or near the IL-28 B gene and the sustained virological response with pegylated interferon plus ribavirin treatment for chronic hepatitis C. Pakistan is a resource limited country, with very low per capita income and there is no proper social security(health insurance) system. The allocated health budget by the government is very low and is used on other health emergencies like polio virus and dengue virus infection. Therefore it is proposed that there should be a well established diagnostic test on the basis of IL-28 B which can predict the antiviral therapy response to strengthen health care set-up of Pakistan. This test once established will help in better management of HCV infected patients.

Immunologic, metabolic and genetic factors in hepatitis C virus infection

The mechanisms that regulate disease progression during hepatitis C virus(HCV)infection and the response to treatment are not clearly identified.Numerous studies have demonstrated that a strong host immune response against HCV favors HCV clearance.In addition,genetic factors and metabolic machinery,particularly cholesterol modulation,are involved in HCV infection.It is likely that the interplay between all of these factors contributes to the outcome of HCV infection.In recent years,the world has experienced its largest epidemic of obesity.Mexico and the United States are the leading sufferers from this epidemic at the global level.Obesity is associated with the development ofnumerous pathologies including hypercholesterolemia which is one of the eight most important risk factors for mortality in Mexico.This may be related to the course of HCV infection in this population.Here,we focus on the urgent need to study the progression of HCV infection in relation to ethnic characteristics.Discoveries are discussed that hold promise in identifying immune,metabolic and genetic factors that,in conjunction,could be therapeutic targets or predictors of the progression of HCV infection.

Genetic vaccination with Flt3-L and GM-CSF as adjuvants: Enhancement of cellular and humoral mmune responses that results in protective immunity in a murine model of hepatitis C virus infection

AIM： To investigate whether transfection of plasmid DNA encoding these cytokines enhances both humoral and cellular immune responses to hepatitis C virus （HCV） in a murine model. METHODS： We established a tumor model of HCV infection using syngenic mouse myeloma cells stably transfected with NS5. Co-vaccination of DNA encoding granulocyte macrophage colony-stimulating factor （GM- CSF） and Flt-3 ligand together with a plasmid encoding for the HCV NS5 protein was carried out. Mice were sacrificed 14 d after the last immunization event with collection of spleen cells and serum to determine humoral and cellular immune responses. RESULTS： Co-vaccination of DNA encoding GM-CSF and Fit-3 ligand together with a plasmid encoding for the HCV NS5 protein induced increased antibody responses and CD4＋ T cell proliferation to this protein, Vaccination with DNA encoding GM-CSF and FIt-3L promoted protection against tumor formation and/or reduction in mice co- immunized with cytokine-encoding DNA constructs, This suggests this strategy is capable of generating cytotoxic T lymphocyte activity in vivo, Following inoculation with plasmid DNA encoding Flt-3L, no increase in spleen size or in dendritic cell （DC） and natural killer cell numbers was observed. This was in contrast to a dramatic increase of both cell types after administration of recombinant Flt3-L in vivo. This suggests that vaccination with plasmid DNA encoding cytokines that regulate DC generation and mobilization may not promote unwanted side effects, such as autoimmunity, splenic fibrosis or hematopoietic malignancies that may occur with administration of recombinant forms of these proteins. CONCLUSION： Our data support the view that plasmid DNA vaccination is a promising approach for HCV immunization, and may provide a general adjuvant vaccination strategy against malignancies and other pathogens.