Optical biosensing of monkeypox virus using novel recombinant silica-binding proteins for site-directed antibody immobilization

The efficient immobilization of capture antibodies is crucial for timely pathogen detection during global pandemic outbreaks.Therefore,we proposed a silica-binding protein featuring core functional domains(cSP).It comprises a peptide with a silica-binding tag designed to adhere to silica surfaces and tandem protein G fragments(2C2)for effective antibody capture.This innovation facilitates precise site-directed immobilization of antibodies onto silica surfaces.We applied cSP to silica-coated optical fibers,creating a fiber-optic biolayer interferometer(FO-BLI)biosensor capable of monitoring the monkeypox virus(MPXV)protein A29L in spiked clinical samples to rapidly detect the MPXV.The cSP-based FO-BLI biosensor for MPXV demonstrated a limit of detection(LOD)of 0.62 ng/mL in buffer,comparable to the 0.52 ng/mL LOD achieved using a conventional streptavidin(SA)-based FO-BLI biosensor.Furthermore,it achieved LODs of 0.77 ng/mL in spiked serum and 0.80 ng/mL in spiked saliva,exhibiting no cross-reactivity with other viral antigens.The MPXV detection process was completed within 14 min.We further proposed a cSP-based multi-virus biosensor strategy capable of detecting various pandemic strains,such as MPXV,the latest coronavirus disease(COVID)variants,and influenza A protein,to extend its versatility.The proposed cSP-modified FO-BLI biosensor has a high potential for rapidly and accurately detecting MPXV antigens,making valuable contributions to epidemiological studies.

Site-directed Mutagenesis of Streptomyces avermitilis aveD Gene

[Objective] The aim of this study was to produce Streptomyces avermitilis strain with site-directed mutagenesis in aveD gene,and so as to provide theoretical basis for genetic breeding of S.avermitilis.[Method] PCR-driven overlap extension was conducted for the site-directed mutagenesis in aveD gene;the mutated aveD gene then was used to construct vector pDC3（pKC1139∷aveD） via molecular manipulations like in vitro enzyme digestion and ligation;the vector pDC3（pKC1139∷aveD） was then introduced to aveD deletion mutant 489 of avermectin-producing strain S.avermitilis 76-9.[Result] Mutant strain 536 of site-directed mutagenesis of S.avermitilis 76-9 was obtained by homologous recombination.The sequencing results show that the sixty-ninth base C in aveD-coding region of mutant 536 was substituted by T,and the corresponding amino acid Thr was mutated to be Ile.[Conclusion] This study laid basis for the development of strains specifically producing avermectin B.

Site-directed Mutagenesis Based on Overlap Extension PCR

[Objective] To establish an efficient, convenient and economical method for site-directed mutagenesis. [Method] The target mutation was introduced into primers designed by DNAMAN5.0 software. Through overlap extension PCR for twice obtained the mutation gene which of the full length of the recombinant Human Tissue type plasminogen activator （Reteplase）. The mutation gene cloned it into pEASY- blunt simple cloning vector for sequencing. [Result] The sequencing results showed that three site mutations were fully consistent with the expected results （10~ site had been added a base-pair of A, C had been changed into G at 137~ site, G had been changed into A at 686~ site）.Three site mutations were introduced by using overlap extension PCR on one-step. The overall rate of obtaining the mutant sites was 100%. Site-directed mutagenesis will clone the recombinant Human Tissue type plas- minogen activator and laid the basis for the functional study. [Conclusion] Site-directed mutagenesis was successfully implemented based on the overlap extension PCR which is an efficient, convenient and economical DNA-directed mutagenesis method.

PEGylation of Hirudin and Analysis of Its Antithrombin Activity in vitro

Hirudin is the most anticoagulant drug found in nature, but its short serum half-life significantly inhibits its clinical anpplication. The PEGvlation of hirudin, the most promising anticoagulant drug, was performed in this paper. The optimal reaction conditions for PEG ylated hirudin were investigated, wh.en the PEGylation react, on.wasconducted under 4℃ after 10h, in the borate buffer at pH 8.5 .with the molar ratio 230 ： 1 of PEG to hirudin, a higher modification extent was achieved. Finally, the bioactivity of PEGylated hirudin was measured in vitro.Compared with unmodified hirudin, 26% of anti-thrombin activity was retained.

Increased L-arginine Production by Site-directed Mutagenesis of N-acetyl-L-glutamate Kinase and pro B Gene Deletion in Corynebacterium crenatum

Objective In Corynebacterium crenatum,the adjacent D311 and D312 of N-acetyl-L-glutamate kinase(NAGK),as a key rate-limiting enzyme of L-arginine biosynthesis under substrate regulatory control by arginine,were initially replaced with two arginine residues to investigate the L-arginine feedback inhibition for NAGK.Methods NAGK enzyme expression was evaluated using a plasmid-based method.Homologous recombination was employed to eliminate the pro B.Results The IC50 and enzyme activity of NAGK M4,in which the D311 R and D312 R amino acid substitutions were combined with the previously reported E19 R and H26 E substitutions,were 3.7-fold and 14.6% higher,respectively,than those of the wild-type NAGK.NAGK M4 was successfully introduced into the C.crenatum MT genome without any genetic markers;the L-arginine yield of C.crenatum MT-M4 was 26.2% higher than that of C.crenatum MT.To further improve upon the L-arginine yield,we constructed the mutant C.crenatum MT-M4 ?pro B.The optimum concentration of L-proline was also investigated in order to determine its contribution to L-arginine yield.After L-proline was added to the medium at 10 mmol/L,the L-arginine yield reached 16.5 g/L after 108 h of shake-flask fermentation,approximately 70.1% higher than the yield attained using C.crenatum MT.Conclusion Feedback inhibition of L-arginine on NAGK in C.crenatum is clearly alleviated by the M4 mutation of NAGK,and deletion of the pro B in C.crenatum from MT to M4 results in a significant increase in arginine production.

Effect of PEGylation on the physicochemical and pharmacokinetic characteristics of bovine serum albumin-encapsulated liposome

There is now little doubt that PEGylation is useful and is in widespread use because it provides a prolonged half-life,a higher stability and a lowerimmunogenicity[1].However,it is of concern that PEGylation may affect the physicochemical and pharmacokinetic characteristics of protein-encapsulated liposome.Thus,we prepared the bovine serum albumin(BSA)-encapsulated liposome(BSA-liposome)with or without PEG and then compared their physicochemical and pharmacokinetic characteristics(Fig.1).BSA-liposomes were prepared by the thin-film hydration method.

Site-directed Chemical Modification of Recombinant Human aFGF Mutant with Polyethylene Glycol

A new product PEGylated rhaFGF was obtained by site-directed chemical modification.When compared with unmodified rhaFGF, PEGylated rhaFGF showed comparable bioactivity and superior stability at 37℃ in mouse serum and the stronger resistant potency to trypsin. This was accompanied by a substantial decreasing tmmunogenicity.Site-specific PEGylation of rhaFGF may increase its therapeutic potency in humans.

Identification of Residue Involved in Nucleotidyltransferase Activity of LinA from Staphylococci by Site-directed Mutagenesis

The lincosamide class of antibacterials is widely used for the treatment of a broad spectrum of infections, and one prevalent route of resistance to lincosamides in pathogenic gram-positive cocco is antibiotic modification. Enzymes encoded by lin genes, belonging to nucleotidyltransferase superfamily, catalyze adenylylation to inactivate lincosamides. LinA can adenylylate lincosamides at either 3?-or 4?-OH of the methylthiolincosamide sugar. The crystal structure of LinA/lincomycin has confirmed its active site. However, the residue interacting with nucleotidyl donors remains elusive. Here, we modeled the complex structure of LinA/lincomycin/Mg^(2+)/AMPCPP to reveal a putative pocket for nucleotidyl donors and suggested the residue R45 in this pocket involved in the recognition of donor substrates NTP and catalysis. ITC and enzyme activity assays show that the mutation of residue R45 impairs LinA nucleotidyltransferase activity in vitro. This work provides insights into the molecular mechanism of the nucleotide binding and transferring activity of antibiotic NTases.

Dynamic micelles with detachable PEGylation at tumoral extracellular pH for enhanced chemotherapy

Although surface PEGylation of nanomedicines can decrease serum protein adsorption in vivo,it also blocks uptake by tumor cells.This dilemma could be overcome by employing detachably PEGylated strategy at tumoral extracellular microenvironment to achieve improved cellular uptake while prolonged circulation times.Herein,the amphiphilic graft copolymers with p H-sensitive ortho ester-linked m PEG in side chains and polyurethanes in backbone,can self-assemble into the free and doxorubicin(DOX)-loaded micelles.The p H-sensitive micelles could undergo several characteristics as follows:(i)PEGylated shells for stability in sodium dodecyl sulfonate(SDS)solution;(ii)De PEGylation via degradation of ortho ester linkages at tumoral extracellular pH(6.5)for gradually dynamic size changes and effective release of DOX;and(iii)enhanced cellular uptake and cytotoxicity via positive DOX.Moreover,the dynamic micelles with detachable PEGylation could quickly penetrate the centers of SH-SY5 Y multicellular spheroids(MCs)and strongly inhibit tumor growth in vitro and in vivo,and might be considered as promising and effective drug carriers in tumor therapy.

Ultrafast solvation dynamics at internal sites of staphylococcal nuclease investigated by site-directed mutagenesis

Internal solvation of protein was studied by site-directed mutagenesis, with which an intrinsically fluorescent probe,tryptophan, is inserted into the desired position inside a protein molecule for ultrafast spectroscopic study. Here we review this unique method for protein dynamics research. We first introduce the frontiers of protein solvation, site-directed mutagenesis, protein stability and characteristics, and the spectroscopic methods. Then we present time-resolved spectroscopic dynamics of solvation dynamics inside cavities of active sites. The studies are carried out on a globular protein, staphylococcal nuclease. The solvation at sites inside the protein molecule＇s cavities clearly reveals characteristics of the local environment. These solvation behaviors are directly correlated to enzyme activity.

Monitoring the autoproteolysis of hiv-1 protease by site-directed spin-labeling and electron paramagnetic resonance spectroscopy

Site-directed spin-labeling with continuous wave electron paramagnetic resonance spectroscopy was used to monitor autoproteolysis of HIV-1 protease, an enzyme essential for viral maturation. Two protein constructs were examined, namely subtype F and the circulating recombinant form CRF01_A/E. As the protease undergoes self-cleavage, protein unfolds and small peptide fragments containing the spin label are generated, which collectively give rise to a sharp spectral component that is easily discernable in the high-field resonance line in the EPR spectrum. By monitoring the intensity of this spectral component over time, the autoproteolytic stability of each construct was characterized under various conditions. Data were collected for samples stored at 4 °C, 25 °C, and 37 °C, and on a subtype F HIV-1 protease sample stored at 25 °C and containing the FDA-approved protease inhibitor Tipranavir. As expected, the rate of autoproteolysis decreased as the storage temperature was lowered. Minimal autoproteolysis was seen for the sample that contained Tipranavir, providing direction for future spectroscopic studies of active protease samples. When compared to standard methods of monitoring protein degradation such as gel electrophoresis or chromatographic analyses, spin-labeling with CW EPR offers a facile, real-time, non-consuming way to monitor autoproteolysis or protein degradation. Additionally, mass spectrometry studies revealed that the N-termini of both constructs are sensitive to degradation and that the sites of specific autoproteolysis vary.

C-X-C chemokine receptor type 5+CD8+T cells as immune regulators in hepatitis Be antigen-positive chronic hepatitis B under interferonalpha treatment

BACKGROUND C-X-C chemokine receptor type 5(CXCR5)+CD8+T cells represent a unique immune subset with dual roles,functioning as cytotoxic cells in persistent viral infections while promoting B cell responses.Despite their importance,the specific role of CXCR5+CD8+T cells in chronic hepatitis B(CHB),particularly during interferon-alpha(IFN-α)treatment,is not fully understood.This study aims to elucidate the relationship between CXCR5+CD8+T cells and sustained serologic response(SR)in patients undergoing 48 weeks of pegylated IFN-α(peg-IFN-α)treatment for CHB.AIM To elucidate the relationship between CXCR5+CD8+T cells and sustained SR in patients undergoing 48 weeks of peg-IFN-αtreatment for CHB.METHODS This study enrolled 60 patients with hepatitis Be antigen(HBeAg)-positive CHB undergoing 48 weeks of peg-IFN-αtreatment.Participants were assessed for eligibility based on criteria such as persistent HBsAg-positive status for at least six months,HBeAb-negative,hepatitis B virus DNA levels exceeding 2×104 copies/mL,and alanine aminotransferase(ALT)levels between 2 and 10 times the upper limit of normal.Blood samples were collected at baseline and at weeks 12,24,48,and a 24-week treatment-free follow-up(week 72)to measure serum interleukin(IL)-21 concentration via ELISA and to analyze CXCR5 and programmed death-ligand 1(PD-L1)expression on CD8+T cells by flow cytometry,CXCR5 is a chemokine receptor that directs immune cells to specific tissues,while PD-L1 is a protein that regulates immune responses by inhibiting T cell activity.RESULTS Patients with CHB exhibited significantly lower levels of circulating CXCR5+CD8+T cells compared to healthy controls(P<0.01).Notably,CXCR5+CD8+T cells were prominently expressed in patients who achieved sustained SR compared to non-SR(NSR).A significant correlation was observed between CXCR5 and PD-L1 expression(r=-0.189,P=0.002).However,there was no significant correlation between serum IL-21 levels and CXCR5+CD8+lymphocytes(r=-0.03,P=0.625)or serum ALT levels(r=0.026,P=0.678).CONCLUSION The enhanced expression of CXCR5+CD8+T cells in patients achieving HBeAg seroconversion during IFN-αtreatment suggests that these cells play a crucial role in antiviral immune responses against hepatitis B.This study highlights the potential of CXCR5+CD8+T cells as immune regulators in CHB,which may inform future therapeutic strategies to optimize antiviral treatments.

Pegylated interferon α-2b up-regulates specific CD8+ T cells in patients with chronic hepatitis B

AIM:To investigate the effect of pegylated interferon (IFN) α-2b on specific CD8+ T lymphocytes in patients with chronic hepatitis B (CHB). METHODS:Twenty-one patients with CHB were treated with pegylated IFN α-2b. Periphery blood mononuclear cells were isolated from fresh heparinized blood by Ficoll-Hypaque density gradient centrifugation (density:1.077 g/L,Pharmingen) at weeks 0,4,8,12,and 24,respectively. Frequency of circulating hepatitis B virus (HBV) epitope-specific CD8 T cells was detected by flow cytometry. Cytokines were detected by cytometric bead assay. RESULTS:The frequency of circulating HBV core or env-specific CD8 T cells was higher (P < 0.05),the number of HBV core specific CD8 T cells was greater at week 24 (P < 0.05),the level of Th1-type cytokines [interleukin (IL)-12,tumor necrosis factor-α,and IFN-γ] was higher,while that of Th2-type cytokines (IL-4,IL-6,and IL-10) was lower in responders than in nonresponders (P < 0.05) after pegylated IFN α-2b treatment. The IL-6 level was correlated with HBV DNA (r = 0.597,P = 0.04),while the inducible protein-10 (IP-10) level was correlated with serum alanine aminotransferase (ALT) (r = 0.545,P = 0.005). The IP-10 level at week 8 after pegylated IFN α-2b treatment could predict the normalization of ALT in CHB patients (positive predict value = 56%,negative predict value = 92%). CONCLUSION:Pegylated IFN α-2b can enhance the immune response of CHB patients by increasing the frequency of HBV specific CD8+ T cells and regulating the Th1/Th2 cytokines.

The Predictive Value of Baseline HBs Ag Level and Early Response for HBs Ag Loss in Patients with HBe Ag-positive Chronic Hepatitis B during Pegylated Interferon Alpha-2a Treatment

Objective To explore the predictive value of baseline HBs Ag level and early response for HBs Ag loss in patients with HBe Ag-positive chronic hepatitis B during pegylated interferon alpha-2a treatment. Methods A total of 121 patients with HBe Ag-positive chronic hepatitis B who achieved HBs Ag loss were enrolled; all patients were treated with PEG-IFNα-2a 180 μg/week. Serum HBV DNA and serological indicators （HBs Ag, anti-HBs, HBe Ag, and anti-HBe） were determined before and every 3 months during treatment. Results The median treatment time for HBs Ag loss was 84 weeks （7-273 weeks）, and 74.38% （90 cases） of the patients needed extended treatment （〉 48 weeks）. The correlation between baseline HBs Ag levels and the treatment time of HBs Ag loss was significant （B = 14.465, t = 2.342, P = 0.021）. Baseline HBs Ag levels together with the decline range of HBs Ag at 24 weeks significantly correlated with the treatment time of HBs Ag loss （B = 29.862, t = 4.890, P = 0.000 and B = 27.993, t = 27.993, P = 0.005）. Conclusion Baseline HBs Ag levels and extended therapy are critical steps toward HBs Ag loss. Baseline HBs Ag levels together with early response determined the treatment time of HBs Ag loss in patients with HBe Ag-positive chronic hepatitis B during pegylated interferon alpha-2a treatment.

Effect of switching from treatment with nucleos(t)ide analogs to pegylated interferon α-2a on virological and serological responses in chronic hepatitis B patients

AIM To investigate the efficacy of switching to pegylated interferon-α-2a(Peg IFNα-2a) treatment in nucleos(t)ide analog(NA)-treated chronic hepatitis B(CHB) responder patients. METHODS A 48-wk prospective and retrospective treatment trial of NA-treated CHB patients who had received entecavir(ETV) for at least 48 wk and had serum hepatitis B virus(HBV)-DNA < 500 IU/m L, serum hepatitis B envelope antigen(HBe Ag) < 100 S/CO, serum alanine aminotransferase, and aspartate aminotransferase levels < 2 × the upper limit of normal of 40 IU/L was performed. The effects on virological and serological responses and adverse reactions to 0.5 mg daily ETV for 48 wk vs switching to Peg IFNα-2a were compared. Forty-four patients were randomized to be switched from NA treatment to the Peg IFNα-2a group, and 44 patients were simultaneously randomized to the ETV group. RESULTS After 48 wk of therapy, the decrease in hepatitis B surface antigen(HBs Ag) levels was greater in the Peg IFNα-2a group than in the ETV group(3.1340 log10 IU/m L vs 3.6950 log10 IU/m L, P = 0.00). Seven patients who were anti-HBs-positive at baseline achieved HBs Ag loss when switched to Peg IFNα-2a(15.91% vs 0%,P = 0.018). The HBe Ag serological conversion rate was higher in the Peg IFNα-2a group than in the ETV group; however, the difference was not significant because of the small sample sizes(34.38% vs 21.88%, P = 0.232). In the Peg IFNα-2a group, patients with HBs Ag levels < 1500 IU/m L at baseline had higher HBe Ag seroconversion and HBs Ag loss rates at week 48 than those with HBs Ag levels ≥ 1500 IU/m L(HBe Ag seroconversion: 17.86% vs 62.5%, P = 0.007; HBs Ag loss: 41.67% vs 6.25%, P = 0.016). Moreover, patients with HBs Ag levels < 1500 IU/m L at week 24 had higher HBs Ag loss rates after therapy than those with HBs Ag levels ≥ 1500 IU/m L(36.84% vs 0%, P = 0.004). However, there were no statistically significant differences in HBe Ag seroconversion rates(47.06% vs 25.93%, P = 0.266). CONCLUSION NA-treated CHB patients switched to sequential Peg IFNα-2a achieved highly potent treatment termination safely.

Formulation and evaluation the bioadhesive properties of drug delivery system based on PEGylated mucin matrices

Objective:To formulate and evaluate the application of PEGylated mucin in oral bioadhesive drug(OBD) delivery system.Methods:The bioadhesive strength of different formulation ratios of polyethylene glycol(PEG) and mucin was evaluated by tensiometry.Co polymer matrices containing mucin and PEG(PEGylated mucin) in the following ratios of 1:1(A),2:1(B),1:2(C), 0:1(D) and 1:0(E) were prepared by co-precipitation.Microparticles were prepared from the matrices using a size reduction technique.Five different samples were prepared using direct mixtures in the appropriate solvenfs having mucin and PEG ratios of 1:1,2:1,1:2,0:1, 1:0 and labeled as(A-E).The matrices were evaluated for their flow properties and the in vitro bioadhesion characteristics of the samples were examined.Results:The range of flow rates of the matrices was 1.35-2.23 g/sec.The angle of repose was in the range of 37.3-39.9 degree.The bulk and tapped densities were within the ranges of 0.41- 0.49.The Hausner’s quotient(HQ) were 1.12, 1.24,1.14,1.25 and 1.2 for matrix batches A-E respectively,The bioadhesive strength of polymer matrices appeared to be directly related to amount of mucin.The order of bioadhesive strength is 2:1】1:1】1:0】1:2】0:1 of PEG:mucin in both simulated intestine fluid(SEP) and simulated gastrointestinal fluid(SGF).The physical properties of the micrometrics properties of the matrices were within the accepted values.Conclusions:OBD preparation containing PEGylated mucin can be prepared by direct compression and be used in drug delivery to the oral cavity.

Improved anti-tumor efficacy and pharmacokinetics of bufalin via PEGylated liposomes

OBJECTIVE To determine the characterization,anti-tumor efficacy and pharmacokinetics of bufalin-loaded PEGylated liposomes compared with bufalin entity.METHODS Bufalin-loaded PEGylated liposomes and bufalin-loaded liposomes were prepared reproducibly with homogeneous particle size by the combination of thin film evaporation method and high pressure homogenization method.The particle size and zeta potential of the liposomes were determined by dynamic light scattering technique.The direct imaging of morphology of liposomes was charactered by transmission electron microscope.The content of bufalin in liposomes was analysed by HPLC method.The entrapment efficiency and the particle size was applied to assess the stability profile,after storage at 4℃ on day 0,7,15,30 and 90.The in-vitro release behaviours of bufalin from liposomes were conducted using dialysis bag technique at 37℃.In-vitro cytotoxicity studies were carried out using MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]assay on several kinds of tumor cel lines including SW620,PC-3,MDA-MB-231,A549,U251,U87 and HepG2.In-vivo pharmacokinetic study of bufalin liposomes was evaluated by HPLC method.RESULTS Their mean particle sizes were 127.6 nm and 155.0 nm,mean zeta potentials were 2.24 m V and-18.5 m V,entrapment efficiencies were 76.31%and 78.40%,respectively.In-vitro release profile revealed that the release of bufalin in bufalin-loaded PEGylated liposomes was slower than that of bufalin-loaded liposomes.The cytotoxicity of blank liposomes has been found within acceptable range,whereas bufalin-loaded PEGylated liposomes showed enhanced cytotoxicity to U251 cells compared with bufalin entity.In-vivo pharmacokinetics indicated that bufalinloaded PEGylated liposomes could extend eliminate half-life time of bufalin in plasma in rats.CONCLUSION The results suggested that bufalin-loaded PEGylated liposomes improved the solubility and increased the drug concentration in plasma.

Combination Therapy with Pegylated Interferon alpha-2b and Adefovir Dipivoxil in HBeAg-positive Chronic Hepatitis B versus Interferon Alone: A Prospective, Randomized Study

Currently available monotherapies of oral nucleoside/nucleotide analogs or interferon are unable to achieve a sustained and effective response in most of patients with chronic hepatitis B（CHB）. The objective of the present study was to compare the efficacy and safety of pegylated interferon（Peg-IFN） alpha-2b plus adefovir dipivoxil combination therapy versus Peg-IFN alpha-2b alone. Sixty-one HBeAg-positive chronic hepatitis B patients were randomized to receive Peg-IFN alpha-2b alone（1.5 μg/kg once weekly） or Peg-IFN alpha-2b plus adefovir（10 mg daily） for up to 52 weeks. Efficacy and safety analyses were performed on all participants who received at least one dose of study medication. The rate of HBeAg seroconversion and undetectable HBV-DNA were evaluated after 52 weeks of therapy. At the end of treatment, 11 of 30（36.7%） patients receiving combination therapy achieved HBeAg seroconversion versus 8 of 31（25.8%） in the monotherapy group（P=0.36）. In contrast, the percentage of patients with undetectable serum HBV DNA was significantly higher in the combination group than in the monotherapy group（76.7% vs. 29.0%, P〈0.001）. Thyroid dysfunction was more frequent in the combination group than in the monotherapy group（P〈0.05）. In HBeAg-positive CHB, combination of Peg-IFN alpha-2b and adefovir for 52 weeks resulted, at the end of treatment, in a higher virological response but without significant impact on the rate of HBeAg seroconversion and possibly an adverse effect on thyroid function.

Combination of pegylated interferon and lamivudine for patients with chronic hepatitis B who have failed treatment

BACKGROUND: Treatment of chronic hepatitis B (CHB) alone with interferon or lamivudine alone or in combination is effective in only a small proportion of patients. Treatment of patients in whom antiviral therapy fails is challenging. This study was made to determine the efficacy of combined pegylated interferon alpha (peg-IFN) and lamivudine in patients with CHB who had failed to respond to antiviral treatment. METHODS: Twenty patients with CHB proven by liver biopsy, with ALT levels >1.5×ULN,HBV DNA levels>141 500 copies/ml, and previous treatment failure with an adequate regimen were treated with a combination of peg-IFN 1.5μg/kg and lamivudine 100 mg/day for 52 weeks and followed up for a further 24 weeks. Biochemical response was defined as normalization of ALT and DNA response as HBV DNA<141 500 copies/ml. Secondary efficacy measures included HBsAg loss, HBeAg loss and appearance of anti-HBe (in cases of HBeAg-positive patients). RESULTS: Twenty patients were treated, of whom 16 were HBeAg positive. At 52 weeks, normal ALT was seen in 10 (50%) (8 of 16 HBeAg+ and 2 of 4 HBeAg), HBV DNA response in 5 (25%) (5 of 16 in HBeAg+ and none in HBeAg-), and HBeAg loss with appearance of anti-HBe in 5 (31.3%) of the 16 HBeAg positive patients. At 76 weeks, 8 (80%) of the 10 patients with normal ALT at 52 weeks relapsed, with normal ALT only in 2 (10%) (1 of 16 HBeAg+ and 1 of 4 HBeAg-), and all 5 patients who had a DNA response at 52 weeks relapsed at 76 weeks and had no DNA response. HBeAg loss with appearance of anti-HBe was seen in 1 (6.3%) of 16 HBeAg-positive patients. None of the patients lost HBsAg. CONCLUSIONS: The combination of peg-IFN and lamivudine for 52 weeks is not effective for treatment of CHB patients with a failed treatment. New treatment strategies need to be developed.