[PreC/C gene-targeting RNA interference suppresses hepatitis B virus replication and expression in human hepatoma cells].

OBJECTIVE: To explore the antiviral efficacy of small interfering RNAs (siRNAs)/shRNA targeting preC/C of HBV in human hepatoma cells Huh-7 and HepG2.2.15 cells. METHODS: Three 21 nucleotide(nt) siRNAs for treating HBV preC/C gene were designed and synthesized according to the HBV genome in GenBank accession numbers (U95551); simultaneously, one 21-nt-long non-homologous siRNA was also designed randomly for negative control. They were cloned into vector pU6 for constructing shRNA-expressing plasmids pU6-C1, pU6-C2, pU6-C3 and control pU6-C4. To assess the function of siRNAs, a reporter gene system was constructed. The HBV preC/C gene was synthesized by PCR with pT-HBV1.3 as the template. The preC/C gene was then inserted into the enhanced green fluorescent protein expression vector (EGFP-N1) in order to construct the recombinant plasmid pEGFP-preC/C (E-C), which carries the EGFP reporter gene. The three shRNA-expressing plasmids-pU6-C1, pU6-C2, or pU6-C3-was each then cotransfected into Huh-7 cells along with either reporter gene expression vector E-C or the controls; or these three plasmids-pU6-C1, pU6-C2, or pU6-C3-was each cotransfected into HepG2.2.15 cells along with the controls. First, upon determination of the number of cells exhibiting EGFP expression in Huh-7cells as detected by an BH-2 fluorescence microscope and FACS-440 flow cytometry at different times after cotransfection, the investigators evaluated the inhibitory efficiency of the three shRNA-expressing plasmids by an EGFP reporter system in cultured cells. Subsequently, the expression amount of HBsAg and HBeAg in HepG2.2.15 cell supernatant at 24, 48, 72 and 96 h post-cotransfection was detected by enzyme-linked immunosorbent assay (ELISA). Immunofluorescence was used to detect the expression of HBsAg and HBcAg at 72 h post-cotransfection in HepG2.2.15 cells. The copy level of HBV mRNA transcripts cDNA in HepG2.2.15 cells was further investigated through quantitative real-time polymerase chain reaction (real-time PCR). RESULTS: In comparison with single plasmid transfection pEGFP-N1 or E-C, fluorescence microscope examination and flow cytometry detection at 48 hours after cotransfection indicated that the expression of the reporter gene EGFP in cotransfected group Huh-7 cell involving pU6-C1, pU6-C2 or pU6-C3 resulted in an 80% reduction in EGFP signal relative to the controls (P < 0.01). It was also found through immunofluorescence that the expression of HBsAg and HBcAg in HepG2.2.15 cells was reduced markedly (P < 0.01), that the copy level of HBV mRNA transcripts cDNA as detected at 48 hours after cotransfection by quantitative real-time PCR was reduced respectively by 73.9% ± 1.2% (P = 0.029), 48.2% ± 1.8% and 35.8% ± 1.4% (P = 0.037, 0.040) relative to the control, that it conformed with that detected by fluorescence microscope/flow cytometry, ELISA, and immunofluorescence (P < 0.01). Thereby further corroborating the antiviral efficacy of RNAi. The efficacy was obvious at 48 h, reaching a peak at 72 h. CONCLUSION: For the first time it has been found that RNAi induced by siRNA/shRNA targeting HBV preC/C gene is effective and specific in inhibiting HBV replication and expression in human hepatoma cells Huh-7 and HepG2.2.15 cells. Our data suggest that RNAi may provide an effective, viable approach in gene therapy to treating major infectious diseases such as HBV/HCV/HIV infection.

[C gene-targeting short hairpin RNA suppresses the replication and expression of hepatitis B virus in BHK-21 cells].

OBJECTIVE: The vaccines currently developed against infectious diseases fail to induce effective antiviral immune responses to control an abrupt outbreak of viral diseases epidemic in a short space of time. Hence there is an urgent need to develop emergency vaccines capable of producing prophylactic effects against infectious diseases. RNA interference (RNAi) is a mechanism that inhibits gene expression by causing the degradation of specific RNA molecules or hindering the transcription of specific genes. The rapidity and uniqueness of RNAi responses can make up for the current inadequacy of antiviral preventive regimes. Here we evaluate the antiviral potential of short hairpin RNA (shRNA) targeting C (core) gene of hepatitis B virus (HBV). It plays essential roles in HBcAg encoding and viral attachment to susceptible cells during its life cycle. The present study was intended to investigate the inhibitory effect of C-specific shRNAs on HBV replication and expression in BHK-21 cells. METHODS: The reporter gene expression vector of pC-EGFP-N1 was constructed by cloning the DNA (PCR product) of HBV C into the EcoRI-HindIII sites of pEGFP-N1 to fuse C to enhanced green fluorescent protein (EGFP) for providing a reporting system for monitoring siRNA function. Plasmid pC was constructed by cloning the DNA of HBV C into the EcoRI-HindIII sites of pCDNA3.1B(-) directly under the control of cytomegalovirus promoter. Two plasmids (S1 & S2) were constructed to express shRNAs targeting C of HBV with the length of 24 nucleotide (nt) homologous in sequence to the HBV C gene. Plasmids were designed and synthesized according to the HBV genome (HBV genotype B, ayw1 subtype) of chronic hepatic B patients from 56 ethnic minorities in China. After cloning and sequencing, the investigators registered them with the GenBank accession numbers of AY517488 (CYN/2002) and AY517489 (CYN/2000), etc. Simultaneously, one of nonspecific shRNA-S3 with a length of 24 nt was also designed randomly for negative control. After cloning into vector pU6 for constructing shRNA-expressing plasmids, they were then cotransfected into BHK-21 cells along with reporter gene expression vector of pC-EGFP-N1. First, upon a determination of the number of cells exhibiting EGFP expression in BHK-21 cells as detected by an Olympus BH-2 fluorescence microscope and FACS-440 flow cytometry (Becton-Dickinson, USA) at different times after cotransfection, the investigators evaluated the gene inhibitory efficiency of both plasmids by an EGFP reporter system in BHK-21 cells. Subsequently, the antiviral efficacy of both plasmids in BHK-21 cells was further investigated by real-time quantitative polymerase chain reaction. RESULTS: In comparison with single plasmid transfection pC-EGFP-N1 or pEGFP-N1, fluorescence microscope and flow cytometry detection at 24 h post-cotransfection revealed that the expression of reporter gene EGFP in cotransfection group involving S1 or S2 and S1 + S2 cotransfection group was reduced significantly by about 90% in EGFP signal versus the control. And the EGFP expression in control plasmid cotransfected S3 or pU6 was not significantly reduced in BHK-21 cells (P < 0.01). It was found that the expression of mRNAs of HBV C and EGFP gene as detected by real-time quantitative PCR was the same as that detected by fluorescence microscope and flow cytometry (P < 0.01), thereby further corroborating the antiviral efficacy of RNAi. The antiviral efficacy extended to almost 48 hours. The results indicted that a DNA vector-based RNAi technology could effectively and specifically inhibit the replication and expression of HBV in BHK-21 cells. CONCLUSION: For the first time it has been found that RNAi induced by shRNA targeting C gene exerts an effective and unique inhibition of HBV replication and expression in BHK-21 cells. Thus RNAi may provide an effective emergency vaccine against major infectious diseases such as HBV infection.

[Transfection of siRNA expressing plasmids targeting S gene inhibits replication and expression of hepatitis B virus in hepatic cancer cells].

OBJECTIVE: To study the inhibitive effects of transfection of siRNA expressing plasmids targeting S gene, one of the 4 open reading frames of hepatitis B virus (HBV), on the replication and expression of HBV. METHODS: Two plasmids expressing 2 siRNAs targeting S gene, one of the 4 open reading frames of HBV (S1 and S2) and one nonspecific plasmid (siRNA-S3), as negative control, with the length of 21 nt heterologous to the HBV/U95551 genome were constructed, and then transfected into the hepatic cancer cells of the line HepG2.2.15. 48 hours later, real-time PCR was used to evaluate the gene silencing efficiency and ELISA was used to detect the expression of HBsAg and hepatitis B e antigen (HBeAg), protein markers of HBV, in the supernatants. RESULTS: The inhibition rates of HBsAg and HBeAg expression of the HepG2.2.15 cells transfected with S1 were 60% and 56% respectively, those of the HepG2.2.15 cells transfected with S2 were 73% and 70% respectively, those of the HepG2.2.15 cells transfected with S1+S2 were 82% and 78% respectively, and those of the HepG2.2.15 cells transfected with S3 were not significantly different from those of the blank control group. RT-PCR showed that the mRNA expression rates of HBsAg and HBeAg in the HepG2.2.15 cells transfected with S1, S2, and S1+S2 were inhibited by 64%-88% t respectively. CONCLUSION: Transfection of the vector plasmids expressing the siRNAs targeting S gene inhibits the expression of HBsAg and HBeAg in hepatic cancer cells. RNAi may provide a viable strategy against viruses for the prevention and treatment of HBV infection.

A peptide of foot-and-mouth disease virus serotype Asia1 generating a neutralizing antibody response, and an immunostimulatory peptide.

The epitopes of the capsid of foot-and-mouth disease virus (FMDV) play important roles in the construction of highly immunogenic subunit vaccines. However few epitopes have been found for FMDV serotype Asia1. In this study we screened for epitopes of the VP1 and VP2 proteins of FMDV serotype Asia1 isolate, YNBS/58. Fragments consisting of amino acids 133-163 of VP1 and amino acids 1-33 of VP2 contained epitopes, and both induced lymphoproliferation in guinea pigs. Only the VP1 fragment induced neutralizing antibodies but the VP2 peptide dramatically increased the neutralizing antibody response induced by the VP1 peptide.

[Expression in Escherichia coli of hepatitis B virus genes from minority nationality patients in Yunnan province with chronic hepatitis B and their antigenicity].

OBJECTIVE: To investigate the expression in Escherichia coli (E. coli) of hepatitis B virus (HBV) genes from minority nationality patients in Yunnan province with chronic hepatitis B (CHB) and their antigenicity. METHODS: Peripheral blood samples were collected from 25 minority nationality patients with CHB in Yunnan province. Twenty-five CHB patients of Han nationality in Yunnan were used as controls. The full length HBV preS2/S and C genes were amplified by PCR, cloned, sequenced, and inserted into the prokaryotic expression vector p lambda PR. The recombinant plasmids p lambda PR-S2S and p lambda PR-C were transfected into E. coli of the line TOP10. The expression of the non-fusion proteins encoded by the HBV preS2S and C genes was determined by sodium dodecyl sulphate polyacrlamide gel electrophoresis (SDS-PAGE) and Western blotting. The antigenicity of the non-fusion proteins was examined by ELISA. Fifty samples of serum of patients with hepatitis A, 50 samples of serum of patients with hepatitis C, and 50 samples of serum of healthy blood donors were used as controls in the study of the antigenicity of non-fusion proteins. RESULTS: SDS-PAGE showed that the recombinant plasmids p lambda PR-S2S and p lambda PR-C were both stably and highly expressed in the E. coli for all 50 CHB patients. The molecular weights of the expressed non-fusion proteins, with a concentration of 16% and a purity of 50%, were between 31,000 and 21,000. Western blotting and ELISA showed that the purified recombinant non-fusion proteins reacted strongly with the antibodies HBpreS2S/SAb and HBcAb and the serum of CHB patients, but there was no cross-activity between the non-fusion proteins and all the serum samples of controls with HA and HC, and normal controls. CONCLUSION: The HBV preS2S and C genes from the minority nationality patients with CHB can be stably and highly expression in E. coli. The non-fusion proteins encoded by the HBV preS2S and C genes have high antigenicity. These findings have potential values in development of HB vaccines.

[Identification of hepatitis B virus genotypes in patients with chronic hepatitis B from different nationalities in ethnic minority areas in Yunnan Province, China].

OBJECTIVE: To determine whether there is evolutionary difference in hepatitis B virus (HBV) genotypes among the patients with chronic hepatitis B (CHB) of different nationalities and its clinical significance. METHODS: Peripheral blood samples were collected from 50 CHB patients, 25 of diverse nationalities and 25 of Han nationality from the ethnic minority regions in Yunnan Province, China, The HBV preS2/S (pre S2/S) and C genes were amplified by PCR. The PCR products were inserted into the vector pBluescriptIISK (pBS). The cloned preS2/S and C genes were sequenced. RESULTS: The sequences of HBV preS2/S and C genes from the 50 patients were 846 (with 49.1% of GC) and 552 (with 46.1% of GC) nucleotides (nt) in length, and encoded 281 and 183 amino acids (aa) respectively. These findings were registered in GenBank Accession Numbers: AY517619, AY517620, AY517488, AY517489, AY517598, AY517599. Compared with the HBV and subtype sequences in the GenBank database, the HBV preS2/S and C genes among all the subjects were homologous to ayw1 in sequence by 97.5% - 98.6% and 94.5% - 97.8% respectively. The "a" determinant region of S genes in all cases were found to be Arginine (AGA) and Lysine (AAA) at corresponding aa 122nd and 160th respectively. HBV genotype B was identified in all patients with CHB (ayw1 subtype). Genotypes A, C, D, E, F, G, and H were not detected in any of them. The quasi-species nature of the HBV in the sera was observed in 2 of the 50 samples examined (4%). There was not a significant difference in the prevalence of HBV genotype B between the 25 diverse nationality patients and the 25 control Han nationality patients (P > 0.05). In the 50 CHB patients, the preS2/S genes were identified to have aa substitutions at the positions R124K (1.1%), L172P (1.3%), M306T (1.5%), and I361M (1.6%), with a frequency of more than 1%. In all subjects, the frequency of aa G145R (0.4%) substitutions was less than 1%. In all subjects, nt variations of C genes caused aa substitutions among aa 27 - 63, 80 - 110, and 135 - 153 involved in T and B cell epitopes. In 45 CHB patients, C genes was identified to have aa substitutions at the positions V 27, N38, V63, Q135, and A147, due to nt variations of 1979A to G, 2012T to A, 2088G to T, 2304C to A, and 2339A to G transitions respectively. The frequency of aa substitutions of C genes was more than 1%. Whereas as for the other 5 severe CHB patients, the C gene variations of A to G, and A to C transitions at nt positions 2159 and 2189 led to aa substitutions of S to G and I to L at positions G87 and L97. No insertion or deletion was found in preS2/S and C regions. HBV genotype B was not relevant to different nationalities (all P > 0.05). CONCLUSION: It is the first time that the genotype of the HBV epidemic strains in the ethnic minority areas of Yunnan Province has been identified as genotype B subtype ayw1. The HBV genotype B is not related with nationality. A novel genotyping method by using PCR, gene cloning, followed by DNA sequencing that can identify all major genotypes has been developed. HBV genotype B is the geographic original strain in this area and is correlated with the severity of liver diseases and curative effect. HBV viral is the only significant variable associated with the CHB patients' prognosis.

Recombinant bivalent vaccine against foot-and-mouth disease virus serotype O/A infection in guinea pig.

In this study, two DNA fragments encoding amino acid (141-160)-(21-140)-(141-160) of the VP1 of FMDV (foot-and-mouth disease virus) serotype O and (138-160)-(21-40)-(138-160) of the serotype A FMDV were chemically synthesized. These two tandem-repeat fragments were ligated and transfected into prokaryotic expression vector pTrcHis A to construct pTH-O-A. The other vector called pTH-O-scIgG-A was constructed similarly only that the two tandem-repeat DNA fragments were linked by the bovine-IgG heavy chain coding sequence. Guinea pigs immunized with the two bivalent vaccines pTH-O-A and pTH-O-scIgG-A showed both specific antibody activity and T cell proliferation responses. FMDV challenge tests showed that 85% and 70% of guinea pigs vaccinated twice with 200 mg of the fusion protein of pTH-O-A were protected from FMDV serotype O and serotype A infection respectively. 70% and 57% of the guinea pigs immunized with the fusion protein of pTH-O-scIgG-A were protected from FMDV serotype O and serotype A infection respectively.