Hepatitis B virus （HBV） infection is a global public health issue， affecting the health of 250 million people worldwide. Despite the significant progress in antiviral therapy for HBV， some patients still experience low-level viremia （LLV） after receiving antiviral therapy and fail to achieve viral clearance， with an HBV DNA load remaining at a relatively low level of 20 — 2 000 IU/mL. LLV is often caused by multiple factors such as the high stability of the virus， the difficulty in clearing the virus with antiviral drugs， host immune factors， and drug resistance， which increase the difficulties in antiviral therapy. In addition， LLV can also cause liver damage， which may eventually progress to severe outcomes such as hepatocellular carcinoma. This article reviews LLV in hepatitis B in terms of diagnosis， influencing factors， clinical significance， and treatment strategies.

This study aims to establish an indirect ELISA method for detecting RVFV antibodies u-sing recombinant proteins of Rift Valley fever virus(RVFV)Gn protein Ⅱ-Ⅲ structural domains as the encapsulated antigen which was expressed by the Escherichia coli(E.coli)expression sys-tem.The gene sequences encoding the Ⅱ and Ⅲ subdomains of RVFV Gn protein were inserted in-to pET-30a(+)to construct the recombinant plasmid pET-RVFV Gn-D Ⅱ-Ⅲ.After transforma-tion of the recombinant plasmid into DE3(BL21)competent cells,the recombinant Gn-D Ⅱ-Ⅲ protein was induced with IPTG and purified using affinity chromatography.An indirect ELISA method for the detection of RVFV antibodies was developed using purified recombinant protein as coating antigen and SPA-HRP as the enzyme-labelled secondary antibody.Western blot analysis confirmed that the RVFV Gn-D Ⅱ-Ⅲ protein was successfully expressed.The optimal expression conditions for RVFV Gn-D Ⅱ-Ⅲ protein were induced with 0.8 mmol/L IPTG at 37 ℃ for 5 h.The Gn-D Ⅱ-Ⅲ protein was purified using affinity chromatography with a purity of 91.9％,and the purified protein was used as the encapsulated antigen to develop an ELISA assay for RVFV anti-bodies.The specificity evaluation showed that the method specifically detected RVFV-positive sera and did not cross-react with sera positive for West Nile virus(WNV),Ebola virus(EBOV),Mar-burg virus(MARV)and tick-borne encephalitis virus(TBEV).When the RVFV Gn-D Ⅲ-Ⅲ posi-tive serum was diluted to 6 400 times,the test result still showed positive results,demonstrating the method had good sensitivity.The repeatability evaluation results indicated that the variation co-efficients for both intra-and inter-batch responses was less than 10％,indicating that the method had good repeatability.In conclusion,the RVFV Gn-D Ⅱ-Ⅲ protein was successfully expressed u-sing the E.coli expression system.The purified recombinant Gn-D Ⅱ-Ⅲ protein was used as the encapsulated antigen to develop an indirect ELISA assay for RVFV antibodies,which provides a preliminary basis for the diagnosis of RVF and the research and development of RVF vaccines.

Feline herpesvirus type Ⅰ(FHV-1)was used as the vector.The gI and gE genes of FHV-1 were replaced with the feline calicivirus(FCV)VP1 gene and the red fluorescent protein(mCherry)gene by CRISPR/Cas9 systems and homologous recombination technology,and the re-combinant virus strain FHV △gI&gE/VP1-mCherry+was successfully rescued.The recombinant virus strain was purified by plaque assay.The biological characteristics and genetic stability of the recombinant virus were analyzed by indirect immunofluorescence assay,plaque morphological anal-ysis,and PCR.The results of the indirect immunofluorescence identification showed that the re-combinant virus FHV △gI&gE/VP1-mCherry+could express the VP1 protein in F81 cells,and the growth characteristics of the recombinant virus were not significantly different from those of the parent virus FHV-1.The plaque morphology and staining results indicated that the area of the plaque formed by the recombinant virus was smaller than that of the parent virus,suggesting that the spread ability of the recombinant virus between cells was reduced after the deletion of the gI and gE genes.The result of PCR showed that the VP1 gene could still be detected after 15 succes-sive passages of the recombinant virus,indicating that the recombinant virus had good genetic stability.In this study,the recombinant virus strain expressing the FCV VP1 protein was successfully prepared,which will lay a foundation for the development of engineered FCV and FHV-1 vaccine.

This study aims to establish an indirect ELISA method for detecting RVFV antibodies u-sing recombinant proteins of Rift Valley fever virus(RVFV)Gn protein Ⅱ-Ⅲ structural domains as the encapsulated antigen which was expressed by the Escherichia coli(E.coli)expression sys-tem.The gene sequences encoding the Ⅱ and Ⅲ subdomains of RVFV Gn protein were inserted in-to pET-30a(+)to construct the recombinant plasmid pET-RVFV Gn-D Ⅱ-Ⅲ.After transforma-tion of the recombinant plasmid into DE3(BL21)competent cells,the recombinant Gn-D Ⅱ-Ⅲ protein was induced with IPTG and purified using affinity chromatography.An indirect ELISA method for the detection of RVFV antibodies was developed using purified recombinant protein as coating antigen and SPA-HRP as the enzyme-labelled secondary antibody.Western blot analysis confirmed that the RVFV Gn-D Ⅱ-Ⅲ protein was successfully expressed.The optimal expression conditions for RVFV Gn-D Ⅱ-Ⅲ protein were induced with 0.8 mmol/L IPTG at 37 ℃ for 5 h.The Gn-D Ⅱ-Ⅲ protein was purified using affinity chromatography with a purity of 91.9％,and the purified protein was used as the encapsulated antigen to develop an ELISA assay for RVFV anti-bodies.The specificity evaluation showed that the method specifically detected RVFV-positive sera and did not cross-react with sera positive for West Nile virus(WNV),Ebola virus(EBOV),Mar-burg virus(MARV)and tick-borne encephalitis virus(TBEV).When the RVFV Gn-D Ⅲ-Ⅲ posi-tive serum was diluted to 6 400 times,the test result still showed positive results,demonstrating the method had good sensitivity.The repeatability evaluation results indicated that the variation co-efficients for both intra-and inter-batch responses was less than 10％,indicating that the method had good repeatability.In conclusion,the RVFV Gn-D Ⅱ-Ⅲ protein was successfully expressed u-sing the E.coli expression system.The purified recombinant Gn-D Ⅱ-Ⅲ protein was used as the encapsulated antigen to develop an indirect ELISA assay for RVFV antibodies,which provides a preliminary basis for the diagnosis of RVF and the research and development of RVF vaccines.

Feline herpesvirus type Ⅰ(FHV-1)was used as the vector.The gI and gE genes of FHV-1 were replaced with the feline calicivirus(FCV)VP1 gene and the red fluorescent protein(mCherry)gene by CRISPR/Cas9 systems and homologous recombination technology,and the re-combinant virus strain FHV △gI&gE/VP1-mCherry+was successfully rescued.The recombinant virus strain was purified by plaque assay.The biological characteristics and genetic stability of the recombinant virus were analyzed by indirect immunofluorescence assay,plaque morphological anal-ysis,and PCR.The results of the indirect immunofluorescence identification showed that the re-combinant virus FHV △gI&gE/VP1-mCherry+could express the VP1 protein in F81 cells,and the growth characteristics of the recombinant virus were not significantly different from those of the parent virus FHV-1.The plaque morphology and staining results indicated that the area of the plaque formed by the recombinant virus was smaller than that of the parent virus,suggesting that the spread ability of the recombinant virus between cells was reduced after the deletion of the gI and gE genes.The result of PCR showed that the VP1 gene could still be detected after 15 succes-sive passages of the recombinant virus,indicating that the recombinant virus had good genetic stability.In this study,the recombinant virus strain expressing the FCV VP1 protein was successfully prepared,which will lay a foundation for the development of engineered FCV and FHV-1 vaccine.

To establish a simple,convenient,sensitive,and specific method for rapid detection of Zi-ka virus(ZIKV),the whole genome sequences of ZIKV isolated from different times and regions were analyzed.The specific primers and probes were designed based on the screened target se-quences located in the conserved region of the ZIKV NS5 gene.By combining RT-LAMP isother-mal amplification technology and immunochromatography technology,a reverse transcription loop mediated isothermal amplification nucleic acid and flow visualization strip(RT-LAMP-VF)detec-tion method for ZIKV was established.The results showed that the method had good specificity and sensitivity.When the ratio of inner,outer,and ring primers(FIP∶LF∶F3)was 4∶2∶1,the detection method can specifically detect 102 copies/pL RNA transcripts or 2.15 pfu ZIKV at 61 ℃for 45 minutes,with no cross reaction with other flaviviruses such as Japanese encephalitis virus and classical swine fever virus.Other RNAs in blood tissue samples did not affect the sensitivity and specificity of RT-LAMP-VF,indicating that the method can be applied to clinical practice.The ZIKV RT-LAMP-VF detection method established in this study is easy to perform and does not require special instruments and equipment.It is particularly suitable for the rapid detection of ZIKV in grassroots units,providing technical support and material support for the establishment of on-site rapid detection and early warning and prediction systems for ZIKV disease.

The PCR-amplified severe fever with thrombocytopenia syndrome virus(SFTSV)Gn-DⅢ-Ⅲ gene was inserted into the pET-30a(+)prokaryotic expression vector to generate the re-combinant plasmid pET-SFTSV-Gn-D Ⅲ-Ⅲ.The plasmid was transformed into E.coli BL21(DE3)for Gn-DⅢ-m protein expression and the expression conditions were optimized.The Gn-DⅢ-Ⅲ protein purified with Ni-NTA column affinity chromatography was applied as the captured antigen to establish an indirect ELISA method for the detection of SFTSV antibody.The results demonstrated that the recombinant plasmid pET-SFTSV-Gn-D Ⅲ-Ⅲ was successfully constructed as identified by PCR and sequencing.The recombinant protein SFTSV Gn-D m-Ⅲ was soluble ex-pression in E.coli under the optimal induction conditions of 0.4 mmol/L IPTG at 25 ℃ for 4 h,and the protein purity was 91.77％after purification by Ni-NTA column.The optimal reaction con-ditions for the indirect ELISA of SFTSV antibody were as follows:coating antigen concentration(5 μg/mL),primary antibody(incubation at 37 ℃ for 1.5 h),and secondary antibody(diluted 1:10 000 and incubated at 37 ℃ for 1 h).The established method had no cross-reactivity with Rift Valley fever virus(RVFV),Ebola virus(EBOV),and tick-borne encephalitis virus(TBEV)posi-tive sera.The method had a high sensitivity,with P/N＞2.1 for SFTSV-positive sera diluted to 81920.Coefficients of variation for intra-and inter-batch reactions were less than 10％.Detection of four SFTSV-infected human clinical serum samples showed the serum samples from patients in re-mission were tested as positive(P/N＞2.1),while serum samples from patients with multiple or-gan failure were detected as negative(P/N＜2.1).The results indicated that the SFTSV Gn-D Ⅲ-Ⅲ protein was successfully expressed and purified,and it was used as the coating protein to estab-lish an indirect ELISA assay for SFTSV antibody,which possesses good specificity,sensitivity and reproducibility.This method might be applied to detect human SFTSV clinical serum samples.

Macrophages play an important role in material-related immune responses and bone formation, but the functionality of macrophage-derived extracellular vesicles (EVs) in material-mediated bone regeneration is still unclear. Here, we evaluated intracellular communication through small extracellular vesicles (sEVs) and its effects on endogenous bone regeneration mediated by biomimetic intrafibrillarly mineralized collagen (IMC). After implantation in the bone defect area, IMC generated more neobone and recruited more mesenchymal stem cells (MSCs) than did extrafibrillarly mineralized collagen (EMC). More CD63
Biomimetics ; Bone Regeneration ; Cell Differentiation ; Collagen ; Extracellular Vesicles ; Macrophages ; Osteogenesis

Objective To explore the value of echocardiography in evaluation of pulmonary venous in total anomalous pulmonary venous connection (TAPVC).Methods Fifty-five children with TAPVC were enrolled in the study.The data of echocardiography and CT angiography were retrospectively analyzed and compared with intraoperative findings.Results Totally 55 patients with TAPVC were classified into supra-cardiac type (n=24),cardiac type (n=20),infra-cardiac type (n=7) and mixed type (n=4) according to the sites of drainage of pulmonary venous in echocardiography.In 15 patients with obstruction of pulmonary vertical vein,the sites of obstruction in the supra-cardiac type mostly presented between vertical vein and superior vena cava or innominate vein,and the sites of obstruction in the infra-cardiac presented all between vertical vein and hepatic or portal vein.In 4 patients with pulmonary vein stenosis,3 cases with local pulmonary vein stenosis were all cardiac type,which presented between individual pulmonary vein and common confluence or right atrium;1 patient with diffuse pulmonary vein stenosis was infra-cardiac type.In 9 patients of abnormal individual pulmonary vein,8 cases were not detected by echocardiography,but all were detected by CT angiography.Conclusion Echocardiography is able to make more comprehensive evaluation for the pulmonary venous drainage,obstruction,and proximal stenosis of individual pulmonary vein in TAPVC.CT angiography is superior in evaluation of abnormalities of connection and amount of individual pulmonary vein,and imaging of distal pulmonary vein.