Single chain antibody fragment display systems: a review / 生物工程学报

Single chain antibody fragment (scFv) is a small molecule composed of a variable region of heavy chain (VH) and a variable region of light chain (VL) of an antibody, and these two chains are connected by a flexible short peptide. scFv is the smallest functional fragment with complete antigen-binding activity, which contains both the antibody-recognizing site and the antigen-binding site. Compared with other antibodies, scFv has the advantages of small molecular weight, strong penetration, low immunogenicity, and easy expression. Currently, the most commonly used display systems for scFv mainly include the phage display system, ribosome display system, mRNA display system, yeast cell surface display system and mammalian cell display system. In recent years, with the development of scFv in the field of medicine, biology, and food safety, they have also attracted much attention in the sectors of biosynthesis and applied research. This review summarizes the advances of scFv display systems in recent years in order to facilitate scFv screening and application.

The role of natural killer cells in anti-infection and tumor therapy / 细胞与分子免疫学杂志

Natural killer (NK) cells are an important part of the body's innate immune system. As the first line of defense against pathogens, they need to be transformed into a mature state under the control of various cell signaling molecules and transcription factors to play cytotoxic and immune regulatory roles. Under the interaction of activated receptors and inhibitory receptors, NK cells are activated to perform a direct cell killing effect by secreting perforin and granzyme, or indirectly eliminate pathogenic microorganisms in the body by secreting various cytokines, such as type I and type II interferons. These functions of NK cells play a very important role in antiviral and anti-autoimmune diseases, especially in anti-tumor.

Transglutaminase 2 inhibits the proliferation of H1 subtype influenza virus in MDCK cells / 生物工程学报

Transglutaminase 2 (TGM2) is a ubiquitous multifunctional protein, which is related to the adhesion of different cells and tumor formation. Previous studies found that TGM2 is involved in the interaction between host cells and viruses, but the effect of TGM2 on the proliferation of influenza virus in cells has not been reported. To explore the effect of TGM2 during H1N1 subtype influenza virus infection, a stable MDCK cell line with TGM2 overexpression and a knockout cell line were constructed. The mRNA and protein expression levels of NP and NS1 as well as the virus titer were measured at 48 hours after pot-infection with H1N1 subtype influenza virus. The results showed that overexpression of TGM2 effectively inhibited the expression of NP and NS1 genes of H1N1 subtype influenza virus, while knockout of TGM2 up-regulated the expression of the NP and NS1 genes, and the expression of the NP at protein level was consistent with that at mRNA level. Virus proliferation curve showed that the titer of H1N1 subtype influenza virus decreased significantly upon TGM2 overexpression. On the contrary, the virus titer in TGM2 knockout cells reached the peak at 48 h, which further proved that TGM2 was involved in the inhibition of H1N1 subtype influenza virus proliferation in MDCK cells. By analyzing the expression of genes downstream of influenza virus response signaling pathway, we found that TGM2 may inhibit the proliferation of H1N1 subtype influenza virus by promoting the activation of JAK-STAT molecular pathway and inhibiting RIG-1 signaling pathway. The above findings are of great significance for revealing the mechanism underlying the interactions between host cells and virus and establishing a genetically engineering cell line for high-yield influenza vaccine production of influenza virus.

Effects of synonymous codon usage bias on mRNA half-life and translational regulation / 生物工程学报

With the widespread application of genomics and transcriptomics in the genetics and cell biology of different species, synonymous codon usage bias has been gradually accepted and used to study the deep connection between biological evolution and biological phenotypes. It is an important part of the life activities that mRNA is expressed into proteins with normal biological activities. The synonymous codon usage patterns, which were named as 'the second genetic codon', can express genetic information carried by themselves at the levels of transcriptional regulations, translational regulations and metabolic activities through molecular mechanisms such as fine-tune translation selection. Some studies have shown that the length of mRNA half-life has significant impacts on mRNA activity and the process of transcription and translation. This review summarized the roles of synonymous codon usage patterns in transcription, translational regulation and post-translational modification, with the aim to better understand how organisms skillfully utilize the genetic effects caused by codon usage patterns to accurately synthesize different types of proteins, so as to ensure the growth or differentiation of the specific gene expression procedures to carry out smoothly and maintain the normal life cycle.

Establishment and application of a TaqMan real-time PCR assay for the detection of encephalomyo-carditis virus / 中华微生物学和免疫学杂志

Objective To establish a TaqMan real-time PCR assay for the detection of encephalo-myocarditis virus ( EMCV) .Methods Based on the conservative region of 3D gene of EMCV published in GenBank , a pair of primers and one TaqMan probe were designed and synthesized .Then a TaqMan real-time PCR assay was set up and the reactive system was optimized .The sensitivity and specificity of the assay was evaluated respectively .The TaqMan real-time PCR assay was then carried out to detect 98 randomly selected swine serum samples and the results were compared with those by using ELISA .Results The Ct value of the templates had a good linear relationship with the log starting quantity , with a correlation coefficient of 0.995.The TaqMan real-time PCR assay was only specific for EMCV and its sensitivity was 100 times higher than that of the ordinary PCR .The coincidence rate between the established assay and the ELISA assay was 98.0%in the detection of 98 blood samples.Conclusion The TaqMan real-time PCR assay for the detec-tion of EMCV was successfully established with advantages of high sensitivity and good specificity .It could be used for detection of EMCV and quantitative analysis .

Construction of pEGFP-C1-JEV eukaryotic expression vector of E gene from JEV and expression fusion protein molecule in BHK-21 cells / 中华微生物学和免疫学杂志

Objective To research the molecular biology characteristics and transient expression in BHK-21 cells of E geue segment from Japanese encephalitis virus(JEV) and construct an eukaryotic expression vector pEGFP-C1-JEV.Methods E gene segment of JEV was amplified by RT-PCR,construct the recombinant vector pEGFP-C1-JEV,which could express EGFP label proteins.Transfect pEGFP-C1-JEV vector into BHK-21 via LipofectAMINETM 2000,to observe expressing of EGFP label protein and transcription of aim gene,and to check up localization and antigenicity of expressed E protein by Immunohistochemistry and Western blot.Results It showed that the recombinant plasmid pEGFP-C1-JEV was successfully constructed and transfected to BHK-21 cells,the normal expression of green fluorescent protein expression rate was higher.RT-PCR showed that gene transcription in BHK-21 and normal expression,expression protein was mainly distributed in the cytoplasm of BHK-21 cells and the envelope in,and can with guinea pig anti-JEV antibody binding.Conclusion pEGFP-C1-JEV vector in BHK-21 cells was normal expression and there were no effect on cell growth and morphology.Meanwhile,on eukaryotic antigens was good antigenicity.This research as a base foundation for E protein gene of JEV eukaryotic expression and function in vitro and applied research.

Preparation and in vitro cytocompatibility of collagen sponge from newborn bovine skin / 中国组织工程研究

BACKGROUND:It is confirmed that collagen sponge prepared from human tendon,bovine tendon,rat tail,pig skin and newborn bovine tendon have good cytocompatibility.OBJECTIVE:To extract collagen from newborn bovine skin,prepare the collagen sponge for biomedical application,and observe the biocompatibility and cytocompatibility of collagen sponge with lamb fibroblasts.DESIGN,TIME AND SETTING:Controlled study was performed in the Key Laboratory of Bioengineering of State Ethical Committee,Life Science and Engineering College,Northwest University for Nationalities from May 2006 to February 2007.MATERIALS:Newborn Galiba bovine within 24 hours and black fur lamb kidney fibroblasts were used.METHODS:Newborn bovine skin was harvested to prepare the collagen sponge with a series of procedures,including depilation,pepsin+glacial acetic acid,salting-out,dialysis and freeze drying.The obtained collagen sponge was inoculated with fibroblast suspension,which were divided into collagen sponge group,negative control group (saline) and positive control group (rubber bung leaching liquor).MAIN OUTCOME MEASURES:Inverted phase contrast microscope and JVC digital camera system were used to observe the cell morphology and growth.Acridine orange dyeing was used to observe the proliferation of cell in collagen sponge at 20 and 35 days of culture.Hematoxylin-eosin staining was used to observe the growth of cells in collagen sponge at 65 days of culture.RESULTS:The cells of positive control group were not adhesive and all died three days later.Those of collagen sponge group and negative control group were normal and adhesive.With the prolong of culture time,the sponge pore decreased gradually,sponge appearance became eminent and transparent,the cell increased in number but decreased in morphology.Acridine orange dyeing at 20 and 35 days of culture showed that a large amount of cells appeared in the co-culture of collagen sponge with lamb kidney fibroblast,and pack of cell clumps grew.Abundant blue nuclei and newborn red collagen fiber were found by hematoxylin-eosin staining.CONCLUSION:The collagen sponge from newborn bovine skin has a good biocompatibility with lamb kidney fibroblast cell of black fur,and no cytotoxicity appears.

Biocompatibility of new-born bovine tendon-made collagen sponge with animal kidney,testicle and skin cells / 中国组织工程研究

BACKGROUND:Industrialization of new-born bovine serum and abundant resource of bovine lendon enable industrialization of medical collagen sponge.OBJECTIVE:To prepare collagen sponge with new-born bovine tendons by inoculating Veto cells,primary embryo skin cell of Tianzhu White Yak and lamb testicle cell of Minxian black fur sheep of the tissue scaffold of collagen sponge.and observe the biocompatibility of collagen sponge with three different cells.DESIGN,TIME AND SETTING:Repetitive measurement was performed at the Key Laboratory of State Nationalities Afrairs Committee,College of Life Sciences and Engineering,Northwest University for Nationalities from February to May 2006.MATERIALS:Tendons of new-born bovine within 24 hours were digested by glacial acetic acid and pepsinum firstly and then salting-out,dialysis and vacum freeze drying were performed to prepare collagen sponge.f2 passage of embryo skin cells of Tianzhu Whit Yak and f2 passage of lamb testicle cells of Minxian black fur sheep were prepared by out laboratory;Vero cells were provided by Union Medical University.METHODS:In a 6-hole plate,the Vero cell,embryo skin cells of Tianzhu White Yak and lamb testicle cells of Minxian Black Fur Sheep were inoculated into the collagen sponge pretreated by ultraviolet and sterilized by ozone.and incubated in 5%CO2 at 37℃.In addition,cells only inoculated ia a culture plate served as control. MAIN OUTCOME MEASURES:Inverted phase contrast microscope was used to observe cell growth condition in the collagen sponge and 6-hole plate at 5,12,24 and 72 hours.In addition,Coomassie brilliant blue as well as HE staining were conducted at 11 days after culture to identify the culture.RESULTS:Five hours after inoculation,cell adherence and expansion was observed at the bottom of culture plate.and some of the cells showed division.On the surface of collagen sponge.a round cell arrangement was observed.After inoculation of 48-72 hours,monolayer was found at the bottom of the plate.On the 11th day of culture.Coomassie brilliant blue and HE staining of three kinds of cells showed there were lager amount of cells well grew in the holes of collagen sponge,and the collagen sponge turned to be eminent,transparent and tenacious.CONCLUSION:The collagen sponge made from new-born bovine tendons exhibit good biocompatibility with three kinds of cells from different animals and tissues,and can be served as culture seaffoId of skin cells,tenal ceils.and testicle cells.