Targeted innovative design of Bt Cry toxin insecticidal mimics / 生物工程学报

Bt Cry toxin is the mostly studied and widely used biological insect resistance protein, which plays a leading role in the green control of agricultural pests worldwide. However, with the wide application of its preparations and transgenic insecticidal crops, the resistance to target pests and potential ecological risks induced by the drive are increasingly prominent and attracting much attention. The researchers seek to explore new insecticidal protein materials that can simulate the insecticidal function of Bt Cry toxin. This will help to escort the sustainable and healthy production of crops, and relieve the pressure of target pests' resistance to Bt Cry toxin to a certain extent. In recent years, the author's team has proposed that Ab2β anti-idiotype antibody has the property of mimicking antigen structure and function based on the "Immune network theory" of antibody. With the help of phage display antibody library and specific antibody high-throughput screening and identification technology, Bt Cry toxin antibody was designed as the coating target antigen, and a series of Ab2β anti-idiotype antibodies (namely Bt Cry toxin insecticidal mimics) were screened from the phage antibody library. Among them, the lethality of Bt Cry toxin insecticidal mimics with the strongest activity was close to 80% of the corresponding original Bt Cry toxin, showing great promise for the targeted design of Bt Cry toxin insecticidal mimics. This paper systematically summarized the theoretical basis, technical conditions, research status, and discussed the development trend of relevant technologies and how to promote the application of existing achievements, aiming to facilitate the research and development of green insect-resistant materials.

The Advances in the Contamination and Detection of Foodborne Pathogen Noroviruses in Fresh Produce / 病毒学报

This article reviewed the researches proceeding on the contamination and detection of the foodborne pathogen noroviruses (NoVs) in fresh produce, which involved the NoVs contaminations in fresh produce, the special attachment of NoVs in fresh produce, the NoVs outbreaks associated with fresh produce and the NoVs detection in fresh produce. There had been an increase in reported infectious disease risks associated with the consumptions of fresh produce for recent 30 years. Because the NoVs, as a primary cause of viral gastroenteritis thoughout the world, were highly contagious, had a low infectious dose, and were persistent in the environment. And also the methods for NoVs detection in food had significantly developed over the last 15 years. Currently NoVs were the most common pathogen accounting for 40% of outbreaks associated with fresh produce (i. e., fruits and vegetables). Data from outbreaks investigations verified fresh produce as the high risk food products for NoVs. The fresh produce were typically eaten raw with no thermal processing, can be contaminated at any step during production and processing from faecally polluted water and fertilizers, the poor hygiene practices by food handlers and the cross-contamination. The attachment of NoVs to the fresh produce was due to the physio-chemical factors of virus protein coat, the special attachment to different fresh produce, and the possibility for internalization of NoVs. It might provide answers to why those high risk foods were more frequently implicated (i. e., lettuce and raspberries). According to the data of foodborne NoVs outbreaks which were associated with fresh produce from EU countries and the USA, the outbreaks in EU countries were mainly associated with NoVs contaminated raspberries and lettuce, while in USA which were associated with NoVs contaminated lettuce. Unfortunately, there were no NoVs detection methods for fresh produce or the data of foodborne NoVs outbreaks which were associated with fresh produce in China. That made it difficult to analyze the NoVs contamination situation in China. The heterogeneous distributions of presumably low levels of virus, which presented in contaminated fresh produce, also made it difficult to detect NoVs. To solve this problem, different sampling methods, viral elution methods and RT-qPCR methods were chosen. For example, according to the isoelectric point of NoVs particles, high pH and high ionic strength solution could be used as means for releasing NoVs. For the elution from acidic fruit, the buffer capacity and the virus recovery could be increased by the addition of tris-HCl. When analyzing pectin containing raspberries or strawberries, the viral elution usually incubated with pectinase at neutral pH to avoid from foaming jelly. In this paper, the latest ISO standard for NoV detection in food and the new approaches for NoV detection were also reviewed to provide references for domestic researches. It was necessary to establish and develop domestic methods for NoV detection in fresh produce, especially the different NoV conventional molecular detection methods with corresponding NoV extraction methods, which targeted to the different adsorption characteristics of different fruits and vegetables, in order to strengthen the national food safety monitoring.

Production and Identification of Broad Spectrum Monoclonal Antibody against a Group of Pyrethroid Insecticides / 分析化学

The objective of this study is to generate broad spectrum monoclonal antibody ( mAb ) against a group of pyrethroid insecticides and to identify its immunological characteristics. The generic hapten 3-phenoxy-benzoic acid ( PBA) was conjugated to carrier protein BSA by activated ester method. Balb/c mice were immunized with PBA-BSA. The titer of polyclonal antibody ( pAb ) was detected by indirect enzyme-linked immunosorbent assay ( ELISA) after five times immunization. The mouse with high titer and sensitivity was selected for cell fusing. The splenocytes of immunized mice were fused with Sp2/0 cells and the cultural supernatants of hybridoma cells were screened by indirect non-competitive ELISA based on the coating antigen PBA-ovoalbumin ( PBA-OVA ) . High-sensitivity and high-specificity mAb was prepared after subcloning using limiting dilution method. Purified mAb was obtained after purified by saturated ammonia sulfate precipitation and protein G affinity column. The immunological characteristics of mAb such as titer, antibody subtypes, affinity constant and the sensitivity to pyrethroid insecticides were characterized by indirect ELISA; The results of UV spectroscopy and SDS-PAGE showed that PBA-BSA artificial antigen was synthesized successfully. A hybridoma cell line (4H11) secreting anti-pyrethroid mAb was established. The titre of ascites was up to 1:6. 5×106, and the mAb was IgG1 subtype. The affinity constant of the mAb to PBA was about 2. 5×107 L/mol, with a IC50 value of 208. 83 μg/L and a detection limit of 21. 23 μg/L to PBA. Simultaneously, beta-cypermethrin, flucythrinate, cypermethrin and fenvalerate were sensitively recognized by the mAb with the IC50 of 1. 01, 2. 15, 3. 16 and 3. 67μg/L, respectively.

Synthesis and identification of antigenic conjugates of podophyllotoxin / 药学学报

Aim To synthesize and identify artificial antigen of podophyllotoxin for the production of podophyllotoxin polyclonal antibody. Methods The hapten was synthesized by two different chemical approaches and characterized by TLC, IR, NMR, and MS. Mixed anhydride reaction (MAR) and active ester method (AEM) were used to couple the podophyllotoxin to carrier proteins (BSA and OVA). Characterization of artificial antigens was done by using spectroscopy and electrophoresis. The anti-podophyllotoxin polyclonal antibodies were obtained through immunizing rabbits. Results The results from IR, NMR and MS showed that 4-O-succinoyl podophyllotoxin (hapten) was successfully synthesized. The coupling molar ratios of the hapten and carrier proteins were 88.6 for Hapten-BSA1, 40.3 for Hapten-BSA2, 17.8 for Hapten-OVA1, and 54.2 for Hapten-OVA2. Hapten conjugates coupled with BSA yielded two sets of the specific and affinitive polyclonal antibodies. One set of antibodies showed an IC50 value of 2.21 μg·mL -1 with a detection limit of 0.12 μg·mL -1. Conclusion Antigenic conjugates were artificially synthesized, and based on these artificial antigens, polyclonal antibodies against podophyllotoxin were raised from rabbits immunized with two different immunogens and characterized with an indirect ELISA format.