Expression of antimicrobial peptide Cecropin P1 in Saccharomyces cerevisiae and its antibacterial and antiviral activity in vitro

BACKGROUND: Cecropin P1, acting as an antimicrobial, has a broad-spectrum antibacterial activity with some antiviral and antifungal properties. It is a promising natural alternative to antibiotics which is originally isolated from the pig intestinal parasitic nematode Ascaris suum. Many studies have shown that Cecropin P1 is helpful for the prevention or treatment of clinical diseases. Therefore, it is very necessary to establish a safe, nontoxic, and efficient expression method of Cecropin P1. RESULTS: The results indicated that the recombinant protein was about 5.5 kDa showed by Tricine­SDS­ PAGE and Western blot. And Cecropin P1 was efficiently secreted and expressed after 12 h of induction, with an increasing yield over the course of the induction. Its maximum concentration was 7.83 mg/L after concentration and purification. In addition, in vitro experiments demonstrated that Cecropin P1 not only exerted a strong inhibitory effect on Escherichia coli, Salmonella sp., Shigella sp., and Pasteurella sp., but also displayed an antiviral activity against PRRSV NADC30-Like strain. CONCLUSIONS: Collectively, the strategy of expressing Cecropin P1 in Saccharomyces cerevisiae is harmless, efficient, and safe for cells. In addition, the expressed Cecropin P1 has antiviral and antibacterial properties concurrently.

Screen time and associated factors among preschool children in Beijing / 中国学校卫生

Objective@#To investigate current status of screen-time in 2-6 years old preschoolers in Beijing, and to describe associated factors of high screen time, and to provide a reference for making interventional measures to prevent and control short-sightness.@*Methods@#A total of 366 preschoolers were chosen through convenience sampling from 5 kindergartens in Beijing urban and rural areas. Questionnaire survey was administered to parents regarding child screen-time.@*Results@#The average screen time of the preschool children in Beijing was (120.5±78.5)min/d, and the rate of high screen time was 75.8%. The average screen time during weekdays was (92.4±72.8) min/d, which was less than the average screen time at weekends (192.4±117.0) min/d. Logistic regression analysis showed that age (OR=1.69, 95%CI=1.19-2.38, P＜0.05) and without an habit of exercise among parents (OR=3.05, 95%CI=1.50-6.19, P＜0.05) were positively associated with, and being girl was the negatively associated with high screen-time (OR=0.49, 95%CI=0.25-0.99, P＜0.05).@*Conclusion@#A large proportion of the preschool children aged 2-6 in Beijing have too long screen time, especailly during weekend, and gender, age, parental habit of exercising and so on have impacts on their screen time. Therefore, the education and prevention work should be conducted to reduce their screen time.

Development of a Rapid and Sensitive Method for Detection of African Swine Fever Virus Using Loop-Mediated Isothermal Amplification

ABSTRACT A loop-mediated isothermal amplification (LAMP) assay was developed for rapid, sensitive and specific detection of African swine fever virus (ASFV). A set of LAMP primers was designed based on the sequence of the ASFV gene K205R. Reaction temperature and time were optimized to 64 oC and 60 min, respectively. LAMP products were detected by agarose gel electrophoresis or visually with the addition of fluorescent dye. The detection limit of the LAMP assay was approximately 6 copies of the target gene per microliter, 100 times more sensitive than conventional PCR. LAMP is a simple and inexpensive molecular assay format for ASFV detection. To date, African swine fever has not been reported in China. LAMP can be used to monitor ASFV spread into China, thereby reducing the threat of ASF.