ABSTRACT
Objective To develop a sensitive, specific, rapid and easy method for detecting E. coli O157 : H7 and other Shiga toxin-producing E. coli in food and clinical specimens. Methods A circular probe and capture probe specific for Shiga toxin-2 (stx2) gene had been synthesized and was used for determining the sensitivity of ramification amplification method (RAM). Different serotypes which contained stx2 gene, including an E. coli O157 : H7, an E. coli O46 : H38, an E. coli O111 : NM, an E. coli O22 : H8 and E. coli ATCC23716 (stx2 gene negative) were used for determining the specificity. All strains were detected by RAM to determine whether they contained stx2 gene. Real-time RAM was further studied to detect stx2 gene. Results The lowest number targets detected by RAM assay was 10 copies of stx2, indicating that RAM assay was as sensitive as conventional PCR. The result of specificity showed that different serotypes of strains were all positive for stx2 gene, while nonpathogenic E. coli ATCC23716 was negative. Among 32 isolates, 28 STEC isolates containing stx2 gene were positive by RAM assay, while others were negative. The RAM results were 100% in concordance with that of PCR. The real-time RAM results also showed that as many as 10 bacteria can be detected and the time of appearance of detectable signal was depended on the target concentration. Conclusion RAM assay can offer an alternative method for PCR to detect E. coli O157 : H7 and STEC in all types of specimens because of its simplicity and isothermal amplification.
ABSTRACT
Objective:To prepare the immunoglobulin Y(IgY) against Avain Influenza Virus (H5N1) and to investgate its inhibitory activity to Influenza virus A (FM1).Methods:Iimmunized by Avain Influenza vaccine,IgY against Avain Influenza Virus was purified from the yolk and then the antibody was enriched by the means:caprylate acid-two-step salt precipitation-gel chromatograph.TD0 of IgY and the inhibory effectiveness were showed by nhibiting cytopathic effect (CPE) thst in MDCK infected with Influenza virus A(FM1).Results:IgY against Avain Influenza Virus was obtained.The TD0 value of IgY against Avain Influenza to MDCK cell line was 1.764 mg/ml,while at the dosage as low as 0.082 8 mg/ml the lnfluenza virus A(FM1) was still inhibited in vitro.Connchusion:Caprylate acid-two-step salt precipitation-gel chromatograph can prepare IgY successfully and the inhibitory effectiveness of IgY is good for inhibition of Influenza virus A(FM1).
ABSTRACT
AIM: To observe the changes of serum nitric oxide and the production level of IL-1 in different period of coxsackievirus B 4 (CB 4V)-induced insulin-dependent diabetic mice.METHODS: The insulin-dependent diabetes mellitus (IDDM) animal model induced by CB 4V infection was established. Serum nitric oxide level was estimated by nitrate reductase method after infection 72 h,1 week, 3 weeks,6 weeks,8 weeks, respectively. At the same time, level of IL-1 produced by peritoneal M? was measued.RESULTS: (1) Changes of serum nitric oxide: serum nitric oxide level in control group remained normal level. The serum nitric oxide level in diabetic group increased significantly at 72 h after infection(P0.05). (2) IL-1 activities: IL-1 activities were increased obviously from 72 h to 3 weeks after virus infection, but decreased to normal level after 6 weeks.CONCLUSION: Nitric oxide may be one of the important factors in the development of CB 4V-induced IDDM.