Objective To analyze the changes in the species and densities of the hosts and vectors of plague in Yuxi, Yunnan province, China, with understanding its epidemic pattern, and to provide scientific evidence for preventing and controlling plague. Methods According to the National Plague Surveillance Protocol and Yunnan Provincial Plague Surveillance Protocol, we collected the surveillance data of the hosts, vectors, pathogeny, and serology from seven counties and two districts of Yuxi from 1985 to 2018. We calculated the densities of plague hosts, rate of flea infestation, and flea index by Excel 2010 software, and estimated the Pearson correlation coefficient between Rattus tanezumi density and Xenopsylla cheopis by R3.5.1 software. Results There were two human plague outbreaks in Yuxi, 1985-2018, involving 11 confirmed cases of bubonic plague (9 cases in Yuanjiang county and 2 cases in Xinping county). A total of 59 331 myomorphous rodents were captured, involving 21 species of 13 genera of 6 families of 3 orders, and the overall capture rate was 3.78% (95% confidence interval:3.75%-3.81%). The dominant species was R. norvegicus, accounting for 57.80% of the total number. A total of 55 137 parasitic fleas were collected, involving 8 species of 8 genera of 5 subfamilies of 4 families. The rate of flea infestation was 28.36%, and the overall flea index was 0.83. The dominant species was X. cheopis, accounting for 46.32% of the total number. Indirect hemagglutination assay detected 11 positive serum samples out of 35 412 samples from host animals, and yielded 100% positive results for 11 serum samples of suspected plague patients. Reverse indirect hemagglutination assay detected 4 out of 7 organ samples from rodent. Four strains of Yersinia pestis were isolated from 89 968 host animals examined, and the test was negative for all 33 028 fleas examined. There was no significant association of R. tanezumi density and X. cheopis (r=-0.09, P=0.658). Conclusion During the recent twenty years, the species and densities of plague hosts and vectors were kept at relatively stable levels, and plague was in a relatively silent period in its epidemic foci. However, the main host R. tanezumi and the main vector X. cheopis are still maintained in a certain number, demanding strengthened plague surveillance and improved surveillance quality for timely detection and prevention of the occurrence and spread of human plague.

Objective　To determine the antibacterial activity of propolis from Henan province against Bacillus anthracis. Methods　The agar diffusion method was used to test for antibacterial activity. Antibacterial effects were measured after exposure to seven formulations of 31% propolis at pH ranging from 5.5-8.5 （5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5）. Additionally, ten dilutions of propolis from 31% to 0.06%（1∶512）, including a 0 control, at pH 5.5 and a dose of 7 μl were examined in triplicate. Results　The diameters (mm) of the zones of inhibition in each pH group, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0 and 8.5, were as follows: 19.16±0.29, 17.67±0.29, 14.67±0.58, 13.67±0.29, 14.00±0.00, 13.33±1.15 and 12.00±0.00 mm, respectively. The diameters in each concentration group, 15.50%, 7.75%, 3.88%, 1.94%, 0.97%, 0.48%, 0.24%, 0.12% and 0.06%, and the control group were: 19.50±1.80, 19.67±1.04, 17.75±0.35, 15.67±0.58, 14.00±2.29, 13.17±1.04, 11.83±1.53, 10.83±1.26, 9.00±0.00 and 0.00±0.00 mm, respectively. Conclusion　Propolis from Henan province had antibacterial activity against B. anthracis, which declined with increasing pH or decreasing concentration.

　　【Abstract】　Objective　To investigate the effect of high temperature on antibacterial activity of antibacterial substances induced in the larvae of house fly by pricking. Methods　The induced hemolymph was bathed at 100 ℃ for 10 sec, 30 sec, 1 min, 3 min,  5 min,  80 ℃ and  60 ℃  for  30 sec, 1 min, 3 min, 5 min, 10 min, then solved in the buffer solution of Na2HPO4?KH2PO4(1/15 mol/L，pH 6.5) and centrifuged, the supernatant was used to test the bacteriostasic efficiency to Micrococcus lysodeikticus and Staphylococcus aureus respectively. Results　Diameter of antibacterial ring against M.lysodeikticus decreased along with the increase of bath time at both 100 ℃ and 80 ℃. No antibacterial ring against S.aureus was found after bathed at 100 ℃ for 1 min or 80 ℃ for 3 min. Diameters of antibacterial ring were similar after bathed at 60 ℃ for different time against both M.lysodeikticus and S.aureus. Conclusion　It suggested that the antibacterial activity of antibacterial substance induced by pricking in the house fly was stable against high temperature in a certain extent. Antibacterial activity weakened along with the increase of bath time at 100 ℃ and 80 ℃, and no obvious change after bathed at 60 ℃ for 10 s-10 min.

Objective To induce and preliminarily isolate antibacterial peptide from Lucilia sericata by polyacrylamide gel electrophoresis. Methods After the 3^rd instar larva of L.sericata being induced for 48 h by pricking the hemolymph was collected and tested against Micrococcus lysodeikticus at different doses and different pH conditions. The bacteriostatic effects were observed and the diameters of clear inhibitory ring were recorded respectively. After being bathed at 100 ℃ and 80 ℃ for 30 s, 1 min, 3 min and 5 min respectively, each hemolymph was centrifugated at 10 000 r/min for 10 min to get rid of unwanted proteins, the supernatant was tested against M.lysodeikticus and displayed by polyacrylamide gel electrophoresis. Results The antibacterial ring diameter of induced hemolymph increased along with the increasing of dose, and decreased along with the increasing of pH. The hemolymph didn’t possess antibacterial activity against M.lysodeikticus after being bathed at 100 ℃ for 3 min and 5 min, but possessed antibacterial activity after other treatments. It was also found that the two samples which were bathed at 100 ℃ for 3 min and 5 min were lack of two special bands compared with other treatments. Conclusion It implies that the induced antibacterial substance in the blowfly should possessed stronger antibacterial activity in acid condition. Bathing at 80 ℃ for 1 to 3 min and then centrifuging can get rid of unwanted proteins in a large extent. Maybe the two special bands are the components of the antibacterial peptides induced in the blowfly.

Objective To investigate the stability of antibacterial activity of antibacterial peptide from Lucilia sericata after treatment at high temperature for different time. Methods After being bathed at 100 ℃,80 ℃ and 60 ℃ for 0 sec,30 sec,1 min,3 min and 5 min,the immunized hemolymph were test against Micrococcus lysodeikticus respectively,the bacteriostatic effects were observed after 24 hs and the diameters of clear inhibitory rings were recorded to express antibacterial activity respectively. Results The immunized hemolymph possessed antibacterial activity against M.lysodeikticus after bathed at 100 ℃ for 1 min and also possessed antibacterial activity after bathed at 80 ℃ and 60 ℃ for 5 min. Conclusion The results imply that the induced antibacterial peptide of the blowfly can keep a certain stable antibacterial activity after treatment at high temperature.

Objective To construct an expression vector carrying the outer surface protein C gene of Borrelia burgdorferi which was cloned and expressed for studies in prevention,diagnosis and pathogenic mechanism of Lyme disease.Methods The ospC gene was amplified from the genome of Borrelia burgdorferi PD₉₁ strain by PCR and recombined with plasmid PET-11D.The recombinant plasmid PET- 11D-ospC was identified with restriction endonuclease analysis and sequencing.Results The ospC gene was cloned correctly into vector PET-11D.The homology of nucleotide sequence of the inserted fragment in the plasmid was between 62% to 86% compared with the published sequence of ospC gene.Conclusion The homology of PD₉₁ strain presented highly difference with foreign isolates,and the PET- 11D-ospC constructed successfully pave the way for the research of Lyme disease.