A cellulase-producing Bacillus was previously isolated from the intestinal tract of domestic bamboo rat and identified as Bacillus subtilis GL-4. In this study, we present the complete genome sequence of B. subtilis GL-4. The genome is 4,271,214 bp long, with a guanine-cytosine content of 43.45%.

Lactic acid bacterium strain LP224 was isolated from the late fermentation stage of sour fish and identified using morphological observation,physiological and biochemical tests and molecular biology techniques. The drug resistance and resistance genes of the strain LP224 were detected by K-B drug sensitive paper diffusion method and polymerase chain reaction（PCR）, and the growth characteristics and tolerance were studied. The results showed that the strain LP224 was identified as Lactobacillus plantarum, which was resistant to 15 antibiotics in 6 categories, including ceftriaxone,streptomycin, ciprofloxacin, sulfisoxazole, vancomycin and lincomycin. Two resistance genes, ermC and tetG, were detected in genomic DNA, while no resistance genes were detected in bacterial plasmid, indicating that the strain was relatively safe. The survival rate of strain LP224 was 35.06% after treatment with 55 ℃ water bath for 30 min, 52.60% in pH 2.5, and 31.67% in 0.3% bile salt concentration, indicating that the strain had strong resistance to heat, acid and bile salts.

Pseudorabies virus (PRV) is an important pathogen that can cause harm to the pig population. Since 2011, there have been a number of large-scale outbreaks of pseudorabies on Chinese farms where animals had been vaccinated with the Bartha-K61 vaccine. In order to understand the epidemiological trend and genetic variations of PRV in Guangxi province, China, 819 tissue samples were collected from swine farms where PRV infection was suspected from 2013 to 2019, and these were tested for infectious wild strains of PRV. The results showed a positive rate of PRV in Guangxi province of 28.21% (231/819). Thirty-six wild-type PRV strains were successfully isolated from PRV-positive tissue samples, and a genetic evolutionary analysis was performed based on the gB, gC, gD, gE, and TK genes. Thirty of the PRV strains were found to be closely related to the Chinese variant strains HeN1-China-2012 and HLJ8-China-2013. In addition, five PRV strains were genetically related to Chinese classical strains, and one isolate was a recombinant of the PRV variant and the vaccine strain Bartha-K61. Amino acid sequence analysis showed that all 36 PRV strains had characteristic variant sites in the amino acid sequences of the gB, gC, gD, and gE proteins. Pathogenicity analysis showed that, compared to classical PRV strains, the PRV variant strains were more pathogenic in mice and had a lower LD50. Taken together, our results show that wild-type PRV infections are common on pig farms in Guangxi province of China and that the dominant prevalent strains were those of the PRV variants. The PRV variant strains also had increased pathogenicity in mice. Our data will provide a useful reference for understanding the prevalence and genetic evolution of PRV in China.

Pseudorabies virus (PRV), the causative agent of Aujeszky's disease, has gained increased attention in China in recent years due to outbreaks of emergent pseudorabies. However, there is limited information about the evolution and pathogenicity of emergent PRV field strains in China. In this study, two PRV field strains were isolated from an intensive pig farm with suspected PRV infection. These were named the GXLB-2015 and GXGG-2016 strains and their growth characteristics together with their genome sequences and pathogenicity were determined. Nucleotide homology and phylogenetic analysis revealed the GXLB-2015 stain was relatively close to the foreign PRV isolated strains with respect to the whole genome sequence. However, it formed an independent branch between the foreign PRV isolates and the previous PRV variants isolated in China. Further recombination and genetic evolution analysis showed that the GXLB-2015 strain was a natural recombinant between the Bartha strain and PRV variants. The GXGG-2016 strain was highly homologous with the Chinese classical strains, but it has a natural deletion of 69 aa in the thymidine kinase (TK) gene. Pathogenicity analysis showed that, the GXLB-2015 strain had the strongest pathogenicity to mice with an LD50 of 103.5, while the GXGG-2016 strain with the TK gene deletion was not pathogenic to mice. Taken together, our data provide direct evidence for the genomic recombination and natural TK gene deletion of PRVs, which may provide a reference for a better understanding of PRV evolution in China and contribute to the clinical control of PRV infection in pig farms.

为了解近年广西地区猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)基因组特征和分子遗传多样性,本研究设计11对特异性引物,对中国广西南宁猪腹泻病例中检测到的1株PEDV GXNN进行了全基因组测定,同时进行相似性比对、遗传进化、基因变异及S基因重组分析.结果显示,广西变异株GXNN与其他PEDV分离株具有相似的基因组特征,基因组全长28 035 bp,与不同参考株核苷酸相似性为96.4％～98.7％,S、OR F3、M 和 N基因核苷酸相似性分别为 93.7％～98.9％、90.9％～99.4％、97.4％～99.7％和 95.6％～99.2％;氨基酸相似性分别为 92.9％～99.5％、91.3％～99.1％、97.4％～99.1％和96.4％～99.5％.GXNN与近年国内大多数分离株亲缘关系较近,处于同一分支,为GII-b亚型,而与经典疫苗毒株、国内早期流行株、国外流行株及广西CH-GX-2015-750A分离株亲缘关系都较远,为不同亚型.与目前常用5个疫苗毒株相比,S基因变异较大,在118、844和905位插入氨基酸Q,在COE(Core neutral-izing epitope)区和主要抗原表位区发生 4 个独特的氨基酸位点突变,其他区域发生14个位点突变;ORF3、M和N基因分别在126位、4D4区和PN-D4区发生126 T/A、199 A/V和103 T/A突变.重组分析发现在S基因的高变区826～3 142 nt存在1个潜在的重组区域.本研究成功获得1株PEDV全基因组序列,对其进行遗传变异分析,为PEDV分子流行病学研究和新型疫苗研发提供参考依据.

为了解2017-2019年广西猪伪狂犬病病毒(PRV)的流行和遗传变异情况,对2017年1月至2019年8月于广西各地区采集的284份疑似伪狂犬病发病猪临床样品进行检测和病毒分离,对分离毒株的gC、gG基因进行克隆、测序、遗传变异分析.被测样品中有85份阳性,阳性率为29.9％,从中共分离到10株PRV毒株,其中9株为国内变异毒株,1株为国内经典毒株.结果显示:广西地区流行的不同亚型PRV毒株在gC、gG基因上均存在相似的核苷酸和氨基酸变异特点,主要与国内变异株亲缘关系较近;广西地区PRV流行毒株主要为国内变异株.本研究结果丰富了广西PRV检测数据资料,为深入评估和预测广西PRV疫病的流行情况提供了可靠的数据基础.

为了解广西近年猪伪狂犬病（PR）流行情况及猪伪狂犬病病毒（PRV）流行株gB、gE、TK基因的遗传变异特点,于2013—2018年采集广西各地区疑似PR发病猪靶组织714份,进行PRV的PCR检测及病毒分离鉴定,并运用DNAStar、MEGA 6.0等生物学软件对分离毒株gB、gE、TK基因进行遗传变异分析。结果显示:样品检测阳性率为24.5%（175/714）,共分离获得PRV流行株38株。受检猪群普遍存在PRV感染,经典毒株及变异毒株并存,而且以变异毒株为主。广西流行株不同亚群PRV在gB、gE、TK基因上均存在相同的氨基酸变异特点,与国内变异株亲缘关系较近。推测广西流行株存在两种不同重组变异形式产生的PRV重组毒株,分别为疫苗株gB基因和变异株gE基因重组产生的重组毒株,以及经典株的TK基因被疫苗株（HB98）的TK基因替换而产生的重组毒株。近年广西受检猪场较普遍存在PRV感染,而且PRV流行株以变异毒株为主,可能存在两种不同重组变异形式产生的重组毒株,猪场需重视及实施针对性PR免疫防控计划。

对广西规模化猪场分离的120株猪源大肠杆菌进行了头孢菌素类、氟喹诺酮类、氨基糖苷类、四环素类、大环内酯类和酰胺醇类药物耐药表型检测,并通过PCR检测菌株的β-内酰胺酶基因(blaTEM、blaCTX-M)、氟喹诺酮类耐药基因(qnrA、oqxA、oqxB)、氨基糖苷类耐药基因(aac(6')-Ib-cr)、大环内酯类耐药基因(ermB)和酰胺醇类耐药基因(floR)携带情况.耐药性检测结果显示,猪源大肠杆菌对头孢西丁、头孢他啶和阿米卡星具有高敏感率(＞74.0％),而耐药率最高为四环素类84.2％,酰胺醇类为70.8％,氟喹诺酮类为68.9％,氨基糖苷类为49.4％,大环内酯类为43.3％,最低为头孢菌素类31.4％.猪源大肠杆菌最低对1种药物耐药,最高对18种药物耐药,111株为多重耐药菌,以11耐(15株)、8耐(13株)和7耐(12株)为主,共有82种耐药谱型.耐药基因检测结果显示,8个耐药基因的阳性率均≥50.0％,其中阳性率最高为bla TEM基因(91.7％),最低为aac(6')-Ib-cr基因(50.0％),共存在53种基因组合类型,主要为blaTEM+blaCTX-M+qnrA+ oqxA+ oqxB+ aac(6')-Ib-cr+ ermB+ floR(14株,11.7％)和bla TEM+blaCTX-M+qnrA +oqxA +oqxB +ermB+ floR(13株,10.8％).耐药基因和耐药表型相关性分析结果显示,blaTEM和bla CTX-M与大肠杆菌对头孢氨苄耐药情况极显著相关(P＜0.01),bla CTX-M与大肠杆菌对头孢拉啶和头孢曲松耐药情况极显著相关(P＜0.01),qnrA、o qxA、oqxB和aac(6')-Ib-cr基因与大肠杆菌对诺氟沙星、氧氟沙星、恩诺沙星和环丙沙星耐药极显著相关(P＜0.01),aac (6')-Ib-cr基因与大肠杆菌对庆大霉素和卡那霉素耐药极显著相关(P＜0.01),floR基因与大肠杆菌对氟苯尼考耐药情况极显著相关(P＜0.01).本研究结果表明广西规模化猪场猪源大肠杆菌仅对极少数抗菌药物具有较高敏感率,多重耐药情况严重,具有丰富的耐药谱型,携带多种耐药基因且具有复杂的基因组合类型,所携带的耐药基因与其耐药表型具有一定的相关性.

To investigate and indentify the contamination of food-borne pathogens in raw livestock and poul-try meats in part of GuangXi from 2015 to 2016,2 326 samples were collected from supermarkets and mar-kets in 4 cities of Guangxi(Nanning,Guigang,Wuzhou and Hezhou),and supposed to analyze 6 kinds of food-borne pathogens,including Salmonella,Staphylococcus aureus,Listeria monocytogenes,Vibrio chol-erae,Vibrio parahaemolyticus,Escherichia coli O157:H7 according to our national food safety stands of GB 4789.The result showed that totally 1 178 strains of food-borne pathogens were detected in the 2 326 samples,with the detection rate of 50.64%.The detection rates of Salmonella,Staphylococcus arureus, Vibrio parahaemolyticus,Vibrio cholerae,Listeria monocytogenes were 27.94%(650/2 326),16.51%(384/2 326),2.75%(64/2 326),1.98%(46/2 326)and 1.46%(34/2 326)respectively,Escherichia coli O157:H7 were not detected.The detection rates of pork,beef,chickens,ducks were 43.80%(654/1493),46.90%(106/226),77.13%(290/376)and 55.41%(128/231)respectively.There were statistically significant differences in the 4 rates(P<0.05).The detection rates of supermarkets and the markets were 58.26%(388/666)and 47.59%(790/1 660).There were statistically significant differences in the 2 rates(P<0.05).The detection rates in Nanning,Guigang,Hezhou,Wuzhou were 70.56%(326/462),56.47%(314/556),43.62%(325/745) and 37.83%(213/563)respectively.There were statistically significant differences in the 4 rates(P<0.05). Thus,the contamination of raw livestock and poultry meats by bacterial pathogens was severe in the 4 cit-ies of Guangxi,in which were mainly contaminated by Salmonella,Staphylococcus aureus.Therefore,pre-ventive measures should be strengthened to ensure the food quality and health of consumers.

试验旨在了解广西部分地区畜禽产品中沙门氏菌血清型分布和耐药状况,以及β-内酰胺酶blaTEM、blaCTX-M基因和氟喹诺酮类抗生素耐药基因qnrA、oqxA、oqxB、aac(6’)-Ⅰb-cr的流行情况.对沙门氏菌进行分离鉴定与血清型分型,采用K-B纸片法对其中随机挑选的80株分离株进行24种抗菌药物敏感性试验,并采用PCR方法进行耐药基因检测.结果显示,从零售生鲜畜禽肉中分离的176株沙门氏菌分属5个血清群,共26种血清型,主要优势血清群为B群60.23％(106/176)、E群18.75％(33/176)和C群15.91％(28/176),主要优势血清型为德尔卑沙门氏菌35.23％(62/176)、鼠伤寒沙门氏菌11.93％(21/176)和伦敦沙门氏菌9.66％(17/176).80株分离株对24种抗菌药物均产生不同程度的耐药,其中对复方新诺明、林可霉素、利福平的耐药率最高,均高于90.00％,对青霉素、氨苄西林、阿莫西林、强力霉素、头孢拉啶、头孢氨苄、头孢曲松、头孢他啶、头孢噻肟、阿奇霉素的耐药率介于50.00％～90.00％之间,对环丙沙星、氧氟沙星、氟苯尼考的耐药率小于10.00％;所有分离株均为多重耐药株,其中最少为2重耐药,最多为17重耐药,多重耐药性主要集中在10～16重耐药,共占总数的78.75％ (63/80).PCR结果显示,80株分离株各基因的检出率分别为:blaTEM 98.75％ (79/80)、blaCTX-M 26.25％(21/80)、oqxA26.25％(21/80)、oqxB 21.25％(17/80)、qnrA 16.25％(13/80)、aac(6’)-Ⅰ b-cr 50.00％(40/80).结果表明,广西畜禽产品源沙门氏菌血清型呈多样性分布,分离株的耐药情况严重,临床日益严重的耐药现象与耐药基因的普遍存在有很大的关系.

目的 了解广西生鲜畜禽产品中致病性大肠杆菌血清型分布、耐药性以及β-内酰胺酶bla TEM、bla CTX-M基因和氟喹诺酮类抗生素耐药基因qnrA、oqxA、oqxB、aac(6')-Ib-cr的流行情况.方法 采用玻片凝集法对2015—2016年间分离自广西生鲜畜禽产品中的249株致病性大肠杆菌进行"O"抗原血清型鉴定;K-B纸片法对已定型菌株进行24种常见抗生素的敏感性试验;PCR方法检测blaTEM、blaCTX-M、qnrA、oqxA、oqxB、aac(6')-Ib-cr.结果 249株致病性大肠杆菌中136株可定型、96株未定型、17株自凝,分别占鉴定菌株的54.6％、38.6％、6.8％;136株已定型菌株分属25个血清型,以O8(19.85％)、O86(8.82％)、O6(6.62％)、O28(6.62％)、O124(6.62％)为主要优势血清型;136株已定型菌株对24种抗生素均产生不同程度的耐药,耐药率从16.18％到100％,且全部为多重耐药,主要集中在12～18重耐药,共占多重耐药的72.06％;136株已定型菌株对6种耐药基因的检出率为qnrA 91.18％(124/136)、oqxA 80.88％(110/136)、oqxB 50.00％(68/136)、aac(6')-Ib-cr 35.29％(48/136)、blaTEM 100.00％(136/136)、blaCTX-M 23.53％(32/136).结论 广西生鲜畜禽产品源致病性大肠杆菌O抗原血清型呈多样性分布,耐药情况严重,临床日益严重的耐药现象与耐药基因的普遍存在有重要的关系.

[Objective]The purpose of this study was to fully study the epidemic characteristics of porcine pseudorabies virus(PRV)in Guangxi to provide a scientific basis for prevention and control of porcine pseudorabies.[Method]From June,2013 to August,2016,473 suspected PRV positive tissue samples and 5041 suspected PRV positive serum samples were collected from pig farms of different scales in 12 cities in Guangxi. The pathogen of porcine pseudorabies and wild virus antibody in tissue and serum samples were detected by PCR and enzyme-linked immunosorbent assay(ELISA)re-spectively.[Result]Positive rate for PRV of tissue and serum samples collected from scale pig farms in Guangxi were 26.43%and 24.50%respectively,and the positive rate of wild virus pathogen in tissue samples was basically consistent with that of PRV antibody in serum samples. The lowest positive rate for PRV occurred in 2015,while the highest in 2016. In Guangxi,PRV could be detected in all seasons,and the positive rate for PRV pathogen in tissue samples and that of antibody in serum samples were the lowest in the third quarter(autumn),which were 19.80%and 14.95%respec-tively. PRV could be detected in samples collected fromten out of the twelve cities in Guangxi,except Wuzhou and Fangchenggang,indicating that PRV infection was prevalent in scale pig farms in Guangxi,with Nanning,Yulin,Beihai and Guilin more serious.[Conclusion]PRV infection is commonin scale pig farms in Guangxi,and positive rate for PRV obviously increases in 2016,which requires intensified efforts to prevent and control PRV in areas where pig industry is developed,and real-time monitoring on PRV epidemiological trend to avoid mixed infection and do a good job in purifica-tion.