鼠巨细胞病毒感染C57BL/6小鼠急性肝炎动物模型的建立与鉴定

目的：建立鼠巨细胞病毒（MCMV）感染C57BL/6小鼠急性肝炎模型并对其感染特点进行分析及鉴定。方法：将24 只C57BL/6小鼠随机分为阴性对照组（n =12）及病毒感染组（n =12），病毒感染组腹腔注射1.0×106 PFU（200 μL）MCMV悬液，阴性对照组注射等体积小鼠胚胎成纤维细胞（MEF）悬液。于感染后第3天和第7天取外周血分离血清检测谷丙转氨酶（ALT）及谷草转氨酶（AST）。同时进行肝组织病毒分离、组织病理学及MCMV IE和M55基因、细胞因子白细胞介素-6（IL-6）、白细胞介素-1β（IL-1β）、肿瘤坏死因子α（TNF-α）的检测。结果：病毒感染组肝组织匀浆病毒分离均为阳性，肝炎发生率为100%。在感染后第3天即发生肝炎病理改变，病毒感染组血清ALT及AST较阴性对照组明显升高（P ＜0.01）；病毒感染组肝脏HE染色第3天可见局灶性炎性细胞浸润及肝脏点灶状坏死，持续至第7天，Ishak评分较阴性对照组明显升高（P ＜0.01）；在感染后第3天病毒感染组肝组织内可检测到MCMV IE及M55基因，且在感染后第7天仍可测得IE基因；感染后第3天及第7天病毒感染组炎性细胞因子IL-6、TNF-α及IL-1β mRNA表达水平明显升高（P ＜0.05）。 结论：成功建立MCMV感染C57BL/6小鼠急性动物肝炎模型，其感染表现主要集中在急性感染前期。     

Ebola Virus RNA Stability in Human Blood and Urine in West Africa’s Environmental Conditions

We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.     

Prevalence,Risk Factors,and Transmission Dynamics of Extended-Spectrum-β-Lactamase-Producing Enterobacteriaceae: a National Survey of Cattle Farms in Israel in 2013

Our objectives were to study the prevalence, risk factors for carriage, and transmission dynamics of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae (ESBLPE) in a national survey of cattle. This was a point prevalence study conducted from July to October 2013 in Israel. Stool samples were collected from 1,226 cows in 123 sections on 40 farms of all production types. ESBLPE were identified in 291 samples (23.7%): 287 contained Escherichia coli and 4 contained Klebsiella pneumoniae. The number of ESBLPE-positive cows was the highest in quarantine stations and on fattening farms and was the lowest on pasture farms (P = 0.03). The number of ESBLPE-positive cows was the lowest in sections containing adult cows (age, >25 months) and highest in sections containing calves (age, <4 months) (P < 0.001). Infrastructure variables that were significant risk factors for ESBLPE carriage included crowding, a lack of manure cleaning, and a lack of a cooling (P < 0.001 for each), all of which were more common in sections containing calves. Antimicrobial prophylaxis was given almost exclusively to calves and was associated with a high number of ESBLPE carriers (P < 0.001). The 287 E. coli isolates were typed into 106 repetitive extragenic palindromic (REP)-PCR types and mostly harbored bla_CTX-M-1 or bla_CTX-M-9 group genes. The isolates on the six farms with ≥15 isolates of ESBLPE were of 4 to 7 different REP-PCR types, with one dominant type being harbored by about half of the isolates. Fourteen types were identified on more than one farm, with only six of the farms being adjacent to each other. The prevalence of ESBLPE carriage is high in calves in cowsheds where the use of antimicrobial prophylaxis is common. ESBLPE disseminate within cowsheds mainly by clonal spread, with limited intercowshed transmission occurring.