森林脑炎研究进展

森林脑炎又名蜱传脑炎(TBE),是由森林脑炎病毒(tick-borne encephalitis virus,TBEV)引起,经蜱传播,以中枢神经病变为特征的急性传染病.1910年,在前苏联亚洲部分发现以中枢神经病变为主要特征的急性传染病.1936年,Tkachev氏首次用小白鼠从患者分离到病毒.1937年从当地主要蜱种全沟硬蜱体内分离到同一种病毒,提出并证实蜱为本病传播媒介.1938年证实了森林中的啮齿类动物为本病贮存宿主.第二次世界大战后,欧洲有关本病的报告越来越多,几乎大部分国家均有报告.1990年由Pletnev AG等人首次完成森林脑炎病毒全基因组序列测定.我国于1942年发现该病,1952年从患者及蜱中分离到森林脑炎病毒,近几年流行又有增强趋势[1].     

首次从啮齿类和食虫类动物中分离到森林脑炎病毒

1988年,我们从采自云南高黎贡山的卵形硬蜱及患者血液中分离到森林脑炎病毒。1990年,又从该地区10种95只啮齿类中查到森林脑炎病毒抗体;并从社鼠(R.confucianus)、小林姬鼠(A.sylvaticus)和灰腹鼠(R.eha ninus)等8种啮齿类及食虫类中分离到15株病毒,选三株用单克隆抗体进行免疫荧光试验、理化特性、生物学特性及中和试验研究。结果表明,其病毒的抗原性、生物学特性及理化特性与东北株及从卵形硬蜱、患者分离的森林脑炎病毒一致。从啮齿类及食虫类分离到森林脑炎病毒在国内属首次报道。这项研究结果进一步证明,啮食类和食虫类在森林脑炎自然疫源地的保存方面起重要作用。     

我国东北地区蜱中检出蜱传埃立克体DNA

应用16S rRNA基因构建的特异性引物进行半套式PCR,检测东北地区蜱标本中埃立克体DNA,并对扩增产物进行克隆和序列测定,与GenBank中已知序列进行同源性比较。结果从全沟硬蜱和森林革蜱中均扩增出了查菲埃立克体DNA,扩增片段与美国分离株(GenBankM73222)相对应片段完全一致,同源性为100%;另外从全沟硬蜱中扩增出了粒细胞埃立克体DNA,扩增片段与美国分离株(GenBankU02521)相对应片段相差2个碱基,同源性为99.7%。表明我国东北边境地区有埃立克体病的病原体存在,该地区可能存在埃立克体病的自然疫源地。     

黑龙江省东宁县山区蜱类的生态调查

我国东北地区有的蜱种已证实是传播森林脑炎、北亚蜱传斑疹伤寒的媒介。近年来,国内文献又报导了从东北牡丹江林区发现了莱姆病(Lyme Disease)病人,病人都有被婢咬史,并从全沟硬蜱(Ixodes persulcatus)的中     

我国新疆首次检出西伯利亚型蜱传脑炎病毒

对新疆地区蜱传病毒类群进行调查,本研究利用Illumia深度测序技术对新疆全沟硬蜱体内的病毒小RNA分子进行筛查,从提取的蜱小RNA组份中共测得32 631条病毒特异性读序,77条读序与蜱传黄病毒基因组序列匹配,核苷酸数合计约占病毒基因组的3.8%~2.4%,其中32条读序与国内尚未发现的西伯利亚型蜱传脑炎病毒一致。为对上述结果进行确证,利用RT-PCR对此型病毒核酸进行检测,从蜱总RNA中分别扩增获得病毒包膜基因与基因组3′末端片段,测序比对表明上述片段序列与西伯利亚南部检出病毒高度近似,核苷酸与氨基酸似然率分别为97.2%~95.5%与99.4%~98.3%。综上所述,本研究利用基于深度测序的病毒筛查方法,首次从我国新疆蜱传脑炎疫源地检出西伯利亚型病毒,为下一步针对病毒的分离与流行病学调查提供了重要线索。     

辽宁省蜱类的生态地理分布

辽宁省已知的蜱类共13种, 分属于2科6属.本文依据不同地理景观区内蜱的种类与数量, 并结合其不同生境类型, 对蜱类的生态地理分布问题作了讨论.四个地理景观区内蜱种类与数量情况如下:(1)黄土丘陵台地干草原与西辽河风沙草原区:黄土丘陵台地干草原区蜱种类少, 但数量多.草原血蜱为优势种, 草原硬蜱数量较少.西辽河沙地草原区有草原血蜱、草原革蜱、草原硬蜱, 前两种均为优势种.(2)辽西山地疏林灌从区:本区有森林革蜱、长角血蜱、全沟硬蜱及日本锐缘蜱, 前两种为优势种.(3)辽东山地森林及林缘草地区:本区蜱种较多, 林区以日本血蜱、嗜群血蜱、全沟硬蜱为多见;林缘草地以长角血蜱、森林革蜱为优势种, 另外还有钝跗硬蜱、血红扇头蜱.(4)平原丘陵农区:木区蜱种虽然不少, 但分布局限, 数量小.有长角血蜱、草原血蜱、森林革蜱、微小牛蜱, 波斯锐缘蜱.     

云南森林脑炎病毒的动物敏感性研究

本文对分离自云南的森林脑炎病毒进行了动物敏感性研究,实验证明云南森林脑炎病毒对小白鼠有较强的致病性,三日龄乳鼠无论经脑内、腹腔、皮下接种均能致病、死亡,但毒力较国内森林脑炎病毒标准株低;三周龄小白鼠经鼻腔接种亦能发病致死。对乳大白鼠、幼年豚鼠和金黄色地鼠能引起发病或死亡,病毒抗原定位主要在脑组织。病理检查表明感染的各种动物脑组织均有明显病变。此外,对鸡胚敏感,能引起BHK_(21)、Vero、Vero-E_6等传代细胞及人胚肾、乳猪肾原代细胞的CPE_0结果表明了云南森林脑炎病毒对细胞、动物的致病性与国内森林脑炎病毒标准株相似,仅毒力稍低。     

家养动物体表蜱中发热伴血小板减少综合征布尼亚病毒分离及鉴定

为了解发热伴血小板减少综合征布尼亚病毒(SFTSV)的传播机制,采集了山东疫区家养牛、羊和狗等动物体表蜱,分类鉴定后,通过Real-time PCR筛查、病毒分离培养和基因组序列分析等方法分离鉴定蜱中的病毒。所采集的蜱,以长角血蜱为主,占91.4%。其中3头SFTSV核酸检测阳性,阳性率为2.14%,并在其中一份羊体表蜱标本中分离到SFTSV病毒,命名为SDLZTick12。序列分析显示与我国在不同省份患者标本中分离的病毒全基因序列具有高度同源性,且病毒的抗原性和生长特性与人源病毒相同。本研究首次在山东疫区蜱中分离到新型布尼亚病毒,并与人源病毒进行了系统比较研究,提示蜱可能为该新病原体的传播媒介,对疾病的防控具有重要的指导意义。     

硬蜱成虫的消化系统和生殖系统解剖

<正> 关于蜱类的内部解剖,国外有许多报道。近年来,我国正在开始这方面的工作,这将为蜱类组织学的研究奠定基础,从而对探讨蜱与疾病的关系,以及对蜱类杀灭机制的研究提供条件。 一、方 法 作者对全沟硬蜱、嗜群血蜱、森林革蜱、草原革蜱和长角血蜱进行了解剖,解剖方法有两种:即活体解剖和固定后解剖。活体解剖时,可先放少许50％酒精或生理盐水,解剖后用Carnoy’s液固定,会使某些器官看得更清楚。固定后解剖,标本多用Smith-Bouin固定。固定前,固定液需加热至45℃,固定液一经与固定标本接触,则不再继续加热。     

东北三省部份地区森林脑炎疫源地流行病学调查

１９９２～１９９４年,对黑龙江省密山市及吉林省珲春市森林脑炎疫源地进行了流行病学调查,对东北三省九地人血清进行了抗体检测。从密山和珲春地区捕获的２１８５只嗜群血蜱和１２３只森林革蜱中分离出了９株森林脑炎病毒。从当地捕获的野鼠血清中查到特异性抗体,阳性率为１２．０％。在黑龙江省的新青、密山及吉林省的珲春、抚松、靖宇等地居民血清中检出特异性抗体,阳性率分别为２．８％、２．２％、１０．９％、１．２％和４．３％。从而认为原森林脑炎自然疫源地仍然相当稳定地存在。随着经济开发,对外口岸开放,旅游事业发展,外来人群进入,其森林脑炎的威胁有可能增加,应引起重视。     

Mixed infection by tick-borne encephalitis virus and Borrelia in ticks

To investigate the relationships between tick-borne encephalitis (TBE) virus and the bacterial spirochaete Borrelia burgdorferi sensu lato in vectors with mixed infections, unfed adult Ixodes persulcatus ticks were collected by flagging from vegetation in southern-taiga forests of the Pre-Urals region of Russia where both infections circulate sympatrically. Prevalences of TBE and Borrelia infections in a total of 4234 ticks were compared over 5 years. No significant differences were revealed between the prevalence of Borrelia infection in ticks with and without TBE virus (29.4+/-7.8% vs 23+/-3.6%), or between the prevalence of TBE virus infection in ticks with and without Borrelia (24.0+/-6.6% vs 18.4+/-3.4%). In ticks with mixed infection (40/689 = 5.8%), concentrations of TBE virus and Borrelia were not significantly correlated with one another. Field observations showed parallel trends in the prevalence of these pathogens in tick populations from year to year (1993-1997) indicating that, in I. persulcatus with mixed infection, Borrelia and TBE virus do not seem to interfere with each other and are apparently not involved in any antagonistic relationships.     

First detection of TBE virus sequences in Ixodes ricinus from Friuli Venezia Giulia (Italy)

We report, for the first time, the presence of tick-borne encephalitis (TBE) virus in the tick Ixodes ricinus collected in the Friuli Venezia Giulia region of north-eastern Italy. Using molecular methods, we demonstrate that the TBE virus carried by ticks from FVG is a western European strain. Sequence analysis of the 5' NCR showed 98.4% identity to the Neudoerfl strain.     

Biological properties of strains of tick-borne encephalitis virus isolated in the natural foci of the eastern part of the Russian plain

Strains of tick-borne encephalitis virus isolated in the natural foci of infection in the eastern part of the Russian Plain (the Kirov region) were examined for their biological properties. The strains examined were 69 strains isolated from ticks Ixodes persulcatus, 62 strains obtained from patients with the clinically manifest form of tick-borne encephalitis and 56 strains isolated from the blood of patients with the inapparent form of infection. Comparative studies on laboratory animals (albino mice, golden hamsters, suckling guinea pigs and other mammals) as well as comparative serologic studies provided evidence which suggested that all virus isolates from the Kirov region were antigenically identical with the strain "Sofin" isolated in the Far East and represent thus a single causative agent of the tick-borne encephalitis virus infection. This strain of virus is supposed to exist in two variants, in dependence on ecological conditions: one of these variants is the eastern variant (strain Sofin and strains from the Kirov region) and the other one is the western variant of tick-borne encephalitis virus.     

我国新分离森林脑炎病毒E基因特征分析

为了解分离自黑龙江省大兴安岭林区全沟硬蜱中的DXAL-5、12、13、16、18,21共6株森林脑炎(TBE)病毒E蛋白基因特征并确定病毒基因型,应用RT-PCR技术对6株病毒E蛋白基因进行体外扩增、克隆、测序.结果发现,6株病毒E蛋白基因的核苷酸序列长均为1 488 bp,推导的氨基酸序列长均为496 aa.与TBE参考毒株E蛋白基因进行比较,这6株病毒与远东亚型同源性最高,其次是西伯利亚亚型,与欧洲亚型同源性最差;在决定亚型特征的氨基酸位点多数属于TBE病毒远东亚型.E蛋白基因推导的氨基酸种系发生树分析表明,6株病毒均在远东亚型分枝内.因此就E蛋白基因而言,DXAL-5、12、13、16、18、21株均属于TBE病毒的远东亚型.新分离毒株与Senzhang株同源性较高,种系发生关系也比较接近,推测疫苗株对新分离毒株仍具有很好的保护作用.但是在E蛋白的A、B和C抗原决定区内,6株病毒均有不同程度的氨基酸改变,这些突变有可能影响E蛋白的功能.     

森林脑炎中和抗体蚀斑减少试验方法的建立及疫苗免疫人体后抗体检测

为评价森林脑炎疫苗的免疫效果,采用森林脑炎病毒的BHK细胞适应株,以BHK细胞为培养基质,建立了检测森林脑炎中和抗体的蚀斑减少试验方法,并用蚀斑减少法、小鼠法及ELISA法检测了原制森林脑炎灭活疫苗免疫人体后的中和抗体水平;免疫血清为按疫苗免疫程序免疫健康志愿者采血分离而制备。结果表明蚀斑减少法与小鼠法的特异性相近且敏感性较好、简便快速,缩短检测周期,为疫苗流行病学调查及新型疫苗的研究提供了快速的检测方法;原制灭活疫苗人体二针免疫后,人体血清中和抗体阳转率仅30％左右,急需提高现用原制灭活疫苗的质量。     

Presence of poly(A) in a flavivirus: significant differences between the 3' noncoding regions of the genomic RNAs of tick-borne encephalitis virus strains.

A poly(A) tail was identified on the 3' end of the prototype tick-borne encephalitis (TBE) virus strain Neudoerfl. This is in contrast to the general lack of poly(A) in the genomic RNAs of mosquito-borne flaviviruses analyzed so far. Analysis of several closely related strains of TBE virus, however, revealed the existence of two different types of 3' noncoding (NC) regions. One type (represented by strain Neudoerfl) is only 114 nucleotides long and carries a 3'-terminal poly(A) structure. This was also found in several TBE virus strains isolated from different geographic regions over a period of almost 30 years. The other type (represented by strain Hypr) is 461 nucleotides long and not polyadenylated. The sequence homology between the two types of TBE virus 3' NC regions terminates at a specific position 81 nucleotides after the stop codon. The second type of 3' NC region more closely resembles the common flavivirus pattern, including the potential for the formation of a 3'-terminal hairpin structure. However, it lacks primary sequence elements that are conserved among other flavivirus genomes.     

Characterization of monoclonal antibodies against Hokkaido strain tick-borne encephalitis virus

A tick-borne encephalitis (TBE) patient was found in Hokkaido in 1993, and TBE viruses were isolated from animals and ticks in our previous studies. To develop a diagnostic reagent to identify TBE viruses, monoclonal antibodies (Mabs) were produced against the TBE virus strain Hokkaido (Oshima 5-10). Seven Mabs were obtained which reacted with the envelope protein of the Oshima 5-10 strain. These Mabs were flavivirus genus-specific, TBE virus complex-specific or TBE virus type-specific. The Mabs are applicable for identification of TBE virus strains.     

Correlation of TBE Incidence with Red Deer and Roe Deer Abundance in Slovenia

Tick-borne encephalitis (TBE) is a virus infection which sometimes causes human disease. The TBE virus is found in ticks and certain vertebrate tick hosts in restricted endemic localities termed TBE foci. The formation of natural foci is a combination of several factors: the vectors, a suitable and numerous enough number of hosts and in a habitat with suitable vegetation and climate. The present study investigated the influence of deer on the incidence of tick-borne encephalitis. We were able to obtain data from deer culls. Using this data, the abundance of deer was estimated and temporal and spatial analysis was performed. The abundance of deer has increased in the past decades, as well as the incidence of tick-borne encephalitis. Temporal analysis confirmed a correlation between red deer abundance and tick-borne encephalitis occurrence. Additionally, spatial analysis established, that in areas with high incidence of tick-borne encephalitis red deer density is higher, compared to areas with no or few human cases of tick-borne encephalitis. However, such correlation could not be confirmed between roe deer density and the incidence of tick-borne encephalitis. This is presumably due to roe deer density being above a certain threshold so that availability of tick reproduction hosts has no apparent effect on ticks'' host finding and consequently may not be possible to correlate with incidence of human TBE.     

Tick-borne encephalitis in a northern zone of coniferous and broad-leaved forests of a focal region of the Amur River basin

The geographical variability of the population of tick-borne encephalitis (TBE) virus in the northern part of the zone of combined coniferous and broad-leaved forests was established; this variability was manifested by higher virulence and homogeneity of TBE virus strains, as shown in experiments on white mice receiving the virus extraneurally, in comparison with the southern part of the zone and by higher virus carriership of the ticks Ixodes persulcatus. With the epizootic situation remaining tense and the danger of TBE virus infection still present, TBE morbidity and mortality rates decreased in the years of the construction of the Baikal-Amur Railroad, which was due to greater attention given to measures for the prophylaxis of TBE during this period.     

Usefulness of copeptin as a potential biomarker in TBE

Objective: The aim of the study was to evaluate the usefulness of copeptin for differentiation of hyponatremia in the course of tick-borne encephalitis (TBE) and for being a prognostic marker of the severity of TBE.

Materials and methods: One hundred and fourteen patients with TBE were included in the study. The control group consisted of 62 patients diagnosed with viral meningitis.

Results: Copeptin concentration did not differ in patients with hyponatremia and normonatremia. Urinary sodium excretion to plasma copeptin (copeptin/UNa Secretion) ratio was significantly lower in Syndrome of Inappropriate Antidiuretic Hormone (SIADH) Secretion patients than in patients with hyponatremia of other origin. Mean copeptin concentration in TBE patients was higher than in control group (VM) patients. There were no differences between patients with severe and mild course of TBE.

Conclusions: Copeptin/UNa ratio may be used as a potential biomarker of SIADH in patients with TBE. Copeptin concentration is significantly higher in patients with TBE than in viral meningitis of other origin, especially in patients aged 18–34 and >49 years old. Copeptin does not differentiate TBE of mild and severe course.