Isolation of St. Louis encephalitis virus from bats (Tadarida b. mexicana) in Texas

A strain of St. Louis encephalitis virus has been isolated from Mexican free-tailed bats (Tadarida b. mexicana) collected at the time of an outbreak of encephalitis in Texas in 1964.     

Isolation of western equine encephalitis virus from an opossum

The first isolation of an arbovirus (western equine encephalo-myelitis virus) from an opossum in the United States is reported.     

Carbon dioxide sensitivity of mosquitoes infected with California encephalitis virus

Four species of mosquitoes became sensitive to carbon dioxide approximately 3 to 4 days after they received intrathoracic injectins of California encephalitis virus. Aedes melanimon and Aedes dorsalis infected orally with California encephalitis virus also became carbon dioxide-sensitive, but mosquitoes infected transovarially did not. Sensitivity to carbon dioxide was inhibited by antiserum to California encephalitis virus. To our knowledge this is the first report of carbon dioxide sensitivity induced in arthropods by a bunyavirus and the first demonstration of this phenomenon by an arbovirus in its proven vector.     

广西猪乙型脑炎病毒的分离及初步鉴定

【目的】了解广西猪乙型脑炎（JE）地方流行毒株特点,为有效防控广西猪JE奠定基础。【方法】对从广西各地猪场采集疑似JE病例猪的脑组织、流产胎儿、死胎、木乃伊胎、公猪精液、猪舍蚊子等靶组织样品进行猪乙型脑炎病毒（JEV）检测,并选择部分阳性样品进行JEV分离鉴定及病毒E基因遗传进化分析。【结果】在采集的465份JE疑似病料样品中,有72份为JEV阳性;通过接种BHK-21细胞、乳鼠及SPF鸡胚,分离获得两株JEV地方分离毒株,分别命名为GP株和LC株;遗传进化分析显示,GP株和LC株之间的核苷酸和氨基酸同源性分别为99.9%和99.8%;两株分离株与疫苗毒株SA14-14-2的核苷酸同源性分别为99.7%和99.9%,氨基酸同源性分别为99.4%和99.6%,且均属GIII型JEV。【结论】广西受检猪群存在较严重的JEV感染,应引起重视并加强防控。     

Isolation of West Nile virus from mosquitoes, crows, and a Cooper's hawk in Connecticut

West Nile (WN) virus, a mosquito-transmitted virus native to Africa, Asia, and Europe, was isolated from two species of mosquitoes, Culex pipiens and Aedes vexans, and from brain tissues of 28 American crows, Corvus brachyrhynchos, and one Cooper's hawk, Accipiter cooperii, in Connecticut. A portion of the genome of virus isolates from four different hosts was sequenced and analyzed by comparative phylogenetic analysis. Our isolates from Connecticut were similar to one another and most closely related to two WN isolates from Romania (2.8 and 3.6 percent difference). If established in North America, WN virus will likely have severe effects on human health and on the health of populations of birds.     

中国东北地区3株日本脑炎病毒株的分离鉴定及基因分型

从黑龙江省某3个猪场采集疑似为日本脑炎病毒感染的病、死猪的脏器以及全血,进行病毒的细胞培养,蚀斑纯化,间接免疫荧光试验,电镜下观察病毒粒子的形态,及RT-PCR检测。结果显示,盲传三代后,出现明显的细胞病变(CPE+~CPE+++);荧光显微镜下细胞胞质内呈现不同强度的绿色荧光信号;电镜下的病毒粒子为40~60nm的球型粒子;PCR检测为日本脑炎病毒阳性。通过对3株分离株Prm扩增序列比较,此3株分离株为基因Ⅲ型。     

Environmental Control of Ovarian Development in Mosquitoes of the Culex pipiens Complex

Gonotrophic dissociation, a condition in which the ovaries remain undeveloped in female mosquitoes that have taken a full blood meal, occurs in Culex pipiens L., when incubated at low temperature (10 degrees to 15 degrees C) with short photoperiod and held at low temperature after feeding. Gonotrophic dissociation occurred sporadically in Culex quinquefasciatus Say after conditioning by low temperature, irrespective of photoperiod. Two major considerations are posed: first, the importance of gonotrophic dissociation to hibernation potential; and, second, the potential of a hibernating female mosquito to serve as a virus reservoir.     

Sulfuric acid-ammonium sulfate aerosol: optical detection in the St. Louis region

Nephelometric sensing of the deliquescence of ammonium sulfate produced by the reaction of sulfuric acid or ammonium bisulfate aerosol with ammonia provides a means for detecting these substances in air. Field experiments show them to be the dominant substances in the submicrometer, light-scattering aerosol in the St. Louis region.     

乙型脑炎病毒SXBJ07株的分离鉴定及序列分析

【目的】分离鉴定乙型脑炎病毒(JEV),确定分离毒株的基因分型及其E区段氨基酸的序列特征。【方法】采用BHK-21细胞培养法,从猪脑组织标本中分离出1株病毒,对其进行细胞和免疫荧光试验,同时采用RT-PCR扩增并克隆该毒株的PrM、E区段核苷酸序列,利用PrM(456~695位)区核苷酸序列与36株参考序列进行基因分型分析,并对E区核苷酸序列与减毒活疫苗株SA-14-14-2株的相应序列进行比对,分析分离株和疫苗株氨基酸的同源性及关键结构域的差异。【结果】分离出的病毒经细胞病变和直接免疫荧光试验证实为乙脑病毒,命名为SX-BJ07;用该病毒感染BHK-21细胞,72 h后所有细胞均发生病变(CPE);用该病毒接种3日龄乳鼠,72 h之内即可导致乳鼠死亡;SXBJ07株PrM(456~695位)区基因分型证实,分离株属于基因Ⅰ型,E区段核苷酸和氨基酸与减毒活疫苗株SA-14-14-2株的同源性分别为87.7%和97.0%,但在E蛋白的活性关键结构域有13个氨基酸存在差异。【结论】从陕西省境内首次成功分离到1株Ⅰ型乙脑病毒,初步确定了该分离株的分子特征,对乙型脑炎的流行病学研究及其防治具有重要意义。     

Suppression and elimination of an island population of Culex pipiens quinquefasciatus with sterile males

The release of 8,400 to 18,000 males per day of Culex pipiens quinquefasciatus Say which had been exposed to a sterilizing agent (thiotepa), suppressed and eliminated an indigenous population of this mosquito on an island off the coast of Florida in a 10-week period. Sterile males were effective in seeking out and mating with females on the island.     

Urban growth and decline: San Jose and St. Louis in the 1960's

The population changes in San Jose and St. Louis between 1960 and 1970 exemplify the two broad trends-urban formation followed by metropolitan dispersal-that have shaped 20th-century urbanization in this country. The fact that these developmental trends were expressed through demographic processes found to be common to both cities, despite their contrasting recent experiences, suggests that generalizations can be made about the complex forces underlying urbanization. The formation of metropolitan San Jose's population parallels the traditional process whereby a region's growth comes to be focused, through migration, on a few urban centers. The modern variant is not characterized by a rural-to-urban shift, however, but by migration flows among urban areas, and particularly to a few most-favored areas, such as San Jose. Migratory growth has left a powerful demographic legacy in San Jose. This legacy is also instructive for studying the migratory formation of any new city's population. Its demographic character determines its demographic destiny, whose likely variations we can now perceive with some clarity. San Jose's population is both youthful and chronically migratory. The presence of many prospective parents and relatively few elderly persons lays a broad foundation for the population's continued growth through natural increase, despite the national downturn in fertility (14). Even without further net in-migration, the population of new cities like San Jose would continue to grow at an above-average rate. The hypermobility of San Jose's population (that is, its propensity for further migration) also has an important bearing on the future. With about 21 migrants entering and 17 departing each year per hundred residents, San Jose's rapid migratory growth rests (as it would in other new cities) on a precarious arithmetic balance. A significant dip in local employment growth could easily reduce net migration to a small fraction of its present high level. Even a slight decline would result in the inflow's no longer exceeding the high volume of outflow. Demographic analysis alone cannot foresee such an employment downturn, but if it happened, the migratory downturn probably would be swift. Hypermobility also works the other way; and given San Jose's focal position in California's expanding metropolitan structure (with its virtually endless supply of migratory growth), net migration could resume with equal swiftness. The outward dispersal of population from central cities that has occurred in St. Louis has been accelerating in other cities as well, and will remain a prominent feature of U.S. urban growth. It may seem paradoxical that in a period noted for something called "urban growth" there are so many declining central cities, but that is merely one indication that the "central city" no longer is the real city, except in name. Real city or not, the central city can expect to come into political conflict with other jurisdictions created in the process of dispersion. In cities like St. Louis, where population is dispersing but old political boundaries are fixed, the problems of the central city are separated from the resources in the suburbs. Transitional problems associated with persistent and severe outmigration also arise: accumulation of disadvantaged citizens, declining demand for city housing, and a diminished replacement capacity in the population. Carried far enough, the last of these problems results in natural decrease, and thereafter the population's decline acquires its own dynamic. As noted earlier, the white population in St. Louis has reached this point: The number of persons dying now exceeds the number being born. For two reasons, this natural decrease can do little other than intensify. First, a substantial proportion of whites are either entering or already within the high-mortality age brackets.The white population's crude death rate therefore will continue to rise. Second, prospective parents are becoming scarce among St. Louis's whites, and the national evidence that parents in general will choose to have smaller families continues to mount. The white population's crude birth rate is therefore likely to fall, barring a dramatic increase in fertility or a strong and sustained inflow of childbearing families. Nor is St. Louis's black population likely to grow substantially. It is expanding steadily through natural increase, but black migration out of the city is more than enough to cancel that increase.