Susceptibility of Bithynia inflata mollusks from different populations to Opisthorchis felineus infestation

The paper reports the results of experimental infection of a specific intermediate host, molluscs Bithynia inflata from differently susceptible populations, with Opisthorchis felineus in one opisthorchis nidus. Non-susceptibility of molluscs from resistant and hyperinfected populations to O. felineus infection is shown.     

Heterogeneity of populations of the mollusc Bithynia inflata according to the degree of trematode infestation in opisthorchiasis foci

Results of studies of differences in the infection rate of natural populations of Bithynia inflata with trematodes (including Opisthorchis felineus) in the nidi of opisthorchiasis in the Sumsk and Chernigov Districts of the Ukrainian SSR and Tomsk District of the RSFSR are given. It has been shown that in the Ukrain over 1/3 of all populations of the specific intermediate host of opisthorchis does not take part in the circulation of the agent due to fundamentally different reasons: resistence to the infection and hyperinfection with parthenites of trematodes.     

Comparative analysis of karyotypes of Opisthorchis felineus from West Siberia

Karyotype of the trematode Opisthorchis felineus from two populations of the Ob and the Tom’ rivers basins in the southeast of the West Siberian plain was investigated. Comparative analysis of the relative length and centromere indices of seven chromosomes showed that they are identical to literature data on the chromosome sets of this trematode species from the lower and upper courses of the Irtysh River. The quality of chromosome spreads improved the former knowledge of the karyotype structure of this species, in particular, the 6th and 7th chromosomes.     

The role of the association of Opisthorchis felineus maritae with the Epstein-Barr virus in the cytogenetic sequelae of an opisthorchiasis infection

The immunofluorescence analysis of Epstein-Barr virus (EBV) antigens in the body of Opisthorchis felineus (OF) helminths was carried out. It was found that EBV antigens located in eggs of helminth. Adding of OF antigens and/or EBV to the lymphocyte human cultures of healthy donors can induce a cytogenetic damage in cells. A role of EBV location in opisthorchis eggs in chromosome damage and cancer development is discussed.     

Effect of light intensity on Opisthorchis viverrini cercarial shedding levels from Bithynia snails--a preliminary study

Opisthorchis viverrini requires Bithynia snails as the first intermediate host and cyprinid fish as the second intermediate host. Very low natural infection rates have been reported in Bithynia snails, but very high rates have been found in cyprinid fish in the same endemic region. This study investigated the effect of light intensity, the most important stimulus, on the quantity of O. viverrini cercariae shed from naturally infected Bithynia (Digoniostoma) siamensis goniomphalos snails. Snails were evaluated for cercariae output every hour after exposure to various light intensities for a total period of 7 h. The same infected snail was tested under different intensities of light: in the dark, and at 1000, 3000 and 5000 lx. The data showed that under exposure to 1000 and 3000 lx of light, the average percentage and number of cercariae released were higher than that exposed to 5000 lx during the first 2 h of the experiment. In contrast, under higher illumination (5000 lx) a longer time (6 h) was required to stimulate the peak emergence of cercariae. Darkness was not able to induce O. viverrini cercariae emergence. Among the three intensities of light, exposure at 1000 lx induced the highest average number of released cercariae per snail and the highest percentage of cercarial emergence within the first 2 h (125, 54.86%), followed by exposure at 3000 lx (69, 25.58%) and 5000 lx (12, 7.78%). The results suggest that the light intensity of 1000 lx for 2 h would be optimal for O. viverrini cercarial shedding from naturally infected B. (D.) siamensis goniomphalos snails.     

Susceptibility of different populations of ticks to entomopathogenic fungi

This study aimed to evaluate the in vitro effect of the entomopathogenic fungi Metarhizium anisopliae sensu lato (s.l.) and Beauveria bassiana sensu lato (s.l.) on two distinct populations of Rhipicephalus microplus, from two different experimental farms. Bioassays were performed with engorged females, eggs and larvae. Fungal infection was evaluated based on biological parameters of treated engorged females, percentage of hatch from treated eggs, and percentage of mortality and mean lethal time (LT90) of treated larvae. When the treatments were compared between the two populations, there were significant differences in the following parameters: pre-oviposition period, hatching period and egg production index. Moreover, the results showed that B. bassiana s.l., isolate Bb 986, was more virulent than M. anisopliae s.l., isolate 959, for engorged females, showing a control percentage of 49%. In the bioassay with eggs, the hatching percentage ranged from 3.1% to 49.5% in one population and from 3.4% to 42.7% in the other, with no significant difference between the two populations. In the bioassay with unfed larvae, the mortality percentage ranged from 91.8% to 98.7% in one population and from 71.0% to 94.0% in the other. The LT(90) varied from 19.52 to 27.51 days in one of the populations and 22.89 to 37.31 days in the other. These results suggest that populations of R. microplus show distinct variation in their susceptibility to B. bassiana s.l. and M. anisopliae s.l.     

Opisthorchis viverrini: identification of a glycine-tyrosine rich eggshell protein and its potential as a diagnostic tool for human opisthorchiasis

A cDNA encoding a novel eggshell protein (OvESP) with high-glycine (49.2%) and -tyrosine (27.8%) content was cloned from the human liver fluke Opisthorchis viverrini. In the adult parasite, the RNA products of the OvESP gene are limited to the vitelline follicles. They have a size of 800 nucleotides and are already present in 2-week-old juveniles. Immune sera of hamsters, experimentally infected, and humans, naturally infected with O. viverrini, detect bacterially expressed recombinant OvESP (rOvESP). A rabbit anti-rOvESP antiserum only reacts with the shells of intrauterine eggs in tissue sections of the parasite. Comparison of rOvESP with the parasite's excretion/secretion products as diagnostic tools for human opisthorchiasis shows a higher sensitivity (0.82-0.48) and specificity (0.97-0.91) of the recombinant protein in the ELISA technique. But the observed weak cross-reactivity of immune sera from mice infected with Schistosoma mansoni, Schistosoma mekongi, and Fasciola gigantica in Western blots of rOvESP indicates that the diagnostic quality of this protein might be compromised if infections by other trematodes are present.     

The influence of the degree of infestation with trematode parthenites on the structure of penial glands in the mollusks Littorina saxatilis of different age

Histological and confocal microscopy studies of the structure of penial glands in the Littorina saxatilis males were carried out. The examined mollusks belong to two age groups and were at different stages of spontaneous infection with a trematode from the pygmaeus species group (Microphallus piriformes). Based on comparative analysis of microscopic sections of copulative organs in infested and non-infested mollusks, data on the modifications in histological structure ofpenial glands were obtained. From these data we can suggest that the infestation have an influence on all parts of the gland. Decrease of secret production and reduction of muscular capsule (down to its disappearance) were observed. We suppose that changes in the penial glands structure prevent their normal functioning. In the mollusks infested on reaching the sexual maturity, gradual reduction of distal part of reproductive system was observed, while in the mollusks infested before the sexual maturity, development of ancillary part of reproductive system was blocked.     

不同地理种群草间钻头蛛（Hylyphantes graminicola）对杀虫剂的敏感性及抗、感种群的相对适合度

采用成蛛浸渍法测定了湖北武汉、湖北来凤、陕西渭南和山东菏泽4个草间钻头蛛地理种群对氰戊菊酯、溴氰菊酯、辛硫磷和甲胺磷4种杀虫剂的敏感性。结果表明：湖北武汉和山东菏泽草间钻头蛛种群对4种杀虫剂的抗药性都较小,处于敏感水平,陕西渭南、湖北来凤种群对甲胺磷和辛硫磷的抗性达到了中抗水平。4个种群对溴氰菊酯和氰戊菊酯均未产生抗药性,说明拟除虫菊酯类杀虫剂对草间钻头蛛的毒力要大于有机磷类杀虫剂。在测定了蜘蛛对不同杀虫剂敏感水平的基础上,以陕西渭南种群为抗性种群（R）,湖北武汉种群为敏感种群（S）,比较研究了这2个种群的生物学特性和相对适合度。结果表明两种群在发育历期和成活率上无显著差异。在繁殖力方面,R种群产卵率、产卵量和孵化率均明显下降。R种群的相对适合度为0．74,对有机磷产生抗性的草间钻头蛛种群存在繁殖不利性。     

Pyrosequencing analysis identifies discrete populations of Haemonchus contortus from small ruminants

The genus Haemonchus consists of blood-sucking parasitic nematodes in the abomasum of ruminants. Members of this genus are responsible for extensive production losses, particularly of small ruminants in the tropics but are also found in temperate regions. In this study, we examined the internal transcribed spacers-1 and -2 of rRNA in Haemonchus spp. The rRNA region spanning the internal transcribed spacers-1, -2 and the 5.8S rRNA gene was amplified by PCR from each of 10 worms from Swedish sheep, a Swedish goat and Kenyan sheep. The fragments were sequenced and examined with respect to genetic differences fixed among the three isolates. These and additional worms were further analysed with Pyrosequencing technology. This technique allowed us to rapidly analyse 110 individuals in three putative polymorphic nucleotide positions that were initially identified with dideoxy sequencing. The geographical isolates could to a large extent be genetically distinguished, but none of the polymorphic positions were consistent among all individuals within each isolate. Furthermore an alignment of our sequences and a consensus sequence published for Haemonchus contortus revealed two differences in positions 123 and 196 in internal transcribed spacers-2. Although these positions were previously reported as heterogenic, no polymorphism was detected among the 30 worms sequenced in the present study. Modelling of the internal transcribed spacers-2 secondary structure based on our data also identified a new putative long-range interaction. The isolates are best described as populations. In conclusion, consistent differences were not identified and the studied isolates are therefore best described as discrete populations. This study also reveals for the first time the potential of Pyrosequencing technology as a tool in the analysis of nematode population genetics.     

Plasmid composition of Yersinia pestis strains from different natural foci]

The study of the plasmid composition of 246 Y. pestis strains from different natural foci in the USSR and other countries revealed that 173 strains (70%) carried three known plasmids with a molecular weight of about 6, 45-50 and 60 megadaltons (MD) respectively. In 20 strains (8%) obtained from different sources additional cryptic plasmids were detected. In some cases the absence of one or two typical plasmids was observed. Replicon pPst was shown to have quite constant molecular weight (6 MD), whereas plasmids pCad and especially pFra exhibited certain variations of their molecular weight (45-49 MD and 60-149 MD respectively) in strains of different origin.     

不同动物源性细胞系对猪丁型冠状病毒的易感性

[目的]探究猪丁型冠状病毒(porcine deltacoronavirus,PDCoV)能否在不同动物源性细胞系中感染和增殖.[方法]本研究将PDCoV四川分离株CHN-SC2015接种来自仓鼠、家禽、猴、人和猪的12种细胞系,将病毒在每种细胞系中盲传至少5代并通过逆转录-聚合酶链式反应(RT-PCR)、实时荧光定量...     

Susceptibility of different European populations of Tribolium confusum (coleoptera: Tenebrionidae) to five diatomaceous earth formulations

Laboratory bioassays were conducted to evaluate the susceptibility of seven populations (strains) of the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), to five commercially available diatomaceous earth (DE) formulations: Insecto, Protect-It, Protector, PyriSec, and SilicoSec. These DEs were applied on wheat, Triticum durum Desf., at two dose rates, 500 and 1000 ppm. The six beetle strains were obtained from Denmark, United Kingdom, Greece, Germany, Italy, and Portugal, whereas a seventh strain came from the Greek strain after laboratory selection with SilicoSec-treated wheat for six generations. Adults of the above-mentioned strains were exposed for 7 d to wheat treated with each DE formulation, and mortality was assessed after exposure. For all DE-dose combinations, significant differences were noted in mortality levels among strains. Generally, the strains from Denmark, United Kingdom, and Germany were the most susceptible to the DEs used, whereas the strain from Portugal was the least susceptible. No significant differences were noted in susceptibility level between the initial Greek strain and the laboratory-selected Greek strain, with the exception of Protector, where the selected strain was significantly more tolerant than the initial strain for both dose rates tested.     

Innate structure of DNA foci restricts the mixing of DNA from different chromosome territories

The distribution of chromatin within the mammalian nucleus is constrained by its organization into chromosome territories (CTs). However, recent studies have suggested that promiscuous intra- and inter-chromosomal interactions play fundamental roles in regulating chromatin function and so might define the spatial integrity of CTs. In order to test the extent of DNA mixing between CTs, DNA foci of individual CTs were labeled in living cells following incorporation of Alexa-488 and Cy-3 conjugated replication precursor analogues during consecutive cell cycles. Uniquely labeled chromatin domains, resolved following random mitotic segregation, were visualized as discrete structures with defined borders. At the level of resolution analysed, evidence for mixing of chromatin from adjacent domains was only apparent within the surface volumes where neighboring CTs touched. However, while less than 1% of the nuclear volume represented domains of inter-chromosomal mixing, the dynamic plasticity of DNA foci within individual CTs allows continual transformation of CT structure so that different domains of chromatin mixing evolve over time. Notably, chromatin mixing at the boundaries of adjacent CTs had little impact on the innate structural properties of DNA foci. However, when TSA was used to alter the extent of histone acetylation changes in chromatin correlated with increased chromatin mixing. We propose that DNA foci maintain a structural integrity that restricts widespread mixing of DNA and discuss how the potential to dynamically remodel genome organization might alter during cell differentiation.     

Susceptibility of endothelial cells derived from different blood vessels to common viruses

Summary We examined whether endothelial cells derived from different blood vessels vary in their susceptibility to viral infection. Five common viral pathogens of humans (herpes simplex 1, measles, mumps, echo 9, and coxsackie B4 viruses) were evaluated for growth in endothelial cells derived from bovine fetal pulmonary artery thoracic aorta, and vena cava. All five viruses replicated in each type of endothelial cell. There were apparent differences in the quantities of measles and mumps viruses produced in pulmonary artery endothelium compared with thoracic aorta and vena cava when endothelial cells were obtained from different animals. However when pulmonary artery endothelial cells were compared with vena cava cells from the same animal, growth of each virus was similar in the two cell types. Four of the viruses replicated in the various endothelial cells without producing appreciable changes in cell morphology. These results indicate that endothelial cells from different blood vessels are equally susceptible to the human viruses evaluated, and that viral replication can occur without major alteration in cell morphology. Endothelial cells could serve as permissive cells permitting viruses to leave the circulation and initiate infection in adjacent tissues, including subendothelial smooth muscle cells. This work was supported by Public Health Service grants HL28220, HL 29492, and HL 24914 from the National Heart, Lung and Blood Institute, Bethesda, MD.     

Differences in genotypes of Helicobacter pylori from different human populations

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.     

Susceptibility of Macaca fascicularis monkeys from Mauritius to different species of Plasmodium.

Macaca fascicularis monkeys from Mauritius were shown to be susceptible via sporozoite inoculation to 7 species of Plasmodium (P. fragile, P. coatneyi, P. gonderi, P. inui, P. cynomolgi, P. knowlesi, and P. fieldi), indigenous to macaques in southeastern Asia. Four monkeys were sequentially infected with different species of Plasmodium to determine maximum and course of parasitemia. In 2 nonsplenectomized monkeys, P. fragile developed maximum parasite counts of only 134 and 155/microliters. For Plasmodium knowlesi, a parasite that is life-threatening to rhesus monkeys, maximum parasite counts were 4,278 and 7,440/microliters. Plasmodium coatneyi developed to what must be considered as moderate levels. After animals underwent splenectomy, parasite counts of P. coatneyi were 58,280, 89,094, 4,464, and 43,524/microliters. The maximum parasite counts for P. gonderi (13,508 and 21,576/microliters) and P. fieldi (1,767 and 17,836/microliters) were lower than would be expected in M. mulatta. In 2 monkeys that developed patent parasitemia with P. inui, the maximum parasite counts (95,046 and 728,748/microliters) indicated that this parasite may be the best adapted species for development in these animals once infection is established. Finally, the reinfection of 2 monkeys with P. cynomolgi suggested that some animals may be basically more resistant than others, whether splenectomized or not, to the production of high-density parasitemia.     

Morphometric and morphological variation between two different populations of Phlebotomus major s.l. from endemic and non‐endemic foci of visceral leishmaniasis in Iran

Populations of Phlebotomus major were examined in two endemic and nonendemic foci of visceral leishmaniasis in Iran. Based on the shape of the aedeagus and ventrally located hairs of coxite and pharyngeal armatures, two morphotypes were found sympatrically in the endemic area of Borazjan. Significant differences in morphometric survey were observed in at least 11 measured characters. The aedeagus of the non‐endemic Miyandoab morphotype, and also of a few specimens from Borazjan, is completely parallel throughout its length with a slightly expanded end. Ventrally located hairs of the middle coxite were longer and more compact. It is close morphologically to P. major neglectus (P. neglectus), which was recently recorded from Iran. It is also morphologically similar to P. notus, which has not yet been reported from Iran and needs further investigation. The aedeagus of the morphotype occurring only in Borazjan is narrower in the middle and the hairs are closer to the base of the coxite and are shorter and more outspread, which makes it similar to P. major krimensis or P. neglectus. The two morphotypes occurring sympatrically in Borazjan do not appear to be subspecies and it may be premature to propose them as separate species. Further investigation is needed to clarify the actual status of P. major s. l. in Iran.