病毒受体及其研究现状

受体在宿主细胞与病毒的相互作用中起着极其重要的作用。病毒受体的特性与病毒的宿主范围、组织嗜性有密切关系,是病毒致病性的主要因素之一。病毒受体的研究方法有经典的研究方法,也有现代分子生物学方法。在病毒受体的研究中,通常以分离纯化的细胞膜代替活体细胞来研究病毒受体。通过对病毒与细胞受体相互作用的深入研究,人们已经发现很多受体阻断剂例如植物凝集素和肝素等物质可以阻断病毒与受体的结合,从而为病毒病的防控提供繁殖一些有效的新方法。     

鸡传染性支气管炎病毒受体研究进展

鸡传染性支气管炎是一种世界性分布的严重影响养鸡业的高度接触性传染病,其病原是一种最早发现的冠状病毒鸡传染性支气管炎病毒(IBV)。IBV入侵细胞的受体是目前IBV研究中的热点之一。已知IBV囊膜上的纤突蛋白(S)是宿主组织和细胞嗜性及致病性的主要决定因素,S蛋白通常断裂为S1和S2两部分,S1与宿主细胞膜上的细胞受体相结合,在S2的作用下病毒囊膜与宿主细胞膜融合,IBV与受体结合之后于中性或微碱性pH时发生构象改变,从而获得病毒进入宿主细胞的能力。对于IBV的受体研究主要集中于IBV可能使用的几种功能性受体,包括氨肽酶N、唾液酸、硫酸乙酰肝素等。     

口蹄疫病毒整合素受体研究进展

口蹄疫病毒(Foot-and-Mouth Disease Virus,FMDV)感染宿主细胞首先是病毒与被感染细胞表面的病毒受体结合,通过网格蛋白介导的内吞途径,酸化的内吞泡运输进入细胞内,然后衣壳迅速解体,释放出基因组RNA,细胞受体决定口蹄疫病毒宿主特异性和组织特异性.对口蹄疫病毒细胞受体的研究将有助于揭示口蹄疫病毒的感染机制、复制过程、致病机理和疫病预防及治疗等,细胞受体的研究已经成为目前口蹄疫病毒研究中的重点领域之一,论文就近年来FMDV整合素受体研究现状进行了综述,并对其发展进行了展望.     

兽医科学中病毒受体的研究进展

病毒受体在宿主细胞和病毒的相互作用中起着重要的作用。受体的特性与病毒的宿主范围和组织特异性密切相关,是病毒致病性的关键因素之一。随着分子生物学、细胞生物学、病毒学等学科的发展及新技术的出现,病毒受体研究逐渐成为相关领域的研究热点,其的研究结果可以为阻断病毒与受体的结合提供基础理论,进一步为病毒性疾病的预防与治疗、抗病毒新药物以及疫苗的研制提供新的思路。     

病毒细胞受体研究技术及其应用现状

病毒感染宿主细胞的过程实质是病毒受体与配体之间的相互作用。病毒受体和配体的研究是明确病毒致病机理的关键,因此关于病毒细胞受体的研究一直是近年来病毒学研究的重点领域。病毒受体的鉴定可通过多种生物技术手段进行,如酵母双杂交法、病毒覆盖蛋白结合技术等。文章对当前的病毒细胞受体研究技术及其应用现状进行了综述,以期为今后的相关研究提供参考。     

病毒受体研究进展

病毒通过与宿主易感细胞表面的特异性受体结合而启动其复制过程。宿主的组织及细胞表面特定受体是决定病毒入侵途径、扩散方式及决定宿主发病特点的主要因素：因此，开展对病毒受体的研究具有重要意义。从受体角度阐明病毒入侵机制，是预防和治疗病毒性疾病的药物及疫苗研发重要领域。     

传染性支气管炎病毒受体研究进展

传染性支气管炎(IB)是由冠状病毒科传染性支气管炎病毒(IBV)引起的高度接触性传染病。该病在世界各地均有发生,给全球养禽业造成巨大的经济损失。IBV感染宿主细胞的第一步是病毒与细胞表面的受体结合,介导病毒颗粒进入细胞内。IBV病毒受体的研究对于揭示IBV的致病和免疫机理具有重要价值。文中就近年来发现的氨基肽酶N、硫酸乙酰肝素和唾液酸受体作综述。     

猫白血病病毒分子致病机制研究进展

猫白血病病毒是引起猫白血病的主要病原,根据病毒与细胞表面受体特异性,将其分为A、B、C和T 4个亚型。不同亚型病毒感染宿主细胞需要特异性受体识别。该病毒表面糖蛋白在病毒感染宿主细胞中发挥重要作用,表面糖蛋白包含3个区域,其中第一和第二受体结合区是病毒表面糖蛋白结合到宿主细胞受体的关键,后者与病毒感染密切相关。     

PEDV编码蛋白拮抗宿主天然免疫的研究进展

猪流行性腹泻病毒(PEDV)属于冠状病毒家族成员,是近年来引起新生仔猪水样腹泻致死的主要病原之一,给养殖业带来了巨大威胁.病毒感染后,宿主细胞通过模式识别受体(PRRs)识别病原相关分子模式(PAMPs),促进I型干扰素等细胞因子的产生,进而抑制病毒的增殖.近年来的研究表明,PEDV能够通过其编码蛋白对宿主的抗病毒天然...     

杯状病毒受体研究进展

杯状病毒科(Caliciviridae)的病毒是一类多样性的病毒,具有广泛的宿主和组织趋向性。对于其受体的研究,近年来取得了一定的进展。鉴定的受体分子主要集中于两类,一类是碳水化合物,包括组织血型抗原(HBGAs)、唾液酸和硫酸乙酰肝素;另一类是细胞蛋白,如连接黏附分子-A(JAM-A),一种分子质量为105 ku的膜蛋白等。此外,病毒与宿主受体相互识别的分子机制也取得了进展,这些研究对于深入了解病毒与宿主间的相互关系及有针对性地进行抗病毒药物、疫苗的研制具有重大意义。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein