雏鹅新型病毒性肠炎病毒强毒在感染鸭胚体内形态发生学和宿主细胞超微病理学研究

将雏鹅新型病毒性肠炎病毒（NGVEV）强毒CH株经尿囊腔途径人工感染10日龄鸭胚,应用透射电镜和超薄切片技术研究病毒在宿主细胞内的形态发生及各组织器官的超微结构变化。结果表明：感染后不同时间剖杀及死亡鸭胚的尿囊膜、肠、心、肝、脑和肌胃组织中,均观察到60～70nm的病毒粒子。病毒粒子主要通过与细胞膜融合而进入细胞质内,然后在细胞核内进行复制和装配。最后病毒粒子通过核膜和细胞膜破裂的方式被释放。病毒侵害的主要靶细胞包括鸭胚尿囊膜上皮细胞、肠上皮细胞、肠道平滑肌细胞、成纤维细胞、肝细胞、肌胃黏膜上皮细胞和心肌细胞等,表现为细胞核内外膜间隙严重扩张,细胞质整体结构严重空化。病毒侵害的主要靶细胞器包括粗面内质网和线粒体,表现为粗面内质网扩张呈囊状;尿囊膜上皮细胞的线粒体出现固缩和异常聚集变化,而其他组织细胞的线粒体均表现为肿胀和嵴断裂、消失。本试验还发现NGVEV可诱导宿主细胞发生严重的细胞凋亡现象,表现为细胞皱缩,胞核内染色质密度增高,核固缩成一个或数个团块凝聚在核膜周边,胞质浓缩深染并形成凋亡小体。     

Changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with porcine reproductive and respiratory syndrome virus and porcine circovirus type 2

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are pathogens, which can significantly affect the swine industry worldwide. Field surveys suggest that simultaneous PRRSV and PCV2 infection is common in pigs. The objective of this study was to measure the changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with PRRSV and PCV2, in order to analyze the synergistic influence of co-infection on the immune system. Changes in peripheral blood leukocyte subpopulations were systematically measured by flow cytometry (FCM). The levels of antibodies to PRRSV and PCV2 were detected by indirect Enzyme-Linked ImmunoSorbent Assay (ELISA) and the indirect fluorescent antibody test (IFA), respectively. Serum viral loads were measured using real-time PCR. The results showed that piglets co-infected with PRRSV and PCV2 exhibited slower generation and lower levels of antibodies to PRRSV and PCV2, and increased amounts and a prolonged presence of both PRRSV and PCV2 in serum, in comparison to the piglets infected with either virus alone. The major finding in our study was that the total and differential leukocyte counts, including white blood cells (WBCs), monocytes, granulocytes and lymphocytes (T, B and NK cells, as well as T-cell subpopulations), dramatically decreased early during co-infection with PRRSV and PCV2 for about two weeks, in contrast with animals singly infected with either PRRSV or PCV2. These results suggest that PRRSV and PCV2 co-infection results in a synergistic decrease in immune cells in the peripheral blood of piglets. These data contribute to the understanding of the immunosuppressive effects resulting from PRRSV and PCV2 co-infection in pigs.     

A Case of Wound Botulism in a Foal Affected by Gastric Ulcers in Italy

The case of a 50-day-old Thoroughbred foal affected by sudden muscular weakness and failure to swallow associated with recumbency is described. The clinical picture suggested a diagnosis of botulism. At necropsy, nonglandular gastric mucosa presented deep ulcerations. No other macroscopic nor microscopic lesions were detected. Clostridium botulinum type B was isolated from the lesions of gastric mucosa, whereas the cecal and colonic content, assayed for both spores and toxins, were negative. Moreover, analyses of all potential environmental sources of toxins near the feeding areas were negative. It was concluded that the colonization of gastric ulcers may have contributed to this unusual case of botulism. To the best of our knowledge, this is the first case of botulism in horses reported in Italy, which is also the first case anywhere of wound botulism caused by infection of gastric mucosa lesions.     

Effect of feed type and essential oil product on equine chewing activity

The ingestive and post-digestion effect of a blend of special essential oil compounds (EO) on eating, chewing and faecal parameters were measured in horses. Ingestive effects appear after no adaptation. Post-digestion effects appear after adaptation. Six Icelandic horses were assigned to two groups in a Latin Square subplot design with EO treatments to four different roughage types and four different concentrates. The horses were fed four different roughage meals and two different concentrate meals on each of the four sampling days. Eating time and saliva were observed during meals. Jaw movements (JM) were recorded using a special chewing halter. Eating time was derived from JM and related to DM intake. The size characteristics of faecal particles were measured by using image analysis. All chewing characteristics measured were significantly affected by roughage (p < 0.001) and concentrate type (p < 0.01). EO had a significant ingestive effect on the frequency of observed saliva during concentrate meals. No significant (p < 0.05) post-digestive or ingestive effect of EO was found for any measured chewing characteristic, which was reflected in the absence of effect on faecal particle dimensions. In conclusion, effect of type of roughage and concentrate was more significant than potential effects of EO.     

Influence of amount and type of dietary fat on deposition, adipocyte count and iodine number of abdominal fat in broiler chickens

This study described the relation between the type and amount of dietary fat on the deposition of abdominal fat by broiler chickens. It was hypothesized that at higher fat intakes, the well-known lowering effect of polyunsaturated fatty acids on the deposition of abdominal fat would be diminished. Experimental diets were formulated to contain three levels of added fat (3%, 6% and 9%). Each level had different proportions of the saturated fatty acids (SFA) and unsaturated fatty acids (UFA) by installing the ratios of 1:1, 1:2, 1:3, 1:4 and 1:5 with the use of tallow and soybean oil. Arbor Acres chicks, aged 7 days, were fed one of the 15 experimental diets until they were aged 42 days. Feed and water were provided ad libitum. There was no systematic effect of the dietary fat type and the amount on the weight gain and the feed intake. The lowest SFA:UFA ratio of 1:5 produced the lowest feed conversion rates, irrespective of the amount of the fat in the diet. The abdominal fat deposition was similar in the birds fed on diets containing either 3% or 6% added fat, but deposition was lower than in those fed 9% fat. A decrease in the SFA:UFA ratio of the diet was associated with a dose-dependent decrease in abdominal fat, irrespective of the amount of fat in the diet. This observation leads to the rejection of the hypothesis stated above. A decrease in the dietary SFA:UFA from 1:1 to 1:4 caused a decrease in the number of the fat cells per surface unit of breast meat. It is concluded that an increased intake of soybean oil at the expense of tallow reduced the abdominal fat deposition and the number of fat cells in the breast meat of broiler chickens.     

天然草地放牧牦牛采食行为及食性选择的研究

对青南地区玉树县境内2牧场的草地植被及成年母牦牛的采食行为和选择性采食习性及其关系进行了探讨,结果表明：B牧场禁牧区的生物量显著高于A牧场的禁牧区及A,B牧场的放牧区（P〈0.05）,B牧场的可食植物量显著高于A牧场（P〈0.05）,A牧场的可食植物量只占地上生物量的一半以下;B牧场分别以小嵩草,矮嵩草,披碱草,针茅,蒲公英等优良牧草为优势种,次优势种,而A牧场以线叶嵩草为优势种,凤毛菊,狼毒,黄帚橐吾等毒杂草及早熟禾等为次优势种;B牧场以小嵩草、矮嵩草等莎草科和为主要采食植物,而在A牧场除以莎草科植物为主要采食植物外,由于可食牧草量的不足,还采食一些本不喜食的植物。矮嵩草和小嵩草是牦牛最喜食,选择性最高的植物;斑块内采食口数A牧场为50.6 bite/patch显著少于B牧场的81.1 bite/patch（P〈0.01）;斑块内采食站数A牧场为8.4 FS/patch显著多于B牧场的5.2 FS/patch（P〈0.001）;采食站内采食口数A牧场为6.6 bite/FS显著少于B牧场的17.4 bite/FS（P〈0.001）;采食速度A牧场为1.32 bites/sec显著慢于B牧场的1.46 bites/sec（P〈0.01）。放牧草地的食物资源的匮乏,使放牧牦牛的食物选择性降低,采食行为的内容变劣,A牧场草地处于严重退化状态;牦牛处于缺营养状态,草地的退化对牦牛的生产性能有很大的影响。     

Characterization of porcine circovirus type 2 (PCV2) infection in swine lymphocytes using mitogen-stimulated peripheral blood lymphocytes from healthy PCV2-carrier pigs

Information regarding the susceptibility of swine lymphocytes to PCV2 is rather limited. To further explore and characterize the PCV2 infection in swine lymphocytes, an in vitro model using concanavalin A (Con A)-stimulated peripheral blood lymphocytes (PBLs) obtained from clinically healthy PCV2-carrier pigs was introduced. It was found that the PCV2 antigen-containing rate was below 2% in PBLs from healthy PCV2-free pigs following treated simultaneously with Con A and PCV2. However, significantly higher PCV2 antigen- and nucleic acid-containing rates could be seen in Con A-stimulated PBLs from clinically healthy PCV2-carrier pigs. Prior to Con A treatment, both of the PCV2 antigen- and nucleic acid-containing rates in PBLs from healthy PCV2-carrier pigs were less than 1%; however, they reached 22.1+/-5.7% by flow cytometry and 27.1+/-6.5% by in situ hybridization, respectively, at 4-day post-incubation with Con A. Phenotyping of PCV2 antigen-containing cells revealed that PCV2-positive cells could be detected in both T and B lymphocyte populations within which IgM-positive B lymphocytes appeared to have a relatively higher positive rate. The Con A-stimulated PBLs also displayed a significantly higher viral load by the measurement of either PCV2 DNA copy number or viral titer when compared with the non-treated PBLs from healthy PCV2-carrier pigs. The results indicate that PBLs, especially IgM-bearing B lymphocytes, are indeed susceptible to PCV2 infection and PCV2 is capable of replicating in dividing lymphocytes. This activation-induced replication may explain in part the pathogenesis of lymphoid depletion in PMWS-affected pigs.     

Identification of bovine viral diarrhea virus type 1 in yaks (Bos poephagus grunniens) in the Himalayan region

Since cattle are widely infected by bovine viral diarrhea virus (BVDV) in India, we searched for pestivirus infection in yaks. Of 71 pure and crossbred yaks from Himalayan region, pestivirus antigen was detected by Ag-ELISA in three animals. Pestivirus in leukocyte and cell culture isolated virus samples originating from positive yaks was also confirmed by RT-PCR using panpestivirus specific primers selected from 5'-untranslated region (5' UTR). The 5' UTR, N(pro) and E2 regions were sequenced and used for genetic typing. Phylogenetic analysis revealed that pestiviruses detected in three Himalayan yaks were similar genetically, belonging to BVDV-1. Antigenic characterisation of yak pestivirus also confirmed the typing as BVDV-1. This is the first report on the identification of BVDV type 1 in yaks.     

基于Cap蛋白研制的猪圆环病毒2型疫苗研究进展

猪圆环病毒相关疾病(PCVAD)是危害世界养猪业的主要疫病之一,主要由猪圆环病毒2型(PCV-2)引起。该病毒可引起感染猪免疫系统的破坏,造成严重的免疫抑制,继而引发多种病毒/细菌的混合感染与继发感染,给世界养猪业造成了巨大经济损失。近年来疫苗免疫接种是防控PCVAD的有效手段,由于衣壳蛋白(capside,Cap)是PCV-2的主要免疫保护性抗原,因此常被用作研制PCV-2基因工程疫苗的理想靶抗原。论文就PCV-2Cap蛋白基因工程疫苗的研究进展进行综述,以期为今后PCV-2新型疫苗的研究提供参考。