Arachidonic acid immunoregulation in lambs persistently infected with border disease virus

To evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene C4 (LTC4), prostaglandin D2 (PGD2) and their plasma fatty acid (FA) precursor, arachidonic acid (AA), in six lambs with congenital border disease (BD). Significantly elevated average plasma LTC4 during the first half year of life was associated with increased PDG2 when compared to uninfected control lambs. Significantly elevated total plasma esterified AA stores suggest an effective BDV-mediated prostenoid immunostimulation. However, at 1 yr old, prostenoid secretion had fallen to normal (LTC4) or below normal (PGD2) levels. In contrast, there remained significantly elevated plasma esterified AA, present as available substrate for formation of these anti-viral immunoregulatory agents. These results suggested that preventing mobilization of AA from lipid stores for effective immune responses may be a viral strategy of BD virus that is associated with long term border disease effects.     

吉林省黄牛“猝死症”的病因学研究

１９９４年以来，对吉林省黄牛“猝死症”的病因进行了多方面的研究，包括细菌学检验、病毒学检验、人工感染试验、毒物检验、牛毛硒元素分析及病尸病理形态学观察。结果表明，Ａ型魏氏梭菌是主要病原菌，其他细菌有协同作用；牛冠状病毒或粘膜病病毒感染、缺硒等为本病的诱因     

河南省新乡市奶牛隐孢子虫感染情况调查

本文应用病原学检查法对新乡市4个奶牛场的102头奶牛进行了隐孢子虫感染情况调查，调查结果：隐孢子虫感染率为20.6%；发病率为5.8% ；不同年龄的奶牛感染情况不同；机体免疫功能较低的奶牛易感染；经鉴定虫种为鼠隐孢子虫（Cryptosporidium muris)。     

我国鸡奇异变形杆菌病研究报告

１９８９年４月作者在我国河南洛阳发现鸡奇异变形杆菌病。本病由肠杆菌科变形杆菌属的奇异变形杆菌（Ｐｒｏｔｕｓｍｉｒａｂｉｌｉｓ）所引起，以肢腿瘫痪、排灰白色或黄绿色水样稀便为临床特征。４周龄内雏鸡最易感，发病率８１．４％，病死率５６．５１％；青年鸡和成年鸡感染，可引起化脓性骨髓炎，死淘率４％左右。用濒死鸡脑组织、骨髓分离菌２４ｈ肉汤培养物（０．１ｍＬ）感染的小鼠，可于２４ｈ左右死亡；经口感染４周龄雏鸡，可复制出与自然病例相同的临床症状、病理变化和６０％的病死率，并可从感染致死鸡的脑、骨髓中回收到本菌。该菌不产生外毒素，可产生毒力强大的内毒素。本病可用氟哌酸、吡哌酸、氧哌嗪、链霉素、庆大霉素治愈。     

伪狂犬病病毒感染诱导和抑制细胞凋亡

用伪狂犬病病毒 (pseudorabies virus,PRV)鄂 A株感染非免疫健康初生仔猪 ,5 d后出现典型的伪狂犬病临床症状。从感染 PRV鄂 A株仔猪的肾脏、肝脏、扁桃体、胸腺、腹股沟淋巴结、颈部淋巴结等组织细胞提取的 DNA,经琼脂糖凝胶电泳呈现大小不等的 180～ 2 0 0 bp整倍数的寡核苷酸片段梯状条带 ,经 PCR方法鉴定为 PRV DNA。末端脱氧核苷转移酶原位标记 [terminal deoxynucleotidyl transferase(Td T) - conjugated d UTP nick end labelling,TUNEL ]法显示 ,部分凋亡的阳性细胞呈现染色质凝聚、细胞核固缩、染色质靠核膜边聚集等形态学变化 ,说明 PRV诱导细胞凋亡是造成急性感染时组织器官广泛损伤的重要原因之一 ;而 PRV感染的大脑、小脑、嗅球及脊髓等神经系统组织中未观察到上述细胞凋亡特征 ,说明 PRV可以抑制急性感染时神经细胞发生凋亡。本试验结果显示 ,在 PRV急性感染状态下 ,病毒诱导细胞凋亡是杀伤细胞的重要途径之一 ,同时这一过程又可通过神经系统病毒基因隐性感染及潜伏期的建立而受到抑制     

番鸭新病——花肝病的研究：Ⅰ．分离毒的致病必及感染途径试验

番鸭花肝的是近年流行的一种新的番鸭疫病，其特征性病变是死亡番鸭的肝、脾、小肠等部位出现灰白色的坏死点，本文自广东省主要疫区分离到几株病毒，这些病毒在番鸭胚上可继代繁殖，其胚液可使番鸭妇病。不同途径感染试验表明该病毒通过肌肉注射、爪垫部注射、口服，同居感染均可使番鸭发病和死亡，并具有典型病变，分离毒不能使半番鸭，本地鸭，鸡发病。     

Dynamics of natural bovine herpesvirus-1 (BoHV-1) infection in a dairy herd

In this study, natural cycling of BoHV-1 infection was investigated in two groups of dairy cattle containing 2120 head. Group 1 comprised 127 animals and they were monitored for BoHV-1 infection virologically and serologically in six consecutive sampling periods. It consisted of naive heifers between 6 and 8 months of age, while in group 2, age, sex and the BoHV-1 serostatus of the animals were disregarded. The animals in group 1 were found to have seroconverted at the second sampling. Results of the serological study showed slight antibody response after natural BoHV-1 infection in the herd and neutralizing titres fell below protective levels in the 6–8 months after the peak. During the 2-year study period, one recurrence was detected after primary infection. Virus isolation studies revealed a cytopathic effect indicative of BoHV-1 in two nasal swabs taken during the fifth sampling period from animals with mild upper respiratory tract symptoms. As the study was carried out under natural conditions, it is not known whether the viruses isolated were from recurrences or re-infections. Data from cross-neutralization tests with herd isolates showed higher antibody response than those with the reference virus. The dynamics of BoHV-1 in both groups were found to be statistically similar.     

Influence of race and post infection temperature on two components of partial resistance to wheat leaf rust in seedlings of wheat

Summary Components of partial resistance, infection frequency and latency period, were determined in 71 winter and spring wheat genotypes in the seedling stage, after infection with three races of leaf rust (Felix 3B, Clement B and Betuwe 85C) at three different day/night temperature regimes (24/18°C, 18/12°C and 12/6°C). The genotypes were split into two groups and two separate experiments were carried out. Five genotypes, SVP 84039, Akabozu, Banco, BH 1146 and Orso, conferred a low infection frequency and a long latency period and Westphal 12A a long latency period, indicating a relatively high level of partial resistance. The correlation coefficient between infection frequency and latency period was low. Race-specificity was not found. There was a significant temperature effect on the latency period. In the second experiment the temperature x genotype interaction was significant. Temperature-response functions of transformed data demonstrated that the latency periods of four relatively resistant genotypes, Westphal 12A, Banco, BH 1146 and Orso and of Sarno and Mirela were most sensitive to temperature. The range between the genotypes with the longest and the shortest latency period was highest at 12°C. Therefore, low temperature regimes are preferred to distinguish differences in level of partial resistance.     

Control of preharvest aflatoxin contamination in maize by pyramiding QTL involved in resistance to ear-feeding insects and invasion by Aspergillus spp.

Several resistance sources and resistance mechanisms to aflatoxin formation and corn earworm (Helicoverpa zea Boddie) damage to maize (Zea mays L.) have been identified. Based on this knowledge, experiments were initiated toward achievement of the following objectives: (1) to confirm earlier determinations on resistance traits of germplasm sources and to identify quantitative trait loci (QTL) associated with each of the traits, and (2) upon estimation of the degree of QTL effects on each trait, to generate a maize population, with chemical and physical resistance to Aspergillus spp. and ear-feeding insects, for inbred development. A 2-year field experiment to evaluate selected genotypes inoculated with A. flavus and infested with corn earworm revealed that significant variation exists among the genotypes for aflatoxin contamination and corn earworm damage. The protection of maize ears against aflatoxin contamination was primarily dependent on resistance to fungal infection and ear-feeding insects, and excellent husk coverage and tightness. A major QTL (p1) identified on chromosome 1S had effects of 54.0, 42.1, and 28.3% on the phenotypic variability for concentrations of silk maysin, 3′-methoxymaysin+apimaysin, and chlorogenic acid, respectively. Markers/QTLs for husk phenotypic traits and total aflatoxin concentrations have been determined, but more detailed mapping of these chromosomic regions will be necessary to locate precise markers/QTLs for husk traits and aflatoxin production. Realizing the complexity of the Aspergillus–aflatoxin-maize system and the factors affecting aflatoxin contamination, we are directing our program toward marker-assisted breeding to enhance or improve general genetic resistance to ear-feeding insects and invasion by Aspergillus spp.     

Variation of grain iron content in a local upland rice germplasm from the village of Huai Tee Cha in northern Thailand

Crown rust caused by Puccinia coronata Cda. f. sp. avenae Eriks., is a major fungal disease of cultivated oats (Avena sativa L.) in Tunisia. Six landrace oats (M_tK₂, JT₅, BJ₃₅, GT₁, ZN₃ and JT₀) locally collected and previously screened for their relative oat crown rust resistance were used in this experiment. These accessions were evaluated during a two cropping season in field plots under heavy natural oat crown rust infection. Assessment criteria to crown rust reactions were AUDPC, latent period, uredinia size and number of uredinia per cm² of infected leaf area. Principal components analysis showed that the variables were grouped in two components. These two principal components explained 83.56% of the total variance. The projection of the point-cloud representing the populations on the plan formed by the principal components ‘Fact 1’ (63.83%), in abscissa, and ‘Fact 2’ (19.73%) in ordinate, permitted to distribute the accessions in several groups. Three landrace oats (M_tK₂, JT₅, and JT₀) showed the lowest value of all the components used. These landrace oats might be good sources of effective and durable resistance to crown rust.