Sequential study of lesion development in experimental haemophilus pleuropneumonia

Recently weaned pigs were infected aerogenically with Haemophilus (Actinobacillus) pleuropneumoniae, serotype 5. At three, six, 12, and 18 hours and one, two, four and seven days after exposure to haemophili a pair of animals were killed and necropsied. Pulmonary oedema with multifocal petechial haemorrhages and a diffuse neutrophilic bronchiolitis and alveolitis were observed at three and six hours after infection. Focal areas of coagulative necrosis developed in areas of intense suppuration at 12 and 18 hours after infection. At one and two days after infection, necrotic areas were surrounded by dense bands of degenerating leucocytes and contained unidentifiable round and elongated cells characteristic of this disease. In subacute lesions a thick layer of granulation tissue formed around the outer margin of developing abscesses. Most of the round and elongated cells in alveolar exudates could not be identified by enzyme histochemistry or electron microscopic examination. Neutrophils in various stages of degeneration and deterioration provided strong evidence that some of the cells were of this type. These findings suggest that neutrophils may play an early and significant role in development of lesions.     

Isolation of Actinobacillus pleuropneumoniae serovar 15-like strain from a field case of porcine pleuropneumonia in Japan

An Actinobacillus pleuropneumoniae strain isolated from a field case of porcine pleuropneumonia in Japan, was closely related to a reference strain of serovar 15, which is a newly proposed serovar according to an analysis of field isolates originating from Australia. The isolate had biological and biochemical properties consistent with A. pleuropneumoniae biovar 1, and reacted strongly to a rabbit antiserum raised against a reference strain of serovar 15 in an agar gel precipitation test. The nucleotide sequence of a hyper variable region in the 16S RNA gene of the isolate was identical to that of the reference strain of serovar 15. The isolate possessed A. pleuropneumoniae-RTX toxin (Apx) II, III, and IV genes, consistent with serovar 15. Its virulence in mice was lower than that of ApxI-bearing strains but higher than that of other ApxIII-bearing strains. This is the first report describing the isolation of A. pleuropneumoniae serovar 15-like strain from a country or region other than Australia.     

猪传染性胸膜肺炎的研究进展

猪传染性胸膜肺炎(Porcine contagious pleuropneumonia,PCP)是由胸膜肺炎放线杆菌(Actinobacillus pleuropneumoniae,APP)引起的一种高度传染性和致死性呼吸道疾病.1957年英国Pattison等首次报道此病[1].此后,本病在欧洲、美洲、澳大利亚、日本、韩国等地均被发现.1990年我国的杨旭夫[2]首次正式确认了我国大型集约化养猪场存在PCP,同时分离出致病菌株,并确定了血清型.     

A Stable L-form of Haemophilus pleuropneumoniae

A stable L-form of Haemophilus pleuropneumoniae (Shope) was isolated from primary pig kidney cell tissue cultures which had been inoculated 28 days previously with glycine induced spheroplasts of this organism.

H. pleuropneumoniae was definitely cytopathic in primary pig kidney cell cultures, producing cell rounding, cytoplasmic vacuolation and nuclear enlargement with peripheral condensation of nuclear DNA. By contrast, the effect of spheroplasts was much less distinct, producing only loss of cytoplasmic granularity coincident with apparent loss of some cytoplasmic RNA, and slight nuclear enlargement.

Both the organism and its L-form were shown to be related by cultural methods, antibiotic sensitivity tests, immunofluorescence and immunodiffusion.

The L-form remained stable after 90 serial passages on agar and 45 in broth, each medium being capable of supporting the growth of both forms of the organism.

     

猪传染性胸膜肺炎疫苗的研究进展

综述了近年来国内外在猪传染性胸膜肺炎的灭活疫苗、亚单位疫苗和基因工程疫苗(重组亚单位疫苗、重组核酸疫苗、活载体疫苗、基因缺失疫苗等)方面取得的研究进展,论述了不同疫苗的优缺点,旨在为猪传染性胸膜肺炎的防控和疫苗的研制提供思路。     

Experiences with vaccination against Haemophilus pleuropneumonia of swine

In a Haemophilus pleuropneumonia problem herd with piglet production and fattening, sows and weaned pigs were vaccinated with a Danish vaccine (Pleurinord). Due to consequent vaccination of the sows the health of the piglets could be improved decisively, resulting in an increased number of raised piglets per sow and year from 16.8 to 20.3. In the vaccinated fattening pigs compared to the unvaccinated ones the following effects were observed: markedly reduced expenses for medication and a markedly reduced frequency of characteristic lesions in the respiratory tract; the improvement of the daily weight gains and the reduction of losses remained behind the expectations. Decisive causes for this were respiratory and enteric diseases unrelated to Haemophilus, which were favoured by serious mismanagement and inadequacies in the feeding regimen and barn climate. On the example of the vaccinated herd it is shown how important the analysis of a multifactorial disease situation is, in order to be able to objectify better or at all the influence of a vaccination program under field conditions. Within a concept of prevention and control of Haemophilus pleuropneumonia the vaccination is a helpful part.     

Serologic studies on porcine strains of Haemophilus parahaemolyticus (pleuropneumoniae): extraction of type-specific antigens.

By the use of phenol water extraction it was possible to obtain strictly serotype-specific antigens from mucoid cell cultures of five serotypes of Haemophilus parahaemolyticus (pleuropneumoniae). These serotype-specific antigens did not cross-react with each other in immunodiffusion tests. The type-specific precipitating phenol-water-fractions were composed of two to four antigenic components, presumably of polysaccharide or lipopolysaccharide nature.     

猪传染性胸膜肺炎放线杆菌的分离与鉴定

从柳州某猪场疑似猪传染性胸膜肺炎病猪中分离到致病菌.通过对分离菌株的理化特性测定,鉴定为猪传染性胸膜肺炎放线杆菌,并用分离菌株制备了灭活疫苗,有效控制了菌株分离场的猪传染性胸膜肺炎病。     

普鲁卡因青霉素硫酸双氢链霉素粉剂对猪胸膜肺炎的疗效实验

为了解普鲁卡因青霉素硫酸双氢链霉素粉剂的抗菌效果,我们在药敏试验的基础上,通过猪传染性胸膜肺炎人工感染动物实验模型进行了疗效对比试验,以便为其临床应用提供科学依据。1材料与方法1.1试验药物注射用普鲁卡因青霉素硫酸双氢链霉素,每支含20万IU普鲁卡因青霉素和25万μg双     

规模化养殖中猪传染性胸膜肺炎的综合防控

猪传染性胸膜肺炎是由胸膜肺炎放线杆菌引起的猪的一种高度接触性、致死性呼吸道传染病,以急性出血性纤维素性胸膜炎和慢性纤维素性坏死性肺炎为特征。胸膜肺炎放线杆菌特异性地寄生于猪的呼吸道,各年龄阶段的猪都易感,但断奶仔猪与育肥猪发病率最高,死亡率依环境和病原毒力而定。     

Detection of strains of Haemophilus pleuropneumoniae using the coagglutination test

Three tests were used for the serological identification of the strains of Haemophilus pleuropneumoniae (Actinobacillus pleuropneumoniae) isolated from pigs and coming from 66 sites where pleuropneumonia, caused by Haemophilus, occurred in pigs. The coagglutination test was found to be the best for the identification of the causal agent; the ring precipitation test was somewhat less sensitive, and worse results were obtained when rapid slide agglutination was used. Of all the field isolates of H. pleuropneumoniae, serovar 2 occurred most frequently (56%), followed by serovar 1 (39%); one strain was identified as serovar 7. Two strains have remained unidentified. The serological identification of the strains was performed on the basis of their comparison with eight type serovars of H. pleuropneumoniae.     

Mortality in swine herds endemically infected with Haemophilus pleuropneumoniae: effect of immunization with cross-reacting lipopolysaccharide core antigens of Escherichia coli

The benefit of increased immunity to cross-reacting lipopolysaccharide core antigens of gram-negative bacteria induced by vaccination with an Rc mutant of Escherichia coli 0111:B4 (strain J5) was evaluated in commercial swine herds endemically infected with Haemophilus pleuropneumoniae. Weanling pigs were vaccinated IM with E coli J5 (group 1) before the expected time of H pleuropneumoniae infection. Clinical signs, antibiotic treatment frequency, mortality, growth performance (days to market weight), and serologic responses of the pigs were monitored for approximately 5 months after vaccination. The results were compared with those of pigs vaccinated IM with a commercial H pleuropneumoniae bacterin (group 2) and with those of nonvaccinated control pigs of the same age (group 3). The treatment frequency and growth performance were similar in the 3 groups. However, vaccination with E coli J5 or with the H pleuropneumoniae bacterin lowered mortality, compared with mortality in the controls. Serum titers against E coli J5 increased after vaccination with the E coli J5 bacterin, but were not increased by vaccination with the H pleuropneumoniae. In contrast, serum titer to E coli J5 increased in all treatment groups as a result of H pleuropneumoniae infection or exposure. The protection against lethal H pleuropneumoniae infections in swine that was provided by vaccination with the E coli J5 and the H pleuropneumoniae bacterin appeared to be immunologically distinct on the basis of serologic analysis, indicating the possibility of different mechanisms of protection.     

辽北地区猪传染性胸膜肺炎的诊断与防治

随着生猪养殖业的发展,猪传染性胸膜肺炎发病率逐渐增加,成为近年来危害养猪业的主要疾病之一.2000-2009年期间,笔者对辽宁省北部地区5个县区40家猪场进行发病调查研究,各养猪场在不同时期都发生过本病,有的猪场多次反复发生.调查中发现有如下特点:近年内发病猪场数量增多,猪群中个体发病率上升,耐药菌株增多,从而使治愈难度加大.2008年笔者对辽北地区18家发病猪场进行了诊治观察,通过对本病调查研究,现将内容报告如下.     

Intravascular macrophages in lungs of pigs infected with Haemophilus pleuropneumoniae

Pigs were inoculated intratracheally with a virulent or an avirulent isolate of Haemophilus pleuropneumoniae serotype 5 and sacrificed during the first 24 hours post-inoculation. Intravascular macrophages were examined by electron microscopic and morphometric techniques. Samples of lung were taken from regions with no macroscopic lesions (Zone 0), 2.5 to 3.0 cm from lesions (Zone 1), and from the immediate edge of lesions (Zone 2). Those pigs inoculated with the avirulent isolate did not develop lesions. Pigs given the virulent isolate consistently developed necrohemorrhagic lesions in the dorsolateral aspect of the caudal and middle lung lobes. Relative volumes of intravascular macrophages in Zones 1 and 2 increased with increased time post-inoculation; in pigs given the avirulent isolate, intravascular macrophage volume decreased with increased time post-inoculation. Cytoplasmic volume to nuclear volume ratios for macrophages in Zone 2 from pigs with necrohemorrhagic lesions progressively increased with increased time post-inoculation. Enlarged intravascular macrophages had large nuclei, prominent nucleoli, and abundant cytoplasm. Increased cytoplasmic volume was the result of increased numbers of lysosomes, phagosomes, rough and smooth endoplasmic reticulum, and large Golgi complexes. Pigs inoculated with the virulent bacteria had IV macrophages with large phagosomes that contained necrotic cell debris and fibrin. Macrophages with phagosomes were more frequent in the 6-, 9-, and 24-hour sample periods of pigs with lesions than in any other group. Intercellular adhesion plaques (ICAP) were present between IV macrophages and subjacent endothelial cells. ICAP's increased in length with increased time post-inoculation in Zones 1 and 2 from pigs with necrohemorrhagic lesions. In later sample periods, multiple closely associated and interlacing IV macrophages formed a discontinuous layer over endothelial cells in Zone 2 samples near necrohemorrhagic lesions. These results suggest that the intravascular macrophage population changes from immature macrophages to mature macrophages or immature epithelioid cells within 24 hours after inhalation of a virulent Haemophilus pleuropneumoniae. Furthermore, intravascular macrophages likely function to clear cellular and acellular debris from the blood in pneumonic conditions.     

Pulmonary clearance of Haemophilus pleuropneumoniae and Serratia marcescens in mice

Bacterial counts (per lung) were made from Swiss White and/or C3H mice, inoculated intranasally with either Haemophilus pleuropneumoniae or Serratia marcescens and killed at specific times. The percentages of bacterial survival and clearance at each time were determined. Serratia marcescens was cleared progressively, but not completely, from the lungs of C3H and Swiss White mice. The overall pulmonary clearance of S marcescens by Swiss White mice was significantly greater than that of C3H mice (P less than 0.01). The pulmonary clearance pattern of H pleuropneumoniae in C3H mice differed according to the dose inoculated. With a larger H pleuropneumoniae median lethal dose (0.1 LD50), the organism multiplied consistently up to 25 times by 12 hours after the inoculations were done, when clinical signs and lesions appeared in a few of the mice. The clearance rates at 24 and 48 hours after inoculations were 60.65% and 10.3%, respectively. Mice given 0.04 LD50 H pleuropneumoniae showed a 10-fold increase of H pleuropneumoniae in the first 4 hours, with clearances reaching 33%, 66%, and 99% at 8, 12, and 24 hours, respectively.     

湖北省猪传染性胸膜肺炎血清学调查

猪传染性胸膜肺炎是由胸膜肺炎放线杆菌(Actionbacillus Pleuropneumoniae,APP)引起的一种呼吸道传染病。该病具有肺炎和胸膜炎的典型症状和病变,急性病例以纤维素性出血性胸膜肺炎、慢性病例以纤维素性坏死性胸膜肺炎为主要特征,急性病死亡率高,慢性耐过猪生长不良。该病近年来在全     

用IHA试验进行猪传染性胸膜肺炎的血清学调查

猪传染性胸膜肺炎 ,系由胸膜肺炎放线杆菌引起的猪的一种呼吸道传染病。以急性出血性纤维素性胸膜肺炎和慢性纤维素性坏死性胸膜肺炎为特征。急性病例大多死亡 ,慢性和亚急性病例常能耐过 ,但可导致生长迟滞 ,并使屠宰猪肺脏废弃率增加。本病也是动植物检疫法规定的二类检疫对象。为了摸清本病在粤东的流行情况 ,我们对粤东 8市县的 1 1个猪场进行了随机抽查 ,报道如下。1　材料与方法1 .1　诊断试剂　购自兰州兽医研究所。1 .2　被检血清　采自粤东 8市县的 1 1个猪场。其中大猪 1 2 2头 ,中猪 1 1 4头。1 .3　血凝反应板　为 96孔 1 1 0°…