Relative importance of larval and adult Mecistocirrus digitatus in inducing resistance to a reinfection in calves

Calves immunized with adult Mecistocirrus digitatus implanted directly into the abomasum did not develop a substantial degree of immunity to a subsequent large oral (challenge) dose of larvae, which developed to maturity. In contrast animals immunized by oral infection developed strong resistance. The calves implanted with adult worms appeared to show a greater degree of susceptibility to maturation of the challenge infection than controls which received a challenge of the same magnitude without any previous immunization. The implanted female adult worms established in the hosts and continued to produce more eggs for a longer time than those which developed to maturity from the oral immunizing infection with third-stage larvae. Passive haemagglutination studies revealed that the implanted adult worms stimulated little or no antibody response in the hosts. In the calves which did not show a response to the adult worm implant the subsequent challenge with an oral infective dose of third-stage larvae also failed to stimulate a response. Likewise the two calves from the group which showed a weak antibody response to the adult worm implant did not show an increased response when challenged. In contrast, calves immunized with an oral infection of third-stage larvae had an antibody response which showed a vigorous rise on challenge in four of the five calves. Thus a direct relationship between resistance to challenge infection and the antibody response determined by the passive haemagglutination and gel-diffusion tests was observed in the calves immunized orally.     

Use of ELISA to assess lungworm infection in calves

The enzyme-linked immunosorbent assay (ELISA) technique was applied to the detection of lungworm infections in calves. In experimentally infected animals different responses to larval and adult worm antigens were observed. The response to adult worm antigens was delayed in vaccinated animals when infection occurred by the gradual uptake of infective larvae from contaminated pasture. A serological survey in The Netherlands demonstrated a high incidence of lungworm infection in both vaccinated and unvaccinated herds. There was a good correlation between anti-adult worm and anti-larval ELISA-titres. ELISA appeared to be a useful technique for assessing the level of lungworm infection in a herd.     

Cross-reactivity between Actinobacillus pleuropneumoniae serotypes comparing different antigens and serological tests

Several antigens were prepared from suspensions of reference strains of the 12 serotypes of Actinobacillus pleuropneumoniae (saline extract [SE], capsular extract [CE], whole cell suspension [WCS], boiled extract [BE], and autoclaved cell antigen [ACA]). The cross reactions between each antigen and the antisera against reference strains of the other 11 serotypes were compared by using the complement fixation test, ELISA and the indirect haemagglutination test. ACA produced the most cross reactions, which, in some serotypes, took place in all the antisera tested. BE produced fewer cross reactions, but these were more abundant than those obtained with SE, CE or WCS. The least cross reactivity occurred with SE in the indirect haemagglutination test. This test is, therefore, the most reliable method for serotyping field strains of A pleuropneumoniae.     

A passive haemagglutination test for detection of antibodies against mycoplasma mycoides subsp. mycoides using glutaraldehyde-fixed sheep erythrocytes

A simple passive haemagglutination test using the microtitre technique was developed for the detection of antibodies against Mycoplasma mycoides subsp. mycoides infection in cattle. Of the four different concentrations (0.1, 0.2, 0.25 and 0.5%) of glutaraldehyde used for the fixation of sheep erythrocytes, antigens prepared with erythrocytes fixed with 0.2 and 0.25% concentrations of glutaraldehyde gave the best results.The test was found to be very practical, sensitive, specific and reproducible. It also compares favourably with the complement fixation test.     

The serological response of foals to vaccination against strangles.

A group of 100 foals was given either a commercial bacterin or an autogenous vaccine consisting of whole cells and an acid extract of Streptococcus equi. During the study, some of the foals developed clinical strangles. Various sets of sera were collected from these foals prevaccination, during vaccination, postvaccination and postinfection. The serological response of these foals was measured by passive haemagglutination and long chain tests. In foals which remained healthy, the highest titres were reached within one to two months postvaccination with a passive haemagglutination 10 x log2 mean titre of 6.78 and the long chain indices of 4.41. These levels persisted for 120 days postvaccination. Those foals which had clinical strangles exhibited lower passive haemagglutination titres (3.78) at one to two months postimmunization, but rose significantly after recovery. Four ponies immunized with formalinized Str. equi bacterin showed a partial protection against the challenge infection. The passive haemagglutination titres, long chain indices and serum bactericidal activity in these ponies were highest at 35 days postvaccination but did not increase after infection.     

Protection of cattle against experimental haemorrhagic septicaemia by the capsular antigens of Pasteurella multocida, types B and E.

Aluminum hydroxide adjuvant vaccines containing endotoxin-free capsular antigens of Pasteurella multocida, types B and E, were administered to cattle. Dose dependent serological responses were observed which were similar for both antigens. The immunised cattle were subjected to intravenous challenge by a virulent type E strain. All animals which received the highest vaccine dose survived and all unimmunised control animals died and a vaccine dose-response relationship was obtained. The results of passive mouse protection and indirect haemagglutination tests (type E) on the sera of immunised cattle corresponded with the degree of protection against challenge of the cattle.     

Detection of serum antibodies against Mycoplasma gallisepticum and Mycoplasma synoviae by a dot-immunobinding technique

Both Mycoplasma gallisepticum (MG) and M. synoviae (MS) antigens prepared for the routine haemagglutination inhibition (HI) test were diluted and absorbed to the separate pieces of durapore membrane for the measurement of dot-immunobinding (DIB) titers of test sera. Besides, durapore strips bearing both antigens were employed for a DIB test with chicken sera definitely diluted 100-fold. Shortening of reaction time of chicken sera with antigens as well as with the secondary serum markedly eliminated non-specific DIB reactions exhibited at low dilutions although the same condition was not so effective on the elimination of non-specific reactions among rabbit hyperimmune sera. Rapid and specific development of DIB antibody which continued at high titer up to 1:640 for 10 weeks postinoculation was proved in the sera of SPF chickens inoculated with MG or MS, while DIB titers of sera from uninoculated chickens remained 1:20 or lower. Non-specific reactions, which occurred in the routine serum plate agglutination test with a part of sera from the inoculated chickens, were not exhibited in the DIB as well as in the HI test with the same sera. Results of the DIB test with serum samples from 287 conventionally reared chickens definitely diluted 100-fold coincided with the results of HI test at a level of 90% with MG and 89% with MS antigen. This technique seems to be useful for a rapid, simple and specific diagnosis of avian mycoplasmosis.     

Studies of the origin of false positive reactions in the serodiagnosis of contagious bovine pleuropneumonia

Four groups of cattle were experimentally immunised by four mycoplasma species of "mycoides-like" group, Mycoplasma (M) capricolum, M. mycoides subsp. mycoides (LC), M. mycoides subsp. capri and M. species group 7 of LEACH (PG50). They were then bled weekly during 2 months to establish antibodies kinetics against homologous and heterologous antigens. The standard method of complement fixation test (CFT) used in Europe and a new ELISA test for diagnosis of contagious bovine pleuropneumonia were performed in comparison with passive haemagglutination test (PHA) against antigens used for experimental immunisation. Cross reactions obtained are rather equal to the degree of similitude between these mycoplasma species. With CFT-cross reactions are transitory and occur only while homologous titers are very high, particularly with "PG50" and the two caprine mycoides strains. ELISA results using a threshold of positivity of optical density of 0.20, were similar to that obtained with CFT except ELISA specificity is not so different from CFT one. This experimental model could explain some natural situations.     

The effect of oxfendazole terminated infections with Haemonchus contortus on the development of immunity in sheep

The relative contribution of third (L3), fourth (L4) or adult stages of Haemonchus contortus to the development of immunity was evaluated in three groups of sheep subjected to infections terminated by oxfendazole treatments at the L3, L4 or adult stage. A control group did not receive immunising infections. All the groups were challenged with 5000 L3, to evaluate the protection provided by the different protocols. All sheep were necropsied at the end of the experiment to count the abomasal worm burdens. A marked reduction in egg counts after challenge infection was only observed in sheep in which the infection was terminated in the adult stage (Group 4). A significant reduction in worm burden was also observed in Group 4. The immunising infections and/or the challenge infection resulted in moderately elevated IgG antibody levels against L3, L4 and adult somatic antigens in all the groups. In contrast, a strong IgG response against H. contortus excretory/secretory (ES) antigens was observed in the groups in which the immunising infection was terminated in the L4 and the adult stage. An elevated lymphocyte proliferation response against Haemonchus ES antigens was found only in the group that had their immunising infection terminated at the adult stage. The combined data suggest that exposure to and elicited immunological responses to ES antigens are important for the development of immunity against H. contortus.     

用抗虫体表膜抗原抗体测定犬细粒棘球绦虫粪抗原

利用Echinococcus granulosus(Eg)成虫表膜抗原抗体夹心ELISA方法检测犬细粒棘球绦虫感染的粪抗原.首先提取Eg成虫表膜抗原,制备抗Eg成虫表膜抗原的血清,然后用间接ELISA和Western blotting方法检测其抗原抗体反应及免疫原性,用间接免疫组化方法对Eg成虫表膜蛋白进行组织定位.利...     

Porcine parvovirus: propagation in microcarrier cell culture and immunogenic evaluation in pregnant gilts

Porcine parvovirus was propagated in PK-15 cells cultured in roller bottles or on microcarrier beads. After inactivation, the virus was used as antigen in the preparation of vaccines. The immunogenic potency and safety of the vaccines were evaluated in specific pathogen free pregnant gilts and guinea pigs. Experimental challenge tests determined the efficacy of the vaccine in preventing porcine parvovirus transplacental infection. Neither viral antigens nor specific antibodies were detected in fetuses from vaccinated gilts. In contrast, fetal death and, or, mummification occurred when unvaccinated gilts were infected. Both virus and, or, antibodies were also detected in fetuses from these unvaccinated gilts. Serum conversion after vaccination was assayed by microserum neutralisation using guinea pig erythrocytes as cell indicators and by haemagglutination inhibition tests. Viral antigens in fetal tissues were detected using ELISA, the immunobeads technique, the haemagglutination test and by virus isolation.     

Nippostrongylus brasiliensis infection in the rat: 2. A comparison of production of antibodies in bile and serum by baby rats,lactating rats and adult rats

Production of bile lgA and serum lgG antibody responses against whole worm antigens and worm metabolic product antigens occurred by 7 to 14 days after a single infection with $\text{N. brasiliensis}$ and was similar in adult rats, lactating rats and baby rats. Production of bile lgA antibodies against phosphorylcholine was greater in adult rats, 7 days after infection, than in baby rats or lactating rats. lgA antibody production by baby rats may be affected by immaturity of the intestinal lgA system, and diversion to the mammary gland of lgA-plasma cell precursors may occur in lactating rats. Such effects may be involved in the failure of baby rats and lactating rats to expel parasites by day 21 at which time in adult rats expulsion was complete.     

Preliminary investigation into the usefulness of the indirect haemagglutination

Summary

To give an impression of the usefulness of indirect haemagglutination (IHA) in the diagnosis of lungworm infections in cattle under practical conditions, five calves vaccinated against Dictyocaulus viviparus and five unvaccinated calves were periodically subjected to clinical, parasitological, and serological examinations over a period of seven months.

All calves grazed on a lungworm‐infected plot. 82% of the observations in unvaccinated calves, which were positive with respect to one or more of the used parameters, concerned IHA‐positive animals which, however, showed negative results with the parasitic parameters. The titre variation of the serological examination was a further indication of the fact that the IHA detected antibodies against lungworm antigens. No indications of false positive reactions were obtained.

An investigation carried out on 46 farms on the correlation between serological and clinical findings on lungworm infections revealed a positive correlation in 80% of the groups between results obtained with both methods.

The authors consider that IHA offers good prospects for the diagnosis of lung‐worm infections.     

Serological studies of Actinobacillus (Haemophilus) pleuropneumoniae strains of serotype 6 and their antigenic relationship with other serotypes

Serological tests such as agglutination, coagglutination, precipitation and indirect haemagglutination were used to study the antigenic relationship of reference and field strains of Actinobacillus (Haemophilus) pleuropneumoniae of serotype 6 with reference strains of other serotypes. Both cell-associated particulate and cell-free soluble antigens prepared from unheated and heat-treated bacterial suspensions of reference and field strains of serotype 6 were used in the studies. Species-specific, common antigenic determinants associated mainly with heat-treated particulate antigens of serotype 6 were cross-reactive in tube agglutination tests with almost all the serotypes. The species-specific antigens were of a minor nature because the cross-reactivities were abolished in both 2-mercaptoethanol agglutination and coagglutination tests. Cell-free saline extracts of both unheated and heat-treated suspensions of serotype 6 strains possessed epitopes specific for serotypes 3, 5 and 8 in addition to their own specific determinants. The epitopes were dominant because the reactions of strains of serotype 6 with antisera against serotypes 3, 5 and 8 persisted in almost all the serological tests used. Serotype 6 strains were antigenically closer to serotype 8 than to serotypes 3 or 5. A combination of serological tests such as coagglutination followed by 2-mercaptoethanol tube agglutination and, or, immunodiffusion tests differentiated serotype 6 strains from those of other cross-reacting serotypes.     

Assessing the agreement between Ostertagia ostertagi ELISA tests performed using the crude adult antigen and the adult and larval stage 4 excretory/secretory antigens

The objective of this study was to determine the agreement between ELISA tests conducted using three O. ostertagia antigens: crude adult worm, larval stage 4 (L4) excretory/secretory (ES) and adult ES. This study was carried out on 289 Holstein cows from five herds in Prince Edward Island and one herd in Nova Scotia. Composite milk samples of these cows were collected (between May and September 2002) from the respective provincial laboratories and sent to the Atlantic Veterinary College where each sample was tested for antibodies to O. Ostertagi using an indirect microtitre ELISA test. Results were expressed as optical density ratio (ODR) values. Each milk sample was tested with three ELISA tests, with each test using a different O. ostertagi antigen. There was a slight rise in ODR values of both adult antigens, between May and August, with higher values obtained using the adult ES antigen. L4 ES ODR values were generally higher than those for both adult antigens during the study period, except for May. There was a more dramatic rise in L4 ES ODR values between May and August. Rises in ODR in May and end of July coincided with periods of mass maturation of L4 to adult worms. The results of the study showed that the concordance correlation coefficient (CCC) between tests performed using both ES and the crude antigens were low (crude adult versus adult ES=0.31, crude adult versus L4 ES=0.30). The highest CCC was observed between tests done using both ES antigens (CCC=0.56). Generally, the study results suggest that the antibody response (detectable by the ELISA) is mainly directed against ES antigens (especially L4) than the crude adult worm antigen.     

Immunodiagnosis of experimental Parelaphostrongylus tenuis infection in elk

Elk infected with the meningeal worm, Parelaphostrongylus tenuis (Protostrongylidae), do not consistently excrete larvae in feces, making the current method of diagnosing live animals using the Baermann fecal technique unreliable. Serological diagnosis could prove more useful in diagnosing field-infected animals but depends on the identification and availability of good quality antigen. To mimic field infections, 2 elk were inoculated with 6 infective L3 larvae of P. tenuis, and another 2 with 20 L3 larvae. Fecal samples were examined for nematode larvae using the Baermann technique and serum samples taken were tested for anti-P. tenuis antibody with ELISAs by using the excretory-secretory (ES) products of L3, and sonicated adult worms as antigens. One animal passed first-stage larvae in its feces 202 days postinoculation, but passed none thereafter. The remaining 3 inoculated animals did not pass larvae. In contrast to parasite detection, antibodies against larval ES products were detected in all animals starting from 14 to 28 days postinoculation and persisted until the termination of the experiment on day 243 in 2 animals that harbored adult worms. Antibodies against somatic antigens of the adult worm were not detected until day 56 but also persisted until the end of the experiment in the animals with adult worms. In 2 elk that had no adult worms at necropsy, anti-ES antibodies were detected transiently in both, while anti-adult worm antibodies were present transiently in one. These findings confirm the superiority of P. tenuis larval ES products over somatic adult worm antigens as serodiagnostic antigens, as previously observed in studies of infected white-tailed deer, and extend the application of the newly developed ELISA test in diagnosing and monitoring cervids experimentally infected with P. tenuis.     

IgM单抗体内,外杀伤日本血吸虫的研究

本文报道应用急性感染日本血吸虫的Ｂａ１ｂ／ｃ小鼠脾细胞和ＳＰ２／０骨髓瘤细胞融合，获得了一株具有抗血吸虫攻击感染保护作用的ＩｇＭ单抗ｓｓｊ１４。在被动免疫转移试验中，这株单抗在小鼠体内提供了２７．６９％～６８．５％的减虫率。体外ＡＤＣＣ试验显示该单抗参与了巨噬细胞和嗜酸性粒细胞介导的杀伤血吸虫童虫的作用，免疫化学特性测定表明该单抗同时对血吸虫尾蚴、成虫和虫卵三期虫体抗原起反应，靶抗原的分子量为２９０ＫＤ，分别位于血吸虫童虫和成虫的表膜及虫卵的卵壳。靶抗原表位的化学性质为多糖类，它同时被辐照致弱尾蚴免疫的大鼠血清、血吸虫慢性感染人血清和小鼠血清所识别。本文结果表明，ＩｇＭ抗体和多糖类抗原在血吸虫病免疫保护作用中发挥了重要的作用。     

Detection of Dermatophilus congolensis antibody in the milk of streptothricosis infected cows

Passive haemagglutination and agar gel diffusion tests were used to detect specific antibody to Dermatophilus congolensis antigens in serum and milk of eight streptothricosis infected Friesian milking cows. All the sera and milk samples showed the presence of antibody but titres were higher in sera. Precipitating antibodies were detected only in three sera. A possible implication of this finding is discussed with respect to passive immunity in the young calves from infected dams.     

Effectiveness of antigens from various developmental stages of Ascaris suum in the deomonstration of the migratory phase of experimental ascariasis in pigs]

Tests of the efficiency of antigens prepared from different developmental stages of Ascaris suum in indirect haemagglutination test in the course of proving the migration phase of experimental ascariasis in pigs show that the antigens prepared by ultrasound from the invasive larval stage of A. suum in comparison with antigens of sexually mature stages have higher serological activity. By using this antigen it is possible to prove specific antibodies in experimentally invaded pigs from 6 to 120 days after invasion as opposed to the other tested antigens (the detectability of antibodies from the 7th-8th day to the 64th day after invasion).