Efficacy of a multivalent Bacteroides nodosus vaccine against foot rot in sheep in Britain

A multivalent Bacteroides nodosus foot rot vaccine was tested by comparing the prevalence of foot rot in 317 vaccinated ewes and lambs with the prevalence in 422 unvaccinated control sheep. The vaccine conferred statistically significant protection against foot rot. The vaccine also demonstrated a therapeutic effect in animals with foot rot, after one injection.     

Antibody responses of sheep vaccinated with foot rot vaccines

Enzyme-linked immunosorbent assay (ELISA) and crossed immunoelectrophoresis (IEP) were used to investigate antibody responses of sheep vaccinated with a double adjuvanted or single adjuvanted commercial foot rot vaccine. ELISA detected an antibody response of greater magnitude to the double adjuvant vaccine compared with the single adjuvant vaccine. Sera from sheep vaccinated with double adjuvant vaccine recognised at least six antigens of Bacteroides nodosus in crossed IEP while sera from the single adjuvant vaccinated sheep recognised one antigen. The use of non-denatured antigens of B nodosus in ELISA and crossed IEP enabled quantitative comparisons of antibody responses to the different foot rot vaccines to be made.     

Colostral transfer of Bacteroides nodosus antibodies in sheep.

Ovine contagious foot rot may cause lameness in sheep, resulting in decreased wool growth and low weight gain. Affected neonatal lambs are difficult to treat, and treatment is labor intensive; thus, a method of prevention is warranted. Vaccination of ewes with a multivalent vaccine in an oil adjuvant induced development of antibody to the somatic O antigen of Bacteroides nodosus, and this antibody was detected in serum of newborn lambs after consumption of colostrum from the vaccinated ewes. Antibody titers were determined in 48 unvaccinated ewe/lamb pairs, and in 50 once-vaccinated and 78 twice-vaccinated pairs. Serum and colostrum O-agglutinin titers to B nodosus were determined by a microtitration agglutination test. Lambs from vaccinated ewes had significantly (P less than 0.05) higher O-agglutinin titers than those from unvaccinated ewes, and double vaccination of ewes resulted in the highest potentially protective titers (greater than 1:2,400) in ewes and lambs.     

坏死杆菌白细胞毒素作为腐蹄病亚单位疫苗候选抗原的研究前景

腐蹄病（foot rot）是侵害反刍动物趾间皮肤及深层软组织为主的,严重影响奶牛生产性能和产奶质量的一种常见疾病。由于传统的灭活菌苗具有免疫效果差、副反应严重及大量生产困难等缺点,使腐蹄病基因工程疫苗的研究成为热点。笔者对坏死杆菌白细胞毒素作为腐蹄病亚单位疫苗候选抗原研究的最新进展进行综述,希望为腐蹄病亚单位疫苗的研究提供参考。     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.     

Genetic-associated resistance to foot rot in selected Targhee sheep

Three Targhee rams obtained from the Ohio Agricultural and Experimental Station had been identified as foot rot resistant on the basis of results of challenge exposure. In the first breeding trial, when rams were bred to 20 foot rot-susceptible ewes, the percentages of foot rot-resistant offspring from the 3 foot rot-resistant rams were 68, 82, and 100, compared with 55 and 60 for foot rot-resistant offspring from 2 known foot rot-susceptible rams. In the second year, the foot rot-resistant rams were mated with ewes of unknown foot rot status. The foot rot-resistant status of their lambs was compared with that of range-raised lambs whose parents' foot rot status was unknown. During the first year, challenge exposure to the disease consisted of confinement of the lambs in moist or wet pens with sheep affected with the naturally acquired disease. This protocol was repeated for lambs born during the second-year breeding trial. In addition, the right front foot of each lamb was inoculated with a broth culture of Bacteroides nodosus. During the second year, when data that included infected feet from all lambs were analyzed, 41% of the progeny of the foot rot-resistant rams and 17% of the offspring of parents of unknown foot rot status were unaffected by the disease. When the B nodosus-inoculated foot was not included in the analysis, however, 61% of the progeny of the foot rot-resistant rams and 29% of the others were unaffected. The resistance to foot rot undoubtedly is hereditary. The mechanism of resistance may be in the interdigital skin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cellular and humoral local immune responses in sheep experimentally infected with Oestrus ovis (Diptera: Oestridae)

Cellular and humoral local responses were investigated following repetitive artificial Oestrus ovis infections in lambs. The presence of larvae induced a huge local recruitment of either leucocytes (T and B lymphocytes, macrophages) or granulocytes (eosinophils, mast cells and globule leucocytes). This cellular response was more pronounced in the ethmoid and sinus (development sites of second and third instar larvae) than in the septum or turbinates where first instar larvae migrate. Infected lambs produced Oestrus ovis specific IgG and IgA antibodies in their mucus. This local humoral response was mainly directed against larval salivary gland antigens and not against larval digestive tract antigens. Compared to the control animals, the sinusal mucosa of infected animals was extremely thickened and the epithelium exhibited hyperplasia, metaplasia and eosinophilic exocytosis. The possible roles of these local immune responses in the regulation of O. ovis larvae populations in sheep are discussed.     

Importance of pilus-associated antigen in Bacteroides nodosus vaccines

The performances of two cellular vaccines, one sparsely piliated and the other well piliated, were compared on irrigated pasture with those of vaccines containing their respective, purified pili. There were statistically significant differences among the four vaccines in the mean numbers of feet per sheep which developed severe foot rot during 27 weeks of exposure. The incidence of severe foot rot was significantly lower in the two pili-vaccinated groups than in the group vaccinated with well-piliated cells, which were in turn substantially more effective than the sparsely piliated. However, the two pili vaccines did not prevent infection of the interdigital skin so that the differences in vaccine performance were much less marked when interdigital skin lesions were included. The number of feet affected by blowfly strike was closely associated with the presence of the most severe lesions and consequently there were far fewer struck feet in the two pili vaccine groups than in the two cellular vaccine groups. Analysis of serum agglutinin titres led to the same assessment of vaccinal efficacy as that derived from the analysis of severe foot rot lesions. Individually the agglutinin response to vaccination was not universally associated with resistance or susceptibility to severe foot rot but mean titres were significantly higher in the two pili vaccine groups than in the highly piliated-cell vaccine group, which were all in turn significantly higher than in the poorly piliated-cell vaccine group.     

Clinical and immunological responses of ewes following vaccination with an experimental formalin-inactivated Chlamydia psittaci (ovis) vaccine and subsequent challenge with the live organism during pregnancy

The protection afforded by an experimental, killed, adjuvanted vaccine derived from the A22 strain of Chlamydia psittaci (ovis) against ovine enzootic abortion was studied. The vaccine was used undiluted (group A), at a dilution of 10(-3) (group B) and at a dilution of 10(-6) (group C). A fourth control group (group D) was inoculated with all components of the vaccine except the chlamydial antigen. A group of rams (group R) was also vaccinated with the chlamydial antigen diluted to 10(-3). Animals were challenged 70 days after mating with the A22 strain of C. psittaci (ovis) and were studied throughout pregnancy and the subsequent lambing period. Their cell-mediated immune responses were examined using a skin test and their humoral immune responses were studied using an ELISA. Tests for excretion of chlamydiae in their faeces and genital tract during pregnancy and after parturition and in the faeces of their lambs were made. The reproductive performance of the ewes was assessed by calculating the average weight of lambs produced per ewe in each group. The experimental vaccine protected the ewes in groups A and B against challenge with C. psittaci (ovis) as none showed clinical signs of OEA or excreted chlamydiae. The average weight of lambs produced per ewe in both groups was greater than 4 kg. Both groups seroconverted after vaccination but not all of them were positive to the skin test. The experimental vaccine at 10(-6) dilution of antigen did not protect the ewes as three of 10 ewes displayed clinical OEA and excreted chlamydiae in the products of parturition.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of colostral antibodies on the immunization of lambs against adenoviruses

The effect of colostral antibodies on the immune response in lambs following adenovirus vaccination was studied. Young lambs of different ages, born from vaccinated ewes, were vaccinated with an inactivated and aluminium hydroxide-adsorbed sheep adenovirus vaccine. In a group of lambs vaccinated at 5–7 days of age, the titre of humoral antibodies declined in parallel to unvaccinated controls. In lambs vaccinated at 24–35 days of age, antibody titres to adenovirus stabilised and persisted after an initial fall. Cell mediated immunity, as measured by blastogenic responses of circulating lymphocytes, was stimulated in both groups, but higher numbers of IgG-producing cells became evident in the group of lambs vaccinated at 24–35 days of age.     

Trichostrongylus colubriformis and Haemonchus contortus infections in light bodyweight Merino lambs

OBJECTIVE; To show that low bodyweight is a predisposing cause of high Trichostrongylus colubriformis and Haemonchus contortus burdens and egg counts in Merino lambs. DESIGN: A comparison was made, among lambs of different bodyweights, on the effect on immunity of a primary or secondary viable infection with T colubriformis or H contortus larvae. PROCEDURE: Sixty-one Merino lambs, 1 or 6 months of age, were penned indoors and given primary, or both primary and secondary, infection of T colubriformis or H contortus. Faecal egg counts, worm counts and parasite-specific immunoglobulin concentrations were examined for their relationships with bodyweight. RESULTS: Bodyweight at the start of a primary infection was correlated with worm burden, worm fecundity and jejunal IgA antibody concentration. Merino lambs weighing less than 23 kg at the time of first exposure to T colubriformis or H contortus had impaired ability to develop protective mucosal immunity and to resist homologous challenge. CONCLUSION: If the goal is to ensure that lambs develop immunity before weaning, then every endeavour should be made to achieve the combination of critical bodyweight and exposure to moderate levels of nematode infection as soon as possible.     

Comparison of humoral and cellular immune responses to inactivated swine influenza virus vaccine in weaned pigs

Humoral and cellular immune responses to inactivated swine influenza virus (SIV) vaccine were evaluated and compared. Fifty 3-week-old weaned pigs were randomly divided into the non-vaccinated control group and vaccinated group containing 25 pigs each. Pigs were vaccinated intramuscularly twice with adjuvanted UV-inactivated A/SW/MN/02011/08 (MN/08) H1N2 SIV vaccine at 6 and 9 weeks of age. Whole blood samples for multi-parameter flow cytometry (MP-FCM) and serum samples for hemagglutination inhibition (HI) assay were collected at 23 and 28 days after the second vaccination, respectively. A standard HI assay and MP-FCM were performed against UV-inactivated homologous MN/08 and heterologous pandemic A/CA/04/2009 (CA/09) H1N1 viruses. While the HI assay detected humoral responses only to the MN/08 virus, the MP-FCM detected strong cellular responses against the MN/08 virus and significant heterologous responses to the CA/09 virus, especially in the CD4+CD8+ T cell subset. The cellular heterologous responses to UV-inactivated virus by MP-FCM suggested that the assay was sensitive and potentially detected a wider range of antigens than what was detected by the HI assay. Overall, the adjuvanted UV-inactivated A/SW/MN/02011/08 H1N2 SIV vaccine stimulated both humoral and cellular immune responses including the CD4-CD8+ T cell subset.     

A field trial to assess the therapeutic and prophylactic effect of a foot rot vaccine in sheep

An 18-week field trial was conducted on a sheep ranch to evaluate the therapeutic and prophylactic effect of a commercial foot rot vaccine. Two hundred sheep were included in the study, 100 with detectable foot rot lesions and 100 without. Approximately 50 sheep from each group were selected randomly and vaccinated twice against foot rot at a 6-week interval in the late spring 1984; the remaining sheep acted as nonvaccinated controls. Therapeutic effect of the vaccine was demonstrated by a cure rate of 53% in vaccinated, foot rot-affected sheep vs a cure rate of 19% in nonvaccinated, foot rot-affected sheep. Prophylactic effect of the vaccine was demonstrated by a foot rot prevalence at the end of the 18-week period of 9% for vaccinated sheep vs 53% for nonvaccinated sheep. Associations of foot rot lesions and vaccination with body condition were found to be significant, as was the association between foot rot lesions and mortality.     

Sex-related responses to vitamin B12 and trace element supplementation in prime lambs

Bodyweight, plasma vitamin B12 and blood selenium concentrations were monitored in prime lambs given different forms of supplementation at 2 sites in separate years. At the first site treatment groups comprised control, vitamin B12 injection, selenium given orally and a combination of vitamin B12 and selenium. At the second site cobalt and selenium supplied in a glass bullet was compared with an untreated group. Significant sex-related responses were observed to treatment in terms of bodyweight and at site 2 in plasma vitamin B12 concentrations. A marked bodyweight response to glass bullet supplementation was observed in castrated male lambs but not in ewe lambs. These studies show that sex differences should be considered when investigating trace element deficiencies.     

Effect of pilus dose and type of Freund's adjuvant on the antibody and protective responses of vaccinated sheep to Bacteroides nodosus

Groups of sheep were immunised twice with one or other of six vaccines consisting of purified pili from Bacteroides nodosus at three dose levels (10, 38 and 154 micrograms) and emulsified with either complete (CFA) or incomplete Freund's adjuvant (IFA). Beginning one month after vaccination the sheep were homologously challenged on irrigated pasture, with naturally transmitted foot rot for a period of 26 weeks. Statistical analyses of the number of feet per sheep with severe foot rot demonstrated that there was a significant effect of vaccinal dose but neither an adjuvant effect nor an interaction between dose and adjuvant. Similar conclusions were reached when the titres of antipilus agglutinins in the serum were analysed. By both criteria the responses to doses of 154 and 38 micrograms of pili were significantly better than to 10 micrograms, but not significantly different from each other. The IFA vaccines caused less reaction at the sites of injection than the CFA vaccines and within the former the vaccines containing 10 and 38 micrograms pilus produced less reaction than those containing 154 micrograms. Hence a vaccine containing 38 micrograms of purified pili in IFA is nearly optimal for homologous protection against severe foot rot and is acceptable in terms of the reaction at the injection site.     

Modulation of the cellular immune responses to T-cell-dependent and T cell-independent antigens in lambs with induced bovine viral diarrhea virus infection

Functional interaction between lymphoid cells and lymphotropic viruses is particularly evident for bovine viral diarrhea virus (BVDV) in cattle and its closely related virus, the border disease virus (BVDV) in sheep. The most important aspect of acute or chronic phases of BVDV or BDV infection was the host's increased susceptibility to secondary bacterial or viral infection. To study the ability of BVDV to alter the development of the cellular immune responses to concomitant inoculation with T cell-dependent and T cell-independent antigens, lambs were inoculated twice with rabbit RBC and Escherichia coli lipopolysacharide (LPS) and then were infected with a cytopathic strain of BVDV at postinoculation day 3. Leukopenia characterized by lymphopenia developed after BVDV infection. Increased [3H]thymidine incorporation was observed in resting or lectin-stimulated blood mononuclear cells in the first weeks after inoculation in BVDV-infected lambs, but was followed by decreased [3H]thymidine incorporation after the second inoculation for up to 8 weeks after initial inoculation. In contrast, transient decrease of blastogenic responses, associated with toxic effect of LPS, was detected in inoculated noninfected lambs, but was followed by stimulation of cellular immune responses. Inoculated noninfected lambs had good in vitro cellular immune response to rabbit RBC and LPS antigens, whereas lymphocytes from BVDV-infected lambs could not mount lasting cellular immune responses to antigens or BVDV. Results suggest that BVDV infection in lambs modulates the ability of lymphocytes to respond to lectins or antigenic stimuli according to the time after infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serologic response of domestic ferrets (Mustela putorius furo) to canine distemper and rabies virus vaccines

Nine unrelated 12-week-old naive domestic ferrets (Mustela putorius furo) were used to evaluate the serologic responses to commercial canine distemper virus (CDV) and rabies virus (RV) vaccines. Five of the ferrets (group 1) were inoculated 3 times at 2-week intervals with a multivalent modified-live virus vaccine of canine cell-line origin, containing CDV and an inactivated RV vaccine. Four of the ferrets (group 2) were inoculated once with the multivalent modified-live virus vaccine containing CDV and were not inoculated with the RV vaccine. Both group-1 and group-2 ferrets seroconverted to the CDV component of the vaccine. Group-1 ferrets also seroconverted after RV vaccination and maintained serum antibody titers to both CDV and RV for at least 7 months. Domestic ferret sera were found to have IgG epitopes similar to sera of domestic dogs and cats. Domestic ferret sera did not contain antibodies to feline coronavirus or FeLV antigens.     

Effects of vaccination against 18 immunogens in beef replacement heifers at weaning.

Humoral immune responses to vaccination, mean daily body-weight gains, morbidity, and mortality were compared in groups of beef replacement heifers from weaning to 4 months after weaning. The only difference in management among groups of heifers was the number and type of vaccines they received. Heifers were vaccinated at weaning (mean age, 205 days) and again 28 days later against 0, 1, 9, 10, 17, or 18 antigens, using commercially available monovalent and multivalent vaccines. The common vaccine component in all treatment groups was a modified-live bovine respiratory syncytial virus. Mean daily gain, morbidity, mortality, and serum neutralization antibody titers to bovine respiratory syncytial virus did not differ among treatment groups. Although the study revealed the safety of vaccinating beef heifers against 18 antigens at weaning, our data emphasized the need for serial vaccination to induce a measurable serum antibody response.     

Immunopotentiation of cattle vaccinated with a soluble Brucella abortus antigen with low LPS content: an analysis of cellular and humoral immune responses.

The adjuvant effects of dimethyl dioctadecyl ammonium bromide (DDA) alone or in combination with trehalose dimycolate (TDM) or muramyl dipeptide (MDP) on bovine humoral and cellular responses to a soluble protein extract of gamma irradiated Brucella abortus strain 19 (SPEBA) were investigated. Thirty-five beef steers were randomly allotted to nine groups. Three of these groups received SPEBA (2 mg protein per dose) subcutaneously in combination with adjuvants, one group received the reduced dose of B. abortus strain 19 (S19), and one group received SPEBA alone. Controls included groups receiving adjuvant preparations only or no vaccine. Immune responses to the various immunizations were assessed sequentially for 56 days using various in vitro and in vivo assays. The humoral response to B. abortus was measured using standard serologic tests, an enzyme-linked immunosorbent assay, and a quantitative fluorometric immunoassay. The cell-mediated immune (CMI) response was measured by antigen-specific lymphoproliferation (LP), interleukin 2 (IL 2) production, and soluble suppressor factor release. Skin testing at day 35 for delayed-type hypersensitivity (DTH) to SPEBA was also performed. Minimal humoral responses were induced with SPEBA alone. The highest and most sustained serum antibody responses to B. abortus antigens were elicited by the S19 vaccine. A combination of SPEBA with DDA + TDM induced higher antibody levels than SPEBA with DDA or SPEBA with DDA + MDP. Responses to DTH among the groups receiving SPEBA were most notable in the SPEBA with DDA + TDM groups. Increased IL 2 production was greatest in the S19 and SPEBA with DDA + TDM vaccinates. The results indicated that a combination of DDA + TDM best potentiated immune responses to a soluble B. abortus antigen preparation and may be useful as adjuvants for future vaccines.     

Influence of dietary protein on parasite establishment and pathogenesis in Finn Dorset and Scottish Blackface lambs given a single moderate infection of Haemonchus contortus

An experiment was conducted to examine the influence of dietary protein on parasite establishment and pathogenesis of Haemonchus contortus in lambs of two breeds. Finn Dorset and Scottish Blackface. The lambs were introduced to high protein (170 g crude protein (CP) kg-1 dry matter (DM) or low protein (88 g CP kg-1 DM) diets at three months old and infected one month later with 125 larvae (kg bodyweight)-1. Blood and faecal samples were collected for analysis and bodyweights recorded weekly. The lambs were killed 20 weeks after infection. A second experiment was conducted in Blackface lambs solely to determine the influence on parasite establishment of the high and low protein diets following infection with 125 larvae kg-1. These lambs were killed five or 14 weeks after infection. Results showed that in Scottish Blackface lambs dietary protein did not significantly influence the establishment of H contortus. However, in Finn Dorset lambs dietary protein may have influenced parasite establishment since lambs on the low protein diet had a higher faecal egg output four weeks after infection and more severe clinical signs than infected lambs of the same breed on a high protein diet.