Effect of muramyl dipeptide on immunogenicity of Corynebacterium pseudotuberculosis whole-cell vaccines in mice and lambs

Colostrum-deprived lambs and CF1 mice were vaccinated with water-in-oil emulsion vaccines containing nonviable whole cells (WC) of Corynebacterium pseudotuberculosis with and without muramyl dipeptide (MDP). Efficacy of vaccines was determined from the survival of mice and lesions in lambs after IV injection of 10(4) colony-forming units of C pseudotuberculosis. In mice, protection was related to the concentration of WC in the vaccine. At 50, 100, or 150 micrograms of WC, protection was good (78.8%). At 10 or 25 micrograms of WC, protection was considerably less (54.7%). At high WC concentrations, protection could only be moderately increased to 82.3% with high (50 and 100 micrograms) concentrations of MDP or increased to 90% protection with low (5 and 10 micrograms) concentrations of MDP. At low WC concentrations, protection significantly decreased to 32% (P less than 0.025) with high concentrations of MDP, but significantly increased to 72.5% (P less than 0.025) with low concentrations of MDP. Therefore, the amount of protection with lower concentrations of WC and MDP was comparable with the amount of protection with higher concentrations of WC without MDP. In lambs, high prechallenge antibody titers (geometric mean titers from 5.1 to 5.4 by day 35) were observed after vaccination with WC. Protection and vaccination site abscesses in lambs were related to the concentration of WC and MDP. Pulmonary or vaccination site abscesses were not observed in 4 of 4 lambs vaccinated with 1 mg of WC + 50 micrograms of MDP.     

Comparison of protection induced in lambs by Corynebacterium pseudotuberculosis whole cell and cell wall vaccines

Colostrum-deprived lambs were vaccinated IM with 10 mg (dry weight) of Corynebacterium pseudotuberculosis whole cells (WC) or cell walls (CW) and their immunity was challenged by IV injection of 3.1 X 10(4) colony-forming units of C pseudotuberculosis. Before challenge exposure, the logarithmic mean antibody titers were 2.0837 in lambs that were vaccinated with WC, 2.6858 in lambs that were vaccinated with CW, and 1.4214 in control lambs. Significant protection was demonstrated by fewer abscesses and organisms in the lungs of lambs vaccinated with WC or CW (P less than 0.05) than in control lambs. By the same criteria, more protection was provided to lambs vaccinated with CW than to lambs vaccinated with WC.     

The effect of antibody to caseous lymphadenitis in ewes on the efficacy of vaccination in lambs

The effect of maternal antibody to the toxin of Corynebacterium pseudotuberculosis, produced by caseous lymphadenitis (CLA) in ewes or by vaccinating ewes before lambing, on the efficacy of vaccination against CLA in their lambs was examined. Lambs were allocated to treatments according to either the vaccination history of their dam or level of CLA toxin antibody of their dam. They were vaccinated twice using 2 different inoculation regimes and then artificially infected with CLA organisms. The number of lambs with CLA lesions was assessed at slaughter. In one experiment high levels of CLA toxin antibody activity in ewes were associated with decreased efficacy of CLA vaccination in their lambs, when lambs were vaccinated at 2 and 8 weeks or 8 and 14 weeks of age. In a second experiment the efficacy of lamb vaccination at 8 and 12 weeks, but not at 14 and 18 weeks of age, was decreased. In sheep flocks with a high prevalence of CLA, vaccinating lambs against CLA at less than 10 weeks of age may not produce optimum protection against CLA in lambs. There was no difference in infection rate between lambs from vaccinated and unvaccinated ewes. However, vaccination of lambs at 2 and 8 wks was less effective that vaccination at 8 and 14 weeks, probably due to reduced immunocompetence in young lambs. In sheep flocks where significant numbers of lambs receive their primary vaccination at less than 3 weeks of age vaccination programmes to control CLA in lambs may be less effective.     

Efficacy of a flock-specific pseudotuberculosis vaccine in goats

In a flock with 33 adult goats repeated abscesses due to Pseudotuberculosis occurred. For the owners refused a sanitation program based on testing and removing, the goats were vaccinated with a flock specific, whole-cells lysate vaccine of Corynebacterium pseudotuberculosis. Partly simultaneously or 14 days later vaccinations against Clostridiosis (Covexin8) and against Erysipelas (Erysorb plus) were performed at different application sites. After a twofold basal vaccination in a 4 week interval the goats were revaccinated in half year intervals. The local (swelling at the injection site) and systemic reactions (temperature elevation, antibody activity) after vaccination and the clinical status of the flock (core body temperature, adspection, abscesses, lymph nodes) were investigated over a period of two years. Due to the vaccination program the rate of new cases of clinical pseudotuberculosis were reduced significantly. In the last 3 months of the investigation no clinical cases occurred. The vaccination with the C. pseudotuberculosis-vaccine induced a significant increase in antibody activities detected by ELISA. Due to interaction of maternal antibodies with the antigen of the vaccine lambs should be vaccinated at the earliest at an age of 9 weeks. Vaccinating the C. pseudotuberculosis-vaccine separately in time to Covexin8 and Erysorb plus induced with increasing numbers of revaccinations higher antibody activities against C. pseudotuberculosis than simultaneous vaccinations with all the 3 vaccines. But this difference does not justify the additional expense of separate vaccinations in time. Despite considerable local and systemic reaction the C. pseudotuberculosis-vaccine is recommended to support sanitation programs.     

Efficacy of Corynebacterium pseudotuberculosis bacterin for the immunologic protection of sheep against development of caseous lymphadenitis

The efficacy of a Corynebacterium pseudotuberculosis bacterin to protect sheep immunologically against development of caseous lymphadenitis was evaluated in controlled challenge-exposure experiments. Sixty-three mixed-breed, white-faced lambs were used. The lambs were 10 to 12 weeks old and were randomly assigned to 3 groups (21 lambs/group). Group 1 was vaccinated once, using 2 ml of a C pseudotuberculosis bacterin (given subcutaneously) in the right axillary region at the beginning of the study. Group 2 was vaccinated twice; the 1st vaccination was given at the same time that lambs in group 1 were vaccinated and the 2nd vaccination was given 4 weeks later. Group 3 (nonvaccinated controls) was given physiologic saline solution (2 ml, subcutaneously). Each lamb was challenge exposed (ie, given 2 ml of live Corynebacterium pseudotuberculosis inoculum [6 X 10(6) colony-forming units/ml], subcutaneously at 4 different sites) during the 20th week of the study. All lambs were killed and necropsied during week 33. The mean number of abscesses per lamb was 7 for group 1, 4 for group 2, and 32 for group 3. Significant differences in the size of the abscesses were not found between the groups. Results of the study indicated that the vaccine provided immunologic protection of lambs against challenge exposure to Corynebacterium pseudotuberculosis.     

A field trial to evaluate a whole cell vaccine for the prevention of caseous lymphadenitis in sheep and goat flocks.

A field trial to evaluate a whole cell vaccine for the prevention of caseous lymphadenitis (CLA) in sheep and goats was performed in one goat herd and one sheep flock over a period of three years. In goats, there was a nonstatistically significant trend for fewer cases of CLA in the vaccinated animals compared to the controls. In sheep, from six months to 36 months postinitial vaccination, the proportion of vaccinated sheep that developed CLA was significantly less (p less than 0.05) than in the control sheep. The antibody titers to Corynebacterium pseudotuberculosis as detected by microagglutination assay were significantly different (p less than 0.0001) at all times except at the initial vaccination. Swellings occurred at the vaccination site at an incidence level of 29.6% in goats and 34.1% in sheep. The vaccine appeared to be efficacious in reducing the proportion of sheep that developed CLA when challenged naturally in a field situation.     

Use of a toxoid vaccine to protect goats against intradermal challenge exposure to Corynebacterium pseudotuberculosis

Two groups of male, 9-week-old goats (5 goats/group) were vaccinated subcutaneously with formalized exotoxin of Corynebacterium pseudotuberculosis, with Freund's incomplete adjuvant. Each goat was given 2 vaccinations, 2 weeks apart. At each vaccination, each group 1 goat was given 0.5 ml of toxoid, and each group 2 goat was given 1 ml of toxoid. Twenty days after the 2nd vaccination, vaccinated goats and 5 nonvaccinated 12-week-old goats (controls) were inoculated intradermally (challenge exposed) with live C pseudotuberculosis, monitored for 13 weeks, and euthanatized. At necropsy, 5 of the 10 vaccinated goats did not have C pseudotuberculosis lesions, 3 had abscesses limited to the inoculation site and draining lymph node, and 2 had disseminated bacterial lesions. Of the 5 nonvaccinated controls, 4 had disseminated abscesses and 1 had a single abscess in an internal node. Serologically, 9 of the 10 vaccinated goats developed positive (greater than or equal to 1:8) antibody titers against the exotoxin within 1 week after inoculation; the 10th goat seroconverted 2 weeks after inoculation, whereas control goats required 3 weeks to develop a positive antibody response. Therefore, early during an infection with C pseudotuberculosis, antibodies against the exotoxin may protect a goat against spread of the organism. All goats were injected intradermally before challenge exposure, 10 days after challenge exposure, and at 4, 8, and 12 weeks after challenge exposure with a skin-test reagent composed of fragmented bacterial cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of Corynebacterium pseudotuberculosis lung lesions in the transmission of this bacterium to other sheep

SUMMARY: :Five groups of 5 shorn and 5 unshorn caseous lymphadenitis (CLA)-free Merino wether weaners were each placed in feedlot pens with 6 Merino ewes, 2 or more of which had CLA lung lesions but no discharging superficial lesions. The sheep were kept together for 5 months.
Twenty-eight per cent of the shorn weaners and 20% of the unshorn weaners developed antibodies to Corynebacterium pseudotuberculosis. At slaughter, 8% of the shorn weaners and 12% of the unshorn weaners had CLA lesions in either lungs, lymph nodes or both. In the absence of contact with CLA-infected ewes, a control group of 5 shorn and 5 unshorn weaners failed to develop antibodies to C. pseudotuberculosis or CLA lesions in the same period. This showed that sheep with CLA abscesses in the lungs but no discharging superficial abscesses were a source of C. pseudotuberculosis infection to other sheep. Aust Vet J. 64: 261–263     

Differences between breeds of sheep in their responses to Bacteroides nodosus vaccines

In a field experiment on irrigated pasture, sheep of several breeds were vaccinated twice, subcutaneously, in the upper neck, with Bacteroides nodosus vaccine containing either depiliated cells (DC vaccine), or whole, piliated cells (WC vaccine) and the responses were measured over the following 14 weeks. DC vaccine was as effective as WC vaccine in protecting against the development of foot-rot under conditions of moderate challenge, although the WC vaccine induced significantly higher pilus agglutinating antibody titres. Foot-rot developed in significantly more vaccinated Merinos (Peppin and Saxon strains) than in Romney Marsh, Dorset Horn or Border Leicester breeds. Agglutinating antibody titres after WC vaccination were significantly lower in the Peppin Merino than in the other sheep for the first 6 weeks, while after DC vaccination the titres remained elevated longer in the Border Leicester and Saxon Merino and were significantly higher from 6 weeks onwards. Reactions at the inoculation sites were generally larger in the British breeds than in the Merinos and among the former the reactions were largest, most numerous and most frequently discharged their contents in the Dorset Horn. Bodyweight gains in all vaccinated sheep were initially reduced, compared with controls, but the differences were no longer significant after the eighth week.     

The spread of Corynebacterium pseudotuberculosis infection to unvaccinated and vaccinated sheep

SUMMARY The decrease in the prevalence of Corynebacterium pseudotuberculosis after two generations of vaccination against the disease it causes, was used to estimate the rate of control of caseous lymphadenitis (CLA). Three groups of 150 sheep, of which 50 in each group were artificially infected with C pseudotuberculosis and 100 in each group were uninfected sheep, were run separately for 40 months and shorn 5 times to promote the spread of CLA. One lot of 50 infected sheep and 2 lots of 100 uninfected sheep were vaccinated against CLA. The rate of spread of CLA was recorded. Sheep vaccinated against CLA and naturally exposed to infection had a 74% lower infection rate than unvaccinated sheep. Sheep vaccinated against CLA and exposed to only vaccinated infected sheep had a 97% lower infection rate. Unvaccinated sheep had a 76% infection rate, with 77% of the transmission occurring at the 4th and 5th shearings, without any discharging CLA abscesses being observed. This study supports the view that in Australian wool producing flocks, CLA spreads mainly from sheep with discharging lung abscesses to sheep with shearing cuts. Vaccinated sheep infected with CLA have 96% fewer lung abscesses compared with unvaccinated infected sheep and are therefore less likely to spread this disease to other sheep .     

Experimental Corynebacterium pseudotuberculosis infection in lambs

Lambs were inoculated IV with 3.2 X 10(3) colony forming units (CFU) to 3.2 X 10(6) CFU of Corynebacterium pseudotuberculosis from a 6-hour broth culture supplemented with 0.1% sorbitan monooleate. After 28 days, multiple abscesses were observed in the lungs and lymph nodes. The number of abscesses in the lungs correlated with the inoculation dose. Two lambs given 10(5) CFU and 10(6) CFU died. Multiple abscesses occurred in other lambs given 10(6) CFU to 10(4) CFU and few abscesses occurred in lambs given 10(3) CFU. Corynebacterium pseudotuberculosis was isolated from lung abscesses, inoculation site abscesses, and lymph node abscesses, but not from normal tissues. Because this procedure consistently induced abscesses in the lungs, we believe it will be a suitable challenge system for studies on the prevention of caseous lymphadenitis in sheep.     

Effect of passively-acquired antibodies and vaccination on the immune response to contagious ecthyma virus

Lambs which received colostrum from ewes vaccinated with contagious ecthyma (CE) virus and other lambs vaccinated with CE virus were compared for serum anti-CE immunoglobulin (Ig)G levels, delayed-type hypersensitivity (DTH) responses to CE viral antigen, and protective immunity to challenge with CE virus. Ewes vaccinated 3-4 weeks prior to parturition transferred CE antibody to lambs via colostrum. Although these lambs had higher levels of antibody at challenge than lambs vaccinated when 1-4 days old, only the vaccinated lambs were protected against challenge with CE virus at 1 month of age. Furthermore, the presence of colostrum-derived maternal antibody prevented an active antibody response in lambs to vaccination and/or challenge with CE virus, except where pre-inoculation titres were low. In contrast, the DTH response to CE viral antigen and induction of protective immunity by CE vaccination were not impaired by passively-acquired antibody. Actively immunised lambs could be distinguished from those only receiving passively-acquired antibody by the DTH response to heat-killed CE viral antigen.     

Protection in alpacas against Corynebacterium pseudotuberculosis using different bacterial components

Corynebacterium pseudotuberculosis is a Gram positive bacterium that produces caseous lymphadenitis in sheep and goats, and a granulomatous lymphadenitis in llamas and alpacas. To evaluate the immune potential of different doses of cell wall and toxin components of C. pseudotuberculosis from alpaca origin, 12 adult alpacas were allotted at random to four groups, and SC inoculated in the left flank with vaccines composed of low and high doses of bacterial crude antigens, cell wall: 250 and 500 microg/ml and toxin: 133 and 265 microg/ml, respectively. The vaccines were supplemented with 20 microg/ml of muramyl dipeptide as adjuvant. Three alpacas were sham inoculated with adjuvant as a control. After 3 weeks, immunized and naive alpacas were challenged intradermally in the right flank with 1 x 10(6) colony forming units (CFU) of C. pseudotuberculosis. The alpacas were sacrificed at days 28, 58 and 112 after inoculation, and the degree of protection induced by vaccines was demonstrated by the absence of abscesses and/or bacteria. The alpacas vaccinated with high dose of toxin, did not show abscesses. In contrast, the alpacas vaccinated with a low dose of toxin showed abscesses at the inoculation site, regional, and renal lymph nodes. The cell wall vaccinated alpacas showed a lesser degree of protection than the other groups with superficial and internal abscesses. The control alpacas had persistent fever and abscesses at the inoculation site, regional, and internal lymph nodes. In addition, a robust and early humoral response was observed in all vaccinated alpacas after challenge, lasting at least 3 months. The results suggest that the toxin of C. pseudotuberculosis is a very important antigen, inducing a dose dependant protective immunity against this bacterium in alpacas.     

Corynebacterium pseudotuberculosis infection in goats. VIII. The effect of vaccination against experimental infection

The effect of an inactivated vaccine against C. pseudotuberculosis infection was tested on castrated male kids from a herd free from caseous lymphadenitis. The animals were divided into 3 groups with 8 animals in each. Group 1 was immunized with crude filtrated C. pseudotuberculosis toxoid and whole killed organisms, while Group 2 in addition was given levamisole. The kids were vaccinated twice at an interval of 4 weeks. Group 3 consisted of unvaccinated animals. All groups were challenged subcutaneously with live bacteria 4 weeks after the last vaccination. Unvaccinated animals showed the most severe course of illness after challenge. Development of abscesses in the regional lymph nodes (Inn. subiliaci) was significantly more common in unvaccinated than in vaccinated kids at necropsy 2 months after challenge. There was, however, no such difference between the vaccinated groups, and there was no difference between any of the groups as regards abscess formation at the inoculation site. In each of the 2 vaccinated groups, there was a titre rise following vaccination in the hemolysis inhibition test, whereas no such rise was seen in the bacterial agglutination test. The titre values in both tests increased significantly after challenge in all the groups, the increase being most rapid in the vaccinated animals. The present investigation indicates that development of caseous lesions in lymph nodes in goats, following subcutaneous inoculation with C. pseudotuberculosis, can be reduced by an inactivated vaccine containing whole organisms and crude toxin.     

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.     

Lesions in sheep following administration of a vaccine of a Freund's complete adjuvant nature used in the control of ovine paratuberculosis

CASE HISTORIES: Occurrences of adverse reactions in seven sheep flocks in Australia following vaccination against paratuberculosis where veterinary attention was requested are reviewed. All cases occurred within the 3-year period following commencement of use of a vaccine of a Freund's complete adjuvant nature, at a time when approximately six million doses of vaccine had been administered.

CLINICAL FINDINGS: In the first case, 26/58 (45%) Merino sheep vaccinated as adults had palpable tissue reactions at or near the site of vaccination; enlarged prescapular lymph nodes were palpated in 17 (29%), and nine (16%) sheep had both palpable lesions at the site of vaccination and enlarged prescapular lymph nodes. The reactions included caseous nodules up to 5.5 cm in diameter. In the other cases, fistulating or granulomatous wounds were occasionally found at the recommended site of injection behind the ear, and myiasis was rare. Occurrences of inappropriate choice of injection site were recorded, including injection into the axilla of two Merino rams, and lesions in the tissues of the maxilla and nose of almost 50% of 350 Border Leicester lambs. Four outbreaks of progressive paralysis due to injection into cervical musculature were reported, described as ‘OJD staggers’ by producers.

DIAGNOSIS: Granulomatous cellulitis and lymphadenitis associated with oil droplets typical of ‘oil granulomata’. Injection of vaccine into the dorsal cervical area resulted in progressive paralysis due to myonecrosis and suspected granulomatous leptomeningitis.

CLINICAL RELEVANCE AND CONCLUSIONS: Although lesions at and near the site of injection are common, adverse reactions to vaccination were rare and included mortality from cervical spinal injection, production losses from injection in the maxilla or axilla or if myiasis resulted, and potential marketing losses if animals or carcasses are discounted as a result of the lesions. Risk factors for adverse reactions included inadequate restraint of sheep, breed of sheep, experience of the operator, poor injection technique, and inappropriate placement of vaccine. Increasing attention to the proper restraint of animals, restricting vaccination to the recommended site behind the ear, careful placement of the vaccine into subcutaneous tissue to avoid drainage of vaccine material into tissues such as the spinal cord, and post-vaccination supervision to address welfare concerns should adverse reactions occur are recommended.     

Lesions in sheep following administration of a vaccine of a Freund's complete adjuvant nature used in the control of ovine paratuberculosis

CASE HISTORIES: Occurrences of adverse reactions in seven sheep flocks in Australia following vaccination against paratuberculosis where veterinary attention was requested are reviewed. All cases occurred within the 3-year period following commencement of use of a vaccine of a Freund's complete adjuvant nature, at a time when approximately six million doses of vaccine had been administered. CLINICAL FINDINGS: In the first case, 26/58 (45%) Merino sheep vaccinated as adults had palpable tissue reactions at or near the site of vaccination; enlarged prescapular lymph nodes were palpated in 17 (29%), and nine (16%) sheep had both palpable lesions at the site of vaccination and enlarged prescapular lymph nodes. The reactions included caseous nodules up to 5.5 cm in diameter. In the other cases, fistulating or granulomatous wounds were occasionally found at the recommended site of injection behind the ear, and myiasis was rare. Occurrences of inappropriate choice of injection site were recorded, including injection into the axilla of two Merino rams, and lesions in the tissues of the maxilla and nose of almost 50% of 350 Border Leicester lambs. Four outbreaks of progressive paralysis due to injection into cervical musculature were reported, described as "OJD staggers" by producers. DIAGNOSIS: Granulomatous cellulitis and lymphadenitis associated with oil droplets typical of "oil granulomata". Injection of vaccine into the dorsal cervical area resulted in progressive paralysis due to myonecrosis and suspected granulomatous leptomeningitis. CLINICAL RELEVANCE AND CONCLUSIONS: Although lesions at and near the site of injection are common, adverse reactions to vaccination were rare and included mortality from cervical spinal injection, production losses from injection in the maxilla or axilla or if myiasis resulted, and potential marketing losses if animals or carcasses are discounted as a result of the lesions. Risk factors for adverse reactions included inadequate restraint of sheep, breed of sheep, experience of the operator, poor injection technique, and inappropriate placement of vaccine. Increasing attention to the proper restraint of animals, restricting vaccination to the recommended site behind the ear, careful placement of the vaccine into subcutaneous tissue to avoid drainage of vaccine material into tissues such as the spinal cord, and post-vaccination supervision to address welfare concerns should adverse reactions occur are recommended.     

Effects of porcine zona pellucida immunocontraceptives in zoo felids.

Methods of contraception are necessary for management of zoo felids; however, the most commonly used contraceptive (melengestrol acetate implant) is associated with serious adverse reactions with long-term use. Porcine zona pellucida (pZP) vaccines are promising as contraceptives, but their safety in zoo felids has not been tested. pZP vaccine was administered to 27 female felids representing 10 species, including African lion (Panthera leo), Asian leopard (P. pardus), jaguar (P. onca), tiger (P. tigris), snow leopard (P. uncia), cougar (Felis concolor), Siberian lynx (F. lynx), Canada lynx (F. canadensis), serval (F. serval), and bobcat (F. rufus), in 15 facilities. Over 6 wk, each animal received three i.m. injections of 65 microg pZP with Freund's complete adjuvant (FCA), Freund's incomplete adjuvant, or carbopol as the adjuvant. Behavioral signs of estrus were seen in 14 of the vaccinated felids. An unacceptably high incidence of adverse reactions was seen including injection site swelling, lameness, limb swelling, or abscessation (or all) in five felids after injection with FCA as the initial adjuvant. Adverse behavioral signs, including increased irritability and aggression, were seen in four felids. Six of the felids were assayed for antibodies against pZP during the 12 mo after vaccination; all showed antibody production. Antibody levels appeared to peak 1-4 mo after vaccination began, although elevated antibody levels persisted in two animals for > 12 mo after the first injection. All vaccinated felids were ovariohysterectomized 3-13 mo after vaccination. Folliculogenesis was present in all treated animals, and there was no histopathologic evidence of inflammatory damage to ovaries. Contraceptive efficacy was not specifically evaluated in this study; however, two of the three felids housed with an intact male became pregnant during the study, one of which gave birth to healthy cubs.     

Cross-protection from Bacteroides nodosus vaccines and the interaction of pili and adjuvants

The effects of vaccination of Merino sheep with the purified pili or the whole cells of Bacteroides nodosus strain 198, either in oil or alum-oil adjuvant, on the severity of foot-rot induced with the homologous strain (198) and a heterologous strain (217) were determined in a field experiment, on flood irrigated pasture. The efficacy of the whole cell vaccines was comparable to that of purified pili vaccines, against homologous challenge, when both had a similar content of pilus antigen although the purified pili vaccines induced significantly greater homologous pilus agglutinating antibody titres than the whole cell vaccines. However, against heterologous challenge, the whole cell vaccines in oil (CO) or alum-oil (CAO) provided significantly greater protection than a purified pili-in-oil (PPO) vaccine, the number of severely affected feet in sheep vaccinated with PPO being similar to that of the unvaccinated group. The group vaccinated with purified pili in alum-oil (PPAO) was intermediate between these two extremes. The superior performance of the PPAO in comparison to the PPO vaccine, against heterologous challenge, was associated with significantly higher mean ELISA titres to the outer membrane complex. Western blot analyses implicated a role in cross-protection for outer membrane proteins, in particular a protein Mr 78,000. The PPO vaccine produced fewer, smaller and less persistent vaccination reactions at the inoculation sites than did the other vaccines. Bodyweight gains in the period prior to challenge were much lower for the groups vaccinated with CO and CAO than for the controls and those vaccinated with purified pili, due presumably to the larger vaccination reactions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Responses of female lambs to Rev-1 (brucellosis) vaccination

In order to investigate Rev-1 vaccination immunogenicity, 60 indigenous (Makuii) non-infected female lambs 3–4 months of age in northwestern Iran were systematically divided into two groups: 40 into a treatment (T) group and 20 into a control (C) group. Lambs in Group T received 1 ml of Rev-1 vaccine by s.c. injection and blood samples were collected from both groups at 15 days and 2, 4, 6, 8, 10, 12 and 14 months after vaccination. The seroagglutination test (SAT) and the 2-mercaptoethanol test (2-MET) were carried out on the sera. Control lambs were negative in all the examinations. The results of the SAT showed that the mean( ± SD) antibody titre of lambs in Group T was maximum (725 ± 112 IUml⁻¹) at Day 15, then declined gradually until the fourth month and was in the normal range (31 IU ml⁻¹) thereafter. The results of the 2-MET were negative in Group C but in Group T the antibody titre was at a maximum level (161.7 ± 46.6 IUml⁻¹) at Day 15, decreased to 1.2 ± 2.5IUml⁻¹ at 4 months post-vaccination and was negativ; thereafter. In the second part of the trial, 20 vaccinated and ten control lambs received 0.25 ml melitin by i.d. injection 10.5 months after vaccination. The control group showed no reaction but 13 (65%) of the vaccinated lambs showed an oedematous swelling at the site of injection within 48 h, which indicated that the delayed-type hypersensitivity test (DTHT) could be useful in the diagnosis of Brucella infection in lambs. In the third stage of the experiment, four vaccinated and three control lambs were injected with Brucella melitensis strain 16M at a rate of more than 123 × 10⁶ bacteria per lamb 14 months after vaccination. Rectal temperature (Tem), heart-rate (HR) and respiration rate (RR) were measured three times a day (at 08:00, 14:00 and 21:00 h) 3 days before until 9 days after injection. SAT was carried out on the day before injection and at the time of slaughter. The mean Tem, HR and RR did not significantly change but the mean( ± SD) SAT titre in the T lambs 9 days after injection was 47.5 ± 9.9 IU ml⁻¹ (vs. 8.66 ±6.1 IU ml⁻¹ in the control lambs) (P < 0.01). All lambs were slaughtered on the ninth day. Fewer bacterial cultures of samples taken from the uterus, spleen, liver and lymph nodes were positive in T lambs compared with the controls. The lower proportion of Brucella-positive lambs in the vaccinated group compared with the control group indicates that vaccination with Rev-1 improved the resistance of lambs to the experimental infection.