Vaccination experiments on pregnant mice with E. coli vaccines prepared from septicaemic and enteropathogenic strains of E. coli

Experiments have been carried out with vaccination of pregnant mice against E. coli, followed by i.p. challenge of the offspring at one week of age.With a septicaemic strain the results were highly significant, and the method is therefore recommendable for testing of vaccines against such strains of E. coli.Results were less clear-cut with enteropathogenic strains of E. coli. However, with mortality rates of 40 to 45 % in baby mice born by non-vaccinated mothers and less than 15 % in baby mice born by vaccinated mothers, the difference in percentage mortality seems sufficient to warrant the use of the method also in the control of vaccines against enteropathogenic E. coli strains.     

Antibody response to Mycoplasma hyopneumoniae infection in vaccinated pigs with or without maternal antibodies induced by sow vaccination

Vaccination with bacterins is an important tool for the control of Mycoplasma hyopneumoniae infection of pigs. Because such vaccination often involves piglets that have suckled M. hyopneumoniae antibody-positive dams it is important to understand the effect of pre-existing (passively acquired) antibody on vaccine-induced immunity. To investigate this issue experimentally, 20 sows that were seronegative for M. hyopneumoniae were selected from a M. hyopneumoniae-infected herd and then randomly allocated to one of four treatment groups (five sows/group): Group A, vaccinated sows/vaccinated piglets; Group B, vaccinated sows/non-vaccinated piglets; Group C, non-vaccinated sows/vaccinated piglets; Group D, non-vaccinated sows/non-vaccinated piglets. Sows (Groups A and B) were vaccinated 14 days before farrowing and seroconverted within the next 14 days. Conversely, none of the non-vaccinated sows was seropositive at farrowing. Piglets (Groups A and C) were vaccinated when they were 7 days of age. Regardless of treatments none of the piglets had any evidence of an active immune response until many of those of Groups A and C and a few of those of Groups B and D seroconverted after it had been shown that at least some pigs of all groups had been naturally infected with a field strain of M. hyopneumoniae. This pattern of immune responsiveness (i.e. the collective results of Groups A, B, C and D) suggested that vaccination of pigs had primed their immune system for subsequent exposure to M. hyopneumoniae, and that passively acquired antibody had little or no effect on either a vaccine-induced priming or a subsequent anamnestic response. According to the statistical analysis sow serological status did not interfere with the antibody response in early vaccinated piglets. In conclusion, the results pointed out that early vaccination of piglets may assist M. hyopneumoniae control independently from the serological status of sows.     

Susceptibility to Tropical Theileriosis of Calves Born to Dams Immunized with Theileria annulata (Hisar) Cell Culture Vaccine

The susceptibility/immune status to tropical theileriosis of calves born of immunized dams was evaluated. Six cows were vaccinated with the Theileria annulata cell culture vaccine in the eighth month of pregnancy. Sera from the immunized dams exhibited very high post-vaccination antibody titres as determined by the indirect fluorescent antibody (IFA) test. The calves born to these dams did not show antibodies against T. annulata at the time of birth (IFA titres of <1:20). The new-born calves were fed colostrum from their mothers and were challenged with T. annulata-infected ground tick supernate at 5–7 days of age. All the calves developed fever (from day 5–6 onwards) and parasitological reactions (from day 8–9 onwards) after challenge. There was a significant decrease in the haemoglobin and packed cell volume of the calves after challenge. All the calves showed signs of acute theileriosis by day 9–10 after challenge and had to be treated with buparvaquone in order to save their lives. The study indicated that detectable levels of anti-theilerial antibodies were not transferred from immune dams to their offspring. All the calves born to immunized dams were fully susceptible to theileriosis and thus themselves needed vaccination.     

Cell-mediated immune responses to a killed Salmonella enteritidis vaccine: lymphocyte proliferation, T-cell changes and interleukin-6 (IL-6), IL-1, IL-2, and IFN-gamma production

Two experimental approaches were used to investigate the immunological responses of chickens to a commercial killed Salmonella enteritidis (SE) vaccine. In the first, the effects of host age on antigen-specific proliferative responses and cytokine production were examined. Compared with non-vaccinated controls, 4-wk-old vaccinated chickens showed higher proliferation to SE LPS and flagella. The lymphoproliferation responses to these antigens of 8-mo-old vaccinated chickens were not different compared to the non-vaccinated controls. Increased production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) by antigen-stimulated splenocytes following vaccination were, in general, more often observed in 4-wk-old compared with 8-mo-old chickens, whereas serum levels of these cytokines were consistently higher in the vaccinated birds compared with controls regardless of age. The second set of experiments were designed to determine the effects of SE vaccination on mitogen- or antigen-induced splenocyte proliferation and serum nitric oxide (NO) and cytokine levels. Splenocytes from vaccinated chickens stimulated with SE flagella showed significantly increased numbers of TCRgammadelta+ cells at 7 days post-vaccination compared with non-vaccinated birds. In contrast, no differences were noted with CD4+, CD8+, or TCRalphabeta+ cells at any time points examined. Higher levels of NO production were observed following stimulation with SE flagella at 4, 7, 11, and 14 days after SE vaccination while serum levels of IFN-gamma, IL-1, IL-6, and IL-8 were elevated only at day 7 post-vaccination. In conclusion, younger chickens mounted a more robust antigen-specific immune response to the SE vaccine compared with older birds and vaccination induced not only T-cell-mediated responses but also host innate and pro-inflammatory responses.     

Effect of maternal immunity on the immune response to oral vaccination against rabies in young foxes.

OBJECTIVE: To determine effect of maternal antibodies on immune response to oral vaccination against rabies in young foxes. ANIMALS: 250 cubs from 48 vixens. PROCEDURE: Sera were obtained from cubs of 36 vaccinated (maternally vaccinated [MV+]) and 12 nonvaccinated (MV-) vixens between 23 and 71 days of age and tested for neutralizing antibodies. Seventy-one MV+ cubs and 33 MV-cubs were vaccinated orally with modified-live virus vaccine SAD B19. Geometric mean titer (GMT) was determined in these cubs approximately 21, 39, and 57 days after vaccination. In a subsequent experiment, 10 vaccinated MV+ cubs, 6 vaccinated MV- cubs, and 6 control cubs were challenge inoculated with virulent rabies virus approximately 100 days after vaccination. RESULTS: Serum GMT of nonvaccinated MV cubs (0.23 U/ml) was significantly greater than that of non-vaccinated MV- cubs (0.15 U/ml). The GMT of vaccinated MV+ cubs 21, 39, and 57 days after vaccination were 2.85, 2.11, and 0.79 U/ml, respectively, and were significantly less than those of vaccinated MV- cubs (12.19, 6.76, and 4.02 U/ml, respectively). All challenge-inoculated cubs with GMT < 0.5 U/ml succumbed to rabies. CONCLUSION AND CLINICAL RELEVANCE: Partially impaired immune response in cubs < 8 weeks old from vaccinated vixens causes insufficient protection against rabies. Inhibition of the immune response persists longer than the period during which maternal antibodies are detectable. Thus, oral vaccination campaigns for young foxes in areas where vaccination has been performed need to be reconsidered.     

Influence of parental serum immunoglobulins on morbidity and mortality of beagles and their offspring

Serum IgA, IgG, and IgM concentrations were determined for Beagle sires and dams of 717 matings to assess the relationship of parental immunoglobulins with the morbidity and mortality of their pups. A significant relationship was not found between parental immunoglobulins and pup mortality. Pups born to dams with low serum IgA (P less than 0.001) and IgM (P less than 0.02) concentrations, however, were found to have an increased incidence of sneezing, coughing, nasal discharge, and conjunctivitis. Thirty-eight percent of pups born to dams with IgA less than or equal to 40 mg/dl developed these same conditions during the first 18 weeks of life, compared with 32% of pups of dams with IgA of 41 to 65 mg/dl and 27% of pups of dams with IgA greater than 65 mg/dl. Similarly, 41% of pups born to dams with low IgM (less than or equal to 135 mg/dl) developed abnormal respiratory tract signs, compared with 34% and 30% of pups born to dams with medium (136 to 175 mg/dl) and high (greater than 175 mg/dl) IgM, respectively. Serum IgA concentrations of the sires were also associated with abnormal respiratory tract signs in pups, but this influence was evident only at 10 to 18 weeks of age. To determine biologic variability of serum IgA, 60 Beagle dams were selected from 3 serum IgA categories, low (10 to 21 mg/dl), medium (60 to 80 mg/dl), and high (125 to 210 mg/dl). A second serum IgA was determined from a sample taken 2 years later.(ABSTRACT TRUNCATED AT 250 WORDS)     

Association of the time that elapsed from last vaccination with protective effectiveness against foot-and-mouth disease in small ruminants

Routine and emergency vaccination of small ruminants against foot-and-mouth disease (FMD) is mandatory in many endemic countries, yet data on the field effectiveness of the vaccines used is scarce. We conducted an investigation of a serotype O FMD outbreak that took place in a sheep and goat pen, and estimated the effectiveness of various routine vaccination statuses. We also evaluated the protection provided by colostrum administration and emergency vaccination. Animals which were routinely vaccinated twice were not clinically affected while disease incidence was observed among animals routinely vaccinated only once (p = 0.004 according to a two-sided Fisher''s exact test). In groups vaccinated only once, there was a significant association between the average time that elapsed since last vaccination and the disease incidence (n = 5; Spearman correlation coefficient: r_s = 1.0, p < 0.01). In addition, non-vaccinated lambs fed colostrum from dams vaccinated more than 2 months before parturition had a mortality rate of 33%. Administration of emergency vaccination 2 days after the occurrence of the index case was the probable reason for the rapid blocking of the FMD spread within 6 days from its onset in the pen.     

The effect of season and vaccination for Glässer's disease and post-weaning Colibacillosis in an outdoor pig unit endemically infected with virulent strain of Haemophilus Parasuis serotype 5 and pathogenic Escherichia coli

The objective of this field trial was to determine if vaccination against Haemophilus parasuis serovar 5 (HPS 5) and pathogenic serotypes of Escherichia coli would improve nursery pig performance in an outdoor unit in different seasons. The unit was concurrently infected with HPS 5 and with different serotypes of E. coli. All piglets were born to HPS 5 vaccinated sows. The trial was carried out in four (two summer and two winter) groups. Group 1 (E. coli and HPS vaccinated, summer season) (n = 362): Piglets were vaccinated pre-weaning with inactivated E. coli-VT2e-toxin and post-weaning against HPS 5. Group 2 (non-vaccinated, summer season) (n = 349): Piglets were not vaccinated. Group 3 (E. coli and HPS vaccinated, winter season) (n = 358): The animals were analogously treated as Group 1. Group 4 (non-vaccinated, winter season) (n = 353): Piglets were not vaccinated. The following parameters were evaluated: A: average daily nursery weight gain (ADG), B: nursery mortality, C: feed efficiency (FE). No significant weight differences were detected within the vaccinated and non-vaccinated summer or winter raised groups of weaners. Summer raised weaners were significantly (P<0.05) heavier from day 35 on than winter raised animals. ADG and FE of summer raised pigs were significantly better (weeks 1-3 P<0.05; fourth week post-weaning P<0.01) during the nursery period than that of the winter raised groups. Winter raised vaccinated weaners showed during the last week of nursing significantly (P<0.05) better daily gain and feed efficiency compared with the non-vaccinated winter raised animals. Non-significant ADG and FE differences were detectable between the summer raised vaccinated or non-vaccinated groups of pig. Winter raised non-vaccinated animals suffered significantly (P<0.05) higher nursery mortality (10.63%) compared to the winter raised vaccinated animals. Implication: In cases of concurrent infections with HPS 5 and with different serotypes of E. coli, especially during winter season, vaccination against both diseases is suggested.     

Intramuscular vaccination of young calves with a Salmonella Dublin metabolic-drift mutant provides superior protection to oral delivery

In homologous and heterologous challenge trials using calves 相似文献   

Ear necrosis reduction in pigs after vaccination against PCV2

The influence of sows vaccination against PCV2 on the prevalence of ear necrosis syndrome (ENS) reduction among weaners was analyzed using 12,931 piglets from 45 consecutive batches, born to both, vaccinated and non-vaccinated sows. The results were statistically tested with a nonparametric Kruskal-Wallis and Chi-square tests.The results show that vaccination against PCV2 significantly reduced the prevalence of ENS (p < 0.05). The percentage of affected pigs born to vaccinated sows was about over two times lower than in both groups of pigs born to non-vaccinated females (before the vaccination implementation and after its withdrawing). Even more distinct were the differences in the intensity of the lesions (p < 0.05). In the group of pigs born to vaccinated sows, the percentage of severe lesions was three times lower than in the pigs born to non-vaccinated sows.It conclusion, it could statement that vaccination against PCV2 might be effective in reduction of ENS.     

Classical swine fever (CSF) marker vaccine. Trial I. Challenge studies in weaner pigs

Two commercial marker vaccines against classical swine fever virus (CSFV) and companion diagnostic tests were examined in 160 conventional pigs. To test the vaccines in a "worst case scenario", group of 10 weaners were vaccinated using a single dose of an E2 (gp55) based vaccine at days -21, -14, -10 or -7, and subsequently challenged at day 0. The challenge virus was CSFV 277, originating from a recent outbreak of classical swine fever (CSF) in Germany. In all groups, only 5 out of 10 pigs were challenged; the remaining 5 pigs served as vaccinated contact controls. Also, three control groups, each consisting of 10 non-vaccinated pigs, were challenged in parallel to the vaccinated animals. CSFV could be isolated from all non-vaccinated pigs. Among these pigs 40% displayed a chronic course of the infection (virus positive for more than 10 days). Pigs vaccinated 21 or 14 days before challenge displayed no clinical signs of CSFV after challenge. However, they were still able to replicate CSFV when challenged, as measured by reisolation of CSFV from leukocytes of the directly challenged pigs. CSFV could be isolated from the leucocytes of 25% of the pigs vaccinated 21 days before challenge and 50% of the pigs vaccinated 14 days before challenge. Chronic infection was not observed, but transmission to one vaccinated contact pig occurred. From all pigs vaccinated 10 or 7 days before challenge, CSFV could be reisolated. We observed a chronic course of infection in 5% of pigs vaccinated 10 days before challenge and in 30% of pigs vaccinated 7 days before challenge. The mortality rate was 20% in the pigs vaccinated 10 days before challenge, and varied between 20 and 80% in pigs vaccinated 7 days prior to challenge. The contact animals had lower mortality (0-20%) than directly challenged pigs, probably mirroring the delayed time point of infection. There was thus some protection against clinical illness by both marker vaccines, but not a solid protection against infection and virus shedding. The efficacy of the vaccine was best if used 3 weeks before challenge and a clear correlation between time interval from vaccination to challenge and the level of virus shedding was observed. Each vaccine had its own accompanying discriminatory ELISA, but 18% of the virus positive pigs never seroconverted in these tests.     

The effect of a homologous bacterin given to sows prefarrowing on the development of Glässer's disease in postweaning pigs after i.v. challenge with Haemophilus parasuis serotype 5

The trial was carried out to evaluate the impact of maternal antibodies on the development of Gl?sser's disease after i.v. exposure of weaned pigs with a homologous serovar of Haemophilus parasuis (HPS). Two groups of weaned pigs were formed. Group one VI (n = 10): born to vaccinated sows, weaners i.v. challenged one week postweaning and euthanatized 14 days postweaning. Group two NVI (n = 10 wearners): born to non vaccinated sows, i.v. challenged one week postweaning euthanatized 14 days postweaning. One week postweaning all weaners were i.v. inoculated with HPS serovar 5. The following parameters were evaluated: clinical signs (depression, centralnervous signs, fever, lameness), macroscopic lung, pleura, peritoneum, liver and joint changes, and mortality. All trial sows were HPS seronegative prior to vaccination. The HPS vaccinated sows were proven seropositive on day 3 p.p. (values > 0.24), the non vaccinated ones were tested seronegative (values < 0.23). The progeny of sows vaccinated prefarrowing with two doses of HPS serovar 5 bacterin were partially protected against HPS caused clinical and pathological signs. The majority of clinical signs as fever, depression, recumbency, lack of response to verbal stimuli and lameness showed significant (P < 0.05) milder clinical symptoms in VI than in NVI animals. Respiratory signs (P = .169) and involvement of the central nervous system as ataxia, muscular tremor, incoordination of hind legs and convulsions (P = 1) showed no significant differences between the groups. Except lesions of pericard (VI vs. NVI, P = .14) and pleura (VI vs. NVI, P = .14) there were significant (P < 0.05) macroscopic differences at necropsy in lung, liver, joints and cerebrospinal fluid between the offspring of vaccinated sows and the ones of non vaccinated dams. No HPS were isolated from the nasal mucosa of the pigs prior to inoculation. HPS serovar 5 was recovered at necropsy from the nasal mucosa of all pigs in both groups. One pig from group VI presented in all examined organs the presence of HPS serovar 5. The remaining animals in group VI revealed in lung, pericard, pleura, liver, joints and cerebrospinal fluid no presence of HPS. The rate of isolation between VI and NVI groups revealed a significant (P < 0.05) difference. All the survived piglets of group NVI showed positive ELISA titres against HPS serovar 5 (values > .24). The piglets that died or were euthanatized before the end of the study have not been subjected to ELISA serological testing. One piglet died in group VI before the end of the study. Non of the remaining animals in group VI showed seroconversion to HPS serovar 5. Implications: Vaccination of sows did not influence the colonisation of nasal mucosa, but progeny of sows vaccinated prefarrowing with two doses of HPS serovar 5 bacterin were partially protected against HPS caused diseases.     

Effects of oral vaccination against Lawsonia intracellularis on growing-finishing pig's performance in a pig production unit with endemic porcine proliferative enteropathy (PPE)

The aim of the present study was to evaluate the effect of oral vaccination against Lawsonia intracellularis (LI) on growing-finishing pig's performance. In a large Hungarian growing-finishing pig production unit, pigs with positive LI status were randomly divided into 2 groups and treated as follows: Group one: growing pigs (n = 4112) were LI vaccinated with an avirulent oral live vaccine (Enterisol Ileitis Boehringer Ingelheim Vetmedica, Inc., St. Joseph, USA). Group two: growing pigs (n = 4188 pigs) have not received LI vaccination. Culling and mortality rates, reasons for culling or mortality, and average daily weight gain were evaluated. Porcine proliferative enteropathy (PPE) caused culling and mortality rates were lower (0.2 % vs. 14.9 %, P < 0.001), and vaccinated pigs had lower none-PPE caused culling and mortality rates compared with the non-vaccinated ones (1.4 vs. 2.6 %, P > 0.05). While systemic infections and social stress or cannibalism related culling or mortality were significantly (P < 0.05) lower in vaccinated than in non-vaccinated pigs, reasons for culling or mortality due to non-LI caused diseases were non-significantly different between the vaccinated and non-vaccinated pigs. Average daily weight gain was higher (P < 0.05) in the LI vaccinated group of animals compared with the non-vaccinated ones (780 +/- 45 g vs. 660 +/- 71 g). The present results indicate that that LI vaccination does not only prevent PPE, but might result in more resistance and tolerance against other infectious and management caused losses.     

Comparison of antibody values in sera of pigs vaccinated with a subunit or an attenuated vaccine against classical swine fever

Ten pigs, aged 85 days, were vaccinated with a subunit vaccine containing 32 g of classical swine fever virus glycoprotein E2 (gp E2) (group 1), and a further 10 pigs were vaccinated with a C strain vaccine (10^4±0.15 TCID₅₀/ml), produced by amplification in minipig kidney (MPK) cell culture (group 2). Nine non-vaccinated pigs served as a control group (group 3). Serum samples were collected before (day 0) and at 4, 10, 21 and 28 days after vaccination and were analysed by two commercially available enzyme immunoassays and by a neutralizing peroxidase-linked assay (NPLA). At the same times, peripheral blood was taken for determining the total leukocyte count and the body temperature was taken daily. Antibodies were not detected in serum samples collected before vaccination (day 0), and no side-effects that could be connected with vaccination were observed during the trial. Ten days after vaccination 6/10 pigs vaccinated with the subunit vaccine were seropositive. On days 21 and 28, the ratios of serologically positive to vaccinated pigs were 9/10 and 10/10, respectively. Four of the ten pigs that were vaccinated with the C strain vaccine were positive on day 21 and 9/10 on day 28. However, the results of the NPLA showed that only 4/10 pigs had an antibody titre >1:32 at the end of the trial in both the vaccinated groups, even though the subunit vaccine initiated an earlier and higher level of neutralizing antibodies than the vaccine produced from the C strain. Challenge was performed 28 days after vaccination on four randomly selected pigs from both vaccinated groups. The pigs survived the challenge without showing any clinical signs of classical swine fever (CSF), while two nonvaccinated control pigs died on the 10th and 12th days after infection.     

Efficacy of vaccination in preventing giardiasis in calves

The objective of this study was to evaluate the efficacy of a vaccine in the prevention of Giardia duodenalis infection in calves. Six 2-week old calves were vaccinated subcutaneously with a sonicated G. duodenalis trophozoite vaccine. Six 2-week old control calves received a subcutaneous injection of sterile phosphate-buffered-saline mixed with adjuvant. Injections were repeated after 28 days. Eleven days after the second injection, calves were challenged orally with 1x10(5) purified G. duodenalis cysts from a naturally infected calf. Throughout the study, fecal samples were collected at regular intervals and examined for the presence of G. duodenalis cysts. Blood samples were collected weekly until G. duodenalis challenge and bi-weekly following challenge. Calves were euthanized 14 days after challenge and G. duodenalis trophozoites within the small intestines were enumerated. Serum antibody titers were significantly higher in vaccinated compared to non-vaccinated calves. Vaccinated calves tended to excrete more G. duodenalis cysts in their feces than non-vaccinated calves. The number of trophozoites in the small intestine was not different between vaccinated and non-vaccinated calves. Changes consistent of moderate enteritis were found in the intestines of one vaccinated and one non-vaccinated calf. Despite a serological immune response following vaccination, this vaccine was not efficacious in preventing giardiasis or reducing cyst shedding in calves.     

Duration of immunity induced in chickens by an attenuated live Salmonella enteritidis vaccine and an inactivated Salmonella enteritidis/typhimurium vaccine

The aim of this study was to examine the duration of immunity of different vaccination schemes using the S. enteritidis live vaccine Gallivac Se and the S. enteritidis-S. typhimurium inactivated vaccine Gallimune Se+St. Three groups of Lohman Brown chickens were used. Group one was vaccinated three times orally with Gallivac Se at weeks one, seven and 13 of age. Group two was vaccinated twice orally with Gallivac Se in weeks one and seven and once i.m. with Gallimune Se+St in week 14 of age. A third group was not vaccinated and served as the control group. Eight randomly selected chickens from each of the three groups were challenged with a nalidixic acid resistant S. enteritidis PT4 strain in weeks 24, 51 and 71 of age and the same number of animals were challenged with a S. typhimurium DT 104 strain in weeks 26, 54 and 73 (75) of age.The chickens were euthanised seven days post challenge and the number of challenge strain organisms (log10 cfu) in the liver and on caecal mucosa was determined.The quantitative investigation of the challenge strain in the liver and caecal mucosa revealed a statistically significant (p < 0.05) lower challenge strain burden in the vaccinated groups compared with the non-vaccinated control group up to week 71 (73) of age. The protective effects were demonstrated for both challenge strains.     

Colostral antibody induced interference of inactivated bluetongue serotype-8 vaccines in calves

Since its introduction into northern Europe in 2006, bluetongue has become a major threat to animal health. While the efficacy of commercial vaccines has been clearly demonstrated in livestock, little is known regarding the effect of maternal immunity on vaccinal efficacy. Here, we have investigated the duration and amplitude of colostral antibody-induced immunity in calves born to dams vaccinated against bluetongue virus serotype 8 (BTV-8) and the extent of colostral antibody-induced interference of vaccination in these calves. Twenty-two calf-cow pairs were included in this survey. The median age at which calves became seronegative for BTV was 84 and 112 days as assayed by seroneutralisation test (SNT) and VP7 BTV competitive ELISA (cELISA), respectively. At the mean age of 118 days, 13/22 calves were immunized with inactivated BTV-8 vaccine. In most calves vaccination elicited a weak immune response, with seroconversion in only 3/13 calves. The amplitude of the humoral response to vaccination was inversely proportional to the maternal antibody level prior to vaccination. Thus, the lack of response was attributed to the persistence of virus-specific colostral antibodies that interfered with the induction of the immune response. These data suggest that the recommended age for vaccination of calves born to vaccinated dams needs to be adjusted in order to optimize vaccinal efficacy.     

Vaccination against infectious bovine keratoconjunctivitis: protective efficacy and antibody response induced by pili of homologous and heterologous strains of Moraxella bovis

The protective effect of 2 Moraxella bovis pili vaccines against infectious bovine keratoconjunctivitis (IBK) experimentally induced by homologous or heterologous strain challenge with virulent, haemolytic M. bovis strain, Dal 2d, was measured in trials using weaned calves aged 3 to 7 months. Purified pili vaccines were prepared from haemolytic strain Dal 2d, (pilus serogroup IV), and haemolytic strain Epp 63, (pilus serogroup III). Calves were challenged by conjunctival instillation of 1 x 10(9) colony forming units of virulent M. bovis strain Dal 2d 14 days after the second of 2 subcutaneous doses of vaccine. Each consisted of 200 micrograms of pili in alum-oil adjuvant administered at an interval of 21 days. In trial 1 the level of protection against challenge with the homologous strain was 46.7% (p less than 0.01). Small, rapidly resolving lesions of IBK occurred in some vaccinates compared with a larger proportion of severe lesions that required treatment in non-vaccinated calves (p less than 0.025). In trial 2, the level of protection against IBK after exposure of vaccinates to the homologous Dal 2d strain was 72.7%, but no significant level of protection or reduction in the size and duration of lesions was apparent in similarly challenged calves vaccinated with Epp 63 pili when contrasted with susceptible, non-vaccinated controls. No marked reduction in the duration of infection with M. bovis Dal 2d following challenge resulted from vaccination with pili of either of the serogroups III or IV. Rising homologous serum IgG antibody titres to serogroups III and IV pili were recorded in response to vaccination with each antigen.(ABSTRACT TRUNCATED AT 250 WORDS)     

Program of vaccination and antibiotic treatment to control polyserositis caused by Haemophilus parasuis under field conditions

The present study investigated the effects of vaccinating sows and piglets or piglets alone against Haemophilus parasuis on the prevalence of H. parasuis in nasal swabs, on the humoral and cellular immune responses, and on the production parameters of piglets at 3 Korean farms with a clinical history of polyserositis caused by H. parasuis. Piglets born to vaccinated or non-vaccinated sows were subdivided into 3 groups: vaccinated sows and vaccinated pigs (VS-VP), non-vaccinated sows and vaccinated pigs (NVS-VP), and non-vaccinated sows and non-vaccinated pigs (NVS-NVP). The proportion of piglets with positive nasal swabs was significantly lower (P < 0.05) in the vaccinated animals (VS-VP and NVS-VP groups) than in the non-vaccinated animals (NVS-NVP group) at 35 and 60 d of age at the 3 farms. The overall growth performance (from 7 to 60 d of age) of the vaccinated piglets was significantly better (P < 0.05) than that of the non-vaccinated piglets at the 3 farms. Piglets in the VS-VP group had significantly higher levels (P < 0.05) of H. parasuis-specific IgG antibodies, lymphocyte proliferation, and interferon-γ-secreting cells than piglets in the NVS-VP and NVS-NVP groups on days 1, 7, 21, 35, and 60 after birth at the 3 farms.     

Influence of vaccination route on the efficacy of Aujeszky's disease deletion-mutant vaccine.

In order to compare the effect of the route of immunization on the efficacy of a modified live Aujeszky's disease (AD) vaccine, which had deletions in both thymidine kinase (TK-) and glycoprotein gIII genes (gpIII-), 20 six-week-old pigs were vaccinated by either the intramuscular (IM) (n = 10) or subcutaneous (SC) (n = 10) route. All the animals, including five non-vaccinated control animals, were challenged with virulent AD virus 22 days after vaccination. Four of five non-vaccinated animals died within 12 days after challenge. Although none of vaccinated animals died, three of animals in the SC group exhibited clinical signs, and average daily gains in the SC group were depressed. The animals in the IM group were not found to shed challenge virus, but those in the SC group shed the virus up to 9 days. Virus neutralizing antibody titers in the vaccinated animals were low or non-detectable by 21 days after vaccination. A glycoprotein gII (gpII) screening ELISA detected gpII antibody in all animals in the IM group. While, only 30% of animals in the SC group were positive by the same test. The results of this study indicate that TK-, gpIII modified live AD virus vaccine is effective against challenge with virulent AD virus; however, vaccination by the SC route reduced vaccine efficacy in comparison with IM route.