A cross-protection experiment in pigs vaccinated with Haemophilus parasuis serovars 2 and 5 bacterins, and evaluation of a bivalent vaccine under laboratory and field conditions.

Cross-protection between Haemophilus parasuis serovars 2 and 5 was examined in pigs using a bacterin based vaccine, and subsequently the safety and efficacy of a bivalent vaccine were evaluated. Upon intratracheal challenge of a serovar 2 or 5 strain, pigs immunized with a monovalent vaccine were protected against challenge with a homologous serovar strain, but not with a heterologous serovar strain. Immunization with a bivalent vaccine containing both serovars 2 and 5 bacterins conferred protection in pigs against lethal challenge with each of the serovar strains. A total of 86 pigs from two SPF herds were injected with the bivalent vaccine intramuscularly twice at a four-week interval. No adverse reactions following the vaccination were observed. On day 7 after the second vaccination, vaccinated and non-vaccinated control pigs from herd A were transferred to herd B, where Glasser's disease had broken out. Pigs in the control group developed clinical signs of the disease, and 6 of 8 (75%) pigs died until slaughter, in contrast with only 4 of 46 (9%) pigs in the vaccinated group. In herd C, where there was no outbreak of Glasser's disease, complement fixation antibody titer was raised only in the vaccinated group. A challenge experiment on days 20 and 79 after the second vaccination showed that only the vaccinated pigs were protected. From these findings, the safety and efficacy of the bivalent vaccine were confirmed under laboratory and field conditions.     

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.     

Protective effect of vaccination with culture supernate of M. hyopneumoniae against experimental infection in pigs

The protective activity of Mycoplasma hyopneumoniae inactivated vaccine prepared from sedimented whole cells and cell-free culture supernates was evaluated experimentally using hysterectomy-produced, colostrum-deprived pigs in which mycoplasmal pneumonia had been induced. The culture supernate vaccine containing less than 10(1) colour-changing units (CCU)/0.2 ml of M. hyopneumoniae significantly (P < 0.05) reduced the percentage of lung lesions compared to controls (3.2 +/- 3.9 vs. 12.2 +/- 2.2%), whereas the sedimented whole cells vaccine containing 10(10) CCU/0.2 ml of organisms provided variable protection (18.7 +/- 16.5 vs. 12.2 +/- 2.2%). Serum from the pigs vaccinated with culture supernate reacted with six protein bands of 97, 89, 65, 46, 42 and 41 kDa by immunoblot analysis. From these results, we conclude that vaccination with culture supernate of M. hyopneumoniae can provide protection against M. hyopneumoniae infection and that these antigens in the culture supernate may be closely related to the reduction of lung lesions.     

Serum and mucosal antibody responses and protection in pigs vaccinated against Mycoplasma hyopneumoniae with vaccines containing a denatured membrane antigen pool and adjuvant

Objective To investigate the protective efficacy of a pool of denatured membrane protein antigens of Mycoplasma hyopneumoniae (J strain) in the molecular size range 70 to 85 kDa (F3 antigen) in combination with adjuvants for pigs challenged with M hyopneumoniae .
Design A vaccine efficacy experiment with assessment of serum and respiratory tract antibody responses.
Procedure F3 antigens were emulsified with five different adjuvants. To groups of three pigs per vaccine, four vaccines were given by intramuscular injection, and two vaccines, including one of those given intramuscularly, were given by intraperitoneal injection.
Results Compared to six unvaccinated pigs, animals vaccinated with F3 antigen displayed significantly reduced pneumonia (54% reduction in mean lung score) following experimental challenge. Analysis of post-vaccination, pre-challenge IgG and IgA ELISA antibody absorbances in serum and respiratory tract washings revealed no correlation with lung score. Six weeks after challenge, pigs previously vaccinated intramuscularly mostly demonstrated greater IgG and IgA responses in respiratory tract washings, and greater IgG serum antibody responses, than those vaccinated by intraperitoneal injection.
Conclusion Pigs vaccinated with M hyopneumoniae antigens in the molecular size range of 70 to 85 kDa showed a significant reduction in lung lesions compared with unvaccinated control animals after experimental challenge. IgG and IgA antibody concentrations in serum and respiratory tract washings after vaccination do not provide a useful prognostic indicator of protection from enzootic pneumonia.     

Antibody responses against non-structural protein 3 of bovine viral diarrhoea virus in milk and serum samples from animals immunised with an inactivated vaccine

Antibodies against non-structural protein 3 (NS3, p80) of bovine viral diarrhoea virus (BVDV) were determined in milk from cows vaccinated with an inactivated BVDV vaccine and compared to serum antibody levels. Animals in one herd were vaccinated with an inactivated BVDV vaccine according to the standard protocol and animals from a second herd with an intensive schedule. Serum and milk samples were tested for BVDV NS3 antibodies using five commercial ELISAs. With a few exceptions, vaccination according to the standard schedule did not induce BVDV NS3-specific antibodies in serum or milk. However, after vaccination according to the intensive schedule, anti-NS3 antibodies were detected for a short time in serum and, to a lesser extent, in milk. Bulk milk was a suitable substrate for BVDV monitoring of herds vaccinated with the inactivated BVD vaccine.     

两种灭活方法制备的猪肺炎支原体灭活疫苗的免疫效果比较

为对比使用甲醛、二乙烯亚胺（BEI）两种灭活方法制备的猪肺炎支原体灭活疫苗对猪的呼吸道发病率、肺部病变记分、饲料转化率、日增重、以及猪血清抗体水平等指标的影响,将120头健康仔猪随机分成三个试验组和一个对照组,于7、21日龄对试验组的仔猪进行疫苗接种,所有猪于20、50、80及140日龄采血分离血清,检测血清中猪肺炎支原体抗体水平。结果显示,用BEI灭活的疫苗在呼吸道发病率、肺部病变记分、饲料转化率、日增重、以及猪血清抗体水平等各项指标均好于甲醛灭活的疫苗（P<0.05）,与进口疫苗无显著差异。试验表明,使用BEI灭活方法制备的猪肺炎支原体灭活疫苗的免疫效果好。     

Vaccination Against Pleuropneumonia of Pigs Caused by Haemophilus pleuropneumoniae

A strain of Haemophilus pleuropneumoniae was isolated from a pig with pleuropneumonia from a herd where this condition was frequent. A formalin inactivated culture of this isolate was used as antigen in two vaccine preparations: A and B. Vaccine A had peanut oil + arlacel 80 + tween 80 as adjuvant and vaccine B had aluminum hydroxide gel as adjuvant. Twenty pigs were vaccinated twice with vaccine A and 19 with vaccine B. Twenty additional pigs were not vaccinated. All pigs were transferred to the herd. Eleven pigs in the nonvaccinated group developed pneumonia and seven of these died within eight days after exposure. None of the vaccinated pigs had signs of pneumonia. It is concluded that the vaccines prevented the acute form of pleuropneumonia due to H. pleuropneumoniae.     

The effectiveness of vaccinating gilts against parvoviruses in a herd with endemic parvovirus infection

An inactivated vaccine against swine parvovirosis with a lipoid adjuvant was tested in a herd infested with parvoviruses. The titre of the haemagglutination-inhibition antibodies was studied at the time of the first pregnancy in two groups of gilts included in the herd at the age of 7.5 months - one group vaccinated, the other left untreated. In the vaccinated group the geometrical means of the titres were significantly higher than in the non-vaccinated group throughout the time of study. The difference in the average number of piglets per litter between the two groups was evaluated after parturition. On an average, the gilts of the vaccinated group had 1.5 more live pigs per litter (P less than 0.05). As also found, when the antibody titre increases by log 10, the number of piglets per litter increases by 1.55. On the basis of the results the vaccination of gilts against swine parvovirosis in endemically infested herds is considered an efficient preventive measure having a high economic effect.     

Comparative efficacy of two single-dose bacterins in the control of Mycoplasma hyopneumoniae in swine raised under commercial conditions in Brazil

A field study was conducted in Brazil to evaluate the efficacy of single vaccination of pigs with two bacterins to prevent Mycoplasma hyopneumoniae lung lesions. The first (T1) treatment group (174 pigs) was injected with 2 mL of saline solution; group T2 (177 pigs) with 2 mL of bacterin A, and group T3 (174 pigs) with 2 mL of bacterin B. On days-on-test (DOT) 0, 35, 66, 97 and 125, blood samples and tonsil swabs were collected from selected pigs for antibody determination (indirect ELISA) and PCR assay for the presence of M. hyopneumoniae. Pigs were slaughtered on DOT 126-129 and lung lesions were scored blindly. Bacterin A vaccinated pigs had significantly (P < or = 0.05) lower lung lesion scores (0.2%) than bacterin B (0.4%) or saline-treated pigs (1.2%); there was also a significantly lower (P < or = 0.05) number of pigs with lung lesions (27.1%), than bacterin B (38.2%) or saline-treated (55.4%) pigs. The two vaccines had similar (P>0.05) results in terms of mean weight gain, average daily weight gain, feed efficiency, frequency of PCR positives, and there was similar antibody conversion (ELISA). It was concluded that although the productivity parameters and antibody conversions were similar, bacterin A was more effective in preventing and reducing the severity of lung lesions than bacterin B.     

Evaluation of local and systemic immune responses induced by intramuscular injection of a Mycoplasma hyopneumoniae bacterin to pigs

OBJECTIVE: To evaluate immune responses induced by administration of Mycoplasma hyopneumoniae bacterin to pigs. Animals-60 healthy 7- to 10-day-old cross-bred boars. PROCEDURE: Pigs were assigned to 1 of 4 pig groups (15 pigs/group): vaccinated, challenged; vaccinated, nonchallenged; nonvaccinated, challenged; nonvaccinated, nonchallenged. Vaccinated pigs received IM injections of a mycoplasma bacterin on days 0 and 14, whereas nonvaccinated pigs received saline (0.9% NaCl) solution. Pigs in the challenged groups were inoculated intratracheally with M hyopneumoniae on day 42. Pigs were euthanatized and necropsied 41, 44, 48, and 70 days after the first vaccination, and proportion of lung surface with pneumonic lesions was determined. Percentage of lymphocyte subpopulations and number of interferon-gamma (IFN-gamma) secreting lymphocytes in blood and tissues, cytokine and antibody concentrations in bronchoalveolar lavage (BAL) fluid, and serum antibody concentrations were determined. RESULTS: Vaccination against and infection with M hyopneumoniae induced a local mucosal immune response in the respiratory tract of pigs. Proportion of lung surface with pneumonic lesions in vaccinated challenged pigs was reduced on day 70, compared with nonvaccinated challenged pigs. Vaccination stimulated the production of M hyopneumoniae-specific IFN-gamma secreting blood lymphocytes. Tumor necrosis factor-alpha concentration in BAL fluid on day 70 was increased in nonvaccinated challenged pigs, compared with vaccinated challenged pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination against M hyopneumoniae induced local, mucosal, humoral, and cellular immune responses. Moreover, vaccination reduced the severity of lung lesions in challenged pigs, suggesting that mucosal antibodies, mediation of the inflammatory response, and cell-mediated immune responses are important for control of mycoplasmal pneumonia in pigs.     

Antibody response to an autogenous vaccine and serologic profile for Streptococcus suis capsular type 1/2

An autogenous vaccine was developed, using sonicated bacteria, with a strain of Streptococcus suis capsular type 1/2. The objectives of this study were to evaluate the antibody response following vaccination and to assess the changes in antibody levels in pigs from a herd showing clinical signs of S. suis capsular type 1/2 infection in 6- to 8-week-old pigs. An enzyme-linked immunosorbent assay using the vaccine antigen was standardized. Results from a preliminary study involving 2 control and 4 vaccinated 4-week-old pigs indicated that all vaccinated pigs produced antibodies against 2 proteins of 34 and 43 kDa, respectively, and, in 3 out of 4 vaccinated pigs, against the 117-kDa muramidase-released protein. For the serologic profile, groups of 30 pigs from the infected herd were blood sampled at 2, 4, 6, 8, and 10 weeks of age. The lowest antibody level was observed between weeks 6 and 8, presumably corresponding to a decrease in maternal immunity. A marked increase was seen at 10 weeks of age, shortly after the onset of clinical signs in the herd. For the vaccination field trial, newly weaned, one-week-old piglets were divided into 2 groups of 200 piglets each (control and vaccinated); blood samples were collected from 36 piglets in each group at 2-week intervals for 12 weeks. A significant increase (P 0.05) in antibody response was observed 4 weeks following vaccination and the level of antibodies stayed high until the end of the experiment. In the control group, the increase was only observed at 13 weeks of age, probably in response to a natural infection. The response to the vaccine varied considerably among pigs and was attributed, in part, to the levels of maternal antibodies at the time of vaccination. No outbreak of S. suis was observed in the control or vaccinated groups, so the protection conferred by the vaccine could not be evaluated.     

Varying effects of infections with Mycoplasma hyopneumoniae on the weight gain recorded in three different multisource fattening pig herds

Pigs in three specialized fattening herds were studied with respect to the effect of infection with Mycoplasma hyopneumoniae on weight gain. Individual pigs were weighed four times at 4-week intervals during the fattening period and their daily weight gain over the rearing period was calculated. A blood sample was collected on each weighing occasion and analysed for the presence of antibodies to M. hyopneumoniae. The lungs of the principals were inspected at slaughter and the extent of pneumonic lesions was registered by a specially developed technique that has been proven to warrant a high degree of repeatability. No serum antibodies to M. hyopneumoniae were detected in one of the herds, and no pneumonic lesions were recorded at slaughter in that herd. In the other two herds, the prevalence of pigs with serum antibodies to M. hyopneumoniae increased from 6 to 54% and from 31 to 81%, respectively, during the fattening period. The prevalence of pneumonic lesions at slaughter in these herds was higher the later the pigs seroconverted. On the other hand, the extension of the lung lesions tended to be higher among pigs that seroconverted early during the rearing period. Infections with M. hyopneumoniae acquired early during the rearing, presumably strengthened by secondary infections and environmental errors, was found to decrease the daily weight gain of the pigs. However, even non-complicated M. hyopneumoniae infections acquired late in the fattening period were associated with reduced daily weight gain. That growth reduction was estimated to be at least 60 g (about 6%) after adjusting for herd, pen, initial weight and sex.     

Evaluation of antibody formation, daily weight gain and meat quality after vaccination of piglets against Mycoplasma hyopneumoniae

A Mycoplasma hyopneumoniae vaccine (Respisure, Pfizer AH) was tested for its effects on antibody formation, daily weight gain (DWG) in different growing periods, lung lesions and quality of meat (chemical composition, physicochemical properties and fatty acid composition). Two groups of conventional piglets were used for the investigation. One group of 11 females and 11 males was vaccinated intramuscularly at the age of 1 and 3 weeks. The other group of 22 piglets was left nonvaccinated as control. The results showed that antibodies against M. hyopneumoniae in the vaccinated group had been formed 14 days after the second vaccination and remained present till the end of the study at 147 days of age. In the nonvaccinated group, seroconversion started at 49 days of age and by the end of the study 10 out of 22 pigs had become seropositive. Vaccinated pigs achieved significantly higher daily weight gain (+30 g) and finishing body weight (+6.04 kg) than the nonvaccinated animals. In addition, the vaccinated pigs showed lesions involving 3.27% of the lung surface in average, while in the nonvaccinated pigs 9.04% of the lung surface was affected. Investigation of meat quality showed that the longissimus dorsi muscle of vaccinated pigs contained significantly lower percentage of fat (-0.63%) and its tryptophan/hydroxyproline ratio was significantly lower (-23.57) in comparison with the control animals. In addition, some other parameters also showed a favourable tendency, e.g. lean meat percentage was 0.91% higher, the protein content of the longissimus dorsi muscle was 0.35% higher, its water-binding capacity was also higher by 0.78%, its monounsaturated fatty acid concentration was 2.97% lower, while its polyunsaturated fatty acid content was 1.65% higher in the vaccinated pigs than in the nonvaccinated animals.     

Effect of the Stellamune Mycoplasma vaccine on growth, energy conversion, death, and medication use in fattening pigs on a pig farm chronically infected with Mycoplasma hyopneumoniae

The effect of Stellamune Mycoplasma vaccine, administered to piglets aged 2-15 days and then 13-15 days later, on daily weight gain, energy conversion, and use of medication was examined in fattening pigs on a chronically Mycoplasma hyopneumoniae infected pig farm. Half of the piglets were vaccinated and the other half acted as controls. In the study design, half of the pens in the fattening unit were allocated to vaccinated pigs; the other half to non-vaccinated pigs, pen was the experimental unit. In the fattening pens sows and castrated boars were separated. The study consisted of a total of 37 pens with vaccinated, and 37 pens with non-vaccinated pigs in 12 different compartments within the pig herd. In the finishing period, mean growth performance and mean energy conversion (EV/kg) of vaccinated animals was 65 grams/day higher and 0.07 EV/kg lower than in control pigs. Furthermore, the incidence of individual curative medication against respiratory problems was more than 4 times higher in control pigs than in vaccinated pigs. There was a tendency for a higher number of group medications against respiratory problems in control pigs than in vaccinated pigs. It is concluded that, in this herd, vaccination against M. hyopneumoniae was successful from an economic point of view.     

Detection of neutralizing antibodies against Pasteurella multocida toxin in swine with atrophic rhinitis

Blood sera of 1171 pigs, not vaccinated against PAR, were tested for antibodies against P. multocida toxin in a neutralization test with EBL cell cultures. 277 sera were from 18 herds with clinical PAR; 104 of them (37.5%) had neutralizing antibody titres from 1:2 to 1:1024. No antitoxin was detected in the sera of 866 pigs in 25 PAR nonsuspicious herds. In one nonsuspicious herd, however, 11 of 28 sera were neutralizing in the 1:2 or 1:4 dilution. 30 sows had been vaccinated with inactivated toxigenic P. multocida and/or with the P. multocida toxoid. 21 of these sows had neutralizing sera with titres between 1:8 and 1:4096. The neutralization test presented can be applied for herd diagnosis of PAR and for demonstration of vaccination effects.     

Antibody response of pigs to inactivated monovalent and bivalent vaccines for porcine parvovirus and pseudorabies virus

Groups of pigs vaccinated with an inactivated bivalent vaccine containing porcine parvovirus (PPV) and pseudorabies virus (PRV) developed geometric mean titers (GMT) of humoral antibody for each of the viruses as high or slightly higher than those of other groups of pigs that were vaccinated with inactivated monovalent vaccines containing one or the other of the same viruses. An increase in GMT after challenge exposure of vaccinated pigs to live virus indicated that vaccination did not prevent virus replication. However, an indication that replication was less extensive in vaccinated pigs was provided by the following. Although neither vaccinated nor nonvaccinated (control) pigs had clinical signs after exposure to the live PPV, the effect of vaccination was evident by the fact that GMT were higher in nonvaccinated pigs after exposure than they were in vaccinated pigs. Conversely, all pigs exposed to live PRV had clinical signs, but these signs varied between mild-to-moderate and transient for vaccinated pigs to severe and fatal for nonvaccinated pigs.     

A field trial to evaluate a Mycoplasma hyopneumoniae vaccine: effects on lung lesions and growth rates in swine.

A killed Mycoplasma hyopneumoniae vaccine was evaluated in a single swine herd in which the farrowing barn and weaner rooms were on one Mycoplasma-free farm, while the growing and finishing barn was on a separate farm on which Mycoplasma was present. The study was carried out in a cohort of pigs born in a 12-week period. Pigs born in 6 of the 12 wk were vaccinated and the rest were left as controls. The vaccine was administered twice at approximately 3 and 6 wk of age. Carcass characteristics, lung lesions, and growth rates were recorded on 893, 390, and 220 pigs, respectively. The vaccine reduced the prevalence of pneumonic lesions in slaughter hogs from 69% to 36% (P < 0.001). It also appeared to reduce the prevalence of pleuritis from 20% to 13%, but the difference was only statistically significant at P = 0.07. The vaccine had no effects on carcass characteristics except that carcasses of vaccinated pigs were, on average, 1 kg heavier than those of nonvaccinated pigs, and a smaller percentage of vaccinated pigs were shipped "light" (carcass weight < 70 kg). Two methods were used to estimate the effect of the vaccine on growth rates (as measured by days to 80 kg carcass weight) resulting in estimates of 11 and 2 d reduction attributable to vaccination, respectively. The latter estimate was probably an underestimate for reasons discussed in the paper.     

ISOLATION OF MYCOPLASMA HYOPNEUMONIAE AND ITS ASSOCIATION WITH PNEUMONIA OF PIGS IN AUSTRALIA

Nine strains of mycoplasmas were isolated from the lungs of 5 pigs with clinical signs of naturally acquired enzootic pneumonia. Mycoplasma hyopneumoniae was isolated from the lungs of 1 pig and M. hyorhinis from the lungs of 4. An unidentified mycoplasma, which utilized arginine, grew rapidly in broth culture and produced centred colonies on solid medium, was isolated from the lungs of 4 pigs. The pathogenicity of the isolated strain of M. hyopneumoniae was determined by inoculation of pigs from an enzootic pneumonia-free herd. Enzootic pneumonia was produced in the lungs of all 5 pigs inoculated intranasally and intratracheally with broth cultures of the organism isolatied by limit dilution techniques. Enzootic pneumonia was produced in 3 of 6 pigs inoculated intranasally and intratracheally with M. hyopneumoniae purified by the passage of colonies on agar blocks. M. hyopneumoniae was isolated in pure culture from the lungs of all pigs with induced pneumonic lesions.     

Protective effects of an oral microencapsulated Mycoplasma hyopneumoniae vaccine against experimental infection in pigs.

Oral microencapsulated Mycoplasma hyopneumoniae vaccines were tested for their ability to prevent mycoplasmal pneumonia in pigs. Eighteen four-week-old specific pathogen free pigs were divided into six groups of three. Each pig of groups 1 to 4 was inoculated intramuscularly with formalin-inactivated M hyopneumoniae in adjuvant and boosted orally 14 days later with four different microencapsulated vaccine microspheres. Group 5 was used as a positive control. All 15 pigs of groups 1 to 5 were challenged at 28 days after the first vaccination by an intratracheal inoculation of pneumonic lung suspension. The three pigs of group 6 were used as a negative control. All four vaccinated groups showed some protection when challenged, but the protection was more solid in pigs boosted with vaccine D (group 4) which contained less porcine serum in the microsphere. The study indicates that oral vaccination with M hyopneumoniae could play a role in prevention and eradication of mycoplasmal pneumonia in the pig.