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1.
Objective To evaluate the efficacy of two new-generation porcine pleuropneumonia vaccines when challenged with Australian isolates of Actinobacillus pleuropneumoniae of serovars 1 and 15.
Design The Porcilis APP vaccine and an experimental streptomycin-dependent strain of A pleuropneumoniae were evaluated in a standardised pen trial. Each vaccine/challenge group consisted of 10 pigs.
Results With the serovar 1 challenge, the Porcilis APP vaccine and the live vaccine, compared with the control group, gave significant protection in terms of clinical signs, lung lesions, re-isolation scores and average daily gain (ADG) postchallenge. Only the Porcilis APP vaccine provided significant protection against mortality. In the serovar 15 challenged pigs, the only significant difference detected was that the Porcilis APP vaccinated pigs had a better postchallenge ADG than the controls. None of the Porcilis APP vaccinated pigs showed signs of depression postvaccination and none were euthanased after challenge with either serovar 1 or 15. The pigs vaccinated with the live vaccine showed obvious depression after each vaccination and a total of 3 pigs were euthanased after challenge (one with serovar 1 and two with serovar 15).
Conclusions Both of the vaccines provided significant protection against a severe challenge with serovar 1 A pleuropneumoniae. Neither vaccine was effective against a serovar 15 A pleuropneumoniae challenge. There was evidence that the Porcilis APP vaccine did provide some protection against the serovar 15 challenge because the ADG, after challenge of pigs given this vaccine, was greater than the control pigs.  相似文献   

2.
The objective of this study was to compare the efficacy and safety of single-strain and multi-strain vaccines for the prevention of the respiratory facet of porcine reproductive and respiratory syndrome. The study comprised six groups of pigs (A through F, eight pigs per group). At the beginning of the study (Day 0) Groups C and D were vaccinated with a single-strain vaccine, and Groups E and F were vaccinated with a multi-strain vaccine. The multi-strain vaccine contained five attenuated strains of PRRSV including the strain used as the single-strain vaccine. On Day 28 Groups B (nonvaccinated/challenged control), D, and F were challenged with a highly virulent field strain of PRRSV that was unrelated to any of the strains used for vaccination. Group A was kept as a nonvaccinated/nonchallenged control. On Day 42 all pigs were necropsied. Their lungs and lymph nodes were examined for virus-induced changes. Serum samples obtained at weekly intervals during the study and lung lavage fluids obtained at necropsy were tested for the presence and titer of PRRSV. Serum samples were also tested for antibody. The presence and severity of clinical signs and lesions were the primary means by which vaccine efficacy and safety were evaluated. Both vaccines provided a high level of protective immunity to challenge. However, appreciable lymph node enlargement in pigs vaccinated with multi-strain vaccine, with or without subsequent challenge, raised a question as to its safety. Collectively these results indicate that both single-strain and multi-strain attenuated PRRSV vaccines can be effective immunogens, but additional studies in regard to safety are needed before multi-strain vaccines can be recommended for routine field use.  相似文献   

3.
The immunogenic and protective potentials of an outer membrane-enriched fraction (OM) from a serotype 5 strain of Actinobacillus (Haemophilus) pleuropneumoniae (APP) and the same OM degraded with proteinase K or periodate were evaluated in swine. Groups of pigs were vaccinated with two doses of OM, proteinase K-treated OM (P-OM), periodate-treated OM (PI-OM), or placebo vaccine and challenged intranasally with the homologous strain of APP. Results from triplicate experiments indicated that proteinase K treatment of OM resulted in an improved efficacy. This improved efficacy of P-OM vaccine over untreated OM vaccine was evidenced not only by less severe lung lesions in P-OM vaccinated pigs but also by significant reduction (P less than 0.05) in the number of P-OM vaccinated pigs which developed lung lesions upon challenge with APP. Assessment of sera from vaccinated animals by immunoblotting, complement fixation test, or ELISA indicated that the immunogenicity of some but not all protein or carbohydrate components were reduced (or eliminated) by proteinase K and periodate treatments respectively.  相似文献   

4.
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.  相似文献   

5.
An inactivated vaccine prepared from broth culture supernatant of Mycoplasma hyopneumoniae with an aluminum adjuvant was evaluated in three herds (herd A: specific pathogen-free herd, herd B: high health status herd with no clinical signs of respiratory infection, herd C: low health status herd with serious epidemiological and economical problems). A total of 212 pigs from the three herds were divided into two groups. One group was injected twice with the vaccine at 4-week intervals and the other was a control group. No adverse reactions were noted following the vaccinations either systematically or locally in any of the vaccinated pigs from any of the herds. In herd A, the vaccination provided antibody response within 4 weeks after the second vaccination and antibody responses continued for more than 12 weeks. In herds B and C, the number of pigs with lung lesions, mean percentage of lung lesions, and the numbers of M. hyopneumoniae recovered from pigs at slaughter in the vaccinated group were significantly (P < 0.05) reduced compared to the control group. Furthermore, vaccination resulted in improved average daily weight gain (ADG), improved feed conversion ratio (FCR), and improved days to market weight in herd C, whereas no difference in growth performance was shown in herd B. It is suggested that the inactivated vaccine prepared from broth culture supernatant of M. hyopneumoniae is effective in reducing clinical signs and lung lesions. Also, vaccination resulted in improved growth performance in herds where clinical signs and economic losses were significant.  相似文献   

6.
Pasteurella multocida toxin was purified by affinity chromatography and inactivated by treatment with formaldehyde before use as a single component vaccine against progressive atrophic rhinitis in pigs. Twenty pregnant gilts which were vaccinated twice before farrowing with either low or high doses of the purified toxoid, developed dose-dependent positive serum and colostrum titres to the toxin and, unlike the progeny of 10 untreated control gilts, the offspring of the vaccinated gilts also had serum titres. These titres could be measured in blood samples taken for more than eight weeks from birth for most pigs born to gilts vaccinated with low doses and more than 12 weeks for pigs born to gilts vaccinated with high doses of the vaccine. All the piglets were inoculated intranasally with Bordetella bronchiseptica and toxigenic P multocida. The clinical and post mortem examinations of snouts revealed a significant reduction in the frequency and degree of conchal atrophy in the two groups of pigs from the vaccinated gilts compared with the pigs from control gilts. Clinically 90 per cent of the snouts of pigs born to vaccinated gilts appeared normal whereas only 28 per cent of the snouts of control pigs were not shortened or deviated at eight weeks of age. At slaughter 11 per cent of the pigs born to vaccinated gilts and 81 per cent of the control pigs had severe turbinate atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
This study evaluated the use of an avirulent live Salmonella Choleraesuis vaccine to reduce the seroprevalence and number of Salmonella carrier pigs at slaughter. Seven batches of 500 pigs were included in each of the two study groups: the vaccinated group (VG) that was orally vaccinated and the control group (CG) that received a placebo on the first day of life. The groups were managed in a three-site system and followed up from birth to slaughter. Blood samples (n=378) were collected from each VG and CG to monitor the on-farm seroprevalence in both groups. Mesenteric lymph nodes and blood from animals (n=390) belonging to each group were collected at slaughter. At the first day of life, the seroprevalence in control batches ranged from 77.9 to 96.3 per cent, while in vaccinated batches, it ranged from 66.6 to 92.6 per cent. At weaning (21 days of age), the number of seropositives decreased in both groups (mean of 12 and 3.7 per cent for CG and VG, respectively). At slaughter, batches of VG had a significantly (P<0.0001) lower seroprevalence (46.6±5 per cent) and isolation of Salmonella from lymph nodes (33.1±5 per cent) compared with CG batches (79.7±4 per cent and 59.5±5 per cent, respectively). The results indicate that administration of a Salmonella choleraesuis-attenuated vaccine on the first day of life decreases Salmonella isolation and seroprevalence in pigs at slaughter.  相似文献   

8.
The aim of the present study was to investigate the efficacy of single-dose intradermal vaccination against Mycoplasma hyopneumoniae on a commercial swine unit. A total of 1051 healthy suckling piglets of 28±3 days of age were randomly assigned to one of three experimental groups: (a) intradermal: 346 piglets vaccinated intradermally (Porcilis M Hyo ID Once, Intervet SPAH), (b) intramuscular : 351 piglets vaccinated intramuscularly (Porcilis M1 Intervet SPAH) and (c) controls: 354 piglets injected with a placebo (adjuvant only). Performance parameters such as average daily weight gain (ADG), as well as health parameters and lung lesion scores were monitored from four weeks of age until slaughter. The improvement in ADG over the controls, during the finishing phase, was 27 g/day for the intradermal group and 17 g/day for the intramuscular group. Both intradermal and intramuscular vaccinations were effective in reducing clinical signs and lung lesions caused by M hyopneumoniae. Compared with the controls, approximately 10.4 per cent fewer clinical cases were diagnosed in the intradermal group, and 6 per cent fewer in the intramuscular group, during the finishing period. In conclusion, performance results were better in the vaccinated groups than in the control group, while intradermal vaccination afforded greater protection than intramuscular vaccination, especially with regard to morbidity, lung lesion and pleuritis scores.  相似文献   

9.
The efficacy of a subunit vaccine containing the Apx toxins of Actinobacillus pleuropneumoniae and transferrin-binding proteins was determined. Ten pigs were vaccinated twice with the vaccine. Eight control animals were injected twice with a saline solution. Three weeks after the second vaccination, all pigs were endobronchially inoculated with 10(6.5) colony-forming units (CFU) of an A. pleuropneumoniae serotype 9 strain. In the vaccine group, none of the pigs died after inoculation. Only one pig of the control group survived challenge. Surviving pigs were killed at 7 days after challenge. The mean percentage of affected lung tissue was 64% in the control group and 17% in the vaccine group. Actinobacillus pleuropneumoniae was isolated from the lungs of all animals. The mean bacterial titres of the caudal lung lobes were 5.0 x 10(8) CFU/g in the control group and 3.0 x 10(6) CFU/g in the vaccine group. It was concluded that the vaccine induced partial protection against severe challenge.  相似文献   

10.
Swine dysentery (SD) is an important endemic infection in many piggeries, and control can be problematic. In this study the efficacy of BmpB, a 29.7 kDa outer-membrane lipoprotein of Brachyspira hyodysenteriae, was evaluated as an SD vaccine. Non-lipidated BmpB was expressed in Escherichia coli as a histidine-tagged protein (His6-BmpB), or as an 8 kDa carboxy-terminal portion fused to maltose-binding protein (MBP-BmpB-F604). The purified proteins were emulsified with oil-based adjuvants for intramuscular (im) administrations. In experiment 1, 20 weaner pigs were vaccinated im with 1 mg of His6-BmpB. After 3 weeks, 10 received 1 mg of the protein orally (im/oral), and 10 received 1 mg im (im/im). Ten acted as unvaccinated controls. In experiment 2, 12 pigs were vaccinated im with 1 mg of His6-BmpB, and 12 with 1 mg of MBP-BmpB-F604. Three weeks later, each was given 1 mg of the same protein orally. Twelve pigs acted as unvaccinated controls. All pigs were challenged orally with B. hyodysenteriae 2 weeks after their second vaccination. In both experiments, all pigs vaccinated with His6-BmpB developed serum antibodies to BmpB, and oral administration provided boosting of im-induced serum antibody titres. In experiment 1, seven non-vaccinated control pigs developed dysentery and severe colitis. Three pigs vaccinated im/oral developed diarrhoea; two had severe colitis and one had mild lesions. Four pigs vaccinated im/im developed diarrhoea; one had severe colitis and the others had mild lesions. In experiment 2, six control pigs developed SD with severe colitis. Two His6-BmpB vaccinated pigs developed SD with mild colitis. Nine pigs vaccinated with MBP-BmpB-F604 developed SD and severe colitis. Overall, 50-70% of controls and 17-40% of His6-BmpB vaccinated pigs developed disease. Vaccination with MBP-BmpB-F604 did not induce serum titres against BmpB, nor confer protection. The incidence of disease for the three His6-BmpB vaccinated groups was significantly less (P = 0.047) than for the control groups, with a approximately 50% reduction. BmpB appears to have potential as an SD vaccine component.  相似文献   

11.
In a large Slovakian growing-finishing pig production unit, the effects of oral vaccination against swine erysipelas (SE) were investigated in three groups of pigs of 10 weeks of age. In group 1, the pigs were vaccinated intramuscularly at 1 and 3 weeks after arrival in the growing-finishing barn using an Erysipelothrix rhusiopathiae bacterin. Group 2 pigs were vaccinated at the same time as group 1 using an oral avirulent live SE vaccine administered through drinking water; the pigs in the third group were placebo treated. Clinical signs of acute SE, arthritic changes, average daily weight gain (ADG), feed conversion ratio, and mortality were evaluated. None of the pigs in groups 1 and 2 but 31.7% of the control animals (group 3) showed typical clinical signs of acute SE. More (P<0.01) non-vaccinated pigs had chronic arthritic changes compared with groups 1 and 2. No significant differences in mortality were recorded between the groups. Groups 1 and 2 had higher (P<0.05) ADG and lower feed conversion ratios compared with group 3 pigs. The results demonstrated that the oral avirulent live culture was efficacious in significantly reducing the clinical symptoms caused by E. rhusiopathiae infection, so enhancing the pigs' performance.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
The efficacy of a new vaccine against atrophic rhinitis in pigs was tested in the Netherlands and Denmark. The vaccine contained protein dO (a truncated Pasteurella multocida toxin which is immunogenic and non-toxic), inactivated Bordetella bronchiseptica whole cells, and an adjuvant. The sows were either vaccinated intramuscularly with 2 ml of the vaccine at six to eight and two to four weeks before expected farrowing or left unvaccinated as controls. All the piglets were challenged intranasally with B bronchiseptica when three to seven days old and with P multocida three to four days later. Pigs born to the vaccinated sows performed significantly better than pigs born to the control sows when judged on growth, average daily weight gain and snout scores. The challenge organisms were reisolated more frequently from the control pigs than from the pigs in the vaccinated group. The vaccinated sows and their progeny developed high titres of antibodies against B bronchiseptica and P multocida toxin.  相似文献   

16.
Host response was evaluated following the administration of various treatments, such as probiotics, prebiotics, and vaccination, to reduce Salmonella in swine. Response to the treatments were studied by the evaluation of phagocytosis rates by flow cytometry, by studying the activation of whole-blood phagocytes by bioluminescence, the production of IgA against S. Typhimurium, and by histopathology. Significant differences were observed in the activation of whole-blood phagocytes in all groups of treated pigs (P = 0.0001). In SC54 vaccinated pigs, a significant reduction of Salmonella in the ileum was observed (P < 0.05) and the production of IgA against S. Typhimurium was higher in this group in comparison to uninfected control pigs (P = 0.0007). Furthermore, significant histopathological (P < 0.05) changes were observed in SC54 vaccinated pigs. Villus height and mucus and goblet cells density in the small intestine were reduced in vaccinated pigs in comparison to infected control pigs. Taken together, these findings suggest that SC54 vaccine can stimulate local immunity and reduce the presence of Salmonella in the ileum in swine. Use of SC54 vaccine should thus be considered in further field experiments.  相似文献   

17.
伪狂犬病基因缺失疫苗株(SA215)某些生物学特性研究   总被引：3，自引：0，他引：3  
本试验测定了伪狂犬病ｇＥ－／ｇＩ－／ ＴＫ－／ ＬａｃＺ＋基因缺失疫苗株（ＳＡ２１５）的致细胞病变效应、安全性、免疫原性和免疫期等生物学特性。试验结果显示,该疫苗株能在Ｖｅｒｏ细胞上适应生长,并形成典型的蚀斑。其对１日龄仔猪、怀孕母猪、牛、羊以及家兔安全,无不良接种反应,接种动物不向体外散毒。ＳＡ２１５疫苗接种猪能抵御高剂量（１０７ＰＦＵ）Ｆａ株强毒感染,攻毒后试验猪的发热期、增重受阻天数、散毒滴度均低于Ｂａｒｔｈａ株疫苗接种猪,远远低于对照组猪。ＳＡ２１５接种猪能维持长时间的高水平中和抗体滴度,免疫期可达半年以上。试验结果表明,ＳＡ２１５株是一株安全、免疫原性好、免疫期长的疫苗株。  相似文献   

18.
Four experiments were conducted to examine the effect of porcine circovirus type 2 (PCV2) vaccination on the response of growing and finishing pigs (PIC 337 × 1050) to increasing dietary Lys. Experiments 1 and 2 evaluated 38- to 65-kg gilts and barrows, respectively, and Exp. 3 and 4 evaluated 100- to 120-kg gilts and barrows, respectively. Gilts and barrows were housed separately in different barns. Treatments were allotted in a completely randomized design into 2 × 4 factorials with 2 PCV2 treatments (PCV2-vaccinated and nonvaccinated) and 4 standardized ileal digestible (SID) Lys:ME ratios (2.24, 2.61, 2.99, and 3.36 g/Mcal in Exp. 1 and 2 and 1.49, 1.86, 2.23, and 2.61 g/Mcal in Exp. 3 and 4) within each experiment. There were 5 pens per treatment. At the start of Exp. 1 and 2, there were more pigs per pen (P < 0.001) in vaccinated pens because vaccinated pigs had a greater survival rate than nonvaccinated pigs, and this increase was maintained throughout the experiments. Removal rate approached 30% in nonvaccinated barrows and more than 20% in nonvaccinated gilts. Observation suggested that the removals were largely due to PCV2-associated disease. No PCV2 vaccination × SID Lys:ME ratio interactions (P > 0.10) were observed in any of the 4 studies. In Exp. 1 and 2, PCV2-vaccinated pigs had increased (P < 0.001) ADG compared with nonvaccinated pigs. The growth response was primarily due to increases in ADFI, which suggests that vaccinated pigs have a greater Lys requirement (g/d) than nonvaccinated pigs. In Exp. 1, increasing the SID Lys:ME ratio increased (quadratic; P < 0.04) ADG and G:F, with pigs fed the 2.99 g/Mcal ratio having the greatest ADG and G:F. In Exp. 2, increasing the SID Lys:ME ratio improved (linear; P < 0.001) G:F. In Exp. 3, ADG and G:F increased (P < 0.05) in a quadratic manner as the SID Lys:ME ratio fed increased. In Exp. 4, increasing the SID Lys:ME ratio increased ADG (linear; P < 0.001) and G:F (quadratic; P = 0.03). Although PCV2 vaccination improved growth, the corresponding increase in ADFI did not increase the optimal SID Lys:ME ratio for growing and finishing barrows and gilts.  相似文献   

19.
The Chinese highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) has caused a severe threat to the pig population in Southeast Asian countries. The purpose of this study was to investigate the efficacy of a type 2 PRRSV modified live vaccine (PrimePac? PRRS, lineage 7) against a Thai HP-PRRSV (10PL01, lineage 8). Three-week-old PRRSV-free pigs were randomly assigned into three groups. Vaccinated challenged group (group 1, n?=?16) was immunized with PrimePac? PRRS vaccine at 3 weeks old. The unvaccinated challenged group (group 2, n?=?16) was injected with PBS at 3 weeks old, and unvaccinated unchallenged group (group 3, n?=?10) was served as a negative control. At 9 weeks old, all groups, except the negative control group, were challenged with the Thai HP-PRRSV. All pigs were monitored daily during 10 days post-infection (dpi) and were necropsied at 10 and 17 dpi. The results revealed that vaccinated challenged pigs showed significantly lower (p?<?0.05) mean rectal temperatures, clinical respiratory scores, lung lesion scores, and levels of virus load in serum and lung tissue compared with the unvaccinated challenged pigs. Moreover, vaccinated challenged pigs exhibited PRRSV-specific serum neutralizing antibodies at the end of the experiment. Our findings indicated that the studied type 2 PRRSV vaccine provided partial protection against the Thai HP-PRRSV infection based on the body temperature, levels of viremia, and the severity of lung lesions. These results demonstrated that partial protection of PrimePac? PRRS vaccine might be useful for controlling HP-PRRSV infection in the endemic area.  相似文献   

20.
用健康易感仔猪进行同群感染试验和连续五代返强试验对猪肺炎支原体活疫苗(168株)进行安全性试验,同时也进行了该活疫苗单剂量、单剂量重复和大剂量试验及5批次疫苗免疫商品猪的临床试验。结果发现,猪支原体肺炎活疫苗(168株)免疫猪后,免疫猪和同群感染猪均未观察到典型的临床症状和病理变化;连续五代返强试验,试验猪均未观察到典型的临床症状和病理变化,说明该疫苗株未出现返强。单剂量、单剂量重复和大剂量试验及5批次疫苗的临床试验也未观察到不良反应。这说明受试批次猪支原体肺炎活疫苗(168株)具有良好的安全性。  相似文献   

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