Development of maternal antibodies after oral vaccination of young female wild boar against classical swine fever

An experimental study was performed to investigate the development of maternal antibodies after oral immunisation of young female wild boar against classical swine fever (CSF) using C-strain vaccine. Our results demonstrated that maternal antibodies do not persist in the offspring for more than 3 months. Based on the neutralising serum antibody titres, we assume that piglets of wild sows vaccinated orally twice or immunised once a long time before conception have protective antibodies for approximately 2 months. Furthermore, it seems that the level and the duration of maternal antibodies in the offspring are depend on the age of the female animals at the moment of vaccination as demonstrated in our experiment. The recent vaccination procedure consists of three double vaccinations in spring, summer and autumn. Especially vaccinations in summer and autumn could be crucial for transfer of high maternal antibody titres to the offspring.     

Evaluation of vaccine-induced maternal immunity against classical swine fever

The vaccine-induced maternal immunity against classical swine fever (CSF) was investigated in this study. Eight sows were vaccinated with the Chinese strain of classical swine fever virus (CSFV). The length of time between vaccination and farrowing was 167-217 days. Milk samples from the front, middle and back udder sections and blood samples were taken from the sows on days 3 and 14 after farrowing. Blood samples were obtained from the piglets at the age of 3, 6 and 10 weeks. The antibody level of the milk was examined by ELISA, and that of blood samples by the virus neutralization (VN) test as well. In all 3-week-old piglets and in 80% of the 6-week-old animals the neutralizing antibody level reached the titre of 1:40. In none of the 10-week-old piglets did the titre exceed the value of 1:20, but in about 25% of the piglets it reached 1:20; the half of these piglets came from two litters. In none of the piglets did the antibody level reach the negative threshold in the ELISA test during the study. No significant differences were found between the udder sections in milk antibody level by ELISA.     

Prevalence of African swine fever virus and classical swine fever virus antibodies in pigs in Benue State,Nigeria

Tropical Animal Health and Production - This study investigated the prevalence of African swine fever virus (ASFV) and classical swine fever virus (CSFV) antibodies in pigs in Benue State, Nigeria....     

The effect of Trypanosoma evansi infection on pig performance and vaccination against classical swine fever

Although Trypanosoma evansi is not considered as an important pathogen in pigs, it may interfere with other pathogens or vaccinations by its immunosuppressive nature. In order to determine whether T. evansi alters pig performance and induces immunosuppression in pigs, induction of immune responses by vaccination against classical swine fever (CSF) and by immunization with a control antigen, human serum albumin (HSA), was assessed in T. evansi-infected and non-infected animals. Although T. evansi infection did not have a significant influence on growth performance, feed conversion or PCV, antibody responses against both the test antigen HSA and the CSF vaccine were significantly reduced in T. evansi-infected animals as compared to uninfected animals. Moreover, the reduced response against the CSF vaccine appears to be accompanied by a less well-developed protection against CSF with higher fever responses and leukopenia. This immunosuppression might explain the accounts of poor protection of CSF-vaccinated pigs reported in T. evansi-endemic areas of Vietnam, and suggests that prior treatments with trypanocidal drugs to improve the efficacy of CSF vaccination, may be justified.     

猪瘟单克隆抗体的制备及ACI-ELISA检测猪瘟病毒的研究

本研究用猪瘟石门毒(CSFV-Shimen)免疫BALB/C小鼠,按常规单克隆抗体(McAb)技术方法制作,最终获得4株McAb,分别命名为AC9、CF8、DG5和EC9,4株McAb与基因工程CSFV E2蛋白反应结果表明:AC9、CF8和EC9是抗CS-FV E2蛋白的McAb.用AC9和CF8McAb对CSFV进行抗原捕获间接ELJSA试验(ACI-ELISA),通过一元McAb和二元McAb CAI-ELISA试验的比较,结果表明AC9与CF8两种McAb有协同作用,其捕获CSFV的能力比一元McAb显著提高.方阵试验结果表明:McAb和血清多抗(PcAb)的最佳工作稀释度分别为1:400和1:200.特异性试验和敏感性试验结果显示本法特异性强,敏感性高.最后用ACI-ELISA与PCR对30份病料的检测结果比较,表明ACI-ELISA与PCR检测结果相符.上述结果说明本研究所获得AC9和CF8可用作猪瘟诊断试剂盒的研制,是检测CSFV的有效方法.     

Simultaneous vaccination of piglets against foot-and-mouth disease and classical swine fever

Six-week-old piglets, born of unvaccinated sows, were vaccinated against foot-and-mouth disease (FMD) with a trivalent, inactivated vaccine containing an adjuvant or vaccinated against classical swine fever (CSF) with a live attenuated vaccine or against both diseases simultaneously at two different sites. The antibody response to the FMD vaccine was not significantly influenced by the simultaneous vaccination against CSF. FMD vaccine administered simultaneously with the CSF vaccine produced a significantly higher antibody response to CSF than occurred with CSF vaccination only.     

The influence of maternal immunity on the efficacy of a classical swine fever vaccine against classical swine fever virus,genogroup 2.2, infection

In Thailand, where vaccination is routinely employed, there has been an increased incidence of chronic classical swine fever (CSF) outbreaks during the past decade. The major causative virus has been identified to be the moderate virulence, classical swine fever virus (CSFV) of the genogroup 2.2. An investigation was made into the efficacy of a CSF vaccine against this genogroup 2.2 challenge. Five-week-old pigs, grouped by their level of passive antibody titer were immunized with lapinized Chinese-strain CSF vaccine and challenged with CSFV genogroup 2.2, 13 days after vaccination. The group containing passive titers of lower than 64 at the time of immunization, had significantly higher number of CSFV-specific IFN-gamma secreting cells and was completely protected against the challenge. Interestingly, both cellular and antibody responses were inhibited in the pigs with the higher passive titer. Furthermore, following challenge, CSFV could be isolated from 50% of the pigs in this group. It was demonstrated that the CSF vaccine could induce complete protection in pigs, provided that the maternal derived titer at the time of vaccination was lower than 64. The result implied that an increase in CSFV outbreaks might be due to the inappropriate timing of vaccination as well as the nature of the CSFV genogroup 2.2.     

猪瘟免疫程序及其免疫效果研究

对不同日龄的猪用不同剂量猪瘟兔化弱毒疫苗进行免疫 ,通过正向间接血凝试验进行猪瘟抗体监测。结果表明 ,用 1头份猪瘟弱毒疫苗在配种前 1 5d免疫母猪可保证其仔猪体内母源抗体较高 ;对仔猪首免用 1头份猪瘟疫苗进行超前免疫、在 60日龄用 2头份的猪瘟疫苗进行二免的免疫效果最好 ;阉割等应激反应可降低仔猪的免疫效果     

“猪瘟和非洲猪瘟的综合防治措施”专栏(三) 影响猪瘟流行地区疫苗成功接种的关键因素

猪瘟(Classical Swine Fever,CFS)又称猪霍乱,由猪瘟病毒(CSFV)引起,是能给全球养猪业造成严重经济损失的最重要的病毒性疾病之一.在过去的5年中,多项用于测定猪细胞免疫(Cell-Mediated Immunity,CMI)的技术与其他常规技术一起,被用来研究可影响猪瘟病毒特异性免疫诱导的因素.从一系列试验获得的资料证明,细胞免疫应答可提供抗猪瘟感染的保护性免疫.尽管业已证实商用改良型猪瘟活疫苗能够诱导免疫猪产生完全的保护,但包括母源免疫、首次免疫年龄、免疫接种方案和其他病原体引起的并发症等多种因素,均会严重影响猪瘟疫苗在田闻的免疫效果.     

Factors critical for successful vaccination against classical swine fever in endemic areas

Classical swine fever (CSF) or hog cholera, caused by the classical swine fever virus (CSFV), is one of the most important viral diseases that cause serious economic loss to the swine industry worldwide. During the past 5 years, several techniques for measuring porcine cell-mediated immunity (CMI) were applied, in conjunction with other conventional techniques, to study factors that influence the induction of CSFV-specific immunity. Information, obtained from a series of experiments, demonstrated cell-mediated immune responses in providing protective immunity against CSF infection. Although it has been confirmed that commercially available modified live CSF vaccines are able to induce complete protection in vaccinated pigs, several factors including maternal immunity, the age of primary vaccination, vaccination protocol and complications caused by other pathogens, can greatly affect the effectiveness of CSF vaccines in the field.     

The influence of age and maternal antibodies on the postvaccinal response against swine influenza viruses in pigs

The influence of age and maternal immunity on the development and duration of postvaccinal humoral response against swine influenza viruses (SIV) were investigated under experimental conditions. Piglets born to immune and non-immune sows were vaccinated twice with bivalent inactivated vaccine. Vaccination was done according to 5 different schedules: 1+4, 1+8, 4+8, 8+10 or 8+12 weeks of age. Antibodies to the haemagglutinin type 1 and 3 were determined using the haemagglutination inhibition (HI) test. Maternally derived antibodies (MDA) against H1N1 and H3N2 in the serum of unvaccinated piglets born to immune sows were above the positive level until about 13-14 and 9-10 weeks of life, respectively. No serological responses were seen in any of the groups after the first vaccination. After the second dose of vaccine production of antibodies was observed even before the complete disappearance of maternal antibodies. MDA, however, were associated with reduced antibody response. In MDA-negative piglets, an active humoral postvaccinal response was developed in all vaccinated pigs. The age at which the vaccine was given was associated with the differences in the magnitude of antibody response to SIV. In general those pigs that were vaccinated for the first time at the age of 1 week, developed lower maximum titres after the second vaccination, and become seronegative earlier than pigs that were vaccinated for the first time at 4 or 8 weeks of age.     

影响猪瘟流行地区疫苗成功接种的关键因素

猪瘟（Classical Swine Fever，CFS）又称猪霍乱，由猪瘟病毒（CSFV）引起，是能给全球养猪业造成严重经济损失的最重要的病毒性疾病之一。在过去的5年中，多项用于测定猪细胞免疫（Cell-Mediated Immunity，CMI）的技术与其他常规技术一起，被用来研究可影响猪瘟病毒特异性免疫诱导的因素。从一系列试验获得的资料证明，细胞免疫应答可提供抗猪瘟感染的保护性免疫。尽管业已证实商用改良型猪瘟活疫苗能够诱导免疫猪产生完全的保护，但包括母源免疫、首次免疫年龄、免疫接种方案和其他病原体引起的并发症等多种因素，均会严重影响猪瘟疫苗在田间的免疫效果。     

猪全血溶血对猪瘟抗体检测的影响

为研究猪全血溶血是否对猪瘟抗体效价产生影响,在明溪县某规模养殖场选择注射过2次猪瘟疫苗的肉猪20头,抽取全血各2份,共40份,相同条件保存,使其中1份溶血。将进行溶血处理和未处理的全血离心出的血清进行物理性状观察和ELISA检测,并对检测的OD值进行比较分析。结果发现,是否溶血对ELISA检测的OD值无统计学差异,表明短期内只要保存得当,是否溶血不会造成猪瘟抗体效价的显著降低。     

Transient classical swine fever virus infection in wild boar piglets partially protected by maternal antibodies

An experimental study was conducted to investigate the clinical course of classical swine fever (CSF) in wild boar piglets partially protected by maternal antibodies. Five healthy wild boar piglets with a low serum titre of colostral antibodies against CSF virus were challenged with virulent CSF virus at the age of three months. Apart of reduced food intake and diarrhoea no major clinical symptoms were noticed after challenge. These signs were seen during the second and third week of infection, afterwards the piglets recovered completely. CSF virus could be re-isolated from blood samples taken on day 12 and day 19 post challenge. From blood samples taken later on and from the organ material taken at post mortem examinations no CSF virus could be isolated anymore. It can be concluded that the presence of maternal antibodies influences the clinical course of CSF in terms that the outcome is rather transient than lethal. Such wild boar could play a crucial role in the spread of CSF virus and might contribute to the maintenance of long lasting epizootics.     

Passive transfer of maternal immunoglobulin isotype antibodies against tetanus and influenza and their effect on the response of foals to vaccination.

Influenza and tetanus-specific antibodies of the IgG sub-isotypes are posively transferred to foals via colostrum and inhibit their response to inactivated influenza vaccines and tetanus toxoid. High titres of influenza antibodies of IgGa and IgGb subisotypes and tetanus antibodies of the IgGa, IgGb and IgG(T) subisotypes were detected in postsucking serum samples collected from foals born to mares that had received booster doses of multicomponent vaccines during the last 2 months of gestation. Thereafter, titres declined in an exponential manner but were still detectable in all foals at age 26 weeks, regardless of whether they had been vaccinated prior to age 26 weeks. Mean +/- s.e. half-life of decline of influenza IgGa antibodies (27.0 +/- 2.3 days) was significantly shorter than that of influenza IgGb antibodies (39.1 +/- 2.7 days; P<0.005). Tetanus IgGa and IgGb antibodies declined with half-lives of 28.8 +/- 3.0 and 34.8 +/- 5.1 days, respectively. Titres of tetanus IgG(T) antibodies were substantially higher than those of influenza IgG(T) antibodies in postsucking samples and remained so through age 26 weeks, declining with a half-life of approximately 35 days. Postsucking titres of tetanus and influenza antibodies of the IgA isotype were low and declined rapidly to undetectable levels. Yearlings showed significant increases in titre of influenza IgGa, IgGb and IgG(T) subisotype antibodies but no increase in influenza IgA antibodies in response to 2 doses of multicomponent vaccines containing tetanus toxoid and inactivated influenza A-1 and A-2 antigens. Yearlings also showed strong tetanus IgGa, IgGb and IgG(T) subisotype responses to one dose of vaccine and a substantial further rise in titre in response to administration of a second dose 3 weeks later, but failed to show an increase in titre of tetanus IgA antibodies. The influenza and tetanus IgGa, IgGb and IgG(T) subisotype responses of 6-month-old foals to vaccination followed the same pattern as those shown by yearlings but titres were generally lower. In contrast, 3-month-old foals failed to show increases in titre of either influenza or tetanus IgG subisotypes in response to 2 doses of vaccine and generally needed 1-3 additional booster doses of vaccine to achieve titres similar to those achieved by yearlings after 2 doses. Based on the finding that maternal antibodies exert a significant inhibitory effect on the response of foals to tetanus toxoid and inactivated influenza antigens, it is recommended that primary immunisation of foals born to vaccinated mares should not commence before age 6 months.     

规模化猪场猪瘟免疫状况调查及仔猪首免日龄的优化

为了调查规模化猪场猪瘟的免疫方案,比较及评价其免疫效果,本研究将湖北省7个规模化种猪场作为研究对象,将猪群分为经产母猪、种公猪、后备母猪、哺乳仔猪(0~30日龄)、保育仔猪(30~60日龄)和生长猪(61日龄以上)6个群体,并按各猪群5%~8%的比例采血,检测猪瘟抗体。结果表明,各猪群猪瘟免疫合格率分别为99.55%、96.43%、99.22%、89.88%、81.68%及78.64%,不同免疫方案下,各场猪群表现出不同免疫效果。而从总体上看,保育仔猪的猪瘟抗体水平是各个猪群中最为薄弱的环节。因此本研究在调查的基础上,继续探索了一个规模化猪场的仔猪猪瘟母源抗体消退规律,并且分别设置了14、21、28、35日龄猪瘟疫苗免疫组,于免疫后1周及2周后采血检测猪瘟抗体。结果表明,该场猪瘟免疫最佳首免日龄为28日龄,并根据研究结果将该场原来的首免21日龄调整到28日龄。本研究的开展对规模化猪场制定合理的猪瘟免疫方案具有较好的参考价值。     

三个厂家猪瘟活疫苗免疫效果比较试验

在同一条件下对3个厂家生产的猪瘟细胞源活疫苗进行了免疫效果评价试验,并与猪瘟传代细胞苗免疫效果进行比较。结果发现3个厂家生产的猪瘟细胞源活疫苗存在一定差异,2个厂家的免疫效果较好,1个厂家的免疫效果较差。猪瘟传代细胞苗免疫效果优于猪瘟细胞源活疫苗,猪瘟传代细胞苗免疫1次,抗体合格率高,持续时间长,猪瘟细胞源活疫苗要免疫两次才能获得比较好的效果。同时,我们发现高致病性猪蓝耳病活疫苗（JXA1-R株）对猪瘟抗体产生有一定影响。     

Intranasal vaccination of pigs against Aujeszky's disease: protective immunity at 2 weeks, 2 months and 4 months after vaccination in pigs with maternal antibodies.

The purpose of the study was to evaluate the short- and long-term immunity after intranasal vaccination in pigs with maternally derived antibodies (MDA). In two experiments, 10-week-old pigs with moderate MDA titres against Aujeszky's disease virus (ADV) were vaccinated intranasally with the Bartha strain of ADV to evaluate the protective immunity conferred at 2 weeks, 2 months and 4 months after vaccination. Protection was evaluated on the basis of severity of clinical signs, periods of fever and growth arrest, and duration and amount of virus excreted after challenge with a virulent ADV. During the first 2-3 weeks after vaccination, antibodies to ADV continued to decline as in unvaccinated control pigs. After that, antibody titres stabilized or gradually increased. At 2 weeks, 2 months and 4 months after vaccination, vaccinated pigs were significantly better protected than unvaccinated controls. The vaccinated pigs challenged 2 weeks after vaccination hardly developed any sign of disease. Mild signs of Aujeszky's disease and a growth arrest period of 5 days were observed in vaccinated pigs challenged 2 months after vaccination, whereas vaccinated pigs challenged 4 months after vaccination developed severe signs of disease and a growth arrest period of 13 days. Vaccinated pigs challenged 2 weeks after vaccination did not excrete challenge virus, and pigs challenged 2 or 4 months after vaccination excreted far less virus than unvaccinated controls. The results demonstrate that intranasal ADV vaccination of pigs with moderate MDA titres protected them from 2 weeks to at least 4 months after vaccination. Immunity steadily declined, however, after vaccination.