Passive protection against Salmonella enterica serovar Enteritidis infection from maternally derived antibodies of hens vaccinated with a ghost vaccine

This study evaluated maternal immunity against Salmonella enterica serovar Enteritidis acquired through the egg yolk. Two-hundred 19-week-old specific pathogen free (SPF) broiler breeders which were randomly divided into two groups of equal size were injected with S. Enteritidis ghosts (5 × 10⁹ colony forming units in 0.1 ml per hen) and phosphate-buffered saline (PBS, 0.01 mol⋅l⁻¹, pH 7.4) twice, respectively, with an interval of 2 weeks. An indirect enzyme-linked immunosorbent assay (ELISA) was applied to detect specific antibodies against S. Enteritidis. S. Enteritidis-specific antibody levels in the vaccinated group increased over time and were significantly higher than those of the control group on days 28 (P < 0.001) and 35 (P < 0.001) post-vaccination. Ten 7-day-old chicks from hens that were vaccinated with a S. Enteritidis ghost vaccine were challenged at 14 days of age with 5 × 10⁹ CFU of S. Enteritidis DH091 (homologous to the vaccine strain), 8/10 (80%) chicks from vaccinated hens survived, whereas 3/10 (30%) chicks from unvaccinated hens survived. The chicks acquired high levels of serum antibodies against S. Enteritidis. These results reveal that maternal antibodies in chicks acquired from vaccinated hens through eggs can confer a significant protection against S. Enteritidis infection.     

Resistance to Taenia pisiformis larvea in rabbits: Immunisation using live organism followed by chemotherapy therapy

Viable eggs or activated oncospheres of Taenia pisiformis were inoculated subcutaneously into rabbits. At various intervals the developing larvae were killed by treatment with Mebendazole. Most rabbits receiving oncospheres were protected against challenge infection if they were treated with Mebendazole 1 day after injection and absolute immunity was established in all rabbits if larvae were allowed to develop for 14 days before being killed. In rabbits receiving eggs, 21 days from injection to Mebendazole treatment was required before absolute immunity developed. Eggs appear to require a period of 1–2 weeks for hatching and oncosphere activation in a subcutaneous site. The data also indicate that production of functionally protective antigens occurs early during larval developement.     

Safety and efficacy of a classical swine fever subunit vaccine in pregnant sows and their offspring

In the study three groups with five pregnant sows each were used. The animals were vaccinated twice, 2 weeks apart, in different stages of gestation, i.e. +/-4, +/-8 and +/-12 weeks after insemination and then 14 days later, respectively. From each group of sows three litters were randomly selected and vaccinated twice, 4 weeks apart, at 5 and 9, 7 and 11, and 9 and 13 weeks of life, respectively. Blood for serological investigations by virus neutralisation test and ELISA tests (for E(rns) antibodies and for E2 antibodies, separately) was taken before immunisation, at each vaccination and 2 weeks thereafter. Clinical observations shown that no local nor systemic reactions as well as no adverse effect on gestation occurred after vaccinations in any of the sows. Serological tests detected a low level of antibodies after the first vaccination and a typical booster effect after the second one. In piglets no adverse effect of the vaccination on the body weight gain was found. The presence of maternally derived antibodies (MDA) in non-vaccinated control piglets was observed up to the age of 5-13 weeks of life. The most evident immunological reaction was obtained in piglets vaccinated at the age of 5 or 7 weeks of life and revaccinated 4 weeks later. The CSFV-E2 subunit marker vaccine tested proved to be safe for pregnant sows and immunogenic for MDA positive piglets.     

Immunisation of pigs with live cultures of Streptococcus suis type 2

Repeated intravenous injections of pigs with live virulent cultures of Streptococcus suis type 2 stimulated a strong protective response against subsequent challenge. This protection was transferred passively to susceptible pigs by the inoculation of sera from protected pigs. A strong protective response was also stimulated by repeated inoculations of live cultures of non-pathogenic isolates. The protective response did not eliminate S suis type 2 organisms already established in the tonsils or joints, nor prevent the establishment of subclinical infection in the tonsils.     

Safety of multiple,submucosal inoculations of a live attenuated strangles vaccine in pregnant mares

A live attenuated vaccine against Streptococcus equi was administered submucosally in the upper lip to 224 pregnant and healthy mares to evaluate its safety. After a primary immunisation the mares were inoculated every 3 months until foaling. As control group, 206 mares of the same breeding farm were administered the solvent of the vaccine submucosally. None of the 430 mares presented any clinical evidence of strangles and neither local nor systemic reactions to vaccination were noticed. There was no association between abortion and vaccination. Furthermore no case of S. equi infection was revealed at post mortem examinations of aborted foals.     

生长抑素基因疫苗pVAX1-TRX-SS对妊娠母猪及其后代的影响

妊娠后期母猪使用电转化法肌肉注射pVAX1-TRX-SS质粒,观察其对母猪生产性能及其后代的影响。选择30头胎次相近、生理状况相似的母猪,随机分为3组,在妊娠75d时分别用活体基因导入仪注射2mg pVAX1空载体、2mg pVAX1-TRX-SS和4mg pVAX1-TRX-SS。结果表明,2 mg质粒组试验母猪后代初生重比对照组提高9.70%,4mg组比对照组高14.18%,差异都达到极显著水平(P0.01);4mg质粒组的试验母猪后代断奶重分别比对照组和2mg质粒组提高8.16%和4.13%,差异极显著(P0.01);检测血清中生长抑素抗体(SS-Ab)发现,4mg质粒组试验母猪在免疫后40d血清中SS-Ab的P/N极显著高于2 mg质粒组(P0.01),同时显著高于对照组(P0.05),阳性率达60%;对试验母猪及其后代血清激素及相关蛋白检测表明,4mg质粒组试验母猪血清催乳素(PRL)浓度比对照组高120.23%(P0.05),两试验组母猪血清中胰岛素样生长因子1(IGF-1)有比对照组升高趋势,其中4mg组比对照组高18.54%,但差异不显著(P0.05),试验母猪后代血清中的IGF-1未见显著差异(P0.05);4mg质粒组试验母猪血清IGF结合蛋白(IGFBP-3)显著高于对照组和2mg质粒组(P0.05);血清生化指标的测定结果表明,试验组母猪间及其后代间的各项指标都没有显著差异(P0.05),故该质粒对试验母猪及其后代是安全的。本试验表明pVAX1-TRX-SS质粒能引发试验母猪产生免疫反应,提高母猪的生产性能及其后代的断奶重,且对母猪及其后代安全。     

Gastric cannulation of pregnant sows

The purpose of this project was to study the effect of superalimentation in lactating sows through permanent, surgically placed, gastric cannulas. A surgical technique was developed to install gastric cannulas into pregnant sows to allow superalimentation by introducing feed through the cannula. After induction of general anesthesia, a flexible, T-shaped cannula (22 mm outside diameter) was surgically placed in the dorsal portion of the greater curvature of the stomach and exteriorized through the tenth intercostal space approximately 30 cm left of the dorsal midline. Cannulas were installed on day 85 +/- 5 days of gestation. Anesthesia, surgical procedures, and the subsequent presence of the cannula did not affect the size or number of live pigs at birth. In addition, the prevalence of stillbirths and mummified fetuses was not significantly different than that of noncannulated sows. The gastric cannulas did not affect lactation performance, as litter size and weight were unaffected when compared with that in noncannulated controls. Postmortem examination of euthanatized sows revealed adhesions of the gastric wall to the abdominal wall, thus eliminating the possibility of leakage of the gastric contents into the peritoneum. Detrimental effects of the cannulas on gastric function or capacity were not detected, and cannulas could be maintained through multiple parities.     

Life cycle of Isospora suis in gnotobiotic and conventionalized piglets

Isospora suis had 3 asexual and 1 sexual intra-intestinal conventional life cycle. The first asexual generation was most prominent at 2 days p.i. (post inoculation) and produced 2–7 merozoites. The second-generation meronts were prevalent at 3–4 days p.i. and produced 2–12 large merozoites. At 4–5 days p.i. the third generation meronts were prominent and produced 4–24 small crescent shaped merozoites. Mature sexual stages were most prominent at 5–6 days p.i. The stages were most numeroous in the distal half of the small intestine. At 8–9 days p.i. stages morphologically similar to the second generation of meronts reappeared, followed by the further development into third generation merozoites and sexual stages. This was reflected in a prepatent period of 5 days and a biphasic patent period of 5–8 or 9, and 11–14 days p.i.Intraperitoneal injection of liver/spleen and intestinal lymph node homogenates, respectively, from piglets infected 24 and 48 h, previously with high doses of oocysts, resulted in a patent infection 10–12 days post inoculation of the donor piglets. No differences in the life cycle of I. suis were observed between conventionalized and germ-free piglets. An extra-intestinal life cycle of I. suis related to the second patent period was postulated.     

Prevention of experimental haemorrhagic septicaemia with a live vaccine

Pasteurella multocida serotype B:3,4 isolated from a fallow deer in England was used as a vaccine to prevent haemorrhagic septicaemia. The deer strain was less virulent for calves than typical serotype B:2 of haemorrhagic septicaemia strains. It elicited antibodies in cattle that protected mice against serotype B:2 infection. The live deer vaccine containing 2 X 10(7) viable organisms per dose was used to immunise calves. Six months after vaccination, five of six calves were protected against serotype B:2 challenge. Two calves challenged nine months after vaccination survived the same challenge. The live vaccine was more efficacious than an alum precipitated vaccine in protecting calves against B:2 challenge.     

Randomised, placebo-controlled trial of a live vaccine against porcine reproductive and respiratory syndrome virus in sows on infected farms

A randomised, double-blinded, placebo-controlled study into the effectiveness and safety of a vaccine against porcine reproductive and respiratory syndrome virus (PRRSV) was carried out on three farms with a history compatible with chronic PRRSV infection; representative groups of sows and gilts were injected with a live vaccine against PRRSV, and during the next six weeks no side effects were observed. The remaining sows and gilts on the three farms were then vaccinated with the same vaccine. Again, no side effects were observed. There were significant reductions in abortion, reproductive disease, returns to oestrus and the numbers of stillborn pigs per sow, and significant increases in the numbers of liveborn pigs per sow and weaned pigs per sow among the vaccinated animals.     

Comparison of the pathogenicity for pregnant sheep of Rift Valley fever virus and a live attenuated vaccine

A live attenuated mutant of Rift Valley fever virus, MV P12, was previously shown to be non-pathogenic in young lambs, but capable of producing protective immunity. The studies reported here show that the abortion in sheep caused by an infection with virulent virus is the result of necrosis of the maternal villi and cotyledons arising from an acute inflammation of the maternal caruncles. Pregnant ewes infected with the attenuated mutant virus MV P12 showed none of these lesions in the placenta and gave birth to healthy lambs. Colostrum from ewes infected with MV P12 virus was able to induce protective immunity in the offspring. These data along with previously published results suggest that the mutant virus MV P12 is an excellent candidate for use as a live attenuated veterinary vaccine.     

Efficacy of the classical swine fever (CSF) marker vaccine Porcilis Pesti in pregnant sows

The efficacy of the classical swine fever (CSF) subunit marker vaccine Porcilis Pesti based on baculovirus expressed envelope glycoprotein E2 of CSF virus (CSFV) was evaluated in pregnant sows. Ten gilts were vaccinated with one dose of marker vaccine, followed by a second dose 4 weeks later. Four gilts remained unvaccinated and received a placebo at the same times. Thirty-three days after the second vaccination all animals were artificially inseminated. Neither local or systemic reactions nor an increase of body temperature were observed after vaccinations. All gilts showed a normal course of pregnancy. Thirty-five days after first vaccination all animals developed E2 specific neutralising antibodies with titres in the range of 5.0 and 7.5 log(2). No antibodies to CSFV-E(rns) were found in ELISA.On day 65 of gestation (126 days after the first immunisation) all sows were infected intranasally using 2ml (10(6.6) TCID(50)/ml) of the low virulent CSFV strain "Glentorf". After challenge in two of the unvaccinated control sows a slight transient increase of body temperature was observed, whereas leukopenia was demonstrated in all control animals. In addition all controls became viraemic. Vaccinations with the CSFV subunit vaccine protected the animals from clinical symptoms of CSF. In two sows a moderate decrease of leukocyte counts was detected on day 5 post infection. In contrast to the unvaccinated control sows in none of the vaccinated animals virus was isolated from the nasal swabs or the blood.Approximately 40 days after challenge all sows were killed and necropsy was done. The sows and their offspring were examined for the presence of CSFV in blood, bone marrow and different organs. No virus was found in any of the sows. In contrast, in all litters of the control sows CSFV was found in the blood as well as in the organ samples. Nine out of 10 litters of the vaccinated sows were protected from CSFV infection. Blood samples, lymphatic organs and bone marrow of these animals were all virologically negative. When sera were tested for CSFV-antibodies all sows had developed E(rns)-specific antibodies but no CSFV-specific antibodies were found in any of the progeny.It was concluded that vaccination with CSF subunit marker vaccine Porcilis((R)) Pesti protected 90% of the litters from viral infection when sows were challenged mid-gestation using the CSFV-strain "Glentorf".     

Protection of pregnant mice against placental and splenic infection by three strains of Chlamydophila abortus with a live 1B vaccine

The efficacy of a live 1B vaccine against three strains of Chlamydophila abortus, AB16, LLG and POS, was assessed in pregnant mice in terms of the reduction in the levels of infection recorded in their placentas, fetuses and spleens. The vaccine was more effective against the AB16 strain than against the LLG and POS strains, suggesting that there are antigenic differences between the three strains.