Protection Of Lambs Research Articles

Vaccine Efficacy of Self-Assembled Multimeric Protein Scaffold Particles Displaying the Glycoprotein Gn Head Domain of Rift Valley Fever Virus.

Compared to free antigens, antigens immobilized on scaffolds, such as nanoparticles, generally show improved immunogenicity. Conventionally, antigens are conjugated to scaffolds through genetic fusion or chemical conjugation, which may result in impaired assembly or heterogeneous binding and orientation of the antigens. By combining two emerging technologies—i.e., self-assembling multimeric protein scaffold particles (MPSPs) and bacterial superglue—these shortcomings can be overcome and antigens can be bound on particles in their native conformation. In the present work, we assessed whether this technology could improve the immunogenicity of a candidate subunit vaccine against the zoonotic Rift Valley fever virus (RVFV). For this, the head domain of glycoprotein Gn, a known target of neutralizing antibodies, was coupled on various MPSPs to further assess immunogenicity and efficacy in vivo. The results showed that the Gn head domain, when bound to the lumazine synthase-based MPSP, reduced mortality in a lethal mouse model and protected lambs, the most susceptible RVFV target animals, from viremia and clinical signs after immunization. Furthermore, the same subunit coupled to two other MPSPs (Geobacillus stearothermophilus E2 or a modified KDPG Aldolase) provided full protection in lambs as well.

Protection in lambs vaccinated with Haemonchus contortus antigens is age related, and correlates with IgE rather than IgG1 antibody.

Protection by vaccination with excretory-secretory products (ES) from Haemonchus contortus, containing predominantly proteins of 15 and 24 kDa, against an experimental challenge infection depends on the age of the sheep. Vaccinated sheep 9, 6 or 3 months of age were protected for 83%, 77% and -34%, respectively. There was a significant difference in ES-specific serum IgE response but not in IgG1 response, after the last vaccination between the different age groups. In the protected 9-month-old animals, there was an increase up to 18 times the prevaccination levels, while the increase in the unprotected 3-month-old animals was at most 1.4 times. The 6-month-old animals showed an intermediate increase of approximately six times the prevaccination level. There was no correlation within the 9-month-old sheep between ES-specific IgE levels and protection, measured as worm burden. However, when the different age groups were combined, there was a positive correlation (r = 0.38) between protection and ES-specific IgE levels 1 week after the vaccination. At the end of the experiment, peripheral blood eosinophils and mast cell counts in abomasal tissue were also significantly higher in the vaccinated and challenged 9-month-old sheep than in the vaccinated and challenged 3-month-old or than in the 9-month-old sheep with challenge, but without vaccination. Increased serum IgE levels, eosinophilia and mucosal mast cell hyperplasia are the hallmarks of a Th2 response and were all demonstrated in protected, older sheep, but not in unprotected, younger sheep.

A single oral dose of inactivated rotavirus and ISCOM matrices induces partial protection in lambs

A single oral dose of inactivated rotavirus and ISCOM matrices induces partial protection in lambs

Vaccination schedules to raise antibody concentrations against epsilon-toxin of Clostridium perfringens in ewes and their triplet lambs.

The objective of this experiment was to compare vaccination schedules for ewes and their lambs to raise antibody concentrations to epsilon-toxin of Clostridium perfringens, the causative agent of enterotoxemia. Half of 200 Finnsheep x Dorset ewes were vaccinated with C. perfringens type D toxoid vaccine 3 wk before lambing. Serum samples were obtained from 20 ewes that were to be vaccinated and 20 ewes that would remain unvaccinated before treatment and at wk 2, 1, and 0 before the start of lambing. Antibody concentrations in sera of unvaccinated ewes remained at 2 IU/mL, but they peaked in vaccinated ewes at 15 IU/mL by wk 1 before lambing. Lambs from each of the first 13 and the first 14 sets of triplets from vaccinated and unvaccinated ewes, respectively, received one of three vaccination treatments: no vaccine (control), vaccination on d 1 and 21 of age, or vaccination on d 21 and 42 of age. Antibody concentrations declined in sera of vaccinated ewes from 8.5 IU/mL immediately after lambing to 3 IU/mL 12 wk later. Vaccination of lambs did not increase sera antibody concentration. However, prepartum vaccination of ewes significantly increased lamb antibody concentrations (19 IU/mL) compared with lambs reared by unvaccinated ewes (2 IU/mL). Vaccination of ewes resulted in lambs with higher antibody concentrations until wk 10 postpartum. Concentrations declined to .6 IU/mL in all lambs at 12 wk. Because concentrations of .2 IU/mL may be protective, these results indicate that vaccination of ewes before lambing imparts passive protection in lambs to 12 wk of age, whereas vaccination of young lambs provides no added protection.

Protection in lambs immunised with Haemonchus contortus gut membrane proteins

Substantial protection against Haemonchus contortus was induced in lambs by hyperimmunising them with an integral membrane extract of intestines dissected from adult worms. The procedure was effective in young growing animals but did not afford any cross protection against either Ostertagia circumcincta or Nematodirus battus. A serum transfer experiment suggested that the effector mechanism was serum antibody which bound to the brush border membrane of the parasites intestinal cells. Sheep which had acquired immunity to H contortus by previous exposure to a trickle infection did not recognise the gut membrane proteins, which suggested that these are normally hidden from the host.

Protection of lambs against experimental pneumonic pasteurellosis by transfer of immune serum

Passive protection of specific pathogen-free lambs against experimental pasteurellosis was achieved using antisera from conventionally reared sheep which were either convalescent from experimental pneumonia or inoculated with Pasteurella haemolytica A2 vaccines. The complete immune sera, or immunoglobulin-rich fractions prepared from them, when administered separately or together provided 94–100% protection of recipients compared to control lambs. Antibodies to P. haemolytica in donor sera were quantified by anti-sodium salicylate extract (SSE) and anti-lipopolysaccharide (LPS) ELISA, bactericidal assay, cytotoxin neutralization and indirect haemagglutination. The anti-SSE ELISA titres correlated best with protective efficacy and could be used to measure antibody in recipient lambs immediately before challenge. The degree of protection was unaffected by prior infection with parainfluenza virus Type 3, suggesting that such exposure did not enhance exudation of circulating immunoglobulin into the respiratory tract. It was concluded that systemic humoral immunity alone can prevent pasteurellosis.

Experimental infection and protection of lambs with a minute plaque variant of Rift Valley fever virus.

The injection of a single dose containing 5 X 10(3) plaque forming units (PFU) of a minute plaque variant of Rift Valley fever virus (RVFV) into two susceptible lambs resulted in no detectable viremia, pyrexia or clinical signs of disease. Immunization with the minute plaque variant induced neutralizing antibody as early as seven days postinoculation; however, no complement fixing antibodies were detected. Lambs immunized in this manner were protected when challenged with an infectious dose containing 1 X 10(3) PFU of wild type RVFV. These data indicate that the minute plaque variant may hold promise as a candidate live virus animal vaccine.

Protection of lambs against enteric colibacillosis by vaccination of ewes

Pregnant ewes were vaccinated twice, seven weeks and three weeks before lambing, with a multivalent formalin-killed Escherichia coli vaccine containing an added K99, F41 antigen preparation. Lambs born to vaccinated and unvaccinated ewes were exposed to oral infection with E coli B44 (09:K30, K99, F41). All 10 lambs from vaccinated ewes were protected whereas all 10 control lambs developed severe diarrhoea and five died or were killed in extremis. In the following year, previously immunised ewes were given a single dose of the vaccine two weeks before lambing. Eleven of their 12 lambs were protected against a similar challenge, which caused the death of six of eight control lambs and severe diarrhoea in the two survivors. Higher levels of antibody to the K99, F41 preparation were detected by enzyme-linked immunosorbent assay in the serum and colostrum from vaccinated ewes and in the serum of their lambs when compared with similar samples from control ewes and lambs.

Passive protection of lambs against septicaemic pasteurellosis.

Passive protection of lambs against septicaemic pasteurellosis.

The duration of passive protection against Taenia ovis larvae in lambs.

In an attempt to induce passive protection in lambs against Taenia ovis larvae that would last for the 15-20 weeks from birth to slaughter as fat lambs, one group of ewes was immunized by a series of injections of 2000, 4000, 8000, 16 000 and 32 000 activated oncospheres of Taenia ovis prior to parturition. Another group of ewes was not immunized. All ewes had previously grazed pasture lightly infected with T. ovis eggs. Most lambs from non-immunized ewes developed cysts after oral infection with T. ovis eggs. However, no lambs from immunized ewes developed cysts up to and including 6 weeks after birth. Between 8 and 16 weeks after birth a proportion of lambs were found to be susceptible to infection. By 18 weeks after birth all lambs were apparently susceptible. The 99% confidence band for the mean duration of demonstrable complement-fixing antibody titres was 6.2-7.8 weeks for lambs from immunized ewes. The persistence of maternal protective antibody in some lambs could possibly preclude successful active immunization of all lambs against T. ovis larvae before 18 weeks of age.

Protection of lambs against tetanus.

Abstract Extract Although all domestic animals, apart from birds, are susceptitble to tetanus, the disease in New Zealand is seen most commonly in young lambs. Neonatal infection has been suspected in the field, but postive confirmation of a clinical diagnosis is difficult. The most serious outbreaks occur shortly after docking, especially where the yard hygiene is poor or when docking methods result in slow healing of tail wounds.

Homologous passive protection of lambs against various clostridial diseases

Abstract Extract It has long been established that antibodies to the major anaerobic infections in sheep are transferred to the suckled lamb in the colostrum or first milk. Effective absorption of such antibodies from the gastro-intestinal tract takes place during the first fifteen hours of life; hence, in order to acquire protection the lamb must have suckled during this period. The degree of protection available in the colostrum will depend on the success of the immunization procedures in the ewe.

Experiments on the Protection of Lambs Against Tick Pyaemia by the Use Of Staphylococcal Toxoid

Experiments on the Protection of Lambs Against Tick Pyaemia by the Use Of Staphylococcal Toxoid