Immunized Lambs Research Articles

The Effects of Electrolytic Multivitamins and Neomycin on Antioxidant Capacity and Intestinal Damage in Transported Lambs.

Transport stress can cause damage to animals. In this experiment, 60 four-month-old lambs were randomly divided into three groups: CG (basal diet), EG (basal diet + 375 mg/d/lamb electrolytic multivitamin), and NG (basal diet + 200 mg/d/lamb neomycin). The results were as follows: during road transport, in all groups, the levels of SOD, T-AOC, and GSP-Px, and mRNA expressions of CAT, SOD, Nrf2, HO-1, and Bcl-2 in the jejunum and colon decreased (p < 0.01). However, mRNA expressions of Keap1, IL-1β, IL-2, IL-12, Bax, and Caspase3 in the jejunum and colon and the level of MDA increased (p < 0.01). The concentrations of IgA, IgG, and sIgA in the jejunum and colon also decreased (p < 0.01). In the EG and NG, the levels of SOD (p < 0.05) and T-AOC (p < 0.01) increased, and the level of MDA decreased (p < 0.01). However, in the jejunum, the levels of SOD and T-AOC, the concentrations of IgA and IgG, and mRNA expression of Bcl-2 increased (p < 0.05). mRNA expressions of IL-1, IL-2, and Caspase 3 (p < 0.05), and mRNA expression of IL-12 (p < 0.01) decreased. In the colon, SOD activity and the concentration of sIgA increased (p < 0.01). The level of MDA and mRNA expressions of IL-2 and Caspase 3 also decreased (p < 0.05). In the jejunum and colon, mRNA expression of SOD (p < 0.05) and mRNA expression of Nrf2 increased (p < 0.01). mRNA expression of Keap1 (p < 0.05) and Bax (p < 0.01) decreased. In summary, road transport can cause a decrease in antioxidant activity and immunity of lambs and an increase in oxidative damage. Electrolytic multivitamins and neomycin can improve immune function and potentially reduce oxidative damage to the jejunum and colon.

Selenium nanoparticles effect on foot and mouth disease vaccine in local Awassi breed male lambs.

The goal of this research was to evaluate where selenium nanoparticles impact the activity of antibodies in immunized lambs with foot and mouth vaccines by modulating the immune system. Two groups of lambs of 3-4 months of age were injected with 1 ml of ARRIAH-VAC vaccine intramuscularly in the neck, five Lambs were given selenium nanoparticles (size 100 nm) oral administration of selenium nano dose of 0.1 mg/kg of body mass once every day for sixty days considered as group one (G1) while the other five used as control Group 2 (G2). This resulted in the establishment of an immune response, as evidenced by a rise in antibody titer in the blood using the ELISA test for three serotypes A, O, and Asia 1, when selenium nanoparticles were given orally at a dose of 0.1 mg/kg body weight after immunization, we noticed a significant (p >0:05) selenium nano group increase in IgG response in all immunized groups in contrast to lambs that had only received the foot-and-mouth disease vaccine. We have demonstrated that selenium nanoparticles administered orally significantly enhance immune responses while also increasing body weight.

Defining optimal thresholds for digital Brix refractometry to determine IgG concentration in ewe colostrum and lamb serum in Scottish lowland sheep flocks.

This research aimed to define thresholds for ewe colostrum and lamb serum Brix refractometer measurements in lowland Scottish sheep. This would facilitate the use of this convenient, sheep-side test, enabling quick and accurate identification of poor quality colostrum and prevention of failure of transfer of passive immunity (FTPI) in lambs. Secondary aims were to identify risk factors for poor colostrum quality and FTPI in lambs. Serum samples (n=233) were collected from lambs between 24 and 48hrs after birth, from four lowland Scottish meat sheep farms. Pre-suckle colostrum samples (n=112) were also collected from ewes on two of these farms. Farmers provided information on litter size, ewe body condition score, ewe breed and dystocia. Duplicate digital Brix refractometer measurements were compared with immunoglobulin G (IgG) radial immunodiffusion (RID) testing for all colostrum and serum samples. Receiver operating characteristic (ROC) curves were used to redefine thresholds for Brix testing in colostrum and serum. Linear regression models were constructed with colostrum and serum IgG concentration as the outcomes of interest. Colostrum and serum IgG concentrations were highly variable. The prevalence of inadequate colostrum quality (using <50g/L IgG on RID) was 4.5% (95% CI = 1.5 - 10.1) and the prevalence of FTPI (using <15g/L IgG in serum on RID) was 7.73% (95% CI = 4.64-11.93). A ewe's colostrum IgG concentration was significantly and positively associated with the serum IgG concentration of her lamb(s) (p=0.02). ROC analysis defined a Brix threshold for adequate colostrum quality of >22.10% (sensitivity 80% (95%CI=28.4-99.5), specificity 90% (95%CI=82.3-94.8)). ROC analysis defined a Brix threshold for serum of >8.65% for adequate passive transfer of immunity in Scottish lambs (sensitivity 94% (95%CI=72.7-99.8), specificity 82% (95%CI=76.6-87.2)). To optimise passive transfer of immunity in lambs, we suggest that ewe colostrum Brix measurements be defined as 'poor' (<22%); 'fair' (22-26%) and 'good' (>26%); and lamb serum as 'poor' (<8%); 'fair' (8-9%) and 'good' (>9%). It is recommended that these tests are used as for flock screening, using samples from multiple animals.

Chemometric Approaches to Analyse the Composition of a Ewe's Colostrum.

Colostrum is a major source of immunity in lambs and, in general, in all newborn ruminants. It allows the transfer of antibodies from the ewe to the lamb, and it becomes the exclusive source of nutrients for a newborn. Among the most significant Pearson correlations, the positive correlation between the Brix refractive index (Brix) and protein (0.90) should be noted. Both parameters (protein percentage and Brix) were then positively correlated with the percentage of fat (0.38 and 0.41), urea (0.81 and 0.67), calcium (0.39 and 0.29), and magnesium (0.58 and 0.59), as well as the yellowness (0.78 and 0.75). Somatic cell count (SCC) and pH, parameters which are indicators of subclinical mastitis, were positively correlated (0.49), and SCC was positively correlated with sodium (0.37) and negatively correlated with potassium (-0.28). Among the macroelements in colostrum-calcium, potassium, magnesium, and sodium-the correlations were largely positive. With respect to the colour parameters, yellowness was negatively correlated with lightness (-0.41) and redness (-0.45). The factor analysis split the total of variance into three latent factors. The first factor was named "Colostrum quality of grazing sheep" because it was positively correlated primarily with SCC, pH, Poly Unsatured Fatty Acids (PUFA), and the sum of the omega-3 Fatty Acids (FAs). The second factor, named "Good quality colostrum", was positively correlated primarily with the refractive index, protein and fat percentages, urea content, phosphorus, Mono Unsatured Fatty Acids (MUFA), and yellowness. The third factor was positively correlated primarily with calcium, potassium, magnesium, and sodium, and it was therefore termed "Mineral component of colostrum". Stepwise discriminant analysis showed that the protein percentage, calcium, and magnesium were able to explain more than 85% of the Brix refractive index, which remains a good parameter for simply evaluating the nutritional quality of sheep colostrum at the level of a farm.

A Quantum Vaccinomics Approach for the Design and Production of MSP4 Chimeric Antigen for the Control of Anaplasma phagocytophilum Infections.

Anaplasma phagocytophilum Major surface protein 4 (MSP4) plays a role during infection and multiplication in host neutrophils and tick vector cells. Recently, vaccination trials with the A. phagocytophilum antigen MSP4 in sheep showed only partial protection against pathogen infection. However, in rabbits immunized with MSP4, this recombinant antigen was protective. Differences between rabbit and sheep antibody responses are probably associated with the recognition of non-protective epitopes by IgG of immunized lambs. To address this question, we applied quantum vaccinomics to identify and characterize MSP4 protective epitopes by a microarray epitope mapping using sera from vaccinated rabbits and sheep. The identified candidate protective epitopes or immunological quantum were used for the design and production of a chimeric protective antigen. Inhibition assays of A. phagocytophilum infection in human HL60 and Ixodes scapularis tick ISE6 cells evidenced protection by IgG from sheep and rabbits immunized with the chimeric antigen. These results supported that the design of new chimeric candidate protective antigens using quantum vaccinomics to improve the protective capacity of antigens in multiple hosts.

The succession of fecal bacterial community and its correlation with the changes of serum immune indicators in lambs from birth to 4 months

Early bacterial colonization and succession within the gastrointestinal tract have been suggested to be crucial in the development of host immunity. In this study, we have investigated the changes in live weight and concentrations of selected serum parameters in relation to their fecal bacterial communities as determined by high throughput sequencing of the 16S rRNA gene over the same period in lambs. The results showed that lambs’ growth performance, the serum parameters, fecal bacterial community and fecal bacterial functions were all affected (P<0.05) by age of the lambs. Similarity within age groups of fecal microbiota was lower in the preweaning period and increased sharply (P<0.05) after weaning at 60 days. The similarity between the samples collected from birth to 90 days of age and those collected at 120 days of age, increased (P<0.05) sharply after 30 days of age. Some age-associated changes in microbial genera were correlated with the changes in concentrations of immune indicators, including negative (P<0.05) correlations between the relative abundance of Lachnospiraceae UCG-010, Eubacterium coprostanoligenes group, Ruminococcaceae UCG-005, Ruminococcaceae UCG-009, Ruminococcaceae UCG-013, Ruminiclostridium 6, Ruminococcaceae UCG-008, and Oscillibacter with serum concentrations of lipopolysaccharide (LPS), D-lactate dehydrogenase (DLA), immunoglobulin (IgA, IgM, and IgG), and cytokines (interleukin-1β (IL-1β), IL-6, IL-12, and IL-17), tumor necrosis factor-α (TNF-α), and the relative abundance of these genera increased from 45 days of age. In conclusion, these results suggested that the age-related abundances of particular genera were correlated with serum markers of immunity in lambs, and there might be a critical window in the period from birth to 45 days of age which provide an opportunity for potential manipulation of the fecal microbial ecosystems to enhance immune function.

Pre-Partum Supplementation with Polyunsaturated Fatty Acids on Colostrum Characteristics and Lamb Immunity and Behavior after a Mild Post-Weaning Aversive Handling Period.

Simple SummaryLivestock farming faces the necessity of reducing the use of medicines, particularly antimicrobials, without compromising animal welfare as one main challenge. A strategy to improve animal health, specifically in breeding stock, relies on improved nutrition of the mothers during late pregnancy and on management factors during early life. These could affect mother and offspring physiological functions (calostrogenesis, fetal development or maturation of lamb’s immune system) and potentially modulate their stress-response capabilities. We studied the effect of pre-partum omega-3 (n-3) polyunsaturated fatty acids supplementation on ewe colostrum composition and immunological quality and whether changes resulted in any advantage on lambs’ passive immunization and on their physiological, behavioral, and inflammatory responses when subjected to a post-weaning stressor to confer stress resilience. Gestational supplementation with nutrients rich in essential fatty acids was effective to enhance colostrum quality related to biologically active molecules, such as conjugated linoleic acid, which plays a role in the regulation of the immune response. Stress resilience was studied by assessing lamb’s behavioral response after exposing lambs to a combination of stressors and by measuring plasma cortisol concentrations and immunological responses to specific circulating cytokines. This work highlights the complex relationship between late pregnancy nutrition in the mothers and immune system development in the offspring and explores the potential for programming nutrition interventions to develop more resilient livestock and to tackle the need for a reduction in the use of antibiotics.We studied the effect of pre-natal supplementation with n-3 α-linolenic acid (ALA) combined with a tannin-rich forage on colostrum composition and immunological quality and whether these changes had advantageous effects on lambs’ survival and stress reaction to a post-weaning stressor. Forty-eight Latxa ewes were fed during the last five weeks of pregnancy with two experimental diets: a control diet based on a neutral concentrate and forage (tall fescue hay; CO-FES), and a supplemented diet based on polyunsaturated (PUFA)-rich concentrate and tanniferous forage (sainfoin; ALA-SAIN). After parturition, twenty ewes had their blood and colostrum sampled, and their lambs were monitored until post-weaning. Lambs were afterwards subjected to (i) an aversive handling period (AHP) followed by a behavioral assessment and (ii) inflammatory and lymphocyte proliferation challenge. Feeding ALA-SAIN resulted in changes in colostrum fatty acid composition, specifically higher α-linoleic acid (p < 0.001), conjugate linoleic acid (p = 0.005), vaccenic acid (p = 0.006) and long-chain n-3 PUFA (p = 0.004). Pre-partum nutrition did not affect lamb immunoglobulin (Ig) G apparent efficacy absorption, but circulating IgG tended to be higher (p = 0.054) in ALA-SAIN lambs. ALA-SAIN lambs interacted more frequently with other lambs (p = 0.002), whereas ALA-SAIN females spent more time closer to other lambs (p < 0.001). Plasma cortisol was higher (p = 0.047) and plasma interleukin (IL)-2 lower (p = 0.003) in CO-FES lambs. This research highlights the importance of prenatal nutrition on the immune system stimulation and lambs’ behavior as a strategy to improve lambs’ health and welfare during early life.

Improved vaccination protocol to enhance immunity in lambs of Kuwait farms

The susceptibility of lambs to infective diseases should be minimized by improving the immunity of lambs through effective vaccination procedures to abate lamb mortality in sheep farms. In this regard, field experiments were carried out with 180 pregnant ewes of Naeemi sheep breed at the PAAFR (Public Authority for Agriculture and Fisheries Research Station, Kuwait). The results revealed that the concentration of serum Ig’s in blood samples collected from ewes vaccinated during pregnancy with Pasteurella, Clostridia, FMD (Foot and Mouth Disease) and PPR (Peste des Petits Ruminants) vaccines was significantly elevated as vaccination against these four diseases agents would have ultimately resulted in circulating antibodies protecting the animals against natural exposure. Theconcentration of colostral Ig’s produced by vaccinated ewes during the pregnancy period was significantly (P<0.05) higher than the normal colostrum secreted from unvaccinated ewes during pregnancy, ensuring the positive role of the colostrum in transferring passive immunity. The results clearly illustrated no cases of mortality and abortion, as vaccination has played a role in maintaining the health of ewes by overcoming the targeted pathogens and preventing any abnormalities in the pregnant ewes. The present study confirmed the improved immune status of young lambs born to ewes vaccinated twice during pregnancy, reflecting improved health status. It is recommended to maintain 21 days’ intervals in vaccinating ewes with different vaccines for specific diseases.

Determining the Duration of Maternal Immunity Against Sheep Pox in Lambs.

Maternal immunity may affect vaccination success in young lambs. This study was aimed to determine the duration of the maternal immunity in lambs born from vaccinated ewe against Sheep pox. The level of neutralizing antibody against Sheeppox virus (SPPV) was measured in 14 lambs that were fed colostrum of their immunized mother (MCF lambs; n = 14) or reared with colostrum of ewes that were not immunized against Sheep pox, as the control (C lambs; n = 7), using virus neutralization index. The lambs were randomly divided into four experimental groups and after blood sampling, they were challenged by a virulent SPPV at different postbirth days, including 15 (2 CF and 1 C lambs), 30 (4 CF and 2 C lambs), 60 (4 CF and 2 C lambs), and 90 (4 CF and 2 C lambs) days of age. All the C lambs had no antibody titers against SPPV. Results of the challenge test showed that, up to 60 days of age, the MCF lambs had only localized scabs at the inoculation site and did not show any secondary pock lesions associated with Sheep pox; while all the C lambs were infected (p < 0.05). However, the percentage of lambs with Sheep pox signs was not different between C and MCF lambs after the challenge test at 90 days old lambs (p > 0.05), indicating decrease of maternal immunity. These findings revealed that the duration of maternal immunity against SPPV is ∼60 days, and vaccination is better to be performed at later ages.

PSIII-13 The Effect of the inclusion of liquid brewers yeast during gestation on colostrum quality and passive transfer of immunity in lambs

Abstract Fourteen Suffolk/Suffolk x Hampshire pregnant ewes were utilized to evaluate the effects of liquid brewers yeast on colostrum quality and the transfer of passive immunity in their offspring. Parainfluenza type 3 (PI3) vaccination was used elicit an immune response. Ewes were vaccinated with PI3 at 33 and 18 d prior to expected lambing day. Ewes were randomly assigned to one of two treatments: late gestation diet (CON) or late gestation diet supplemented with liquid brewers yeast at an average rate of 60 g DM/d (LBY). Ewes were fed treatment diets from 45 d prior to expected lambing to 3 d post lambing. Blood was collected from ewes’ via jugular venipuncture prior to vaccination and within 6 hours postpartum. Blood was collected also from the jugular vein of lambs (n = 22) at 3 d of age. Ewe and lamb blood serum was tested for Bovine Parainfluenza 3 Virus and data on anti-PI3 antibody titers was evaluated. Colostrum was collected within 4 hours postpartum and analyzed for colostral IgG concentrations using a refractometer in % Brix. A PROC GLM model was performed in SAS 9.4, where the model for ewe colostrum quality and lamb anti-PI3 titers analyses included the main effect of treatment diet. All vaccinated ewes were positive for PI3 antibodies (&amp;gt;64 titer) immediately prior to and post lambing. All lambs tested positive for antibody titers for PI3 with no differences between treatment (197.3 for CON and 160.8 for LBY; P = 0.43). The colostral IgG concentrations did not differ between CON (30.4% Brix) and LBY (24.6% Brix) ewes(P = 0.21). These results indicate that, although there were numerical differences, the addition of LBY to the ewes’ diet during late gestation did not significantly improve colostrum quality or passive transfer of immunity in lambs.

Combined use of two separate but protective vaccine antigens provides protection against Taenia ovis infection in lambs in the presence of protective maternal antibody

Three recombinant Taenia ovis antigens (To45, To16, To18) each induce protective immunity in lambs or ewes against infection with T. ovis metacestodes. The degree and duration of immunity were assessed in lambs born from vaccinated ewes. Treatment group sizes varied, typically not fewer than 5 animals per group. Ewes were immunised with one T. ovis recombinant protein prior to lambing and the degree and duration of passive immunity in their lambs was assessed by challenge infection up to 18 weeks. Lambs were fully protected up to 6 weeks of age but immunity waned from 6 to 12 weeks and there was no protection when lambs were challenged at 15 weeks. Immunisation of lambs with the homologous recombinant antigen was not effective when vaccinations were given when maternal antibody was high. Lambs were effectively immunised in the presence of passively protective antibody when vaccinated with an antigen that was different to that given to ewes. Vaccination of lambs with a combination of two proteins, To16 and To18, was more effective than giving these single antigens and gave a significant reduction of cyst numbers when lambs were challenged 12 months after immunisation. These results indicate that the use of combinations of T. ovis recombinant antigens could enable complete protection of lambs against infection, if a delivery system becomes available that will maintain antibody at protective levels for 12 months. Alternatively, a third injection given at 6 months may promote the anamnestic response to give long lasting protection.

Passive immunity in lambs: Colostral and serum γ-glutamyltransferase as a predictor of IgG concentration and related to the diseases from birth to 12 weeks of life

The main goal of this study was to find a link between colostrum and the 1-day-old lamb serum γ-glutamyltransferase (GGT) activity and immunoglobulin G (IgG) concentration and their relation with neonatal diseases and beyond. Further, to set a linear relationship between the serum GGT activity (SGGTA) and the IgG concentration (SIgGC) in different days of the neonatal period, thereby determining the feasibility of the GGT activity in the prediction of the colostrum quality and passive immunity and to define a cut-off point for the SGGTA associated with an increased risk of illness or death in lambs. For this purpose, blood samples were obtained from the lambs before the colostrum intake (day 0) and on different days (1, 2, 4, 7, 14 and 28) in the neonatal period. The colostrum was collected from the respective ewes (n = 254) related to the lambs. The most accurate (R&lt;sup&gt;2&lt;/sup&gt; = 0.652) model for predicting the SIgGC or passive immune status was the multiple regression model developed to calculate ln[IgG] from ln[GGT] in healthy neonatal lambs using the serum GGT and IgG values of day 0, 1, 2, 4, 7, 14 and 28. The In[GGT] activity at 24 h after birth in lambs that died or became ill during the neonatal period accounted for approximately 77% and 88% of the variation in the ln[IgG] concentration at 24 h after birth, respectively. The study revealed that SGGTA-24 &amp;gt; 500 IU may be considered as a critical cut-off point for the adequate colostral passive transfer. This study also disclosed that the colostral GGT activity might be used as an indicator to determine the colostrum quality.

Case report: failure of passive transfer and neonatal infections in a cohort of lambs

This case report details an outbreak of neonatal lamb deaths, in which 84 of the 1203 potential lambs (from scanning) died and 70 developed septic polyarthritis. Investigation of the Scottish lowland flock of 650 breeding ewes revealed good lambing-time hygiene; poor ewe nutrition was suspected to have led to poor colostrum quality or quantity, resulting in failure of passive transfer of immunity in lambs. Ewe body condition at lambing was poor, with low blood urea nitrogen and albumin levels in pre-lambing ewe metabolic blood profiles.

Immunization against Kisspeptin-54 perturb hypothalamic–pituitary–testicular signaling pathway in ram lambs

Kisspeptin, a peptide product of KISS1 gene, recently identified as essential upstream gatekeeper in hypothalamic-pituitary-gonadal (HPG) axis. This study was designed to investigate the effect of immunization against kisspeptin-54 on hypothalamic-pituitary-testicular signaling pathway. A total of ten intact 56-days-old ram lambs were used and randomized into the treatment and control groups, which were, respectively immunized by kisspeptin-54 based vaccine and the empty plasmid via intramuscular route. We employed indirect enzyme-linked immunosorbent assay and quantitative real-time PCR to characterize the difference in serum kisspeptin, luteinizing hormone, testosterone hormone concentration and mRNA expression of reproductive-related genes in HPG axis across kisspeptin-54 immunized and control ram lambs. Serum kisspeptin, luteinizing hormone and testosterone concentration in the treatment group was lower (p < 0.05) than that of the control group. Compared with the control group, the mRNA expression of the hypothalamic androgen receptor (AR), KISS1, G protein-coupled receptor (GPR54) and gonadotropin-releasing hormone (GnRH) was altered in the immunized group (p < 0.05). Moreover, mRNA expression of pituitary luteinizing hormone beta (LHβ), follicle stimulating hormone beta (FSHβ), and GnRH receptor as well as, testicular LH receptor and FSH receptor, were remarkably lower (P < 0.05) in the treatment group. We concluded that immunization against kisspeptin-54 reduced serum kisspeptin levels thereby, the normal hypothalamic-pituitary–testicular signaling pathway disrupted. This data provides a great insight for the use of kisspeptin to regulate reproduction.

Immunization of Lambs Against Coccidiosis by Using Ultraviolet Irradiated Eimeria Oocysts for the First Time

The study was conducted to study the effect of Ultra-violet radiated Eimeria oocysts on immune pattern of lambs. For this purpose, Eimeria sp. (E. crandalis, E. granulosa, E. ovinoidalis, E. parva, E. pallida and E. faurei) were collected from infected sheep and propagated in a lamb for increasing the number of oocysts. The collected Eimeria sp. from the lamb, were sporulated in potassium dichromate 2.5% and divided into 3 parts; the 1st part was exposed to UV radiation for half hour and the 2nd part for one hour and the third left without irradiation. Nine lambs were classified into 3 equal groups; G1 was inoculated by half hour UV irradiated Eimeria oocysts, G2 was inoculated by one-hour UV irradiated Eimeria oocysts and G3 was inoculated by non-irradiated Eimeria oocysts. Fecal samples were collected from all lamb groups from 5th to 21th days, identified and count. Challenge by non-attenuated Eimeria was carried out at 21th day post inoculation. The obtained results revealed that immunization of lambs by using one-hour UV irradiated Eimeria oocysts showed low number of oocysts in feces before and after challenge compared to other groups. The same group also showed high level of γ globulin as well as increasing levels of IgG. It was recommended that immunization of lambs by one-hour UV irradiated Eimeria oocysts could protect lambs against Coccidiosis

Anaplasma phagocytophilum MSP4 and HSP70 Proteins Are Involved in Interactions with Host Cells during Pathogen Infection.

Anaplasma phagocytophilum transmembrane and surface proteins play a role during infection and multiplication in host neutrophils and tick vector cells. Recently, A. phagocytophilum Major surface protein 4 (MSP4) and Heat shock protein 70 (HSP70) were shown to be localized on the bacterial membrane, with a possible role during pathogen infection in ticks. In this study, we hypothesized that A. phagocytophilum MSP4 and HSP70 have similar functions in tick-pathogen and host-pathogen interactions. To address this hypothesis, herein we characterized the role of these bacterial proteins in interaction and infection of vertebrate host cells. The results showed that A. phagocytophilum MSP4 and HSP70 are involved in host-pathogen interactions, with a role for HSP70 during pathogen infection. The analysis of the potential protective capacity of MSP4 and MSP4-HSP70 antigens in immunized sheep showed that MSP4-HSP70 was only partially protective against pathogen infection. This limited protection may be associated with several factors, including the recognition of non-protective epitopes by IgG in immunized lambs. Nevertheless, these antigens may be combined with other candidate protective antigens for the development of vaccines for the control of human and animal granulocytic anaplasmosis. Focusing on the characterization of host protective immune mechanisms and protein-protein interactions at the host-pathogen interface may lead to the discovery and design of new effective protective antigens.

Lambs immunized with an inactivated variant of Anaplasma phagocytophilum.

BackgroundAnaplasma phagocytophilum (formerly Ehrlichia phagocytophila) is an obligate intracellular bacterium causing the disease tick-borne fever (TBF) in domestic ruminants. An effective vaccine against the infection has been demanded for livestock by sheep farmers and veterinary practitioners for years.FindingsIn the present study, we immunized lambs with an inactivated suspension of 1 × 108 killed A. phagocytophilum organisms mixed with adjuvant (Montanide ISA 61VG; Seppic). Twelve 9-months-old lambs of the Norwegian White Sheep breed were used. A full two-dose series of immunization was given subcutaneously to six lambs with a 4 week interval between injections. One month after the last immunization, all lambs were challenged with the homologous viable variant of A. phagocytophilum. After challenge, all lambs showed clinical responses for several days, although the immunized lambs reacted with an anamnestic response, i.e. significant reduction in infection rate and a significantly higher antibody titer.ConclusionImmunization with inactivated A. phagocytophilum did not protect lambs TBF.

Immunization of lambs with the S48 strain of Toxoplasma gondii reduces tissue cyst burden following oral challenge with a complete strain of the parasite

This study evaluates the influence of immunizing lambs with the incomplete S48 strain of Toxoplasma gondii, on parasite dissemination following a live oral challenge with a complete strain of T. gondii (M4). Lambs were culled at 14, 28 and 42 days post challenge. Parasite DNA was detected at significantly (p<0.0001) lower levels in samples from the vaccinated/challenged group (0% in heart and 5.9% in skeletal muscles), when compared to the non-vaccinated/challenged animals (75% heart, 87.9% skeletal muscle). S48 T. gondii DNA was found in muscle or lymph nodes until 42 days post infection, suggesting that parasite DNA or tachyzoites could persist longer after immunization than previously thought. Non-vaccinated/challenged animals showed more frequent lesions in muscles and central nervous system than the vaccinated animals.These results demonstrate that vaccination of lambs with the incomplete S48 T. gondii strain, can protect against establishment of tissue cysts following challenge with a complete strain of T. gondii. Consumption of undercooked meat containing T. gondii cysts is a major route of transmission to people, therefore vaccination of food animals may improve the safety of meat for human consumption.

Passive immunity in lambs: Serum lactoferrin concentrations as a predictor of IgG concentration and its relation to health status from birth to 12 weeks of life

This study was designed to evaluate the potential of lactoferrin (Lf) as predictor of passive immunity by establishing correlation between serum Lf and IgG concentration determined by ELISA in healthy lambs before and after colostrum intake at various days of neonatal period, to determine the presumptive effect of serum Lf along with serum IgG levels on lamb health through comparison of values measured for healthy and diseased lambs and to evaluate the impact of colostral Lf concentrations on passive immunity and lamb health. For this purpose, blood samples were obtained from the fifty healthy lambs at birth and 1, 2, 4, 7, 14 and 28 days after birth. Additionally first day blood samples were also collected from 286 lambs. Health status of all lambs (n=336) was monitored from birth to 12 weeks of life. Colostrum samples were obtained within 0–4h of parturition from 193 the ewes related to the lambs tested in this study. Serum Lf and IgG concentrations of day 1, 2, 4, 7, 14 and 28 were significantly higher than the values of pre-suckling time in healthy lambs. There was a weak linear relationship between serum Lf and IgG concentrations in only 1, 2, 4 and 7 day-old healthy lambs (R2=0.073–0.079) except for the first day (R2=0.213). The multiple linear regression model moderately (R2=0.375) estimated the serum IgG concentration as a function of the serum Lf concentration and of the age of lambs at the time of sampling [day 1, 2, 4, 7, 14 and 28] in healthy lambs during the neonatal period. The healthy lambs had significantly higher Lf concentration at 24th hour after the birth (SLfC-24) than ill lambs in the neonatal period (P<0.01) and the period covering 5–12 weeks of life (P<0.01). Similar results were found for SIgGC-24. The morbidity rate of lambs with SLfC-24 <800ng/mL was 3.2 times higher in neonatal period and 1.7 times higher in the period covering 5–12 weeks of life when compared with lambs having SLfC-24 above 800ng/mL. There was a significant (P<0.01) and positive (R=0.261) correlation between CIgGC and CLfC. In conclusion, our study revealed the importance of serum Lf in prevention of disease development in lambs and in prediction of passive immunity. In addition, the positive correlation between colostral Lf and IgG values may be of use in evaluation of colostrum quality.

A Single Vaccination with an Improved Nonspreading Rift Valley Fever Virus Vaccine Provides Sterile Immunity in Lambs

Rift Valley fever virus (RVFV) is an important pathogen that affects ruminants and humans. Recently we developed a vaccine based on nonspreading RVFV (NSR) and showed that a single vaccination with this vaccine protects lambs from viremia and clinical signs. However, low levels of viral RNA were detected in the blood of vaccinated lambs shortly after challenge infection. These low levels of virus, when present in a pregnant ewe, could potentially infect the highly susceptible fetus. We therefore aimed to further improve the efficacy of the NSR vaccine. Here we report the expression of Gn, the major immunogenic protein of the virus, from the NSR genome. The resulting NSR-Gn vaccine was shown to elicit superior CD8 and CD4-restricted memory responses and improved virus neutralization titers in mice. A dose titration study in lambs revealed that the highest vaccination dose of 106.3 TCID50/ml protected all lambs from clinical signs and viremia. The lambs developed neutralizing antibodies within three weeks after vaccination and no anamnestic responses were observed following challenge. The combined results suggest that sterile immunity was achieved by a single vaccination with the NSR-Gn vaccine.