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Failure of passive transfer of immunity (FPT) leads to increased calf morbidity and mortality and requires intensive, time-sensitive, and often expensive management for nondomestic ruminants. Without species-specific information with which to make informed decisions, neonatal data from domestic ruminants are often extrapolated to nondomestic zoo-housed species. To date, there have been no studies evaluating FPT in sitatunga (Tragelaphus spekii). The goal of the present study was to establish parameters to characterize adequate passive transfer in sitatunga calves and compare them to published reference intervals in other species. Medical records of 22 sitatunga calves (12 female, 10 male) were reviewed. Seventeen of these calves were defined as “healthy,” having survived at least 60 days without colostrum administration or a plasma transfusion. Calf weight, serum glucose, serum gamma-glutamyl transferase (GGT), total protein (TP), globulin concentrations, and results of a zinc sulfate turbidity test (ZSTT) were noted where possible. Mean birth weight of healthy calves at 24 hr was 4.5 kg (range: 3.76.5 kg, n = 12). The mean blood glucose in healthy calves was 152 mg/dl (range: 80–182, n = 16), mean serum TP concentration was 5.9 g/dl (range: 4.9–7.5, n = 16), mean serum globulin concentration was 3.3 g/dl (range: 1.7–4.7, n = 17), and mean serum GGT concentration was 466 U/L (range: 91–1901, n = 16). A ZSTT was performed for 10 healthy calves, resulting in four negative ZSTT results despite having no clinical signs of FPT and the calves having been observed nursing before testing. Sitatunga appear to have lower values for normal FPT parameters than those developed for domestic cattle. This study illustrates the difficulty of cross-species comparisons, as even closely related species can vary greatly in biologic parameters.

Most animal studies using passive administration of HIV broadly neutralizing monoclonal antibodies (bnMAbs) have associated protection against high-dose mucosal viral challenge with relatively high serum concentrations of antibody. We recently identified several bnMAbs remarkable for their in vitro potency against HIV. Of these bnMAbs, PGT121 is one of the most broad and potent antibodies isolated to date and shows 10- to 100-fold higher neutralizing activity than previously characterized bnMAbs. To evaluate the protective potency of PGT121 in vivo, we performed a protection study in rhesus macaques. Animals were i.v. administered 5 mg/kg, 1 mg/kg, or 0.2 mg/kg PGT121 24 h before being vaginally challenged with a single high dose of chimeric simian-human immunodeficiency virus (SHIV) SF₁₆₂P₃. Sterilizing immunity was achieved in all animals administered 5 mg/kg and 1 mg/kg and three of five animals administered 0.2 mg/kg PGT121, with corresponding average antibody serum concentrations of 95 µg/mL, 15 µg/mL, and 1.8 µg/mL, respectively. The results suggest that a protective serum concentration for PGT121 is in the single-digit µg/mL for SHIV SF₁₆₂P₃, showing that PGT121 can mediate sterilizing immunity at serum concentrations that are significantly lower than those observed in previous studies and that may be achievable through vaccination with the development of a suitable immunogen.

Abstract Background Colostral immunoglobulin G (IgG) concentration is critical to the attainment of adequate transfer of passive immunity in cattle, however, studies comparing available tools for measurement of colostral IgG concentration in beef cattle are limited. Objectives To report the agreement between 3 commercially available tests for evaluating IgG concentration in beef colostrum. Animals Two hundred six beef-breed cows hospitalized for calving management or dystocia. Methods Retrospective study to assess IgG of whole colostrum measured stall-side via turbidimetric immunoassay (TI) and brix refractometry (BRIX), compared to fat separated (FS) analysis via single radial-immunodiffusion (RID; reference standard), TI-FS and BRIX-FS. Test performance was assessed using Passing Bablock regression, Bland-Altman analysis, and area under the curve to determine optimal thresholds. Results Correlation between RID and TI-FS, BRIX-FS, or BRIX was similar (Spearman's ρ = 0.717, 0.715, 0.716, respectively) but correlation for TI was poor (ρ = 0.586). Regression analysis identified a substantial constant (−214.75 [CI: −272.03 to −178.07]) and proportional (13.24 [CI: 11.81-15.37]) bias between the RID and TI-FS which was similar for TI. TI-FS concentrations of 28.47, 38.75, and 50.62 g/L, BRIX-FS of ≤21.9%, ≤24.0%, and ≤27.4%, and BRIX of ≤21.3%, ≤23.8%, and ≤26.4% indicated IgG concentrations <50, <100, and <150 g/L, respectively; appropriate cutoffs for TI could not be generated. Conclusions and Clinical Importance Both TI and TI-FS demonstrated a large constant and proportional bias compared to RID; BRIX and BRIX-FS were well correlated with RID and remain a reliable method for estimation of colostral IgG concentration in beef cattle.

Failure of passive transfer of immunity (FPT) in dairy replacement calves has been linked to increased neonatal morbidity and mortality and long-term decreases in productivity. The purpose of this study was to estimate the prevalence of FPT in US dairy heifer calves in 2007 and to use nationally representative data to investigate associations of FPT with colostrum and calf management practices. A cross-sectional study was conducted by the USDA's National Animal Health Monitoring System between January and August 2007. Producers from 394 operations in 17 states completed survey questions about colostrum and calf management practices, and serum samples were collected from 1,816 healthy heifer calves on those operations. Serum immunoglobulin G (IgG) levels were determined by radial immunodiffusion, and calves were classified as having FPT if the IgG concentration was less than 10mg/mL. To investigate associations between FPT and management practices, a multivariable analysis was completed using a weighted logistic regression model. The estimated prevalence of FPT in US dairy heifer calves was 19.2%. The odds of FPT were higher for calves on operations that pooled colostrum [odds ratio (OR = 2.2)], allowed nursing (OR = 2.4), or hand fed colostrum more than 4h after birth (OR = 2.7). The odds of FPT were also higher for calves on operations that did not provide a source of heat during cold weather for calves experiencing a dystocia (OR = 1.6), would not seek veterinary assistance when unable to correctly position a calf for delivery (OR = 2.6), or did not routinely monitor serum proteins in calves as a measure of passive transfer (OR = 13.8). The prevalence of FPT in dairy heifer calves has decreased in the last 15 yr, so progress has been made in this important area of calf management. This study identified several management practices associated with FPT that could be targeted for educational campaigns or further research.

We studied the effect on average daily gain (ADG) and health of an additional colostrum feeding to Holstein dairy heifers 12–16 h after the first colostrum feeding, provided within 2 h of birth. Calves (n = 190) with an average birth weight of 38.8 kg (29.5–52.6 kg) were randomly enrolled in blocks to either the control (CON) or colostrum (COL). The CON received 3 L of acidified pasteurized whole milk, and the COL received 3 L of pasteurized colostrum [average: 25.5 (24.7–26.4)% Brix]. Calves were group-housed, weighed, withers height measured weekly. Serum was obtained and analyzed with a% Brix refractometer. Mixed linear models were used to assess the differences in ADG, body weight, and height between the treatment and control. There was no difference in ADG between the COL and CON. However, serum % Brix was higher in the COL group (9.7%) than in the CON group (9.2%). Calves in the COL had more antibiotic treatments for respiratory diseases but fewer antibiotic treatments for otitis than the CON. In conclusion, providing an extra feeding of colostrum did not contribute to ADG of Holstein heifers during the pre-weaning period but did provide them with a higher total serum protein concentration.

Abstract Background Attainment of adequate transfer of passive immunity (TPI) is critical to health of calves; however, studies comparing available tools for measurement of TPI in individual beef animals are limited. Objectives To report agreement between 4 tests evaluating individual TPI status in beef calves. Animals One hundred ninety-six beef calves born to cows and heifers presenting for calving management or dystocia. Methods Retrospective study to assess serum immunoglobulin (IgG) concentrations via turbidimetric immunoassay (TI), gamma-glutamyl transferase (GGT), serum total protein (TP), and single radial immunodiffusion (RID; reference standard). Test agreement was evaluated using Passing-Bablok regression, Bland-Altman analysis, Cohen's kappa, and receiver operating characteristic (ROC) curves with and without covariate adjustment to determine optimal thresholds. Results Correlation between RID and test results varied: TI, ρ = 0.757; TP, ρ = 0.715; GGT: ρ = 0.413. For the TI compared to RID, regression analysis identified a constant (intercept = −0.51 [CI: −2.63, 3.05]) and proportional (slope = 1.87 [CI: 1.69, 2.08]) bias. Based on ROC, TI concentrations of ≤9.89 and ≤13.76 g/L, and TP concentrations of ≤5.5 and ≤6.0 g/dL, indicated IgG concentrations <18.0 and <25.0 g/L, respectively. Conclusions and Clinical Importance Within this cohort of calves, TI demonstrated the best correlation with RID; however, significant bias was identified which led to frequent underestimation of IgG concentration. Serum total protein demonstrated less correlation with RID but had less misclassification than TI. Both TI and TP demonstrated less correlation for calves that received colostrum replacement prompting clinical awareness of colostrum type when evaluating individual TPI in beef calves.

The passive transfer model of myasthenia gravis (PTMG) reflects the effector phase of the human condition and is induced in female rats using monoclonal antibodies. The current guideline recommends administration of monoclonal antibodies (mAb) such as mAb35 via intraperitoneal (I.P.) or intravenous (I.V.) injection, offering rapid absorption, but posing challenges such as injection placement and, in the case of I.P., animal discomfort. In this study, we investigated the suitability of subcutaneous (S.C.) administration as an alternative to I.P. in the rat PTMG model. Female rats were injected with 20 pmol mAb35 /100 g body weight (BW), either I.P. or S.C. and euthanized 48 h post-immunization, or S.C. with 20 or 40 pmol mAb35 /100 g BW and euthanized 48- or 72-hours post-immunization. Control animals received 0.5 mg/kg IgG1 isotype control S.C. or I.P. Muscle weakness, weight loss and clinical manifestations were assessed daily. Additionally, decrement-inducing curare dose and AChR content in the tibialis anterior (TA) were determined using electromyography and radioimmunoassay (RIA) respectively. S.C. mAb35 administration induced body weight loss and MG symptoms comparable to I.P. administration. However, I.P. injection presented a risk of misplacement, making it potentially a less reliable administration method. While MG characteristics were observed regardless of mAb35 dose and route, variability of clinical parameters and TA AChR content differed between approaches. S.C. induction of disease was verified using a different batch of mAb35 with a dose of 40 pmol/100 g BW S.C administered. We demonstrated that S.C. injection offers a consistent induction of PTMG, establishing it as a refined, effective alternative to I.P. administration by reducing procedural invasiveness and improving consistency in symptom onset.

The adequate transfer of passive immunity is a critical factor in neonatal development and survivability. Although well documented in the dairy and equine industries, the recognition of inadequate immunoglobulin transfer on-farm and its impact on the ability of alpaca cria to thrive is largely unknown. Colostrum samples were collected from female alpaca within 24 h of parturition by the owners and whole blood collected from cria by the investigators between 1 and 7 days of age. Direct IgG concentration of milk and serum was determined using radial immunodiffusion assay (RID) and was indirectly estimated using optical and digital Brix refractometry for total solids and clinical refractometry for total serum protein. There was a strong correlation between optical and digital Brix refractometry, and colostral IgG concentration determined by RID. There was a moderate correlation between serum IgG concentration determined by RID and total serum protein in crias. Optical and digital Brix refractometry for colostral IgG estimation and total serum protein for serum IgG estimation are reliable, accurate and easy-to-use tools that can be used on-farm by trained, competent technicians to assess a failure of passive transfer in alpacas. A pilot study at one property only was performed, due to COVID-19 travel restriction interference. Further research is required to determine the reference intervals for these tools to be practical.

[This corrects the article DOI: 10.3389/fnmol.2023.1254854.].

•Experiments were undertaken to investigate protection of young lambs against Taenia ovis infection.•Three different, protective, recombinant antigens from T. ovis were used.•Lambs born from vaccinated dams were protected by maternal antibody.•Specific colostrum-derived antibody inhibited active immunization of lambs using the same antigen.•Lambs were fully protected after vaccination of dams and lambs with different antigens. 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.