Weaning-time immune markers tracked with later vaccine antibody durability in pigs
A piglet’s immune profile at weaning may carry predictive value well beyond the nursery period. In a study of 381 Large White pigs, investigators linked immune and physiological traits measured at 28 days of age to later antibody outcomes after vaccination against Mycoplasma hyopneumoniae and Influenza A virus. The work focused not only on whether animals mounted an antibody response, but also on whether those responses persisted months later.
The central question was practical: can a snapshot taken at weaning identify animals more likely to sustain vaccine-induced humoral immunity? The answer from this preprint is cautious but compelling. Cross-validated classification accuracy landed in the moderate range, between 64.7% and 67.7%, which is not definitive enough for individual-level prediction in routine farm use, yet strong enough to suggest that early-life biology contains measurable information about later vaccine performance.
Two vaccine settings, one developmental window
The design covered two vaccination trials in the same overall cohort. One group received the Mycoplasma hyopneumoniae vaccine and the other received the Influenza A virus vaccine. All animals were vaccinated at weaning and received a booster 21 days later. Long-term antibody status was assessed at 118 days post-vaccination using assay-specific thresholds, while antibody persistence was defined by the decline from each pig’s peak response at 28 or 35 days post-vaccination to the 118-day time point.
That distinction matters because it separates simple seroconversion from the sturdiness of the response over time. In production settings, a response that peaks and fades quickly may offer less practical protection than one that remains stable long after the booster.
To search for predictors, the investigators examined a broad panel of immune and physiological traits measured at weaning. Variable selection relied on Sparse Partial Least Squares Discriminant Analysis, followed by Partial Least Squares Discriminant Analysis classification models. This approach allowed the analysis to identify the smallest set of traits that best separated animals with favorable versus unfavorable long-term antibody profiles.
Shared predictors pointed to baseline immunocompetence
Across both vaccines, eight predictors were shared for long-term antibody status and twelve were shared for antibody persistence. Several of the recurrent markers were hematologic or related to circulating protein fractions, which suggests that broad host physiology at weaning is intertwined with later vaccine behavior.
Higher hematocrit, IgG, platelet count, and plateletcrit were associated with positive long-term antibody status for both vaccines. Those same platelet-linked indices recurred in the persistence analysis, where higher vitamin D, α-1 globulin concentration, platelet count, and plateletcrit aligned with more persistent responses. In contrast, mean corpuscular hemoglobin concentration and neutrophil percentage were linked with negative long-term status, while mean corpuscular hemoglobin concentration and spectral absorbance traits were associated with non-persistence.
These patterns are biologically plausible even if they remain associative rather than causal. Hematocrit may reflect developmental or nutritional status, while IgG at weaning captures passive immune transfer and early immune readiness. Platelet count and plateletcrit may be acting as broader markers of systemic health or inflammatory tone rather than direct mediators of antibody production. Vitamin D and α-1 globulin also fit within a host-defense framework, since both have been tied to immune regulation in other settings, though this study does not establish mechanism.
A second, more concise point emerges from the data: not all useful predictors are classical immune assays. Some are routine physiological readouts that would already be available in a production environment if sampling at weaning were standardized.
Vaccine-specific signals still shaped the response
The shared markers did not erase vaccine-specific biology. The investigators found both general features of baseline immunocompetence and context-dependent determinants, implying that the same pig may show a favorable profile for one vaccine and a less favorable one for another. That is clinically relevant in livestock vaccination programs, where pathogen-specific antigen exposure, vaccine formulation, and host-microbiome interactions may all shape the final antibody pattern.
The persistence endpoint is especially important. A pig that reaches a strong early peak but loses antibody rapidly may not be equivalent, from a protective standpoint, to a pig whose response holds steady for months. By separating long-term status from persistence, the study captures two related but distinct dimensions of vaccine performance.
The moderate accuracy achieved by the models also keeps expectations grounded. These markers are not yet a replacement for conventional management or vaccination practice. They do, however, provide a candidate framework for stratifying animals by likely humoral trajectory, which could become useful in breeding, herd management, or future precision vaccination strategies if validated prospectively.
What the preprint adds, and what it does not
This preprint expands the idea of immunocompetence from a descriptive trait into a measurable predictor of later vaccine performance. The strongest message is not that one marker solves the problem, but that a combination of early-life immune and physiological features at weaning carries reproducible information about later antibody status and persistence.
The limitations are straightforward. The work is pre-peer review, the predictive performance remains moderate, and the findings are associative rather than mechanistic. The markers also need external validation before they can be treated as reliable tools for individual prediction in commercial herds. Even so, the study offers a concrete framework for linking early physiology to later vaccine outcomes in pigs, and it identifies a small set of recurring candidate markers that merit follow-up in independent cohorts.