Pangolin Immune System and Disease Resistance Biology

Published 19 June 2026 • AlphaPanga Research

Pangolins occupy a peculiar position in the study of mammalian immunology. They are intensely studied as potential reservoir hosts for zoonotic pathogens, yet fundamental aspects of their immune systems remain poorly characterised compared to domestic livestock or laboratory rodents. What researchers have established is that pangolins possess a number of unusual immunological features that distinguish them from most other placental mammals, and that these features have significant implications for both conservation medicine and wildlife disease surveillance.

For South African ground pangolins (Smutsia temminckii), the immune system must cope with an environment that includes not only the usual array of bacterial, viral, and parasitic challenges, but also the physiological stresses of periodic torpor-like states, soil exposure through burrowing, and contact with the bacteria-rich contents of termite mounds and ant colonies. Understanding how pangolins manage these challenges helps veterinarians treat confiscated animals and guides decisions about rehabilitation and release programmes run by organisations such as the Pangolin Conservation Support Group in South Africa.

The Innate Immune System in Pangolins

The innate immune system is the body's first line of defence — a rapid, non-specific response to molecular patterns associated with pathogens. In most mammals, this system includes toll-like receptors (TLRs), natural killer cells, complement proteins, and a suite of antimicrobial peptides. Pangolins possess all of these components, but genome sequencing studies have revealed that certain elements differ from what is seen in other mammals.

Interferon Pathway Anomalies

One of the most discussed features of the pangolin immune system is an apparent reduction in the diversity and activity of their type I interferon (IFN) genes. Interferons are signalling proteins that cells release when infected by a virus, alerting neighbouring cells to mount antiviral defences. Comparative genomic analyses published between 2020 and 2024 identified that pangolin genomes have a contracted interferon gene cluster relative to most other mammals, with fewer functional IFN-alpha genes than, for instance, pigs, bats, or humans.

The functional consequences of this contraction are not yet fully understood. It may mean that pangolins mount a slower initial antiviral response, which could theoretically allow certain viruses to establish chronic, asymptomatic infections — the kind of persistent, non-lethal relationship that characterises reservoir host dynamics. Alternatively, the pangolin may compensate through other innate pathways that have not yet been fully characterised. Current evidence does not permit a definitive conclusion, and researchers caution against over-interpreting genomic data in the absence of functional immunological experiments.

NLRP3 Inflammasome Variations

The NLRP3 inflammasome is a multiprotein complex that plays a central role in detecting cellular damage and triggering inflammation. It is particularly important in responding to bacterial infection, sterile tissue injury, and — notably — the kind of uric acid crystals and chitin fragments that might be encountered when processing large quantities of ant and termite material in the digestive system. Pangolin NLRP3 gene sequences differ from those of other mammals at several key residues, and some research groups have proposed that these differences may alter the activation threshold of the complex. What remains unclear is whether this represents a damping of inflammatory responses — which would reduce collateral tissue damage — or a fundamental reorientation of the pathway towards alternative effectors.

Adaptive Immunity: T Cells, B Cells, and Antibodies

The adaptive immune system, which generates antigen-specific responses and immunological memory, is less well-studied in pangolins than the innate arm. Blood samples from wild-caught and rehabilitated pangolins have been used to characterise their lymphocyte populations, but the relatively small number of animals available for study and the logistical difficulties of working with this species mean that published data are limited.

Antibody Responses

Serology — the detection of antibodies in blood — has been used to screen pangolins for exposure to various pathogens. Studies have detected antibodies against a range of viruses, bacteria, and parasites in both African and Asian pangolin species, indicating that the adaptive immune system is fully capable of generating humoral responses. However, the titres (concentrations) of antibodies detected in some studies have been lower than might be expected following similar exposures in other mammal species, which may reflect genuine differences in the magnitude of B-cell responses or simply the small sample sizes involved.

T Cell Populations

Flow cytometry of pangolin peripheral blood has identified CD4+ helper T cells and CD8+ cytotoxic T cells in proportions broadly similar to those seen in other mammals, suggesting that the fundamental organisation of adaptive cellular immunity is conserved. Major histocompatibility complex (MHC) gene diversity — which determines the range of pathogen-derived peptides that can be presented to T cells — has been assessed in a limited number of individuals and appears to be lower than in many other wild mammal populations, a finding consistent with the generally reduced genetic diversity observed in pangolin populations globally due to population bottlenecks.

Pangolins as Pathogen Hosts

The question of which pathogens pangolins carry, and whether any of these pose zoonotic risk, became a matter of intense public and scientific scrutiny from 2020 onwards. Several coronaviruses closely related to SARS-CoV-2 were identified in Malayan pangolins (Manis javanica) seized at customs checkpoints, leading to widespread media reporting. The scientific interpretation of these findings has been nuanced and is important to state accurately.

Pangolins have been confirmed to carry coronaviruses in the genus Betacoronavirus, and some of these share genomic regions with SARS-CoV-2 at high sequence identity. However, the current scientific consensus — based on subsequent phylogenetic analysis — is that pangolins are unlikely to be the direct progenitor host of SARS-CoV-2. The full evolutionary relationship remains an area of ongoing research. What is clear is that pangolins, like many wild mammals, do carry a diverse array of viruses, and that the illegal wildlife trade creates conditions — stress, crowding, close proximity to other species and to humans — that increase the probability of pathogen spillover.

Parasites and Bacterial Infections

Beyond viruses, pangolins host a range of internal and external parasites. Nematode worms of several genera have been recovered from the digestive tracts of wild African pangolins, and tick infestations are common, particularly around the base of the scales and on the unprotected ventral surface. Bacterial infections, including those caused by Salmonella spp. and various environmental bacteria encountered through burrowing, appear to be managed effectively in healthy wild animals but can become life-threatening in stressed, malnourished, or captive individuals.

South African rehabilitation centres report that animals rescued from snares frequently present with severe secondary bacterial infections, often at the site of wire-induced wounds, and that systemic infection is a leading cause of mortality in animals that survive the initial rescue but are too compromised to recover. This underscores the vulnerability of a system designed for the stable ecological context of wild bushveld, not the physiological chaos of capture and confinement.

Immune Function and Torpor

Ground pangolins in South Africa undergo periods of reduced activity during cold winter months, particularly in the drier parts of their range in the Karoo transition zone and the higher-altitude areas of Limpopo. Whether this constitutes true torpor or simply a reduction in foraging activity is debated; body temperature monitoring in fitted animals has shown temperature drops of several degrees during resting periods, which would be expected to slow metabolic processes including immune function.

The interaction between thermoregulation and immunity is relevant to understanding why pangolins appear susceptible to respiratory infections when held in captive environments that are either too cold or subject to temperature fluctuation. Several South African wildlife veterinarians have noted that newly admitted pangolins frequently develop pneumonia within days of admission to rehabilitation facilities, a pattern that may reflect both immunosuppression from capture stress and exposure to novel pathogens in a human-managed environment.

Mucosal Immunity and the Digestive System

Pangolins consume ants and termites in enormous quantities — adult ground pangolins may ingest tens of thousands of insects per night. The digestive system must therefore deal with large quantities of chitin (the structural polysaccharide of insect exoskeletons), formic acid from ants, and the diverse microbial communities inhabiting termite mounds. The mucosal immune system lining the gastrointestinal tract is critical for managing this challenge while tolerating the nutrient content of the prey.

The pangolin stomach is unique among mammals: it is highly muscular (analogous to a gizzard in birds), keratinised on its inner surface, and lacks a conventional mucosa in parts of its structure. How the immune surveillance of the gut is maintained in this unusual context — and whether the reduced surface area of conventional gastric mucosa affects systemic immune function — is not yet well understood and represents a significant gap in pangolin biology.

Implications for Captive Care and Rehabilitation

The immunological vulnerabilities of pangolins in captive settings have direct practical consequences for the rehabilitation programmes that are central to South Africa's pangolin conservation strategy. Current best practice, as described by the African Pangolin Working Group, emphasises minimising the time animals spend in captivity, reducing sources of acute stress, maintaining animals in conditions that approximate the thermal and dietary environment of the wild, and using prophylactic antiparasitic treatment with care to avoid disrupting gut microbial communities that may be important for immune homeostasis.

Veterinary protocols continue to evolve as more animals pass through rehabilitation and data accumulate on treatment outcomes. The limited published data on pangolin pharmacology means that drug dosing is often extrapolated from other species, and adverse reactions, while uncommon, are documented. Building an evidence base for pangolin immunology and clinical veterinary medicine is therefore a genuine conservation priority, not merely an academic one.

Conclusion

The pangolin immune system is neither simple nor fully understood. It bears the marks of an evolutionary history shaped by a highly specialised diet, periodic metabolic stress, and the constant pressure of pathogens encountered through burrowing and insect consumption. Its unusual features — the contracted interferon cluster, the modified inflammasome pathway, the limited MHC diversity — are not signs of immunological weakness but of evolutionary specialisation, refined over tens of millions of years.

What the science is clear about is this: stressed, captive, or trafficked pangolins face immunological challenges they are not equipped to manage. Keeping pangolins alive and in the wild, where their immune systems evolved to operate, remains the most effective conservation intervention available.