TY - JOUR
T1 - The non-invasive measurement of faecal immunoglobulin in African equids
AU - Tombak, Kaia J.
AU - Budischak, Sarah A.
AU - Hauck, Stephanie
AU - Martinez, Lindsay A.
AU - Rubenstein, Daniel I.
N1 - Funding Information:
This work was funded by the Walbridge Fund, the Mary and Randall Hack Foundation, the Princeton Institute for International and Regional Studies , and the National Science Foundation (IBN-0309233, CNS-025214, IOB-9874523, IIS-0705822, IIS-0747369). All research protocols used were approved by Princeton University's Institutional Animal Care and Use Committee. We thank the Kenya Wildlife Service, the National Commission for Science, Technology, and Innovation of Kenya, and Mpala Research Centre for permission to conduct this work and for logistical support. We would like to thank Rosemary Warungu, Margaret Mwangi, Josphat Mwangi, Martin Sisanya, Timothy Sisanya, and Anthony Mwangi for assistance in sample collection and field logistics. Thank you to Laurel Easterling, Monica Seng, Lily Reisinger, and especially Emily Nonnamaker for help in the field and in the laboratory. Thank you to Vanessa Ezenwa for sharing her McMaster salt flotation protocol modified for equids. Special thanks to Kathryn Watt for sharing protocols and advice on faecal immunoglobulin assays from her experience with Soay sheep samples, and to Andrea Graham and Tina Hansen for guidance and assistance in trouble-shooting the modified assay for equids.
Publisher Copyright:
© 2020 The Authors
PY - 2020/8
Y1 - 2020/8
N2 - Eco-immunological research is encumbered by a lack of basic research in a wild context and by the availability of few non-invasive tools to measure the internal state of wild animals. The recent development of an enzyme-linked immunosorbent assay for measuring immunoglobulins in faecal samples from Soay sheep prompted us to optimize such an assay to measure immunoglobulin A (IgA: an antibody associated with parasitic nematode fecundity) in faecal samples from equids. We measured total IgA in domestic donkeys, wild plains zebras, and wild Grevy's zebras sharing the same landscape in central Kenya over two field seasons. Attempts to measure anti-nematode IgA more specifically, using a homogenized extract from a mixture of excreted nematodes, failed to clear background. However, we found that total IgA positively correlated with strongyle nematode faecal egg counts (FECs) in donkeys sampled during the wetter field season - a time when the donkeys were in good condition. Further, this relationship appeared among donkeys with high body condition but not among those with low body condition. Time lags of 1–4 days introduced between IgA and FEC measurements in repeatedly sampled donkeys did not yield correlations, suggesting that IgA and FEC roughly tracked one another without much delay in the wet field season. Such a direct IgA-FEC relationship did not appear for zebras in either the wet or dry field season, possibly due to higher interindividual variation in body condition among the free-roaming zebras than in the donkeys. However, Grevy's zebras had higher overall levels of IgA than either plains zebras or donkeys, potentially associated with their reportedly lower FECs at the population level. Our results suggest that equids may mount an IgA response to nematode egg production when the host is in good condition and that equid species may differ in baseline levels of mucosal IgA.
AB - Eco-immunological research is encumbered by a lack of basic research in a wild context and by the availability of few non-invasive tools to measure the internal state of wild animals. The recent development of an enzyme-linked immunosorbent assay for measuring immunoglobulins in faecal samples from Soay sheep prompted us to optimize such an assay to measure immunoglobulin A (IgA: an antibody associated with parasitic nematode fecundity) in faecal samples from equids. We measured total IgA in domestic donkeys, wild plains zebras, and wild Grevy's zebras sharing the same landscape in central Kenya over two field seasons. Attempts to measure anti-nematode IgA more specifically, using a homogenized extract from a mixture of excreted nematodes, failed to clear background. However, we found that total IgA positively correlated with strongyle nematode faecal egg counts (FECs) in donkeys sampled during the wetter field season - a time when the donkeys were in good condition. Further, this relationship appeared among donkeys with high body condition but not among those with low body condition. Time lags of 1–4 days introduced between IgA and FEC measurements in repeatedly sampled donkeys did not yield correlations, suggesting that IgA and FEC roughly tracked one another without much delay in the wet field season. Such a direct IgA-FEC relationship did not appear for zebras in either the wet or dry field season, possibly due to higher interindividual variation in body condition among the free-roaming zebras than in the donkeys. However, Grevy's zebras had higher overall levels of IgA than either plains zebras or donkeys, potentially associated with their reportedly lower FECs at the population level. Our results suggest that equids may mount an IgA response to nematode egg production when the host is in good condition and that equid species may differ in baseline levels of mucosal IgA.
KW - Equid immunology
KW - Faecal egg count
KW - Faecal immunoglobulin A
KW - Host-parasite dynamics
KW - Non-invasive ecoimmunology
KW - Strongyle nematodes
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U2 - 10.1016/j.ijppaw.2020.05.005
DO - 10.1016/j.ijppaw.2020.05.005
M3 - Article
C2 - 32528845
AN - SCOPUS:85085745867
SN - 2213-2244
VL - 12
SP - 105
EP - 112
JO - International Journal for Parasitology: Parasites and Wildlife
JF - International Journal for Parasitology: Parasites and Wildlife
ER -