Evolution of equine infectious anaemia in naturally infected mules with different serological reactivity patterns prior and after immune suppression.
Abstract: Information on equine infectious anaemia (EIA) in mules, including those with an equivocal reaction in agar gel immunodiffusion test (AGIDT), is scarce. For this, a study was conducted to evaluate the clinical, viral loads and pathological findings of two groups of naturally infected asymptomatic mules, respectively with a negative/equivocal and positive AGIDT reactivity, which were subjected to pharmacological immune suppression (IS). A non-infected control was included in the study that remained negative during the observation period. Throughout the whole study, even repeated episodes of recrudescence of EIA were observed in 9 infected mules, independently from their AGIDT reactivity. These events were generally characterised by mild, transient alterations, typical of the EIA acute form represented by hyperthermia and thrombocytopenia, in concomitance with viral RNA (vRNA) peaks that were higher in the Post-IS period, reaching values similar to those of horses during the clinical acute phase of EIA. Total tissue viral nucleic acid loads were greatest in animals with the major vRNA activity and in particular in those with negative/equivocal AGIDT reactivity. vRNA replication levels were around 10-1000 times lower than those reported in horses, with the animals still presenting typical alterations of EIA reactivation. Macroscopic lesions were absent in all the infected animals while histological alterations were characterised by lymphomonocyte infiltrates and moderate hemosiderosis in the cytoplasm of macrophages. On the basis of the above results, even mules with an equivocal/negative AGIDT reaction may act as EIAV reservoirs. Moreover, such animals could escape detection due to the low AGIDT sensitivity and therefore contribute to the maintenance and spread of the infection.
Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.
Publication Date: 2016-04-06 PubMed ID: 27259822DOI: 10.1016/j.vetmic.2016.04.003Google Scholar: Lookup
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- Journal Article
Summary
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This research studied the development of equine infectious anaemia (EIA) in mules, revealing that even those with initially unclear or negative test results may act as reservoirs for the infection, potentially contributing to its spread due to low detection sensitivity.
Overview of the Study
- The researchers studied equine infectious anaemia (EIA) in mules, specifically those with an equivocal (uncertain) reaction in an agar gel immunodiffusion test (AGIDT), an antibody detection test.
- Two groups of naturally infected, asymptomatic mules were evaluated: one with negative/equivocal AGIDT reactivity, and another with positive AGIDT reactivity.
- The mules were subjected to pharmacological immune suppression (IS), and a non-infected control group was included for comparison.
Observations and Findings
- In both groups of mules, researchers observed recurring episodes of EIA recurrence, characterised by mild, temporary alterations such as hyperthermia (high body temperature) and thrombocytopenia (low platelet count).
- These episodes coincided with peaks in viral RNA (vRNA) – a marker of virus replication – especially after immune suppression.
- The highest total tissue viral nucleic acid loads were found in animals with the most vRNA activity, particularly those with negative/equivocal AGIDT reactivity.
- The levels of vRNA replication were lower than those reported in horses, but the animals still showed typical signs of EIA recurrence.
- No visible (macroscopic) damage was found, but microscopic changes included infiltration of lymphomonocytes (a type of white blood cells) and moderate hemosiderosis (iron overload) in the macrophages’ cytoplasm.
Implications of the Study
- The findings suggest that even mules with unclear or negative AGIDT results can act as reservoirs for EIA.
- These animals could potentially escape detection due to the low sensitivity of the AGIDT, hence contributing to the maintenance and spread of the infection.
Cite This Article
APA
(2016).
Evolution of equine infectious anaemia in naturally infected mules with different serological reactivity patterns prior and after immune suppression.
Vet Microbiol, 189, 15-23.
https://doi.org/10.1016/j.vetmic.2016.04.003 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Antibodies, Viral / metabolism
- Antigens, Viral / metabolism
- Equidae
- Equine Infectious Anemia / immunology
- Equine Infectious Anemia / physiopathology
- Equine Infectious Anemia / transmission
- Horses
- Immunosuppression Therapy / veterinary
- Infectious Anemia Virus, Equine / immunology
- Macrophages / virology
- RNA, Viral / genetics
- Virus Replication
Grant Funding
- 001 / World Health Organization
Citations
This article has been cited 3 times.- Hu Z, Guo K, Du C, Sun J, Naletoski I, Chu X, Lin Y, Wang X, Barrandeguy M, Samuel M, Wang W, Lau PI, Wernery U, Raghavan R, Wang X. Development and evaluation of a blocking ELISA for serological diagnosis of equine infectious anemia.. Appl Microbiol Biotechnol 2023 May;107(10):3305-3317.
- Romo-Sáenz CI, Tamez-Guerra P, Olivas-Holguin A, Ramos-Zayas Y, Obregón-Macías N, González-Ochoa G, Zavala-Díaz de la Serna FJ, Rodríguez-Padilla C, Tamez-Guerra R, Gomez-Flores R. Molecular detection of equine infectious anemia virus in clinically normal, seronegative horses in an endemic area of Mexico.. J Vet Diagn Invest 2021 Jul;33(4):758-761.
- Malossi CD, Fioratti EG, Cardoso JF, Magro AJ, Kroon EG, Aguiar DM, Borges AMCM, Nogueira MF, Ullmann LS, Araujo JP Jr. High Genomic Variability in Equine Infectious Anemia Virus Obtained from Naturally Infected Horses in Pantanal, Brazil: An Endemic Region Case.. Viruses 2020 Feb 12;12(2).
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