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Molecular detection of equine infectious anemia virus in clinically normal, seronegative horses in an endemic area of Mexico.

Abstract: Equine infectious anemia (EIA) is a highly infectious disease in members of the family, caused by equine infectious anemia virus (EIAV). The disease severity ranges from subclinical to acute or chronic, and causes significant economic losses in the equine industry worldwide. Serologic tests for detection of EIAV infection have some concerns given the prolonged seroconversion time. Therefore, molecular methods are needed to improve surveillance programs for this disease. We attempted detection of EIAV in 6 clinical and 42 non-clinical horses in Nuevo Leon State, Mexico, using the agar gel immunodiffusion (AGID) test for antibody detection, and nested and hemi-nested PCR for detection of proviral DNA. We found that 6 of 6, 5 of 6, and 6 of 6 clinical horses were positive by AGID, nested PCR, and hemi-nested PCR, respectively, whereas 0 of 42, 1 of 42, and 9 of 42 non-clinical horses were positive by these tests, respectively. BLAST analysis of the 203-bp 5'-LTR/ segment of PCR product revealed 83-93% identity with EIAV isolates in GenBank and reference strains from other countries. By phylogenetic analysis, our Mexican samples were grouped in a different clade than other sequences reported worldwide, indicating that the LRT/ region represents an important target for the detection of non-clinical horses.
Publication Date: 2021-04-02 PubMed ID: 33797316PubMed Central: PMC8229844DOI: 10.1177/10406387211006195Google Scholar: Lookup
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  • Journal Article

Summary

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This research article details an investigation into the presence of equine infectious anemia virus (EIAV) in horses in Mexico, both with and without clinical symptoms. The study explores the effectiveness of serologic testing, and highlights the importance of molecular detection methods in identifying horses that may not show typical signs of infection, but could nonetheless contribute to the spread of the disease.

Study Overview

The study was undertaken by a group of researchers in Nuevo Leon State, Mexico, who aimed to improve the detection of EIAV in horses. Despite appearing healthy and testing negative through regular serologic tests, the horses were studied using molecular methods to determine if they were carriers of the virus.

Methodology

  • The study involved testing of 6 clinical (showing symptoms) and 42 non-clinical (not showing symptoms) horses.
  • Both groups were tested using the traditional serological method (AGID test – Agar gel immunodiffusion) to detect antibodies, as well as more advanced molecular methods to detect proviral DNA – namely nested and hemi-nested Polymerase Chain Reaction (PCR) tests.

Findings

  • While all six clinical horses showed signs of EIAV in their serological tests, nested PCR tests and hemi-nested PCR tests, none of the 42 non-clinical horses tested positive with the serological test, showcasing the limitations of traditional antibody testing.
  • The molecular methods, however, were successful in detecting EIAV in the non-clinical horses – 1 out of 42 for nested PCR, and 9 out of 42 for hemi-nested PCR – indicating the presence of the virus in horses without symptoms.
  • Further analysis of these positive results revealed that these strains shared 83-93% identity with EIAV isolates listed in GenBank and reference strains from other countries.
  • Phylogenetic analysis grouped the Mexican EIAV samples in a different clade than other strains reported worldwide, highlighting the unique nature of these infections.

Implications

  • The findings not only strengthen the argument for increased use of molecular methods in detecting EIAV, they also underscore the presence of the virus in non-clinical or asymptomatic horses in regions considered endemic for EIA which can contribute to the disease control and prevention strategies.
  • The identified 5′-LTR region also shows promise as a useful target for further investigations into detecting non-clinical carriers of EIAV.

Cite This Article

APA
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. (2021). Molecular detection of equine infectious anemia virus in clinically normal, seronegative horses in an endemic area of Mexico. J Vet Diagn Invest, 33(4), 758-761. https://doi.org/10.1177/10406387211006195

Publication

ISSN: 1943-4936
NlmUniqueID: 9011490
Country: United States
Language: English
Volume: 33
Issue: 4
Pages: 758-761

Researcher Affiliations

Romo-Sáenz, César I
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.
Tamez-Guerra, Patricia
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.
Olivas-Holguin, Aymee
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.
Ramos-Zayas, Yareellys
  • Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Nuevo León, Nuevo León, México.
Obregón-Macías, Nelson
  • Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Nuevo León, Nuevo León, México.
González-Ochoa, Guadalupe
  • Departamento de Ciencias Químico Biológicas y Agropecuarias, División de Ciencias e Ingeniería, Universidad de Sonora, Navojoa, Sonora, Mexico.
Zavala-Díaz de la Serna, Francisco J
  • Facultad de Ciencias Químicas, Laboratorio de Biotecnología, Universidad Autónoma de Chihuahua, Circuito Nuevo Campus Universitario, Chihuahua, Mexico.
Rodríguez-Padilla, Cristina
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.
Tamez-Guerra, Reyes
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.
Gomez-Flores, Ricardo
  • Departamento de Microbiología e Inmunología, Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Nuevo León, México.

MeSH Terms

  • Animals
  • Equine Infectious Anemia / diagnosis
  • Equine Infectious Anemia / epidemiology
  • Equine Infectious Anemia / virology
  • Female
  • Horses
  • Infectious Anemia Virus, Equine / isolation & purification
  • Male
  • Mexico / epidemiology
  • Phylogeny
  • Polymerase Chain Reaction / veterinary
  • Prevalence
  • Serologic Tests / veterinary

Conflict of Interest Statement

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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Citations

This article has been cited 2 times.
  1. Liang H, Zhou B, Hu Z, Chu X, Wang X, Du C, Wang X. Development of a Broad-Spectrum Antigen-Capture ELISA Using Combined Anti-p26 Polyclonal and Monoclonal Antibodies for Detection of Equine Infectious Anemia Virus. Microorganisms 2025 Jun 27;13(7).
  2. Li L, Li S, Ma H, Akhtar MF, Tan Y, Wang T, Liu W, Khan A, Khan MZ, Wang C. An Overview of Infectious and Non-Infectious Causes of Pregnancy Losses in Equine. Animals (Basel) 2024 Jul 2;14(13).
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